Name LastName Student ID 1) (12 points) Imidazopyridine derivatives such as 1-deaza-9H-purines (like 1) and 3- deaza-9h-purines (like 2) represent privileged structures in medicinal chemistry and they have various pharmacological and interesting properties. Provide a synthesis for deazapurines 1 and 2 starting from 2,4-dichloro-3-nitropyridine 3.Use only the functional group reactivity and maintain the generic formula, for example RNH 2. In addition, provide a two-step synthesis for 2,4-dichloro-3-nitropyridine starting from 4-hydroxy-2-pyridinone 4.
2. A. (5 points) Provide reagents for the following deprotection reactions. B. (7 points) A large peptide (or protein) can be synthesized by joining together two smaller peptides. This is known as a convergent peptide ligation. Give the mechanism for this process. Show only the relevant portions of the peptides.
3. (12 points) Tryptophan synthase is an enzyme involved in the biosynthesis of tryptophan from serine and indole. Knowing that pyridoxal phosphate is involved as cofactor, provide the mechanism for the formation of tryptophan.
Name LastName Student ID 1 Which of the following statements is not true about glucose? A. It has four secondary alcohol groups. B. It has six carbons. C. It has four chirality centers. D. It has one primary alcohol group. E. It has one ketone group. 2 Which of the following is not true about D-glyceraldehyde? A. It is an aldose. B. Its chirality center has the S configuration. C. It is dextrorotatory. D. In the Fischer projection, the OH group bonded to the chirality center is on the right. E. It is a triose. 3 What is the name of the C-2 epimer of glucose? A. gulose B. allose C. altrose D. galactose E. mannose 4 Which of the following reagents is the best one to use if you want to reduce an aldose to an alditol? A. Br 2 B. NaBH 4 C. Li in liquid ammonia D. Na in liquid ammonia E. LiAlH 4 5 Which of the following reagents is used in the modified Kiliani-Fischer synthesis to reduce a cyano group to an imine? A. H +, H 2 O, and heat B. H 2 / Pd / BaSO 4 C. H 2 / Pt / CaSO 4 D. NaBH 4 / water E. H 2 / Pt 6 What is the stereochemical relationship between D-galactose and D-glucose? A. They are C-3 epimers. B. They are C-1 epimers. C. They are C-5 epimers. D. They are C-2 epimers. E. They are C-4 epimers.
7. How many stereoisomers can an aldopentose have? A. 4 B. 10 C. 6 D. 8 E. 12 8 Is the anomeric OH group axial or equatorial in beta-d-glucose, and what is the configuration of the anomeric carbon atom? A. equatorial; S B. equatorial; R C. axial; S D. axial; R 9 What product(s) are obtained when D-glucose reacts with ethanol under acidic conditions? A. only ethyl beta-d-glucopyranoside B. ethyl alpha-d-glucopyranoside and ethyl beta-d-glucopyranoside C. only ethyl alpha-d-glucopyranoside D. ethyl alpha-d-glucofuranoside and ethyl beta-d-glucofuranoside E. only ethyl beta-d-glucofuranoside 10 Which of the following are anomers? A. alpha-d-glucose and beta-d-glucose B. D-erythrose and D-threose C. D-glucose and D-mannose D. D-glucose and L-glucose E. D-glucose and D-fructose 11 Which of the following sugars does not contain an alpha-1,4'-glycosidic linkage? A. lactose B. amylopectin C. maltose D. amylose E. glycogen 12 Which of the following sugars is the most stable? A. alpha-d-glucose B. beta-l-galactose C. beta-d-glucose D. alpha-l-galactose E. beta-d-mannose
13. Which of the following are complex saccharides? A. monosaccharides B. disaccharides C. oligosaccharides D. polysaccharides E. b, c, and d 14 What is the stereochemical relationship between D-erythrose and L-erythrose? A. They are epimers. B. They are anomers. C. They are enantiomers. D. They are diastereoisomers. E. They are constitutional isomers. 15 Which of the following reagents will convert an aldose into an aldaric acid? A. HO-/H 2 O B. HNO 3 /heat C. NaBH 4 /H 2 O D. Ag+, NH 3 /HO- E. Br 2 /H 2 O 16 What is the structural relationship between the osazones of D-glucose and D-fructose? A. They are enantiomers. B. They are identical. C. They are epimers. D. They are anomers. E. They are diastereoisomers. 17 What is the approximate equilibrium concentration of the open-chain form of D-glucose in an aqueous solution? A. 2% B. 0.02% C. 10% D. 90% E. 20% 18 Reduction of D-fructose with sodium borohydride gives which pair of alditols? A. glucitol and gulitol B. galactitol and talitol C. gulitol and iditol D. glucitol and mannitol E. allitol and altritol
19 alpha-d-fructofuranose and alpha-d-fructopyranose are A. constitutional isomers. B. diastereoisomers. C. enantiomers. D. epimers. E. anomers. 20 Which of the following has three chirality centers? A. dihydroxyacetone B. D-glyceraldehyde C. D-ribose D. D-threose E. D-glucose 21 What kind(s) of glycosidic linkages are found in glycogen? A. alpha-1,4'- B. beta-1,4'- C. alpha-1,6'- D. a and b E. a and c 22 Which of the following disaccharides contains fructose? A. sucrose B. cellobiose C. maltose D. lactose 23 How many stereoisomers are possible for a ketohexose? A. 12 B. 8 C. 6 D. 10 E. 16 24 The major difference between amylopectin and glycogen is what? A. Glycogen has more alpha-1,6'-linkages. B. Glycogen is a reducing sugar, whereas amylopectin is a nonreducing sugar. C. Amylopectin contains beta-linkages, whereas glycogen has no beta-linkages. D. Amylopectin is a reducing sugar, whereas glycogen is a nonreducing sugar. E. Glycogen contains beta-linkages, whereas amylopectin has no beta-linkages. 25 What is the molecular formula of glucose? A. C 4 H 10 O 4
B. C 6 H 10 O 6 C. C 5 H 10 O 5 D. C 6 H 12 O 6 E. C 5 H 8 O 5 26 Which of the following statements about fructose is not true? A. It contains three secondary alcohol groups. B. It contains one ketone group. C. It contains three chirality centers. D. It contains one primary alcohol group. E. It contains six carbons. 27 Ribose is the sugar used in RNA. What type of sugar is ribose? A. an aldotriose B. an aldopentose C. a ketopentose D. an aldotetrose E. a ketotetrose 28 How many stereoisomers can an aldotetrose have? A. 2 B. 4 C. 6 D. 8 E. 10 29 What is the stereochemical relationship between D-erythrose and D-threose? A. They are diastereoisomers. B. They are enantiomers. C. They are constitutional isomers. D. They are anomers. E. They are C-1 epimers. 30 Which statement describes the stereochemical relationship between D-mannose and D- glucose? A. They are C-5 epimers. B. They are C-3 epimers. C. They are C-1 epimers. D. They are C-4 epimers. E. They are C-2 epimers. 31 Which of the following is not a true statement? A. The simplest aldotriose has one chirality center. B. D-Glyceraldehyde and L-glyceraldehyde are enantiomers. C. Glyceraldehyde and dihydroxyacetone are constitutional isomers.
D. D-Glyceraldehyde is R-glyceraldehyde. E. The simplest ketotriose has one chirality center. 32 What product is formed when glyceraldehyde reacts with an aqueous solution of Br 2? A. 3,3-dihydroxypropanoic acid B. 1,2-dihydroxybutanoic acid C. 2,2-dihydroxypropanoic acid D. 2,3-dihydroxypropanoic acid E. 2,3-dihydroxybutanoic acid 33 What product(s) is (are) obtained from a Kiliani-Fischer synthesis starting with D-erythrose? A. D-ribose and D-arabinose B. D-erythrose and D-threose C. D-ribose and L-ribose D. D-lyxose and D-xylose E. D-glyceraldehyde 34 Which of the following is not a true statement? A. Ketoses cannot be oxidized by Br 2. B. alpha-d-glucose is a nonreducing sugar. C. D-Glucose is the most common aldohexose found in nature. D. The smallest aldose is glyceraldehyde. E. An aldonic acid contains one carboxylic acid group. 35 What kind of compound is formed when one of the secondary alcohol groups of an aldose reacts with the aldehyde group? A. a hemiketal B. a ketal C. a lactone D. a hemiacetal E. an acetal 36 Which of the following statements about anomers is true? A. Anomers are diastereoisomers. B. Anomers are constitutional isomers. C. Anomers are C-2 epimers. D. Anomers are geometrical isomers. E. Anomers are enantiomers.