2-Trimethylsilylethanesulfonyl (SES) versus Tosyl (Ts) Protecting Group in the Preparation of Nitrogen-Containing Five-Membered Rings. A Novel Route for the Synthesis of Substituted Pyrrolines and Pyrrolidines

摘要

The 2-trimethylsilylethanesulfonyl (or SES) protecting group was compared to the tosyl (Ts) group in the preparation of a nitrogen-containing five-membered ring obtained by the aza-Baylis—Hillman/alkylation/RCM route. While deprotec-tion of Ts-protected pyrrolines gave only pyrroles, depro-tection of the same SES-protected compounds gave either pyrroles or free amine pyrrolines depending on the depro-tection conditions. The SES-protected pyrrolines were hy-drogenated to yield pyrrolidines with an excellent diastere-oselectivity. Free amine pyrrolidines were obtained by HF-mediated deprotection of the SES group.