Bifunctionalized Allenes. Part X. An Electrophilic Cyclization Protocol for Convenient Highly Regioselective Synthesis of 3-Sulfonylfuran-2(5H)-ones from 2-Sulfonylallenoates

Abstract

A simple and convenient protocol for the highly regioselective synthesis of 3-sulfonylfuran-2(5H)-ones by electrophilic cyclization reaction of 2-sulfonylallenecarboxylates with neighbouring ester group participation is described.However, the reaction of 2-sulfonylalka-2,3-dien-1-ones with electrophilic reagents proceeded with formation of 2-sulfonylalka-2,4-dien-1-ones by addition-elimination reaction.A possible mechanism involving the cyclization and addition-elimination reaction of 2-sulfonyl-substituted allenic esters and ketones was proposed.Unsaturated -lactones, i.e., butenolides or furan-2(5H)-ones are an important class of compounds because they often occur in natural products and exhibit a broad range of biological activities. 1,2These compounds with different substitution patterns are considered as potential insectides, fungicides, bactericides, antibiotics, anticancer agents, allergy inhibitors, antiinflammatories, antipsoriasis agents, stimulatory agents, cyclooxygenase inhibitors, antimutagen agents, phospholipase A2 inhibitors, etc. 2 Furan-2(5H)-ones are also important intermediates in organic synthesis due to the presence of the conjugated C=C bond as well as the five-membered lactone ring.Much attention has been paid to the development of efficient and diverse synthetic methods for construction of this five-membered ring