Asymmetric synthesis of α,β-diamino acid derivatives with an aziridine-,
azetidine- and γ-lactone-skeleton via Mannich-type additions across α-chloro-
N-sulfinylimines
The efficient asymmetric synthesis of new chiral γ-chloro-α,β-diamino acid derivatives via highly
diastereoselective Mannich-type reactions of N-(diphenylmethylene) glycine esters across a chiral
α-chloro-N-p-toluenesulfinylimine was developed. The influence of the base, LDA or LiHMDS, used for
the formation of the glycine enolates, was of great importance for the anti-/syn-diastereoselectivity of the
Mannich-type reaction. The γ-chloro-α,β-diamino acid derivatives proved to be excellent building blocks
for ring closure towards optically pure anti- and syn-β,γ-aziridino-α-amino esters, and subsequent ring
transformation into trans-3-aminoazetidine-2-carboxylic acid derivatives and α,β-diamino-
γ-butyrolactones
