Stereoselective synthesis of 2,3-disubstituted dihydrobenzofuran using alkyne Prins type cyclization to vinylogous carbonates

Abstract

An intramolecular, alkyne Prins type cyclization of vinylogous carbonates derived from o-alkynyl phenols is developed for the stereoselective construction of trans-2,3-disubstituted dihydrobenzofuran derivatives. Strong Lewis acids like TMSOTf catalyse this reaction efficiently. The presence of mildly electron donating groups on aryl rings increases the efficiency of the reaction.

Alkynyl Prins and Alkynyl Aza-Prins Annulations: Scope and Synthetic Applications

“…Similar chemistry by the Gharpure group has also been accomplished with oxocarbenium electrophiles. 54…”

Diastereoselective Synthesis of Substituted Tetrahydrofurans via Prins Cyclization of Enol Ethers

“…Prins cyclization is an important reaction for the synthesis of tetrahydropyrans and tetrahydrofurans because of its diastereoselectivity . Although there are many reported methods for the synthesis of di- and tetrahydropyrans via the Prins cyclization reaction, methods for the synthesis of tetrahydrofuran are limited. − , We now present a method for the stereoselective synthesis of cis -2,5-tetrahydrofurans using the Prins cyclization reaction of enol ethers having alkyne side chains mediated by indium triflate at ambient temperature in moderate to good yields.…”

Transposition of an acrylate moiety in TMSOTf-mediated reaction of alkynyl vinylogous carbonates gives heterocyclic dienes

“…4 In a program directed at the synthesis of oxa- and aza-cycles using vinylogous carbonates and carbamates, respectively, we disclosed stereoselective synthesis of dihydrobenzofurans ( via oxonium), and indolines and pyrrolidine derivatives ( via iminium) using intramolecular alkyne Prins-type cyclizations (Scheme 1-A). 5 In continuation of our interest in the synthesis of 1,4-heterocycles, 6 we envisioned that 1,4-oxazepanes too could be rapidly accessed using this alkyne Prins-type cyclization protocol starting with appropriate alkynyl vinylogous carbonates. To test this hypothesis, alkynyl vinylogous carbonate 1a was subjected to treatment with TMSOTf in CH 2 Cl 2 at 0 °C.…”