Interception of a Rautenstrauch Intermediate by Alkynes for [5+2] Cycloaddition: Rhodium-Catalyzed Cycloisomerizatlon of 3-Acyloxy-4-ene-1,9-diynes to Blcyclo [5.3.0] decatrienes

摘要

In 1984, Rautenstrauch reported that the 3-acyloxy-1,4-enyne 1 could undergo cyclization to form cyclopentadiene 2 and cyclopentenone 3 in the presence of a palladium catalyst through 1,2-acyloxy migration (Scheme 1). The vinyl metal complex 4, metal carbene 5, and metallacyclohexadiene 6 were proposed as intermediates in this transformation. The scope of this rearrangement reaction has been expanded significantly by the use of π-acidic metals, such as gold- and platinum-based catalysts, for the synthesis of functionalized five-membered rings. The 1,2-acyloxy migration of prop-argyl esters has also been employed in other synthetically useful transformations catalyzed by gold, platinum, ruthenium, copper, and more recently rhodium.