Chem 634 Professor Fox Exam 1 October 12 2004 3 hours Your Name 1 Chem 634 Exam 1 Your Name 1 Provide reagents for the following transformations More than one step may be required Mechanistic details are not needed five parts 3 pts each OTMS O a b Ph Ph O OH tBu tBu c CO2 Me O O 2 Chem 634 Exam 1 1 Your Name continued O d e O O NEt2 O O NEt2 TMS HO2C O 3 Chem 634 Exam 1 Your Name 2 Predict if each of the following reactions would proceed as written If you feel that the reactionwould proceed simply write will proceed as written If you feel that the reaction would not proceed as written provide a brief but detailed explanation and indicate the structure of the product s that would be formed instead of or in addition to the product that is drawn 3 points each a b HO O tBu tBu Ph2CuLi then H O Ph OH 4 Chem 634 Exam 1 2 Your Name continued Et c Me2CuLi O Et then H O d CO2Me N Me CO 2Me N 5 Chem 634 Exam 1 Your Name 3 Identify the type of selectivity for each reaction Circle the correct answer 2 pts each chemoselectivity a regioselectivity EtMgBr OH CHO OH vs Et Et diastereoselectivity enantioselectivity chemoselectivity b OH 1 BH3 vs regioselectivity HO 2 H2O2 diastereoselectivity enantioselectivity chemoselectivity c OH Et2Zn PhCHO OH Et vs Et Me N OH regioselectivity diastereoselectivity enantioselectivity chemoselectivity H3C d LiAlH4 H3C O H O H regioselectivity OH vs diastereoselectivity O enantioselectivity 6 H3C H OH O Chem 634 Exam 1 4a Your Name Propose a structure for intermediate A Propose an arrow pushing mechanism for the formation of A and B For this part of the problem it is not necessary to explain the stereochemical aspects of the reaction Just push the arrows and show how the final product is formed 9 pts O MgBr O Ph Ph O 2 equiv A H3O Ph Ph B 7 Chem 634 Exam 1 4b Your Name Propose a model that explains the diastereoselectivity of the reaction 6 pts O MgBr O Ph Ph O 2 equiv A H3O Ph Ph B 8 Chem 634 Exam 1 Your Name 5 a Write a detailed mechanism for the reaction below 8 pts Ph H3C I O 1 Pd PPh3 4 CH3 PhB OH 2 Na2CO3 O 2 9 Chem 634 Exam 1 Your Name 5 b Unlike the reaction of 1 to 2 the reaction of 3 does not give the analogous product 5 Instead product 4 is obtained Write a mechanism for the formation of 4 and explain why 5 is not obtained 7 pts Ph H3C I O Pd PPh3 4 CH3 1 I O 3 Pd PPh3 4 H O PhB OH 2 Na2CO3 PhB OH 2 Na2CO 3 2 H Ph C9H8O 4 O 5 not formed 10 Chem 634 Exam 1 Your Name 6 a Propose a structure for intermediate A Propose an arrow pushing mechanism for the formation of A and B For this part of the problem it is not necessary to explain the stereochemical aspects of the reaction Just push the arrows and show how the final product is formed 8 points O N Cl O K2CO 3 A C12H22NOCl N B 11 Chem 634 Exam 1 Your Name 6b Provide a detailed model that explains the diastereoselectivity of the reaction What conclusion can you make about the stereoselectivity of the enolization event 7 points O N Cl O K2CO 3 A N B 12 Chem 634 Exam 1 Your Name 7 Outline a multistep synthesis using any materials with 6 carbons or less 20 points H OH H Me Me 13 Chem 634 Exam 1 Your Name 7 cont 14
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