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)(CHCMe 2 Ph)(Me 2 Pyr) 2 (Ar = 2,6- i -Pr 2 C 6 H 3, Me 2 Pyr = 2,5-dimethylpyrrolyl) in diethyl ether or THF yields Mo(NAr)(CHCMe 2 Ph)(OR)(Me 2 Pyr) species where R = (CH 3 ) 3 C ( 1, 22% isolated yield), (CH 3 ) 2 CH ( 2, 83%), Ar ( 3, 81%), (CF 3 ) 2 CH ( 4, 45%), or (CF 3 ) 2 (CH 3 )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.