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Solutions to Problems . 493 0 0 N(CH₂)₄Cl N + O 1. NH3 + 2. HCN Chiral, but 3. racemic 39. (a) CH₂CHO (i.e., not optically active) Stereocenter (b) The use of an optically active amine (an S enantiomer is shown) means that the addition product is actually a mixture, because a second stereocenter is which can be either R or S. This therefore, a mixture of R,S and S,S products. Because these are diastereomers of each other, they don't necessarily form in identical yields. In fact. the S.S product (illustrated) greatly predominates. and, after hydrolysis and removal of the phenylmethyl group with mainly S amino acid is obtained. 40. Allicin is structurally related to cysteine, which should be readily available if you can first devise an approach to serine. NaOH. NCH(CO₂CH₂CH₃)₂ Aldol cond. (compare Problem 38(d)] 1. 2. Na SH N Hydrolysis at this stage would make