Two-fold tandem acyl-group shift/cyclization via gold catalysis

Abstract

A complex cascade involving allendiynes in the presence of a cationic gold catalyst is described. The process features two sequential acyl-group shift/cyclization steps eventually delivering a bicyclic furan derivative from the acyclic precursor. A controlled sequence of molecular events can thus readily deliver the desired heterocycle with a remarkable selectivity.

Regio‐ and Site‐selective Molecular Rearrangements by Homogeneous Gold Catalysis

“…The point of dissimilarity of this work compared to Chan's approach [141,147] is that the former transformation is triggered by 1,3‐acyl shift, whilst the later by 1,2‐acyl shift. Also, the gold activated two‐fold tandem 1,3‐acyl shift/1,5‐acyl shift/cyclization of diyne allenoate precursors to bicyclic enones 107 selectively was documented by Malacria and Fensterbank [171] . Regiodivergent cyclic products can be accessed from 1,6‐diyne carbonates 106 by the activation of gold in different oxidation state (Au(I) and Au(III)) as well as possessing ancillary ligands of different electronic nature and steric bulk.…”

“…Also, the gold activated two-fold tandem 1,3-acyl shift/1,5-acyl shift/cyclization of diyne allenoate precursors to bicyclic enones 107 selectively was documented by Malacria and Fensterbank. [171] Regiodivergent cyclic products can be accessed from 1,6-diyne carbonates 106 by the activation of gold in different oxidation state (Au(I) and Au(III)) as well as possessing ancillary ligands of different electronic nature and steric bulk. Nevertheless, in all cases, the reaction is triggered by a selective 1,3-acyloxy shift to afford highly substituted different cyclic products 107, 108 and 109 (Scheme 26, eq 2).…”