Gold-Catalyzed Regioselective Synthesis of Crowded Cyclopentadienes by Migratory Cycloisomerization of Vinylallenes

1,2-Silyl Rearrangement in Gold Carbene Chemistry: Synthesis of Furyl-Decorated Tetrasubstituted Silylallene Derivatives

The gold-catalyzed reaction of 2-en-4-ynones with alkynylsilanes provides fully substituted allene derivatives bearing furyl and silyl groups. This transformation would involve generation of a gold furyl carbene intermediate, which regioselectively undergoes a nucleophilic attack by the alkynylsilane at the electrophilic carbene carbon atom with the formation of a β-gold vinyl cation species. The subsequent release of the gold catalyst, accompanied by a 1,2-silyl shift, leads to the formation of tetrasubstituted allene products.

Enantioselective and Regiodivergent Gold and Chiral Brønsted Acid Catalyzed Cycloisomerization/Diels-Alder Reaction of 1,10-Dien-4-yn-3-yl Acetates: Synthesis of Norbornene-Embedded Tricarbocycles

A synthetic method for the enantioselective and regiodivergent synthesis of hexahydro-2H-2,4a-methanonaphthalen-4-yl and octahydro-2,4-methanoazulen-1-yl esters that relies on the gold(I)- and chiral Brønsted acid-catalyzed cycloisomerization/Diels-Alder (CDA) reaction of (E)-1,10-dien-4-yn-3-yl acetates is described.

Ni-Catalyzed 1,5-Sigmatropic Ester Shift on Cyclopentadiene Rings: Regioselective Conversion of 5,5-Disubstituted Cyclopentadienes to CH2-Cyclopentadienes

Described herein is a nickel(II)-catalyzed regioselective rearrangement of 5,5-disubstituted cyclopentadienes to fully functionalized CH2-cyclopentadienes via successive 1,5-sigmatropic shifts of the ester group on the quaternary carbon and hydrogen under mild basic conditions. The obtained CH2-cyclopentadienes were also readily applied in the preparation of highly functionalized dibenzo[e,g]azulene derivatives in two steps.