No 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

Cyclopropane derivatives Cyclopropane derivatives Q 0021Cyclopropyl Building Blocks for Organic Synthesis. Part 85. A Versatile Access to 1-Cyclopropyl-2-aryl-1,3,5-hexatrienes -Domino Heck-Diels-Alder Reactions of 1,3-Dicyclopropyl-1,2-propadiene. -An efficient three-step synthesis of the allene (V) is described. It is found to undergo Pd-catalyzed domino Heck-Diels-Alder reaction with aryl halides and dienophiles via hexatriene intermediates. - (KNOKE, M.; DE MEIJERE*, A.; Synlett 2003, 2, 195-198; Inst. Org. Chem.,

ca. 30 refs.]. -(DE MEIJERE*, A.; SCHELPER, M.; KNOKE, M.; YUCEL, B.; SUENNEMANN, H. W.; SCHEURICH, R. P.; ARVE, L.; J.

Cyclohexane derivatives Q 0040 Small Ring Building Blocks for Organic Synthesis. Part 110. Domino Heck--Diels-Alder Reactions of Differently Substituted Cyclopropylallenes. -A sequential Heck and Diels-Alder reaction is a useful access to 4,5-disubstituted 3-alkenylcyclohexenes starting from easily prepared cyclopropylallenes (I) and commercially available aryl halides and dienophiles. The title compounds are obtained with yields of 8-86% (33 examples) and diastereomeric ratios ranging from 1.4:1 to 4.9:1. -(KNOKE, M.; DE MEIJERE*, A.; Eur.