The application of ruthenium alkylidenes such as 1 to the catalysis of polycyclization reactions is reported. Several acyclic precursors have been synthesized and reacted with 1. These precursors vary in topology and contain acetylenic and/or cycloolefinic metathesis relays. The cyclization reactions proceed in moderate to good yields to produce polycyclic polyenes when the precursors are subjected to catalytic amounts of 1. In general, precursors bearing n relay units generate polycycles containing (n + 1) rings.
An Enantioselective Cascade Cyclopropanation Reaction Catalyzed by Rhodium(I): Asymmetric Synthesis of Vinylcyclopropanes
作者:Òscar Torres、Anna Roglans、Anna Pla-Quintana
DOI:10.1002/adsc.201600789
日期:2016.11.17
N‐Tosylhydrazone‐yne‐ene substrates are satisfactorily prepared and their cyclization under rhodium catalysis is evaluated. A cascade process involving rhodium vinyl carbene formation – through carbene/alkyne metathesis – and cyclopropanation has been developed to stereoselectively afford vinylcyclopropanes.
Transition-metal-catalyzed cycloisomerization reactions with skeletalrearrangement of 1,n-enynes to afford cyclic dienes (particularly exo-cyclization products) have been well studied. However, there are few reports on the nonmetal-catalyzed skeletalrearrangement of enynes and skeletalrearrangement of electron-deficient enynes such as n-en-2-ynones. Here, we describe BF3·MeCN-catalyzed synthesis