From sugar unit A From sugar unit B From sugar unit C

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1 ame 215 F12-Exam o. Page 2 I. (26 points) Raffinose is a trisaccharide occurring in cottonseed meal. Answer the following questions as directed in the boxes. (1) ( points) Label each of the glycosidic bonds in raffinose using a small arrow ( ). (2) ( points) Classify each glycosidic bond in raffinose as α or β right next to each of the arrows you have shown. () (2 points) Is raffinose a reducing sugar? yes no (circle one) () (2 points) ow many D sugars are formed upon complete acid hydrolysis of raffinose? (circle one) (5) (2 points) ow many reducing sugars are formed upon complete acid hydrolysis of raffinose? (circle one) (6) (2 points) Describe the glycosidic linkage between the sugar units B and C [e.g., β(1->6)]: C 2 A C 2 B 2 C C raffinose C 2 1 (7) (12 points) Draw Fischer projections for the open chain forms of the carbohydrates produced when raffinose is treated with excess dimethyl sulfate and a, and then the permethylated product is hydrolyzed with warm dilute acid. raffinose (C ) (C ) 2 S (excess) a (excess) 2 (solvent) From sugar unit A From sugar unit B From sugar unit C permethylated raffinose (C ) + 2 Δ + +

2 ame 215 F12-Exam o. Page II. (8 points) arbosine is a naturally occurring disaccharide. It is a dimer of L-rhodinose (as pyranose forms) joined together by an α(1 ) glycosidic linkage. Draw in the box below the structure of narbosine having the equatorial anomeric, using a conformational representation. 2 C L-rhodinose III. (1 points) Vancosamine is a small portion of vancomycin, one of the most powerful antibiotics that are effective against drug-resistant bacteria. Show in the boxes provided below: i) if the vancosamine structure given is a D- or L-sugar; ii) draw an open-chain Fischer projection formula of vancosamine; and iii) draw its two pyranose chair conformations. C ii) Draw in a Fischer openchain form. iii) Draw two chair conformations of vancosamine. 8 C 2 vancosamine i) stereochemical designation: D ; L 2 Circle the one that applies. IV. (9 points) Using the pka and structure information given on page 11, answer the following questions. (1) (6 points) Draw the structure of the major species for each of the following three amino acids at p 5. histidine at p 5 aspartic acid at p 5 arginine at p (2) ( points) The amino acid among above three (i.e., histidine, aspartic acid, and arginine) that has the highest isoelectric point (pi) is:

3 ame 215 F12-Exam o. Page V. (22 points) In a recent publication, an interesting sequence of the Dieckmann condensationdecarboxylation reactions was used in the synthesis of a pharmacologically significant alkaloid molecule [rg. Lett. 2012, 1, 852]. Ph 2 C C C 2 C 1. LMDS (1 euiv), 0 C 2. + workup Ph 2 C C 2 C (1) (18 points) Draw in the box below a step-by-step, curved-arrow mechanism for the above Dieckmann condensation reaction, including the last protonation step. Use LiRR' for LMDS. Ph 2 C C C 2 C Ph 2 C C 2 C (2) Treatment of the product shown above with + / 2 with heat produces a ketone product. Draw in the box the structure of the expected product from the reaction below. 18 Ph 2 C C 2 C +, 2 Δ + C 2 + C C 2

4 ame 215 F12-Exam o. Page 5 VI. (20 points) Complete the following reactions by providing in each of the boxes the structure of the starting compound, intermediate, or product. Indicate stereochemistry for the product/intermediate and if more than one stereoisomer is formed, draw one structure and write + enantiomer or + diastereomer. (1) [Synlett 2012, 2785] + C 2 C 1. a workup (2) [J. Mol. Catal. A: Chemical 201, 66, 6] C MgC (mild base) 2, 0 C () [rg Lett. 200, 6, 719] C CuLi workup () C 1 20 C 2 C Ph C 2 C a + -workup +, 2 Δ + C C C 2

5 ame 215 F12-Exam o. Page 6 VII. (21 points) Complete the following reactions by providing in each of the boxes the structure of the intermediate or product. Indicate stereochemistry for the product/intermediate and if more than one stereoisomer is formed, draw one structure and write + enantiomer or + diastereomer. (1) [Synlett ] (excess) (solvent) Br C 2 Cl 2 (solvent) S S (C 2 C ) S 2! (2) [ACS Catal. 2012, in press] S BF (C 2 C ) 2 or Ts β anomer ac (catalytic) C (solvent) a (2 equiv) Br (2 equiv) + 2 abr + 2 C

6 The Reagent List 215 F12 Exam - Page 9 Page 9 Shown below is a list of key reagents (not always the whole recipe) that may be useful for solving questions on the final exam. reagent classification or specialized use From s oxidation Chem 210 KMn oxidation peroxyacid epoxidation (e.g., - or meta-chloroperoxybenzoic acid or MCPBA) i. ; ii. (C ) 2 S or Zn ozonolysis i. ; ii. 2 2 ozonolysis a 2 base, nucleophile a base KC(C ) bulky base 2 /Pd hydrogenation 2 /Pd, BaS, quinoline hydrogenation i. B or 9-BB; ii. 2 2, a hydroboration PBr e.g., R- R-Br SCl 2 e.g., R- R-Cl p-c C 6 S 2 Cl (p-tscl) tosylate formation C S 2 Cl (MsCl) mesylate formation -bromosuccinimide (BS) Br source of electrophilic Br =========================================================================== Ch. 1 C ClCr - (PCC) oxidant Cr / 2 S / 2 /acetone oxidant i. ClC(=)-C(=)Cl, (C ) 2 S; ii. (C 2 C ) oxidant Ch. 1 ab nucleophilic hydride LiAl nucleophilic hydride diisobutylaluminum hydride (DIBAL) nucleophilic hydride RMgX nucleophilic carbon RLi nucelophilic carbon -C C 6 S (p-ts) (pka ~ -1) organic-soluble acid Raney i SC 2 C 2 S; SC BF (C 2 C ) 2 Lewis acid desulfurization thioacetal/thioketal formation hydrazone formation oxime formation

7 215 F12 Exam - Page 10 Ch. 15 SCl 2 R-C(=) R-C(=)Cl Ag 2, a, 2 oxidant - + C2 2 (diazomethane) e.g., R-C(=) R-C(=)C Ch. 17 Li[C(C ) 2 ] 2 strong, bulky base (lithium diisopropylamide or LDA) Li[Si(C ) ] 2 strong, bulky base (lithium hexamethldisilazide or LMDS) K 2 C weak base

8 The 20 naturally occurring amino acids 215 F12 Exam - Page 11 eutral amino acids 2 C Alanine Asparagine 2 Cysteine 2 S 2 Glutamine Glycine 2 2 Leucine 2 Isoleucine SC Methionine 2 Phenylalanine Proline 2 Serine 2 Threonine Tryptophan Tyrosine Valine Acidic amino acids 2 Aspartic acid Basic amino acids 2 Arginine 2 istidine 2 2 Glutamic acid 2 Lysine 2 pka Values for the Ionizable Functional Groups of an α-amino Acid Amino acid α-c(=) + α- side chain Alanine Arginine Asparagine Aspartic acid Cysteine Glutamic acid Glutamine Glycine istidine Isoleucine Leucine Lysine Methionine Phenylalanine Proline Serine Threonine Tryprophan Tyrosine Valine