The following data indicate that the dehydration of certain amino acid derivatives is stereo-specific.

Divide the task of analyzing these data among you to determine the nature of the stereo Controlled eliminations. Assign the absolute configuration (R,S) to compounds la-Id and the E,Z configuration to compounds 2a-2d. Draw a Newman projection of the active conformation of each starting compound (la-Id). As a team, apply your understanding of this information to determine the absolute configuration of the unassigned stereo-center (marked by an asterisk) in compound 3, which was dehydrated to afford compound 4, an intermediate in an approach to the synthesis of compound 5, an antitumor agent.

(P1 and P2 are protecting groups)

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1, CH SO,CI, pyridine CO CH CH CO CH C,H 2. R,N base с-с NHCo,CH,C,Hs R NHCO-CH2CH a CH H CHy b CH(CH H CH(CH3)2 d H OH O OCH OCH3 1, CH, SO-CI. pyridine H O NH HH 2. R,N base P s NH NHP NHP 0 O NH NH