4-Endo-Trig Cyclization Processes Using Bis(collidine)bromine(I) Hexafluorophosphate as Reagent: Preparation of 2-Oxetanones, 2-Azetidinones, and Oxetanes.

摘要: Reaction in methylene chloride of bis(collidine)bromine(I) hexafluorophosphate with α,β-unsaturated acids and N-sulfonamides was found to lead diastereospecifically the corresponding 2-oxetanones 2-azetidinones moderate yields (23−60%), by an almost unknown 4-endo cyclization. This process allow synthesis these interesting classes products one step from common substrates. Similarly, reaction cinnamic alcohols led, same cyclization procedure, oxetanes (20−36%); presence a gem-dimethyl group α alcohol function appeared beneficial.