Domino Heck–Diels–Alder Reactions of Differently Substituted Cyclopropylallenes

Abstract

Several substituted cyclopropylallenes were coupled under Heck conditions with aryl iodides and aryl bromides, respectively, and the 1,3,5-hexatrienes resulting with ring-opening of the cyclopropyl group, were captured in situ by a number of reactive dienophiles to yield oligosubstituted cyclohexene derivatives (8-86 %, 33 examples) with diastereomeric ratios ranging from 1.4:1 to 4.9:1. The influences of the number, the

Transition metals in organic synthesis: Highlights for the year 2005

“…1-Cyclopropyl-1,2-dienes were used in Heck reactions to form 1,3,5-trienes [419]. Related reactions of 3,4-dienoates with aryl halides forming 4-aryl-2,4-dienoates were reported [420].…”

Transition Metal Chemistry of Cyclopropenes and Cyclopropanes

“…de Meijere demonstrated that allenylcyclopropanes 587 undergo cascade Heck-type arylation−Diels−Alder cycloaddition with activated dienophiles to produce isomeric vinylcyclohexene derivatives 588 and 589 (Scheme ). , The first step of this sequential transformation involves arylpalladation of the allenyl moiety in 587 to afford π-allylpalladium species 590 , which, upon consecutive β-carbon and β-hydride elimination, produces unstable triene 591 . The latter undergoes [4 + 2] cycloaddition with activated dienophiles, which presumably proceeds stepwise via a mesomerically stabilized 1,6-zwitterionic intermediate 592 , to give a diastereomeric mixture of 588 and 589 , with the thermodynamically more favorable 588 being a major product (Scheme ). ,

190

…”

The Heck Reaction Applied to 1,3- and 1,2-Unsaturated Derivatives, a Way towards Molecular Complexity

“…3-(1’-Arylalkenyl)-substituted cyclohexenes 37 were achieved in moderate to good yields [ 24 ]. Then the methodology was extended to differently substituted cyclopropylallenes [ 25 ]. When the reaction was performed without the added dienophile, the intermediate coupling product 36 was isolated and characterized, unfortunately it underwent polymerization within a few hours at room temperature.…”