Molecules 2005, 10, 1377-1386 molecules ISS 1420-3049 http://wwwmdpiorg Synthesis and Potent Antimicrobial Activity of Some ovel -(Alkyl)-2-Phenyl-1H-Benzimidazole-5-Carboxamidines Hakan Göker 1, *, Mehmet Alp 1 and Sulhiye Yıldız 2 1 Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Ankara University, 06100 Tandogan, Ankara-Turkey; Fax: (+90)3122131081 2 Department of Microbiology, Faculty of Pharmacy, Ankara University, 06100 Tandogan, Ankara- Turkey * Author to whom correspondence should be addressed E-mail: goker@pharmacyankaraedutr Received: 7 June 2005; in revised form: 25 October 2005 / Accepted: 26 October 2005 / Published: 30 ovember 2005 Abstract: A series of 22 novel 1,2-disubstituted-1H-benzimidazole--alkylated-5- carboxamidine derivatives were synthesized and evaluated for in vitro antibacterial activity against S aureus and methicillin resistant S aureus (MRSA), E coli, E faecalis and for antifungal activity against C albicans Compound 59 [1-(2,4-dichlorobenzyl)-- (2-diethylaminoethyl)-1H-benzimidazole-5-carboxamidine], with a 3,4-dichlorophenyl group at the C-2 position, displayed the greatest activity (MIC = 312 µg/ml against both some bacteria and the fungus C albicans) Keywords: 1H-Benzimidazole carboxamidines, methicillin-resistant S aureus (MRSA), antibacterial activity and antifungal activity Introduction We have already reported the synthesis of a series of 1,2-disubstituted-1H-benzimidazole-alkylated-5-carboxamidine derivatives and their very potent antibacterial activities against S aureus and methicillin resistant S aureus [1] The study revealed that compounds I IV (Figure 1) exhibited the best activity, with MIC values of 078-039 µg/ml against these species As part of a continuing program focused on development of new antimicrobial benzimidazole carboxamidines, we planned to modify the structure of compounds I IV
Molecules 2005, 10 1378 Figure 1 H I H H II H H III H IV Results and Discussion Chemistry Syntheses of the target benzimidazoles (Tables 1, 2) were achieved by two different methods, as shown in Scheme 1 Scheme 1 Method A C O 2 a C 1-8 O 2 b EtO H O 2 c R'H H 9-18 O 2 d R'H H 19-28 R R 1 2 R 3 e R'H 2 40-61 R 4 c Method B C 2 e C 29-32 33-39 : H 29 : isopropyl 30 : n-butyl 31 : benzyl 32 R 2 R 3 R 4 b EtO H R 2 R 3 R 4 Reagents : a : 2 b : H(g)/EtOH c : R' 2 /EtOH d : H 2 /PdC e : a 2 S 2 O 5 adduct of benzaldehydes
Molecules 2005, 10 1379 Method A involved nucleophilic displacement in DMF of the chloro group of 4-chloro-3-nitrobenzonitrile by reaction with several amines to give 1 8 (Table 3) The cyano group was then converted into the imidate ester, using a modified Pinner method [1], and the imidate esters were used directly to make the corresponding benzamidines 9 18 (Table 4) Their reduction with H 2, Pd/C produced 19 28 (Table 5) Condensation of these derivatives with the a 2 S 2 O 5 adducts of several benzaldehydes afforded the corresponding benzimidazoles 45 52, 55 and 59 61 [2] Method B involved cyclization of 29 32 with the a 2 S 2 O 5 adducts of various benzaldehydes to afford 5-cyanobenzimidazoles 33 39 (Table 6), following this, the cyano groups were converted into the imidate esters, as in method A, and these were used to prepared the corresponding amidine compounds 40 44, 53, 54 and 56 58 For its practical advantages this method was used in particular for cyanobenzimidazoles, which have better solubility in EtOH, although the yields were low o Table 1 Formulas and in vitro antibacterial and antifungal activities of 40-61 R'H R 2 R 3 Substituents Minimal inhibitory concentration, µg/ml R R 2 R 3 R 4 S a MRSA MRSA* E c E f C a 40 >50 >50 >50 >50 >50 >50 41 CH(CH 3 ) 2 >50 >50 >50 >50 >50 >50 42 CH(CH 3 ) 2 F >50 >50 >50 >50 >50 >50 43 (Et) 2 CH 2 CH 2 F >50 >50 >50 >50 >50 >50 44 (Me) 2 CH 2 CH 2 >50 >50 >50 >50 >50 >50 45 (Me) 2 CH 2 CH 2 125 125 125 >50 50 125 46 CH(CH 3 ) 2 CH 3 C >50 >50 >50 >50 >50 >50 47 CH(CH 3 ) 2 CH 3 OCH 3 OCH 3 >50 >50 >50 >50 >50 >50 48 Cyclopropyl COOCH 3 >50 >50 >50 >50 >50 >50 49 PhCH 2 COOH >50 >50 >50 >50 >50 >50 50 PhCH 2 COOCH 3 125 25 312 >50 50 25 51 Cyclohexyl COOH >50 >50 >50 >50 >50 >50 52 n-butyl >50 >50 >50 >50 >50 >50 53 (Me) 2 CH 2 CH 2 n-butyl F >50 >50 >50 >50 >50 >50 54 CH(CH 3 ) 2 CH(CH 3 ) 2 F >50 >50 >50 >50 >50 >50 55 (Me) 2 CH 2 CH 2 Ph 125 312 125 >50 25 125 56 (Me) 2 CH 2 CH 2 PhCH 2 125 125 125 >50 25 125 57 (Et) 2 CH 2 CH 2 PhCH 2 125 125 625 50 125 125 58 (Me) 2 CH 2 CH 2 PhCH 2 50 125 125 >50 50 25 2,4-di-- 59 (Et) 2 CH 2 CH 2 benzyl 312 312 312 125 625 312 60 (Et) 2 CH 2 CH 2 PhCH 2 CH 2 OCH 3 OCH 3 >50 >50 >50 >50 >50 >50 61 Isobutyl PhCH 2 CH 2 625 625 625 >50 125 125 Ref OH t-butyl 078 078 078 Sult 039 25 25 156 R 4
Molecules 2005, 10 1380 Table 1 Cont o R R 2 R 3 R 4 S a MRSA MRSA* E c E f C a Amp 078 50 078 Cip 039 Flu 156 Sa: Staphylococcus aureus (ATCC 25923); MRSA (methicillin resistant Staphylococcus aureus, ATCC 43300); MRSA* (Methicillin resistant Staphylococcus aureus, clinical isolate); E c: Escherichia coli (ATCC 25922); E f: E faecalis (ATCC 29212); C a: Candida albicans (ATCC 10231); Ref: this compound was found to be the most active compound against S aureus by Weidner-Wells et al [3]; Sult: Sultamicillin; Amp: Ampicillin; Cip: Ciprofloxacin; Flu: Fluconazole Antimicrobial Activity The benzimidazoles 40 61 were tested by the macro-broth dilution [4] assay for in vitro antibacterial activity against Gram positive Staphylococcus aureus, methicillin resistant Staphylococcus aureus (MRSA, a clinical isolate from a wound), Enterococcus faecalis and Gram negative Escherichia coli and for antifungal activity against Candida albicans The MIC values are listed in Table 1 The synthesized compounds and reference drugs were dissolved in water or DMSOwater (40 %) at a concentration of 400 µg/ml The concentration was adjusted to 100 µg/ml by fourfold dilution with media culture and bacteria solution at the first tube Data was not taken for the initial solution because of the high DMSO concentration (10 %) We have already reported that 3,4-dichloro substitution on the 2-phenyl group of amidinobenzimidazoles plays an important role in their antibacterial activity [1] Thus, the most active compound, 59, and less active compounds 45, and 55 57 all have a 3,4-dichlorophenyl group at the C-2 position Replacement of 3,4-dichloro substitution with other functions such as fluoro, cyano, methoxy, carboxyl or methyl ester caused a reduction in inhibitory activities, and only compound 50, having a methyl ester group, exhibited moderate activity against MRSA with a MIC of 312 µg/ml More lipophilic substituents on the benzimidazole -atom such as phenyl, benzyl and 2,4-dichlorobenzyl do lead to quite active compounds (55 59), however substitution with methyl, butyl and isopropyl (cf 46, 47, 52 54) gave no significant activity Introduction of,-diethylaminoethyl substitution on the cationic amidine 59 led to inhibitory activity against E coli and C albicans This is a very important result, as it represents the first example to date of inhibitory activity against E coli with these amidinobenzimidazoles Except for compound 59, none of the compounds showed important inhibitory activity against E faecalis and C albicans Conclusions Introduction of aromatic amidine groups into the benzimidazole system gives a good profile of Gram-positive antibacterial activity In particular, 1-(2,4-dichlorobenzyl)--(2-diethylaminoethyl)-1Hbenzimidazole-5-carboxamidine (59), having a 3,4-dichlorophenyl at the C-2 position, exhibited the greatest activity, with a MIC value of 312 µg/ml against S aureus and MRSA Detailed mechanistic studies are required to understand the potent activity of this compound
Molecules 2005, 10 1381 Acknowledgments This work was supported by Ankara University Research Fund (Project o: 0000018-2003) The Central Lab of the Faculty of Pharmacy of Ankara University provided support for acquisition of the MR, mass spectrometer and elemental analyser used in this work Experimental General Uncorrected melting points were measured on an Electrothermal 9100 capillary melting point apparatus 1 H-MR spectra were recorded employing a Varian Mercury 400 MHz FT spectrometer, chemical shifts (δ) are in ppm relative to TMS, and coupling constants (J) are reported in Hertz Mass spectra were taken on a Waters Micromass ZQ using the ESI(+) method Microanalyses were performed by Leco CHS-932 Some H salts of compounds 40 61 were prepared by using dry H gas in EtOH or isopropanol All chemicals and solvents were purchased from Aldrich Chemical Co or Fischer Scientific Compounds 29 32 were synthesized as described in our previous study [2] Table 2 Physical and spectral data for compounds 40 61 o Mp ( O C) Yield (%) 40 >300 35 41 >290 40 42 >300 28 43 >300 41 44 45 46 47 48 100-110 95-100 200-210 100-110 285-290 37 18 30 26 60 Formula Calculated Found C 14 H 11 4 2H H 2 O C: 4650 H: 418 : 155 C: 4624 H: 399 : 153 C 17 H 16 2 4 2H 15H 2 O C: 4566 H: 473 : 125 C: 4567 H: 445 : 124 C 17 H 17 F 4 2H 15H 2 O C: 5152 H: 559 : 141 C: 5190 H: 531 : 141 C 20 H 24 F 5 3H 2H 2 O C: 4815 H: 626 : 141 C: 4801 H: 602 : 1399 *C 18 H 20 5 4H 15H 2 O 05C 2 H 6 O C: 4227 H: 597 : 1297 C: 4254 H: 604 : 1301 C 18 H 19 2 5 15H 025H 2 O 025C 3 H 8 O C: 4999 H: 514 : 1554 C: 4997 H: 514 : 1523 C 19 H 19 5 15H 2 O 01C 3 H 8 O C: 6615 H: 655 : 1998 C: 6619 H: 597 : 1982 C 20 H 24 4 O 2 18H 2 O C: 6242 H: 722 : 1455 C: 6262 H: 694 : 1421 C 19 H 18 4 O 2 3H 2 O 03C 3 H 8 O C: 5880 H: 654 : 1378 C: 5872 H: 620 : 1336 1 H-MR δ ppm (DMSO-d6) (if not stated otherwise) 759-797 (arom 7H), 831 (s), 930 (s), 953 (s) 121 (d, 6H), 403 (m, 1H), 76 (m, 2H), 78(d, J=85, 1H), 783 (d, J=2, 1H), 792 (d, J=84, 1H), 805 (d, J=15, 1H), 906 (s), 942 (s), 954 (d) 129 (d, 6H), 408 (m, 1H), 751 (t, 2H), 767 (d, J=83, 1H), 787 (d, J=84, 1H), 808 (s, 1H), 844 (m, 2H), 908 (s), 948 (s), 962 (d) 129 (t, 6H), 326 (4H), 346 (2H), 400 (2H), 756 (t, 2H), 784 (d, J=84, 1H), 792 (d, J=84, 1H), 828 (s, 1H), 852 (m, 2H), 967 (s), 993 (s), 1021 (1H), 1096 (s) (CD 3 OD): 305 (6H), 366 (t, 2H), 403 (t, 2H), 769 (m, 1H), 782 (m, 2H), 799 (d, 1H), 8102 (s, 2H), 854 (s, 1H) 223 (s, 6H), 258 (t, 2H), 353 (t, 2H), 756 (dd, J=84, 16, 1H), 780 (d, J=88, 1H), 786 (d, J=84, 1H), 806 (s, 1H), 825 (dd, J= 84 18, 1H), 850 (d, J=18, 1H) 123 (d, 6H), 395 (m, 1H), 397 (s, 3H), 776 (m, 2H), 809 (m, 5H) (DMSO-d 6 + 1 drop D 2 O): 117 (d, 6H), 385-390 (10H), 715 (d, J=84, 1H), 74 (s, 2H), 762 (m, 2H), 797 (s, 1H) 077 (2H), 091 (d, 2H), 279 (1H), 389 (s, 3H), 753 (d, J=8, 1H), 767 (d, J=84, 1H), 804 (s, 1H), 809 (d, J=78, 2H), 838 (d, J=8, 2H) MS (ESI+) m/z 271 273 (33) 347 349 (65) 351 (11) 297 354 342 344 (33) 376 378 (69) 380 (11) 318 353 335 Synthesis Method and Isolation Column Chromatography if not stated otherwise Crys Ethanolic H CH 2 2 : Isopropanol : 3 (100 : 60 : 4) CH 2 2 : Isopropanol : 3 (100 : 60 : 3) CH 2 2 : Isopropanol : 3 (100 : 60 : 3) CH 2 2 : Isopropanol : 3 (100 : 60 : 3) CH 2 2 : Isopropanol : Ethylamine (100 : 50 : 3) CH 2 2 : Isopropanol : Propylamine (100 : 50 : 4) CH 2 2 : Isopropanol : Propylamine (100 : 50 : 3) Cryst Isopropanol
Molecules 2005, 10 1382 49 50 260-270 265-275 34 52 51 >300 64 52 53 54 55 56 57 150-155 205-210 115-120 295-300 130-135 120-130 22 32 20 30 49 46 C 22 H 18 4 O 2 2H 2 O C: 6501 H: 545 : 1377 C: 6495 H: 523 : 1378 C 23 H 20 4 O 2 025H 2 O C: 7103 H: 531 : 1440 C: 7107 H: 514 : 1432 C 21 H 22 4 O 2 2H 15H 2 O C: 5455 H: 588 : 1212 C: 5426 H: 589 : 1262 C 18 H 20 4 2H 22H 2 O 05C 3 H 8 O C: 5384 H: 704 : 1288 C: 5398 H: *** : 1281 C 22 H 28 F 5 3H 2H 2 O C: 5014 H: 669 : 1329 C: 5034 H: 652 : 1292 C 20 H 23 F 4 3H 125H 2 O C: 5107 H: 611 : 1191 C: 5105 H: 631 : 1155 C 24 H 23 2 5 3H 125H 2 O C: 4934 H: 491 : 1198 C: 4945 H: *** : 1187 C 25 H 25 2 5 3H 125H 2 O C: 5018 H: 514 : 117 C: 5006 H: 522 : 1149 C 27 H 29 2 5 3H 2H 2 O C: 5068 H: 567 : 1094 C: 5066 H: 562 : 1092 58 ** 33 ** C 25 H 25 2 5 59 60 61 120-125 127-130 288-290 35 30 19 H C 27 H 27 4 5 3H H 2 O C: 4664 H: 471 : 1007 C: 4680 H: 482 : 986 C 30 H 37 5 O 2 3H H 2 O C: 5434 H: 699 : 1056 C: 5440 H: 680 : 1045 C 26 H 26 2 4 15H C: 6004 H: 533 : 1077 C: 6005 H: 550 : 1066 Table 2 Cont 473 (s, 2H), 735-830 (aromat 12H) 371 388 (s, 3H), 453 (s, 2H), 727-756 (m, 7H), 803-806 (m, 3H), 837 (d, J=84, 2H), 121-142-163-177-198 (m, 10H), 378 (1H), 765 (d, J=84, 1H), 787 (d, J=84, 1H), 81 (s, 1H), 815 (d, J=8, 2H), 847 (d, J=76, 2H), 919 (s), 950 (s), 963 (d) (Base) : 064 (t, 3H), 101 (m, 2H), 156 (m, 2H), 433 (t, 2H), 756 (m, 3H), 776 (m, 3H), 795 (d, J=86, 1H), 823 (d, J=14, 1H), 918 (s), 941 (s) 078 (t, 3H), 120 (m, 2H), 170 (m, 2H), 290 (s, 6H), 351 (t, 2H), 403 (t, 2H), 445 (t, 2H), 755 (m, 2H), 801 (m, 3H), 810 (d, J=86, 1H), 842 (d, J=13, 1H), 977 (s), 997 (s), 1028 (s) 134 (d, 6H), 166 (d, 6H), 42 (m, 1H), 48 (m, 1H), 754 (m, 2H), 774 (d, J=87, 1H), 786 (m, 2H), 822 (2H), 921 (s), 958 (s), 968 (d) 285 (s, 6H), 344 (t, 2H), 392 (t, 2H), 737-780 (m, 10H), 841 (d, J=12, 1H), 952 (s), 983 (s), 1007 (s), 1081 (s) 290 (6H), 350 (t, 2H), 403 (q, 2H), 574 (s, 2H), 704 (m, 2H),734 (m, 3H), 782 (m, 4H), 802 (d, J=19, 1H), 842 (d, J=14, 1H), 971 (s), 986 (s), 1015 (d), 1114 (s) 127 (t, 6H), 324 (4H), 345 (2H), 399 (2H), 572 (s, 2H), 698 (m, 2H), 727 (m, 3H), 781 (m, 4H), 801 (d, J=2, 1H), 835 (s, 1H), 961 (s), 981 (s), 1011 (s), 1097 (s) (CD 3 OD): 329 (6H), 363 (t, 2H), 399 (t, 2H), 557 (s, 2H), 703 (m, 2H), 726 (m, 3H), 761 (dd, J=84, 2, 1H), 768 (d, J=81, 1H), 782 (d, J=2, 1H), 795 (m, 2H), 842 (s, 1H) 125 (t, 6H), 323 (m, 4H), 341 (t, 2H), 384 (2H), 571 (s, 2H), 673 (d, J=88, 1H), 730 (dd, J=84 2, 1H), 762-781 (m, 5H), 793 (d, J=2, 1H), 835 (s, 1H), 964 (s), 983 (s), 1013 (s), 1096 (s) 129 (t, 6H), 308 (t, 2H), 325 (4H), 348 (d, 2H), 384 (s,3h), 389 (s,3h), 404 (q, 2H), 483 (t, 2H), 69 (m, 2H), 712-731 (m, 6H), 803 (d, J=88, 1H), 827 (d, J=88, 1H), 836 (s, 1H), 987 (s), 1008 (s), 1044 (s), 111 (s) 096 (d,6h), 206 (m, 1H), 293 (t, 2H), 316 (t, 2H), 463 (t, 2H), 667 (d, J=72, 2H), 703 (t, J=72, 2H), 711 (m, 1H), 745 (2H), 770 (m, 2H), 801 (d, J=88, 1H), 812 (s, 1H), 902 (s), 944 (s), 975 (s) 385 363 293 382 339 452 454 (68) 456 (12) 466 468 (68) 470 (11) 494 496 (68) 498 (12) 466 468 (71) 470 (13) 562 (80) 564 566 (51) 568 (14) 500 465 467 (67) 469 (11) * Hygroscopic; ** Very hygroscopic, not measurable; *** o satisfactory result Cryst EtOH CH 2 2 : Isopropanol : Propylamine (100 : 100 : 6) Cryst Ethanolic H CH 2 2 : Isopropanol : 3 (100 : 50 : 4) CH 2 2 : Isopropanol : Ethylamine (100 : 50 : 3) CH 2 2 : Isopropanol : Ethylamine (100 : 50 : 3) CH 2 2 : Isopropanol : 3 (100 : 50 : 15) CH 2 2 : Isopropanol : Ethylamine (100 : 50 : 5) CH 2 2 : Isopropanol : Ethylamine (100 : 50 : 3) CH 2 2 : Isopropanol : 3 (100 : 50 : 05) CH 2 2 : Isopropanol : 3 (100 : 50 : 05) CH 2 2 : Isopropanol : isopropylamine (90 : 30 : 2) CH 2 2 : Isopropanol : ethylamine (100 : 50 : 05) 4-(2,4-Dichlorobenzyl)amino-3-nitrobenzonitrile (7) A mixture of 2,4-dichlorobenzylamine (352 g, 20 mmol) and 4-chloro-3-nitrobenzonitrile (2 g, 1095 mmol) in DMF (3 ml) was heated under reflux for 4h at 120 C The mixture was allowed to cool and EtOH was added The resultant yellow precipitate was filtered, washed with water and crystallised from EtOAc-n-hexane; yield 57 %; mp: 192 o C; 1 H-MR (CD 3 ): 466 (d, J=56, 2H), 68
Molecules 2005, 10 1383 (d, J=92, 1H), 724 (m, 2H), 747 (d, J=2, 1H), 758 (dd, J o =92, J m =2, 1H), 855 (d, J=2, 1H), 878 (brt, 1H) 4-(2-Phenylethyl)amino-3-nitrobenzonitrile (8) 2-Phenylethylamine (13 g, 108 mmol) and 4-chloro-3-nitrobenzonitrile (1g, 54 mmol) were allowed to react for 2 h, at 100 o C and the product wasisolated as described for 7; yield 79 %; mp: 111 o C; 1 H-MR (CD 3 ): 304 (t, J=71, 2H), 361 (q, J=68, 2H), 689 (d, J=88, 1H), 725-737 (m, 4H), 758 (dd, J o =88, J m =2, 1H), 844 (brt, 1H), 847 (d, J=2, 1H) Table 3 Formulas and melting points of 1 8 C O 2 Comp Formula Ref 1 H C 7 H 5 3 O 2 Commercial 2 methyl C 8 H 7 3 O 2 Lit [1] 3 iso-propyl C 10 H 11 3 O 2 Lit [2] 4 n-butyl C 11 H 13 3 O 2 Lit [2] 5 phenyl C 13 H 9 3 O 2 lit [5] 126 o C, 126 o C 6 benzyl C 14 H 11 3 O 2 Lit [2] 7 2,4-dichlorobenzyl C 14 H 9 2 3 O 2 --- 8 PhCH 2 CH 2 C 15 H 13 3 O 2 --- General Procedure for Synthesis of 9 18, 40 44, 53, 54, 56 58 1 8 (45 mmol) and 33 39 (Table 6, 1 mmol) were suspended in absolute EtOH, cooled in a icesalt bath, and dry H gas was passed through the solution for 40 min The solution was stirred in a stoppered flask at room temperature for 3 days and then diluted with dry ether The imidate esters precipitated as yellow solids, which were washed with ether then dried under vacuum at room temperature All imidate esters were used directly without characterisation A suspension of imidate ester H in absolute EtOH was stirred with corresponding the amines (15-2 fold excess) overnight at 25-30 o C The reaction mixture was evaporated and diluted with ether, the precipitate was filtered, washed with ether, then dried Compounds 9 18 (Table 4) were used without purification as H salts for the next steps since they were prepared completely pure In contrast, crude products 40 44, 53, 54, 56 58 were treated with dilute a 2 CO 3 solution, then water Further purification methods are given in Table 2 Table 4 Formulas, spectroscopic data, mp and yields of 9-18 Comp R Formula 9 butyl C 11 H 16 4 O 2 MR δ ppm (DMSO-d 6 ) 0895 (t, 3H), 134 (m, 2H), 156 (m, 2H), 341 (q, 2H), 722 (d, J=92, 1H), 795 (dd, J=92, 24, 1H), 86 (t, 1H), 867 (d, J=24, 1H), 92 (brs) Mass (ESI+) 237 10 iso-propyl methyl C 11 H 16 4 O 2 Lit [1] mp ( o C) Yield (%) 200-4 62
Molecules 2005, 10 1384 11 (CH 3 ) 2 (CH 2 ) 2 C 11 H 17 5 O 2 Table 4 Cont 224 (s, 6H), 258 (t, 2H), 35 (t, 2H), 714 (d, J=88,1H), 75 (dd, J=88, 2, 1H), 809 (brs, 2H), 848 (d, J=2, 1H) 252 220-230 () Lit [6] 12 cyclo-propyl C 10 H 12 4 O 2 Lit [1] 13 cyclo-hexyl C 13 H 18 4 O 2 Lit [1] 14 Benzyl C 14 H 14 4 O 2 Lit [1] 15 (CH 3 ) 2 (CH 2 ) 2 phenyl C 17 H 21 5 O 2 16 iso-butyl PhCH 2 CH 2 C 19 H 24 4 O 2 17 (C 2 H 5 ) 2 (CH 2 ) 2 PhCH 2 CH 2 C 21 H 29 5 O 2 18 (C 2 H 5 ) 2 (CH 2 ) 2 2,4-dichloro benzyl C 20 H 25 2 5 O 2 232 (s, 6H), 269 (2H), 34 (brs), 356 (t, 2H), 712 (d, J=93, 1H), 728-749 (m, 5H), 785 (dd, J=92, 23, 1H), 861 (d, J=23, 1H), 985 (s, 1H) (CD 3 OD): 105 (d, 6H), 207 (m,1h), 305 (t, 2H), 325 (d, 2H), 372 (m, 2H), 721 (m, 2H), 73 (m, 4H), 779 (dd, J=92 24, 1H), 853 (t, 1H), 859 (d, J=24, 1H) (CD 3 OD): 111 (t, 6H), 268 (q, 4H), 278 (t, 2H), 303 (t, 2H), 357 (t, 2H), 47 (s, 2H), 721 (m, 2H), 73 (m, 4H), 781 (dd, J=88,24, 1H), 862 (d, J=24, 1H) (CD 3 OD): 111 (t, 6H), 268 (q, 4H), 279 (t, 2H), 357 (t, 2H), 478 (t, 2H), 698 (d, J=92, 1H), 730 (dd, J=86 24, 1H), 737 (d, J=88, 1H), 753 (d, J=2, 1H), 778 (dd, J=92, 24, 1H), 868 (d, J=24, 1H) 328 341 384 438 440 (65) 442 (12) Hygros 110 () 87 247-9 75 236-9 85 203-5 89 Table 5 Formulas, spectroscopic data, mp and yields of 19-28 R'H H 2 Comp R Formula 19 butyl C 11 H 18 4 MR δ ppm (DMSO-d 6 ) 088 (t, 3H), 136 (m, 2H), 156 (m, 2H), 31 (t, 2H), 501 (brs, 2H), 557 (brs, 2H), 646 (d, J=8, 1H), 69 (s, 1H), 707 (d, J=84, 1H), 858 (s, 2H), 874 (s, 2H) MS (ESI+) mp ( o C) Yield (%) 207 285 94 20 iso-propyl methyl C 11 H 18 4 Lit [1] 21 (CH 3 ) 2 (CH 2 ) 2 C 11 H 19 5 (+ one drop D 2 O): 22 (s, 6H), 254 (t, 2H), 34 (t, 2H), 657 (d, J=8, 1H), 685 (m, 2H) 222 Lit [6] 22 cyclo-propyl C 10 H 14 4 Lit [1] 23 cyclo-hexyl C 13 H 20 4 Lit [1] 24 benzyl C 14 H 16 4 Lit [1] 25 (CH 3 ) 2 (CH 2 ) 2 phenyl C 17 H 23 5 (+ one drop D 2 O) : 227 (s, 6H), 263 (t, 2H), 35 (t, 2H), 685-726 (8H) 298 * 90
Molecules 2005, 10 1385 Table 5 Cont 26 iso-butyl -CH 2 CH 2 Ph C 19 H 26 4 27 (C 2 H 5 ) 2 (CH 2 ) 2 -CH 2 CH 2 Ph C 21 H 31 5 28 (C 2 H 5 ) 2 (CH 2 ) 2 2,4-dichlorobenzyl C 20 H 27 2 5 * o sharp melting point 092 (d, 6H), 196 (m, 1H), 29 (t, 2H), 317 (t, 2H), 331(2H), 439 (t, 1H), 503 (2H), 566 (t,1h), 657 (d, J=84, 1H), 687 (d, J=16, 1H), 698 (dd, J=84 16, 1H), 72-73 (m, 5H), 857 (s, 1H), 89 (s, 1H) (CD 3 OD): 109 (t, 6H), 265 (q, 4H), 277 (t, 2H), 296 (t, 2H), 347 (t, 2H), 352 (t, 2H), 668 (d, J=8, 1H), 701 (d, J=2, 1H), 714-73 (m, 6H) (CD 3 OD): 114 (t, 6H), 276 (4H), 289 (2H), 357 (t, 2H), 454 (s, 2H), 637 (d, J=8, 1H), 706 (d, J=2, 2H), 725 (dd, J=82 2, 1H), 731 (d, J=84, 1H), 749 (d, J=2, 1H) 311 98-100 94 354 * 95 408 410(65) 412(11) * 92 General Procedure for Synthesis of 19 28 Compound 9 18 (35 mmol) in EtOH (75 ml) was subjected to hydrogenation using 40 psi of H 2 and 10 % Pd-C (40mg) until uptake of H 2 ceased The catalyst was filtered on a bed of Celite, washed with EtOH, and the filtrate was concentrated in vacuo The crude o-phenylenediamines (grey purple black in colour) were used for the subsequent steps without crystallisation (Table 5) In order to prevent halogen reduction of compound 28, 15 psi of H 2 pressure was employed Table 6 Formulas, spectroscopic data, mp and yields of 33-39 C R 2 R 3 R 4 Comp R 2 R 3 R 4 Formula MR Mass mp δ ppm (CD 3 ) (ESI+) ( o C) 33 C 14 H 8 3 Lit [2] 34 C 14 H 7 2 3 Lit [2] 35 F C 14 H 8 F 3 Lit [2] 36 iso-propyl F C 17 H 14 F 3 Lit [2] 37 n-butyl F C 18 H 16 F 3 Lit [2] 38 benzyl C 21 H 13 2 3 39 benzyl C 21 H 13 2 3 547 (s, 2H), 705 (m, 2H), 73-755 (m,7h), 782 (d, J=2, 1H), 816 (d, J=15, 1H) 527 (s, 2H), 691(m, 2H), 726-757 (m, 8H), 816 (1H) 91 378(50) 380(33) 382(6) 91 378(54) 380(31) 382(5) Yield (%) 192 75 195-6 73 İsolation Cryst EtOHwater Cryst EtOHwater
Molecules 2005, 10 1386 General Procedure for Synthesis of 33 39, 45 52, 55, 59 61 The corresponding benzaldehydes (15 mmol) were dissolved in EtOH (50 ml) and sodium metabisulfite (16 g) in H 2 O (10 ml) was added in portions The reaction mixture was stirred vigorously and more EtOH was added The mixture was kept in a refrigerator for a several hours The precipitate was filtered and dried (yields over 93 %) The mixture of these salts (1 mmol) and 19 28 and 29 32 (1 mmol) in DMF (1-2 ml) was heated at 120 o C for 4h The reaction mixture was cooled, poured into H 2 O, and the solid was filtered Purification methods are given in Tables 2 and 6 References 1 Göker, H; Özden, S; Yildiz, S; Boykin, DW Synthesis and potent antibacterial activity against MRSA of some novel 1,2-Disubstituted-1H-Benzimidazole--alkylated-5-carboxamidines Eur J Med Chem 2005, 40, 1062-1069 2 Göker, H; Kus, C; Boykin, DW; Yildiz, S; Altanlar, Synthesis of some new 2-substitutedphenyl-1H-benzimidazole-5-carbonitriles and their potent activity against Candida species Bioorg Med Chem 2002, 10, 2589-2596 3 Weidner-Wells, MA; Ohemeng, KA; guyen, V; Fraga-Spano, S; Macielag, MJ; Werblood, HM; Foleno, BD; Webb, GC; Barrett, JF; Hlasta, DJ Amidino benzimidazole inhibitors of bacterial two-component systems Bioorg Med Chem Lett 2001, 11, 1545-1548 4 a) ational Committee for inical Laboratory Standards Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria that Grow Aerobically, 5th ed; Approved Standard (M7A5); ational Committee for inical Laboratory Standards: Wayne, PA, 2000; b) Shadomy, S; Pfaller, MA Laboratory Studies with Antifungal Agents: Susceptibility Tests and Quantitation in Body Fluids In Manual of inical Microbiology 5th Ed ; Balows, A; Hausler, WJ; Hermann, KL; Isenberg, HD; Shadomy, HJ, Eds; Washington DC, 1991; Chapter 117, p 1173 5 Ritter, H DE 723751, 1942 6 Roesner, M; Raethner, W DE 2839989, 1980 Sample availability : Available from the authors 2005 by MDPI (http:wwwmdpiorg) Reproduction is permitted for noncommercial purposes