Stereoselective Approach to Multisubstituted Enolates from Unactivated Alkynes: Oxyalkylidenation of Alkynyl Ketone Enolates with Aldehydes

The preparation of multisubstituted enolates with precise regio- and stereocontrol is a nontrivial task when conventional deprotonation methods are used on the corresponding carbonyl compounds. We describe herein an approach to preparing stereodefined enolates by leveraging the stereoselective oxyfunctionalization of unactivated alkynes, particularly in the context of the alkynylogous aldol reaction. trans-Iodo(III)acetoxylation of alkynes and subsequent Sonogashira coupling allow for the facile preparation of multisubstituted enynyl acetates, which can be deacetylated by MeLi into the corresponding enolates. The alkynyl enolates react with aldehydes to afford γ,δ-unsaturated β-diketones through a cascade of alkynylogous aldol addition, intramolecular Michael addition, and ring opening of the oxetene intermediate

Stereoselective Synthesis of β‑Alkoxy-β-amido Vinylbenziodoxoles via Iodo(III)etherification of Ynamides

A trans-iodo(III)etherification reaction of ynamides with benziodoxole triflate and alcohols is reported. Despite the sensitivity of ynamides and enamides toward Brønsted acid, the reaction could be successfully performed under carefully controlled conditions to afford β-alkoxy-β-amido vinylbenziodoxoles in moderate to good yields. The products could be subjected to a sequence of cross-coupling via C–I(III) bond cleavage and electrophilic halogenation of the resulting α-alkoxyenamides, allowing for the preparation of densely functionalized esters