RCM vs Oxacycloisomerization through Divergent Reactivity of Dienyl‐ or Ynenylcycloalkanols using Grubbs Catalyst: an Access to Carbobicycles and Fused Bicyclic Dihydrofurans

Abstract

AbstractStarting from simple cyclic 1,3‐ketoesters, a three‐steps sequence including allylic or propargylic allylation, 1,2‐addition reaction of functional Grignard reagent and alkylidene ruthenium‐catalyzed cyclization yields to carbobicycles and/or bicyclic dihydrofurans depending on the nature of the insaturation (diene or enyne). If the classical ene‐ene ring closing metathesis is observed with dienyl substituents, similar enynes led to enyne ring closing metathesis or oxacycloisomerization products depending on the chain length. In the case of ene‐yne systems with appropriate longer carbon chains, under the same conditions, metathesis reations give access to bicyclic dihydrofurans through oxacycloisomerization, demonstrating that it is possible to orient the activity of the Grubbs reagent.