Synthesis of Monoalkoxide Monopyrrolyl Complexes Mo(NR)(CHR‘)(OR‘ ‘)(pyrrolyl): Enyne Metathesis with High Oxidation State Catalysts

Addition of 1 equiv of ROH to Mo(NAr)(CHCMe2Ph)(Me2Pyr)2 (Ar = 2,6-i-Pr2C6H3, Me2Pyr = 2,5-dimethylpyrrolyl) in diethyl ether or THF yields Mo(NAr)(CHCMe2Ph)(OR)(Me2Pyr) species where R = (CH3)3C (1, 22% isolated yield), (CH3)2CH (2, 83%), Ar (3, 81%), (CF3)2CH (4, 45%), or (CF3)2(CH3)C (5, 80%). Ring-closing enyne metathesis by various catalysts leads to cyclic products that arise through initial addition of the triple bond to a methylene species (initially neophylidene) to yield an α- or a β-substituted metallacyclobutene intermediate.