Question

2. N-bromosuccinimide is a synthetically diverse reagent. List four additional types of reactions, other than oxidation of a pyridines, in which NBS can be used. 3. Dihydropyrimidines can form with similar conditions and building blocks to the mechanism for the Hantzsch Ester following a Biginelli synthesis. Provide a mechanism for the formation of the following dihydropyrimidine. 4. Rosiglitazone, 12, is a type-2 diabetes drug that helps control the metabolism of carbohydrates and fatty acids. Provide a mechanism for the conversion of 7 to the pyridine 11 POC 150C Na DMF 80C Mg MeOH HOAc 11 toluene, refux

Answer 1

NBS N-Boromosuccianide (NBS) is a powerful reagent which is widely used in organic chemistry for a number of synthetic. transformations . » Addition to alkane RA When tho THE Halohydrin Addition of NBS to alkene results in electrophilic addition, net markonikove addition and antistereo chemical reas selectivity to produce Halohydrin 2) Allglie Bromination alkens ho Ra Br NBS - > alkene free radical takes place addition. Allylbromide substitution of alkene instead of electrophilic

3) Bromination of u NBS carbonyl derivative la ci H BYT ccly Br Acetylchloride X-Bromo aid chloride This is a powerful method of d-halogen -ation of carberge derzelties 4) Oxidatie decarboxylation of x-amino acids R u ... NBS NH₂ HNH -CO, V-HBO 138 Bromination of NH ₂- takes place which undergoes decarboxylation to produce imine and condensation elimination of HB also takes place. re itts stereo oduce