Synthesis of Benzofulvenes by Palladium‐Catalyzed Cyclization of 1,2‐Dialkynylbenzenes

Abstract

A palladium-catalyzed cyclization of enediynes for the synthesis of benzofulvenes 2 in yields of 59-76 % was accomplished by treatment of dialkynylbenzenes 1 with 5 mol-% of PdX 2 and 3 equiv. of CuX 2 in acetonitrile at 60°C for 2 h.

Palladium‐Catalyzed Cyclization of Enediynes to Benzopyranones

“…[6] Recently, we found that treatment of 1,2-dialkynylbenzenes with five mol% of PdCl 2 and two equivalents of CuCl 2 gave benzofulvenes in good chemical yields. [7] Our continued interest in the cyclization reactions of enediynes for the synthesis of heterocycles [8] encouraged us to investigate the cyclization reaction of methyl 2-[6-substituted-3(Z)-hexen-1,5-diynyl]benzoates (1) in the presence of catalytic amount of PdCl 2 and three equivalents of CuCl 2 to give functionalized dibenzo-…”

Synthesis of Trifluoromethanesulfanylbenzofulvenes via a Cascade Electrophilic Cyclization under Mild Conditions

“…Initially, we focused on the regioselective construction of the halogenated benzofulvenes 23. The halogenation reactions of benzofulvenes are mostly directed by using electrophilic halogenating agents, which have high oxidizing ability 24. Therefore, the advanced reactions using readily available halide anions directly should be undoubtedly easier to handle.…”

Regioselective 5‐endo‐dig Electrophilic Iodocyclization of Enediynes: A Convenient Route to Iodo‐substituted Indenes and Cyclopenta‐Fused Arenes

“…Alabugin and co‐workers have developed a two‐step strategy for the synthesis of benzofulvene by Bu 3 SnH‐mediated 5‐ exo ‐ dig radical cyclization of a diaryl enediyne. Subsequently, Lee et al . have explored the synthesis of benzofulvenes by Bergman cyclization using a Pd/Cu catalyst.…”