Some applications and chemistry of (S)-2-(diphenylmethyl)-pyrrolidine

Abstract

The synthetic utility of (S)-2-(diphenylmethyl)-pyrrolidine (1) and its amide derivative, (S)-2-(diphenylmethyl)-5-oxo-pyrrolidine (2) were examined in two contexts; as chiral auxiliary compounds in asymmetric alkylation reactions and Diels- Alder reactions; as chiral solvating agents (CSAs) for (^1)NMR evaluation of chiral acids and alcohols. In the former case, it was shown that monoalkylation of N-acyl derivatives of (1) and (2) using lithiated bases led to poor diastereoselectivities (1:1 to 1.12:1) and poor yields (28 to 33 %), while alkylation reactions using HMPA proceeded with modest diastereoselectivities (1.49:1 to 4.25:1). The results of the Diels-Alder study remain premature at present. In the latter case, (1) was an excellent chiral solvating agent (CSA) for chiral carboxylic acids, however it was less effective for chiral alcohols. The amide derivative (2) was substantially less effective as a CSA for chiral carboxylic acids and failed completely to resolve chiral alcohols.