Gold-Catalyzed 1,2-Oxyalkynylation of N-Allenamides with Ethylnylbenziodoxolones

Abstract

A gold-catalyzed 1,2-oxyalkynylation of N-allenamides with ethylnylbenziodoxolones (EBXs) has been achieved for the first time. The reaction, which follows a redox-neutral Au(I)/Au(III) catalytic pathway, was enabled in an attempt to exhaust the EBX reagents atom-economically by putting the nucleophilic carboxylate part of EBXs to appropriate use. This constitutes the first example for gold-catalyzed β-alkynylation of N-allenamides to construct highly valuable 1,3-enynes. The potential of the sequence is further documented by some follow-up transformations.

Gold‐Catalyzed Cross‐Coupling Reactions: An Overview of Design Strategies, Mechanistic Studies, and Applications

“…[183,184] Scheme17. [187] Chem.E ur.J.2020, 26,1442 -1487 www.chemeurj.org 4 ]i nt he presence of selectfluor.T his study shows that by tuning the nature of oxidants, one could achieve product selectivity or generate unique products. [183,184] Scheme18.…”

“…The oxidation of Au I to Au III is proposed to be ap lausibles tep involved in the mecha-nism. [187] Ap henanthryll igand (phen) framework was utilized to facilitatethe oxidation of Au I to Au III .Notably,the reaction afforded direct access to 1,3-enynes through double functionalization routes.T oc onclude, all these studies have established that homogeneous Au catalysis mediated by TIPS-EBX is an excellent methodf or the synthesis of al arge variety of building blocks in materials science and chemistry through direct alkynylation strategies. The Waser group later reported an improved methodology for the Au-catalyzed direct alkynylation of heterocycles (Scheme 18 b) by using modified TIPS-EBX reagents.…”

“…[186] Very recently, Patil and co-workers have strategized an atom-economical 1,2oxyalkynylation of N-allenamides with TIPS-EBX partners (Scheme 18 d). [187] Ap henanthryll igand (phen) framework was utilized to facilitatethe oxidation of Au I to Au III .Notably,the reaction afforded direct access to 1,3-enynes through double functionalization routes.T oc onclude, all these studies have established that homogeneous Au catalysis mediated by TIPS-EBX is an excellent methodf or the synthesis of al arge variety of building blocks in materials science and chemistry through direct alkynylation strategies.…”

“…(d) Au and phencatalyzed 1,2-oxyalkynylation of N-allenamideswith TIPS-EBX. [187] [Au(PPh 3 ) 2 ]-[Au(C 6 F 5 ) 4 ]i nt he presence of selectfluor.T his study shows that by tuning the nature of oxidants, one could achieve product selectivity or generate unique products.…”

Photocatalytic Umpolung ofN- andO-substituted alkenes for the synthesis of 1,2-amino alcohols and diols

“…The Patil group reported a gold catalysed 1,2oxyalkynylation of allenenamides with EBXs (Scheme 1B, b, X ¼ alkynyl), involving both redox and p-activation by the gold catalyst. 49 Consequently, 1,2-oxyalkynylation remains limited to allenenamides as substrates and photocatalytically generated radical cations have never been intercepted with EBX reagents. 50 Herein, we show that ene-carbamate radical cations can be generated under oxidative photoredox conditions using 4-CzIPN-derived organic dyes.…”