Synthesis of Cyano Cyclic Olefins Through Ring‐Closing Metathesis.

Abstract

Ring-closing metathesis has become a very powerful, versatile, and widely used method for the construction of cyclic ring systems in organic synthesis. 1 The superior reactivity of Grubbs second generation catalyst 1, which has air-stability and thermal stability, is very important for the formation of tri-and tetra-substituted olefins having electron withdrawing groups. Recently, Weinreb, 2a Salim, 2b and Rutjes 2c reported on the formation of carbocyclic and heterocyclic olefin by ring-closing metathesis of halogen (F, Cl, CF3) substituted olefins. Literature survey reveals that most of bisterminal olefins with electron withdrawing groups such as CO2Et, Br, and CN resulted in little to no yield of the RCM product under the condition of using the Grubbs first generation catalyst, 3 but the microwave irradiation on olefin with carboxymethyl substituent (CO2Me) provided the desired product. 4