Palladium‐Catalyzed Triple Cyclization of 2,7‐Alkadiynylic Carbonates with Allenes Bearing a Carbon Nucleophile

Abstract

Palladium-catalyzed tandem reactions of 2,7-alkadiynylic carbonates with allenes bearing a carbon nucleophile such as malonate and bis(phenylsulfonyl)methane for the efficient syntheses of fused tricycles, such as 3,5,6,7-tetrahydro-1H-indeno[5,6-c]furan, 1,2,3,5,6,7-hexahydrocyclopenta[f]isoindole, and 1,2,3,5,6,7-hexahydro-s-indacene derivatives, have been reported. The reaction forms two five-membered rings and one benzene ring fusing them in the middle.

An Allene Approach to Tetrahydrofuran‐Fused Bicyclo[2.2.2]oct‐2‐enes

“…During the last 10 to 15 years much attention has been paid to transition metal‐catalyzed cyclization reactions of different types of allenes . In this area, we have studied the cyclization of allenes bearing a nucleophilic functionality in the presence of 2,7‐alkadiynyl carbonates affording tricyclic products A , B , [ 3b] or C . Interestingly when 2‐(buta‐2,3‐dienyl)malononitrile was used instead of allenoic acids, allenyl amides, or allenyl malonate or bis(phenylsulfonyl)methane, tetrahydrofuran‐fused bicycle[2.2.2]oct‐2‐enes 3 was formed unexpectedly.…”

4D bioprinting: the next-generation technology for biofabrication enabled by stimuli-responsive materials

“…As the humidity shifts in the surrounding environment, some of the biological systems release or absorb moistures. These phenomena thus inspired the development of humidity-responsive materials [87,88]. Naumov and co-workers developed a new material whose motion could be quickly actuated upon humidity change [89].…”

Palladium‐Catalyzed Double Cyclization Processes Leading to Polycyclic Heterocycles: Recent Advances

“…The group of Ma reported an interesting approach to tricyclic heterocycles starting from 2,7‐alkadiynylic carbonates and suitably functionalized allenes, based on an initial Pd(0)‐promoted propargyl‐allene rearrangement (by Pd(0) attack to the triple bond with simultaneous elimination of the methyl carbonate anion) followed by double carbocyclization and electrocyclization. Thus, tetrahydroindenofurans and hexahydrocyclopentaisoindoles were synthesized through an ordered sequence of steps involving propargylic rearrangement, carbocyclization (by intramolecular triple bond insertion), intermolecular carbopalladation of the internal C=C bond of the allene moiety, intramolecular carbanion allylation, electrocyclization, and aromatization (Scheme ) . More recently, this methodology was extended to the synthesis of tetrahydrofuran‐fused bicycle[2.2.2]oct‐2‐enes starting from 2,7‐alkadiynyl carbonates and 2‐(buta‐2,3‐dienyl)malononitrile (Scheme ) …”

“…Synthesis of tetrahydroindenofurans and hexahydrocyclopentaisoindoles from 2,7‐alkadiynylic carbonates and suitably functionalized allenes …”