Selective Functionalization of Antimycin A Through an N- Transacylation Reaction. Arnaud Chevalier, Yanmin Zhang, Omar M. Khdour and Sidney M.

Transcription

1 Supporting Information Selective Functionalization of Antimycin A Through an - Transacylation Reaction for Arnaud Chevalier, Yanmin Zhang, mar M. Khdour and Sidney M. echt 1

2 Figure S1. Chemical structures of naturally occurring congeners of antimycin A. 2

3 The following abbreviations are used throughout the text of the SI file: AMA, Antimycin A; APCI, Atmospheric pressure chemical ionization; Boc, tert-butyloxycarbonyl; BP, benzotriazol-1-yloxytris(dimethylamino)phosphonium hexafluorophosphate; CBz, Benzyloxy carbonyl; DIEA,,-diisopropylethylamine; DMF,,-dimethylformamide; Fmoc, 9- fluorenylmethyloxycarbonyl; BTU, -benzotriazole-,,','-tetramethyluronium hexafluorophosphate; RMS, high resolution mass spectrometry; PyBP, benzotriazol-1-yloxytripyrrolidinophosphonium hexafluorophosphate; tbu, tert-butyl; TFA, trifluoroacetic acid. General Methods All experiments requiring anhydrous conditions were conducted in flame-dried glassware fitted with a rubber septum under a positive pressure of dry argon. Reactions were performed at room temperature unless otherwise indicated. Analytical thin layer chromatography was performed using glass plates pre-coated with silica gel (0.25 mm, 60 Å pore size, mesh, Silicycle) impregnated with a fluorescent indicator (254 nm). TLC plates were visualized by exposure to ultraviolet light (UV) or by staining using I 2. Flash column chromatography was performed employing silica gel (60 Å pore size, µm, standard grade, Silicycle). 1 MR and 13 C MR spectra were recorded on Varian IVA 400 (400 Mz) and Varian IVA 500 (500 Mz) spectrometers at 25 C. Proton chemical shifts are expressed in parts per million (ppm, δ scale) and are referenced to residual protium in the MR solvent (CDCl 3, DMS-d 6 or CD 3 D). Splitting patterns are designated as follows: s, singlet; br s, broad singlet; br t, broad triplet; d, doublet; dd, doublet of doublets; t, triplet; q, quartet; qt, quintuplet; sx, sextuplet; m, multiplet. igh resolution mass spectra were obtained at the Arizona State University CLAS igh Resolution Mass Spectrometry Facility. The chemicals used for synthesis were purchased from Aldrich Chemical Co., Sigma Chemical Co., Alfa Aesar, Fisher Scientific, 3

4 akwood Chemicals, Combi-Blocks and TCI. TF was distilled under argon using sodiumbenzophenone ketyl and C 2 Cl 2 was distilled under argon using calcium hydride. Experimental Procedures 3-Formamido-2-hydroxybenzoic Acid (2a). The compound was prepared following the procedure reported by Rahn et al. 1 To a solution of 2.97 g (16.2 mmol) of 3-nitrosalicylic acid in 100 ml of TF was added 450 mg of palladium on carbon and the resulting suspension was maintained under 25 psi of hydrogen and shaken for 3 h. The catalyst was removed by filtration through a Celite pad and the filtrate was concentrated to dryness. The resulting dark gray-green solid (2.25g, 91%) was used directly for the next step. Following the procedure reported by Pettit et al., g (14.7 mmol) of the crude 3-amino-2- hydroxybenzoic acid was suspended in 30 ml of formamide and heated at 150 C for 30 min under an argon atmosphere. The cooled reaction mixture was diluted in 250 ml of satd aq ac 3 and neutralized by adding 1 M aq KS 4. After the aqueous solution had reached an acidic p, 100 ml of EtAc was added and the phases were separated. The aqueous phase was extracted with four 100-mL portions of EtAc. The combined organic layer was dried over MgS 4 and concentrated to dryness, affording compound 2a as a brown powder: yield 2.47 g (97%). The MR spectra were found to be in accordance with the data presented in a previous report. 2 4

5 -Butyl-3-formamido-2-hydroxybenzamide (2b). Compound 2a (1.00 g; 5.50 mmol) and 2.65 g (6.00 mmol) of BP reagent were dissolved in 30 ml of dry DMF and cooled to 0 C. Propylamine (2.80 ml; 27.5 mmol) was then added and the resulting reaction mixture was stirred under argon overnight. After the reaction was complete, the reactiomn mixture was diluted with 150 ml of EtAc and washed with 100 ml of a sat. aq solution of 4 Cl followed by two 100-mL portions of brine. The organic layer was then dried over MgS 4 and concentrated to dryness. The crude product was purified on a silica gel column (20 4 cm); elution was with 9:1 to 8:2 hexanes EtAc. The first fraction was recovered and kept for reformylation treatment. The second fraction contained the desired compound which was recrystallized from hexane-et 2 to furnish 2b as a beige powder: yield 623 mg (48%). The first fraction containing deformylated compound 2c was concentrated, and re-formylated following the procedure presented previously using formamide at 150 C under argon atmosphere. The residue from this reaction was recrystallized from hexane-et 2 to furnish a second batch of compound 2b: yield 550 mg (44%); mp 96 C; 1 MR (CDCl 3 ) δ 0.93 (t, 3, J = 7.4 z), 1.39 (sx, 2), 1.59 (qt, 2, J = 7.4 z), 3.43 (q, 2, J = 7.4 z), 6.67 (br s, 1), 6.81 (t, 1, J = 8.1 z), 7.16 (d, 1, J = 8.0 z), 8.04 (br s, 1), 8.45 (m, 2) and (s, 1); 13 C MR (CDCl 3 ) δ 13.9, 20.2, 31.5, 39.7, 113.7, 118.5, 120.1, 124.1, 127.3, 150.8, and 169.9; mass spectrum (APCI), m/z (M+) + (C requires m/z ). 5

6 2-Benzyloxy--butyl-3-formamidobenzamide (2d). A mixture of 108 mg (0.46 mmol) of compound 2b and 253 mg (1.83 mmol) of K 2 C 3 in 2 ml of dry acetonitrile was stirred under argon for 10 min. Benzyl bromide (113 µl; 0.98 mmol) was added and the resulting reaction mixture was stirred under argon for 8 h. After the reaction was complete (monitoring by TLC using 2:1 hexanes EtAc), the reaction mixture was filtered through a cotton plug, concentrated to dryness and applied to a silica gel column (8 3cm). Elution with 8:2 to 1:1 hexane EtAc gave the desired product 2d as a yellowish wax: yield 125 mg (84%); silica gel TLC R f 0.30 (1:1 hexanes EtAc); 1 MR (CDCl 3 ) (major rotamer) δ 0.87 (t, 3, J = 7.4 z), 1.30 (sx, 2), 1.43 (qt, 2, J = 7.4 z), 3.36 (q, 2, J = 7.4 z), 4.92 (s, 2), 7.17 (m, 2), (m, 3), 7.67 (d, 1, J = 8.0 z), 7.75 (br s, 1), 8.04 (br s, 1), 7.78 (m, 1), 8.23 (s, 1) and 8.35 (d, 1, J = 8.0 z); 13 C MR (CDCl 3 ) The rotamer mixture precluded confident attribution of each signal (cf actual spectrum); mass spectrum (APCI), m/z (M+) + (C requires m/z ). R BTU, DIEA DCM,rt,15h 0.2Mconc R 6

7 General procedure for the transacylation reaction. A solution containing 30.0 mg (0.13 mmol) of compound 2b, 58.0 mg (0.15 mmol) of BTU and 0.15 mmol of the corresponding carboxylic acid in 650 µl of freshly distilled C 2 Cl 2 was added 66.3 µl (0.38 mmol) of DIEA. The reaction was maintained under argon and stirred for 15 h. After the reaction was complete (monitoring by silica gel TLC using 2:1 hexanes EtAc), the reaction mixture was diluted with 25 ml of EtAc and washed with 20 ml of satd aq 4 Cl and then 20 ml of brine. The organic layer was dried over MgS 4 and concentrated to dryness under diminished pressure. The crude product was purified by chromatography on a silica gel column (7 2 cm). -Butyl-3-hexanamido-2-hydroxybenzamide (1c). The compound was prepared using 17.6 mg (0.15 mmol) of hexanoic acid. The crude product was purified by chromatography on a silica gel column (7 2 cm). Elution with 9:1 hexanes EtAc gave the desired product 1c as a colorless wax: yield 35.4 mg (91%); silica gel TLC R f 0.3 (2:1 hexanes EtAc); 1 MR (CDCl 3 ) δ 0.89 (t, 3, J = 7.0 z), 0.95 (t, 3, J = 7.4 z) (m, 6), 1.60 (qt, 2, J = 7.4 z), 1.73 (qt, 2, J = 7.5 z) 2.40 (t, 2, J = 7.4 z), 3.43 (q, 2, J = 7.4 z), 6.70 (br s, 1), 6.78 (t, 1, J = 8.1 z), 7.11 (dd, 1, J = 8.0 and 0.7 z), 7.92 (s, 1), 8.45 (d, 1, 8.0z) and (s, 1); 13 C MR (CDCl 3 ) δ 13.9, 14.1, 20.2, 22.5, 25.4, 31.5, 31.6, 38.1, 39.6, 113.5, 118.6, 119.3, 123.3, 128.4, 150.6, and 171.9; RMS (APCI), m/z (M+) + (C requires m/z ). 7

8 -butyl-3-(-formylhexanamido)-2-hydroxybenzamide (3a): Depending on the conditions used for the previous reaction (Cf Table 1 in the article) the compound 3a can be isolated as a side product. silica gel TLC R f 0.25 (2:1 hexanes EtAc). 1 MR (CDCl 3 ) δ 0.84 (t, 3, J = 7.0 z), 0.96 (t, 3, J = 7.4 z) 1.23 (m, 4), 1.39 (sx, 2, J = 7.4 z), (m, 4) 2.40 (brt, 2), 3.39 (brs, 2), 6.70 (t, 1, J = 5.1 z), 6.80 (t, 1, J = 8.1 z), 7.16 (dd, 1, J = 0.7 z, J = 8.0 z), 7.35 (d, 1, 8.0z), 9.59 (s, 1) and (s, 1); 13 C MR (CDCl 3 ) δ 13.9, 14.0, 20.2, 22.5, 23.7, 31.1, 31.4, 35.3, 39.8, 116.1, 118.6, 124.2, 126.9, 134.0, 157.5, 162.9, and 175.9; RMS (APCI), m/z (M+) + (C requires m/z ). 2-(Benzyloxy)--butyl-3-(-formylhexanamido)benzamide (3b): The compound was prepared using 50.0 mg (0.15 mmol) of compound 2d, 19.5 (0.17 mmol) of hexanoic acid and 63.7 mg (0.17 mmol) of BTU. The crude product was purified by chromatography on a silica gel column (7 2 cm). Elution with 8:2 to 2:1 hexanes EtAc gave the desired product 3b as a colorless wax: yield 47 mg (72%); silica gel TLC R f 0.5 (2:1 hexanes EtAc); 1 MR (CDCl 3 ) δ (m, 6, J = 7.0 z), (m, 6), 1.36 (qt, 2, J = 7.4 z), 1.62 (br s, 2), 8

9 2.25 (br s, 2), 3.30 (br s, 2, J = 7.4 z), 4.85 (br s, 2), 6.70 (br s, 1), (m, 3), (m, 4), 8.19 (dd, 1, J = 7.9 and 0.7 z) and 9.56 (s, 1); 13 C MR (CDCl 3 ) δ 13.8, 13.9, 20.3, 22.4, 23.8, 31.1, 31.4, 35.5, 39.8, 81.7, 125.8, 128.2, 129.0, 129.1, 129.2, 129.4, 133.1, 133.2, 135.3, 153.0, 162.8, and 175.6; mass spectrum (APCI), m/z (M+) + (C requires m/z ). 3-Acetamido--butyl-2-hydroxybenzamide (4a). The compound was prepared using 9.10 mg (0.15 mmol) of acetic acid. The crude product was purified by chromatography on a silica gel column (7 2 cm). Elution with 85:15 hexanes EtAc gave the desired product 4a as a colorless solid: yield 29.8 mg (94%); mp 114 C; silica gel TLC R f 0.30 (2:1 hexanes EtAc); 1 MR (CDCl 3 ) δ 0.94 (t, 3, J = 7.4 z) 1.42 (sx, 2, J = 7.4 z), 1.61 (qt, 2, J = 7.4 z), 2.22 (s, 3), 3.44 (q, 2, J = 7.4 z), 6.61 (br s, 1), 6.80 (t, 1, J = 8.0 z), 7.10 (dd, 1, J = 8.0 and 0.8 z), 7.92 (s, 1), 8.45 (d, 1, J = 8.0z) and 13.2 (s, 1); 13 C MR (CDCl 3 ) δ 13.8, 22.2, 25.0, 31.6, 39.6, 113.6, 118.5, 119.4, 123.4, 128.3, 150.6, and 170.1; mass spectrum (APCI), m/z (M+) + (C requires m/z ). 9

10 -Butyl-2-hydroxy-3-(6-phenylhexanamido)benzamide (4b). The compound was prepared using 29.2 mg (0.15 mmol) of 6-phenylhexanoic acid. The crude product was purified by chromatography on a silica gel column (7 2 cm). Elution with 85:15 hexanes EtAc gave the desired product 4b as a colorless wax: yield 48.2 mg (99%); silica gel TLC R f 0.2 (4:1 hexanes EtAc); 1 MR (CDCl 3 ) δ 0.95 (t, 3, J = 7.4 z) (m, 4), (m, 4), 1.76 (qt, 2, J = 7.7 z), 2.40 (t, 2, J = 7.5 z), 2.61 (t, 2, J = 7.6 z) 3.43 (q, 2, J = 7.4 z), 6.59 (t, 1, J = 5.2 z), 6.79 (t, 1, J = 8.0 z), 7.08 (dd, 1, J = 8.0 and 0.8 z), 7.16 (m, 3), 7.25 (m, 2), 7.89 (br s, 1), 8.46 (d, 1, J = 7.1 z) and 13.2 (s, 1); 13 C MR (CDCl 3 ) δ 13.8, 20.2, 25.6, 28.9, 31.3, 31.6, 35.8, 38.0, 39.6, 113.5, 118.6, 119.3, 123.4, 125.8, 128.3, 128.4, 128.5, 142.6, , and 171.8; RMS (APCI), m/z (M+) + (C requires m/z ). 3-Benzamido--butyl-2-hydroxybenzamide (4c) The compound was prepared using 18.5 mg (0.152 mmol) of benzoic acid. The crude product was purified by chromatography on a silica gel column (7 2 cm). Elution with 85:15 hexanes EtAc gave the desired product 4c as a colorless solid: yield 36.4 mg (92%); mp 134 C; silica gel TLC R f 0.25 (4:1 hexanes EtAc); 1 MR (CDCl 3 ) δ 0.95 (t, 3, J = 7.4 z) 1.41 (sx, 2, J = 7.4 z), 1.61 (qt, 2, J = 7.4 z), 3.45 (q, 2, J = 7.4 z), 6.62 (br s, 1), 6.86 (t, 1, J = 8.0 z), 7.15 (dd, 1, J = 8.0 and 0.8 z), (m, 3), 7.92 (d, 2, J = 7.1 z), 8.66 (d, 1, 8.0z), 8.72 (br s, 1) and (s, 1); 13 C MR (CDCl 3 ) δ 13.9, 22.2, 25.0, 31.6, 39.7, 113.6, 118.6, 119.6, 123.4, 127.2, 10

11 128.4, 128.9, 132.1, 135.0, 151.1, and 170.1; mass spectrum (APCI), m/z (M+) + (C requires m/z ). -butyl-2-hydroxy-3-picolinamidobenzamide (4d). The compound was prepared using 18.7 mg (0.15 mmol) of picolinic acid. The crude product was purified by chromatography on a silica gel column (7 2 cm). Elution with 85:15 hexanes EtAc gave the desired product 4d as a colorless solid: yield 35.2 mg (89%); mp 165 C; silica gel TLC R f 0.2 (4:1 hexanes EtAc); 1 MR (CDCl 3 ) δ 0.96 (t, 3, J = 7.4 z), 1.41 (sx, 2, J = 7.4 z), 1.62 (qt, 2, J = 7.2 z), 3.46 (q, 2, J = 7.4 z), 6.52 (br s, 1), 6.88 (t, 1, J = 7.9 z), 7.14 (dd, 1, J = 8.0 and 0.8 z), 7.47 (m, 1), 7.89 (td, 1, J = 7.7 and 1.6 z), 8.27 (d, 1, J = 7.8 z), 8.68 (m, 2), 10.7 (br s, 1) and 13.3 (s, 1); 13 C MR (CDCl 3 ) δ 13.9, 20.3, 31.6, 39.7, 113.8, 118.6, 119.7, 122.4, 123.4, 126.5, 128.2, 137.6, 148.5, 150.1, 151.7, 162.5, and 170.0; mass spectrum (APCI), m/z (M+) + (C requires m/z ). Boc 3--Boc-glycylamido--butyl-2-hydroxybenzamide (4e) The compound was prepared using 26.5 mg (0.152 mmol) of -Boc-glycine. The crude product was purified by chromatography on a silica gel column (7 2 cm). Elution with 9:1 to 8:2 hexanes EtAc gave the desired product 11

12 4e as a colorless solid: yield 40.3 mg (87%); mp 130 C; silica gel TLC R f 0.3 (8:2 C 2 Cl 2 EtAc); 1 MR (CDCl 3 ) δ 0.95 (t, 3, J = 7.4 z), 1.41 (sx, 2, J = 7.4 z), 1.44 (s, 9), 1.60 (qt, 2, J = 7.2 z), 3.43 (q, 2, J = 7.4 z), 3.95 (m, 2), 5.29 (br s, 1), 6.58 (br s, 1), 6.79 (t, 1, J = 7.9 z), 7.08 (d, 1, J = 8.0 z), 8.42 (d, 1, J = 7.1 z), 8.50 (br s, 1), and 13.1 (s, 1); 13 C MR (CDCl 3 ) δ 13.7, 20.1, 28.3, 31.4, 39.5, 45.3, 80.6, 113.5, 118.3, 119.6, 123.2, 127.6, 150.8, 167.8, and ; mass spectrum (APCI), m/z (M+) + (C requires m/z ). -Butyl-3-(tert-butyloxycarbonyl)propylamido-2-hydroxybenzamide (4f). The compound was prepared using 26.5 mg (0.15 mmol) of mono-tert-butyl succinate. The crude product was purified by chromatography on a silica gel column (7 2 cm). Elution with 8:2 hexanes EtAc gave the desired product 4f as a colorless wax: yield 42.9 mg (93%) silica gel TLC R f 0.15 (4:1 hexanes EtAc); 1 MR (CDCl 3 ) δ 0.95 (t, 3, J = 7.4 z), 1.41 (sx, 2, J = 7.4 z), 1.44 (s, 9), 1.60 (qt, 2, J = 7.2 z), 2.66 (m, 4), 3.43 (q, 2, J = 7.4 z), 6.56 (br s, 1), 6.78 (t, 1, J = 7.9 z), 7.07 (dd, 1, J = 8.0 and 0.8 z), 8.06 (br s, 1), 8.42 (d, 1, J = 7.1 z) and 13.2 (s, 1); 13 C MR (CDCl 3 ) δ 13.8, 22.2, 28.2, 30.8, 31.6, 32.7, 39.6, 81.1, 113.6, 118.5, 119.3, 123.4, 128.3, 150.7, 170.0, and 172.0; mass spectrum (APCI), m/z (M+) + (C requires m/z ). 12

13 CBz Fmoc -Butyl-3-(-Fmoc-Lys(CBz))amido-2-hydroxybenzamide (4g): The compound was prepared using 76.4 mg (0.15 mmol) of -Fmoc-Lys(CBz)-. The crude product was purified by chromatography on a silica gel column (7 2 cm). Elution with 2:1 hexanes EtAc gave the desired product 4g as a colorless solid: yield 81.2 mg (97%); mp 158 C; silica gel TLC R f 0.25 (1:1 hexanes EtAc); 1 MR (CDCl 3 ) δ 0.95 (t, 3, J = 7.4 z), (m, 4), 1.5 (br s, 2), 1.59 (qt, 2, J = 7.2 z), 1.75 (br s, 1), 1.95 (br s, 1), 3.17 (br s, 2), 3.42 (q, 2, J = 7.4 z), 4.21 (t, 1, J = 6.8 z ), 4.34 (br s, 2), 4.47 (m, 1), 4.96 (br s, 1), 5.05 (m, 2), 5.76 (br s, 1), 6.61 (br s, 1, J = 5.1 z), 6.78 (t, 1, J = 7.9 z), 7.07 (d, 1, J = 8.0 z), (m, 9), 7.59 (br s, 2), 7.73 (d, 2, J = 7.2 z), 8.40 (d, 1, J = 7.1 z), 8.49 (br s, 1) and (s, 1); 13 C MR (CDCl 3 ) δ 13.8, 20.2, 22.6, 29.6, 31.5, 32.0, 38.7, 39.6, 40.4, 47.2, 56.0, 66.7, 67.2, 113.8, 118.4, 120.0, 123.6, 125.1, 127.2, 127.6, 127.8, 128.1, 128.6, 136.7, , , 143.8, 143.9, 151.0, 156.7, and 170.2; RMS (APCI), m/z (M+) + (C requires m/z ). -Butyl-2-hydroxy-3-(6-pyridiniumhexanamido)benzamide (4h): The compound was prepared using 41.0 mg (0.15 mmol) of compound 6b. The crude product was purified by chromatography on a silica gel column (7 2 cm). Elution with 98:2 to 9:1 C 2 Cl 2 Me 13

14 gave the desired product 4h as a yellowish wax: yield 49.8 mg (85%); silica gel TLC R f 0.25 (95:5 C 2 Cl 2 Me); 1 MR (MeD) δ 0.98 (t, 3, J = 7.4 z) 1.42 (sx, 2, J = 7.4 z), 1.48 (qt, 2, J = 7.4 z), 1.61 (qt, 2, J = 7.8 z), 1.80 (2, J = 7.8 z), 2.09 (qt, 2, J = 7.8 z), 2.49 (t, 2, J = 6.7 z), 2.81 (s, 1), 3.39 (t, 2, J = 6.7 z), 4.66 (t, 2, J = 7.8 z), 6.85 (t, 1, J = 8.2 z), 7.49 (d, 1, J = 7.8 z), 8.02 (d, 1, J = 7.8 z), 8.09 (t, 2, J = 6.7 z), 8.57 (t, 1, J = 7.6 z), 8.98 (s, 1) and 8.99 (s, 1); 13 C MR (MeD) δ 14.1, 21.1, 25.8, 26.4, 31.9, 32.4, 37.1, 38.8, 40.3, 62.8, 116.0, 119.1, 123.3, 127.1, 128.2, 129.4, 145.7, 146.7, 153.3, 171.3, and 174.4; RMS (APCI), m/z (M) + (C requires m/z ). -Butyl-2-hydroxy-3-(6-triphenylphosphoniumhexanamido)benzamide (4i) : The compound was prepared using 70 mg (0.15 mmol) of (5-carboxypentyl)triphenylphosphonium bromide (6d). The crude product was purified by chromatography on a silica gel column (7 2 cm). Elution with 9:1 to 8:2 C 2 Cl 2 EtAc gave the desired product 4i as a yellowish wax: yield 64.1 mg (89%); silica gel TLC R f 0.30 (8:2 C 2 Cl 2 EtAc); 1 MR (CDCl 3 ) δ 0.87 (t, 3, J = 7.4 z), 1.32 (sx, 2, J = 7.4 z), (m, 8), 2.29 (t, 2, J = 7.1 z), 3.07 (m, 2), 3.36 (q, 2, J = 7.4 z), 6.65 (t, 1, J = 8.1 z), 7.09 (t, 1, J = 5.7 z), 7.26 (d, 1, J = 8.0 z), (m, 12), 7.73 (t, 3, J = 7.6 z), 7.87 (s, 1), 8.14 (d, 1, J = 8.0 z), and 13.2 (s, 1); 13 C MR (CDCl 3 ) δ 13.7, 20.1, 21.8, 22.0 (d, J(C-P) = 4.4 z), 22.3, 24.3, 29.6 (d, J(C-P) = 16.3 z), 31.3, 36.8, 39.5, 114.3, (d, J(C-P) = 86.2z), 118.4, 120.9, 123.5, 127.5,

15 (d, J(C-P) = 12.4 z), (d, J(C-P) = 9.8 z), 135.3, 150.5, and 171.6; 31 P MR (CDCl 3 ) δ 23.26; RMS (APCI), m/z (M) + (C P requires m/z ). R 2 R 1 R BTU, DIEA DCM,rt,15h 0.2Mconc R R 2 R 1 General procedure for the transacylation reaction applied to AMA. A solution containing 30.0 mg (~57 µmol) of AMA mixture, 26.0 mg (68.4 µmol) of BTU and 68.4 µmmol of the corresponding carboxylic acid in 300 µl of freshly distilled C 2 Cl 2 was added 30 µl (0.38 mmol) of DIEA. The reaction mixture was maintained under argon and stirred for 15 h. After the reaction was completed (monitoring by silica gel TLC using 2:1 hexanes EtAc), the reaction mixture was diluted with 25 ml of EtAc, and washed with 20 ml of satd aq 4 Cl, then with 20 ml of brine. The organic layer was dried over MgS 4 and concentrated under diminished pressure. The crude product was purified by chromatography on a silica gel column (5 2 cm). R 2 R 1 -Acetylantimycin A (5a). The compound was prepared using 4.1 mg (68.4 µmmol) of acetic acid. The crud product was purified by chromatography on a silica gel column (5 2 cm). Elution with 2:1 to 3:2 hexanes EtAc gave the desired product 5a as a colorless wax: yield 23 15

16 mg (75%): silica gel TLC R f 0.30 (2:1 hexanes EtAc); 1 MR (CDCl 3 ) δ 0.85 (t, 3, J = 6.8 z) (m, 3), (m, 18), 1.48 (qt, 1, J = 6.8 z), 1.71 (m, 2), 2.25 (s, 3), 2.40 (m, 1), 2.52 (t, 2, J = 9.2 z), 5.00 (m, 1), 5.08 (t, 1, J = 9.5 z), 5.29 (t, 1, J = 7.6 z), 5.72 (qt, 1, J = 6.6 z), 6.88 (t, 1, J = 6.7 z), 7.13 (d, 1, J = 7.5 z), 7.21 (d, 1, J = 8.0 z), 7.89 (s, 1), 8.49 (d, 1, J = 8.0 z), and 12.6 (s, 1); 13 C MR (CDCl 3 ) δ 11.7, 11.8, 13.7, 13.9, 14.9, 16.7, 17.8, 18.9, 22.3, 22.4, 24.8, 26.4, 26.9, 28.1, 28.4, 28.9, 29.1, 31.4, 34.1, 41.2, 43.2, 50.1, 53.6, 70.8, 74.8, 75.2, 112.5, 118.9, 119.6, 124.1, , 169.4, 170.0, and 175.1; mass spectrum (APCI), AMA 1 m/z (M+) + (C requires m/z ); AMA 2 m/z (M+) + (C requires m/z ); AMA 3 m/z (M+) + (C requires m/z ); AMA 4 m/z (M+) + (C requires m/z ). -(6-Phenylhexyl)antimycin A (5b). The compound was prepared using 13.2 mg (68.4 µmmol) of phenylhexanoic acid. The crude product was purified by chromatography on a silica gel column (5 2 cm). Elution with 2:1 to 3:2 hexanes EtAc gave the desired product 5b as a colorless wax: yield 38.2 mg (99%); silica gel TLC R f 0.40 (2:1 hexanes EtAc); 1 MR (CDCl 3 ) δ 0.86 (t, 3, J = 6.8 z) (m, 3), (m, 18), (m, 4), (m, 7), (m, 1), 2.42 (t, 2, J = 9.5 z), 2.53 (t, 1, J = 9.8 z), 2.62 (t, 2, J = 7.6 z), 4.99 (m, 1), 5.09 (m, 1), 5.29 (t, 1, J = 7.6 z), 5.73 (qt, 1, J = 6.5 z),

17 (t, 1, J = 6.7 z), 7.16 (m, 3), 7.24 (m, 2), 7.89 (s, 1), 8.51 (d, 1, J = 8.0 z) and 12.6 (s, 1); 13 C MR (CDCl 3 ) δ 11.8, 11.9, 13.9, 14.1, 15.1, 16.9, 18.0, 19.1, 22.5, 22.6, 25.3, 26.6, 27.1, 28.5, 28.8, 28.9, 29.0, 29.3, 31.2, 31.3, 31.6, 33.8, 34.2, 35.8, 37.9, 41.4, 43.3, 50.2, 53.8, 71.1, 74.9, 75.4, 112.7, 119.1, 119.8, 124.3, 125.8, 128.3, 128.5, 142.6, 150.6, 169.5, 170.2, 171.8, and 175.3; mass spectrum (APCI), AMA 1 m/z (M+) + (C requires m/z ); AMA 2 m/z (M+) + (C requires m/z ); AMA 3 m/z (M+) + (C requires m/z ); AMA 4 m/z (M+) + (C requires m/z ). + R 2 R 1 -(4-(Pyridinium)butyl)antimycin A (5c). The compound was prepared using 16.8 mg (68.4 µmmol) of compound 6a. The crude product was purified by chromatography on a silica gel column (5 2 cm). Elution with 100% C 2 Cl 2 to 95:5 C 2 Cl 2 Me gave the desired product 5c as a colorless wax: yield 30.8 mg (74%); silica gel TLC R f 0.3 (95:5 C 2 Cl 2 -Me); 1 MR (MeD) δ 0.88 (br t, 3) ppm (m, 3), (m, 19), (m, 3), (m, 1), 2.42 (t, 2, J = 6.7 z) 2.49 (m, 1), 2.60(m, 1), 2.65 (m, 2), 4.75 (t, 2, J = 6.7 z), 4.83 (m, 4), 4.99 (m, 2), 5.35 (d, 1, J = 7.1 z), 5.66 (t, 1, J = 6.2 z), 6.91 (t, 1, J = 7.7 z), 7.72 (d, 1, J = 7.7 z), 7.90 (d, 1, J = 7.8 z), 8.1 (br s, 2), 8.58 (t, 1, J = 7.5 z) and 8.98 (m, 2); 13 C MR (MeD) δ 11.8, 12.1, 14.1, 14.3, 15.4, 17.2, 18.3, 19.3, 22.7, 22.71, 23.48, 23.51, 27.6, 27.8, 27.9, 29.7, 30.0, 30.2, 32.5, 33.2, 35.2, 42.4, 43.9, 51.4, 55.1, 62.4, 72.8, 75.5, 76.9, 116.7, 119.8, 125.3, 128.2, 129.5, 146.0, 147.0, 152.9, 170.7, 171.0, 17

18 172.9, 175.0, and 176.9; mass spectrum (APCI), AMA 1 m/z (M) + (C requires m/z ); AMA 2 m/z (M) + (C requires m/z ); AMA 3 m/z (M) + (C requires m/z ); AMA 4 m/z (M) + (C requires m/z ). -(6-(Pyridinium)hexyl)antimycin A (5d). The compound was prepared using 31.3 mg (68.4 µmmol) of compound 6b. The crude product was purified by chromatography on a silica gel column (5 2 cm). Elution with 100% C 2 Cl 2 to 95:5 C 2 Cl 2 Me gave the desired product 5d as a colorless wax: yield 50.7 mg (95%); silica gel TLC R f 0.3 (95:5 C 2 Cl 2 Me); 1 MR (MeD) δ 0.88 (br t, 3) δ (m, 3), (m, 19), (m, 3), (m, 2), 1.80 (t, 2, J = 7.3 z ), 2.51 (t, 2, J = 7.3 z ), 2.60 (m, 1), 2.81 (s, 1), 4.65 (t, 2, J = 6.7 z), 4.83 (br s, 4), 4.99 (m, 2), 5.35 (d, 1, J = 7.2 z), 5.66 (t, 1, J = 6.2 z), 6.92 (t, 1, J = 7.8 z), 7.75 (d, 1, J = 7.7 z), 7.88 (d, 1, J = 7.8 z), 8.09 (t, 2, J = 6.7 z), 8.57 (t, 1, J = 7.5 z), 8.95 (s, 1) and 8.96 (s, 1); 13 C MR (MeD) δ 11.8, 12.1, 14.1, 14.3, 15.4, 17.2, 18.29, 18.33, 19.3, 19.4, 22.7, 23.5, 25.8, 26.4, 27.6, 27.9, 29.4, 29.7, 30.0, 30.2, 32.0, 32.6, 35.2, 36.8, 38.9, 42.4, 51.3, 55.1, 62.8, 72.8, 75.5, 76.9, 117.1, 119.9, 125.6, 128.1, 128.4, 129.5, 145.8, 146.8, 152.7, 170.5, 171.0, 173.4, and 176.9; mass spectrum (APCI), AMA 1 m/z (M) + (C requires m/z ); AMA 2 m/z (M) + (C requires m/z ); AMA 3 m/z (M) + (C requires m/z ); AMA 4 m/z (M) + (C requires m/z ). 18

19 -(4-(Triphenylphosphonium)butyl)antimycin A (5e). The compound was prepared using 29.4 mg (68.4 µmmol) of compound 6c. The crude product was purified by chromatography on a silica gel column (5 2 cm). Elution with 100% C 2 Cl 2 to 85:15 C 2 Cl 2 EtAc gave the desired product 5e as a colorless wax: yield 46.8 mg (90%); silica gel TLC R f 0.25 (9:1 C 2 Cl 2 EtAc); 1 MR (CDCl 3 ) δ 0.86 (br t, 3, J = 6.8 z) (m, 3), (m, 18), 1.46 (qt, 1, J = 6.8 z), (m, 2), 2.01 (m, 2), 2.40 (m, 1), 2.52 (t, 1, J = 9.8 z), 2.79 (m, 2), 3.31 (t, 2, J = 14.2 z), 4.96 (br s, 1), 5.06 (t, 1, J = 9.4 z), 5.27 (t, 1, J = 7.5 z), 5.67 (t, 1, J = 6.1 z), 6.85 (t, 1, J = 6.7 z), 7.38 (d, 1, J = 7.9 z), 7.55 (d, 1, J = 7.8 z), 7.68 (m, 12), 7.79 (s, 3), 8.12 (m, 2) and 12.1 (s, 1); 13 C MR (CDCl 3 ) δ 11.8, 13.8, 14.1, 15.1, 16.8, 17.9, 18.0, 18.5, 19.1, , 22.5 (d, J(C-P) = 4.8 z), 25.6, 26.6, 27.1, 28.4 (d, J(C-P) = 26.3 z), 29.0, 29.3, 31.5, 34.2, 35.7, 35.9, 41.4, 43.3, 50.2, 53.7, 71.0, 74.8, 75.4, 114.8, (d, J(C-P) = 86.3z), 119.2, 122.5, 125.5, 127.7,, (d, J(C-P) = 12.6 z), (d, J(C-P) = 10 z), (d, J(C-P) = 2.9 z), 150.7, 168.5, 170.2, 171.0, and 175.3; mass spectrum (APCI), AMA 1 m/z (M) + (C P requires m/z ); AMA 2 m/z (M) + (C P requires m/z ); AMA 3 m/z (M) + (C P requires m/z ); AMA 4 m/z (M) + (C P requires m/z ). 19

20 -(6-(Triphenylphosphonium)hexyl)antimycin A (5f). The compound was prepared using 31.3 mg (68.4 µmmol) of compound 6d. The crude product was purified by chromatography on a silica gel column (5 2 cm). Elution with 100% C 2 Cl 2 to 9:1 C 2 Cl 2 EtAc gave the desired product 5f as a colorless wax: yield 50.7 mg (95%); R f 0.25 (9:1 C 2 Cl 2 EtAc); 1 MR (CDCl 3 ) δ 0.83 (t, 3, J = 6.8 z) (m, 3), (m, 15), 1.48 (qt, 1, J = 6.8 z), (m, 7), 2.42 (t, 1, J = 6.7 z) 2.52 (t, 1, J = 9.8 z), 3.10 (m, 2), 4.95 (m, 1), 5.04 (t, 1, J = 9.4 z), 5.29 (t, 1, J = 7.6 z), 5.67 (qt, 1, J = 6.2 z), 6.84 (t, 1, J = 6.6 z), 7.47 (d, 1, J = 7.9 z), 7.68 (m, 10), 7.76 (m, 3), 7.88 (m, 1), 7.98 (d, 1, J = 7.9 z), 8.11 (s, 1) and (s, 1); 13 C MR (CDCl 3 ) δ 11.8, 13.8, 14.1, 15.1, 16.8, 16.9, 18.0, 18.5, 19.1, 22.0, 22.1, 22.5 (d, J(C-P) = 4.8 z), 24.6, 26.6, 27.1, 29.2 (d, J(C-P) = 26.3 z), 29.7, 31.5, 36.6, 41.3, 50.2, 53.7, 71.0, 74.7, 75.4, 115.9, (d, J(C-P) = 87.2z), 119.4, 123.3, 125.5, 127.9, (d, J(C-P) = 12.8 z), (d, J(C-P) = 10.2 z), (d, J(C-P) = 2.9 z), 150.1, 167.8, 168.0, 170.2, and 175.3; mass spectrum (APCI), AMA 1 m/z (M) + (C P requires m/z ); AMA 2 m/z (M) + (C P requires m/z ); AMA 3 m/z (M) + (C P requires m/z ); AMA 4 m/z (M) + (C P requires m/z ). 20

21 4-Pyridiniumbutanoic Acid (6a). 4-Bromobutyric acid (500 mg, 3.00 mmol) was heated at reflux in 5 ml of dry pyridine for 5h. The cooled reaction mixture was stirred and treated slowly with acetone to effect precipitation of the pyridinium salt. The white precipitate was isolated by filtration, then triturated with acetone and diethyl ether to give the desired compound 6a as a colorless solid: yield 546 mg (74%); mp 120 C; 1 MR (D 2 ) δ 2.34 (qt, 2, J = 7.7 z), 2.53 (t, 2, J = 7.7 z), 4.70 (t, 2, J = 7.7 z), 8.10 (t, 2, J = 7.6 z), 8.58 (t,, 1 J = 7.5 z) and 8.89 (d, 2, J = 7.5 z); 13 C MR (D 2 ) δ 25.7, 30.0, 60.7, 128.8, 144.3, and 176.4; mass spectrum (APCI), m/z (M) + (C requires m/z ). 6-Pyridiniumhexanoic Acid (6b) 6-Bromohexanoic acid (500 mg, 2.56 mmol) was heated at reflux in 4mL of dry pyridine for 4 h. The cooled reaction mixture was stirred and treated slowly with acetone to effect precipitation of the pyridinium salt. The white precipitate was isolated by filtration to give the desired compound 6b as a colorless solid: yield 610 mg (87%); mp 106 C; 1 MR (D 2 ) δ 1.40 (m, 2), 1.67 (qt, 2, J = 7.7 z), 2.06 (qt, 2, J = 7.7 z), 2.40 (t, 2, J = 7.7 z), 4.64 (t, 2, J = 7.7 z), 8.09 (t, 2, J = 7.9 z), 8.56 (qt, 1, J = 7.8 z) and 8.87 (d, 2, J = 7.8 z); 13 C MR (D 2 ) δ 23.4, 24.5, 30.0, 33.4, 61.5, , 144.1, and 178.7; mass spectrum (APCI), m/z (M) + (C requires m/z ). 21

22 4-(Triphenylphosphonium)butanoic Acid (6c). 4-Bromobutanoic acid (500 mg, 3.00 mmol) was dissolved in 3 ml of toluene and then treated with 791 mg (3.02 mmol) of triphenylphosphine. The reaction mixture was heated at reflux under argon for 12 h. The cooled reaction mixture was maintained at 4 C for 4 h to afford maximal crystallization of the phosphonium salt. The crystalline solid was isolated by filtration, and triturated with acetone and diethyl ether to give 6c as a colorless solid: yield 620 mg (60%); mp 230 C; 1 MR (DMSd 6 ) δ 1.73 (m, 2), 2.49 (m, 2), 3.63 (m, 2) and (m, 15); 13 C MR (DMS-d 6 ) δ (d, J(C-P) = 9.8 z), 20.1 (d, J(C-P) = 204 z), 33.6 (d, J(C-P) = 71.4 z), (d, J(C- P) = 342 z), (d, J(C-P) = 49 z), (d, J(C-P) = 41 z), (d, J(C-P) = 11 z) and 173.3; 31 P MR (DMS-d 6 ) δ 23.7; mass spectrum (APCI), m/z (M) + (C P requires m/z ). 4-(Triphenylphosphonium)hexanoic Acid (6d). 6-Bromohexanoic acid (657 mg, 2.56 mmol) was dissolved in 3 ml of toluene and then treated with 674 mg (2.57 mmol) of triphenylphosphine. The reaction mixture was heated at reflux under argon for 12 h. The solvent was concentrated under diminished pressure and the resulting gummy white solid was dissolved a the minimum amount of chloroform and crystallized by adding slowly adding acetone. The suspension was kept at 4 C for 5 h after which the crystalline solid was isolated by filtration to afford 6d as a colorless solid: yield 657 mg (56%); mp 205 C; 1 MR (CDCl 3 ) δ 1.63 (m, 22

23 6), 2.34 (m, 2), 3.58 (m, 2) and 7.82 (m, 15); 13 C MR (CDCl 3 ) δ 22.0 (d, 3J(C-P) = 20 z), 22.9, 24.1, 29.6 (d, 1J(C-P) = 64 z), 34.3, (d, 1J(C-P) = 340 z), (d, 2J(C-P) = 48 z), (d, 3J(C-P) = 40 z), (d, 4J(C-P) = 12 z) and 176.0; 31 P MR (CDCl 3 ) δ 24.1; mass spectrum (APCI), m/z (M) + (C P requires m/z ). (1) Rahn,.; Dunkel, R.; Kunz, K.; Peris, G.; Benting, J.; Dahmen, P.; Wachendorff-eumann, U.; Franken, E.-M.; Malsam,.; Becker, A.; adano,.; Substituted benzoxazolecarboxamides and benzothiazolecarboxamides as fungicides and their preparation and use for fighting harmful microorganisms, Bayer CropScience AG, W A2. (2) Pettit, G. R.; Smith, T..; Feng, S.; Knight, J. C.; Tan, R.; Pettit, R. K.; inrichs, P. A. J. at. Prod. 2007, 70,