Chem 634 Pre Problem Set February 10 2004 Prof Fox 1 Assign all stereochemistry R or S E or Z a b CH3 H OH d c Br Cl CHO O CH2 Br O Cl 2 For each pair which is more stable c b a t Bu t Bu t Bu t Bu t Bu t Bu Br OH OH Br 3 Indicate the relationship for each pair below enantiomers diastereomers or meso a CH3 H OH H OH CH3 b CH3 HO H HO H CH3 OH S S S HO R HO OH 4 For each pair indicate which is more stable Use a clear picture to explain why Br Br Br Br t Bu t Bu 5 Provide a detailed arrow pushing mechanism for the following reaction Br Bu3 SnH H AIBN O H O H 6 Draw Newman projections for the staggered and eclipsed forms of n butane Give the relative energies of all of the eclipsed and staggered conformers 7 Gauche butane is 0 8 kcal mol higher in energy than anti butane The A strain of a methyl group on cyclohexane is 1 7 kcal mol Use Newman projections to explain the relationship in detail 8 Provide a mechanism NaSMe O O Br SMe 9 The reaction below is an S N2 process However the absolute configurations of the starting material and products are both R Explain Hint this is a trick question R Br HO O R NaH S S 10 Which reaction is faster A or B Why A HBr HO B Br HBr OH Br 11 Which reaction is faster A or B Why A B HBr HO Et Et HO Br Et HBr Et Br 12 Provide a detailed explanation Br NaOtBu but Br NaOtBu X 13 Provide a detailed arrow pushing mechanism OTs H catalytic H CH3 H H 2O H CH3
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