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
aza-Baylis−Hillman/alkylation/RCM route. While deprotection of Ts-protected pyrrolines gave only pyrroles, deprotection of the same SES-protected compounds gave either pyrroles or free amine pyrrolines depending on the deprotection conditions. The SES-protected pyrrolines were hydrogenated to yield pyrrolidines with an excellent diastereoselectivity. Free amine pyrrolidines were obtained by HF-mediated