Photochemically generated nitrilium phosphane-ylid tungsten complexes and their reactivity towards alkyne and nitrile derivatives

Abstract

The photochemically generated nitrilium phosphane-ylid tungsten complex 2 reacts with different activated alkynes, dimethyl acetylenedicarboxylate (DMAD) (i) and ethyl acetylenecarboxylate (ii), and nitriles, ethyl cyanoformate (ECF) (iii) and 1-piperidinonitrile (iv), giving [3+2] cycloaddition products such as the 2H-1,2-azaphosphole complexes 3 (i) and 4 (ii), the 2H-1,4,2-diazaphosphole complex 5 (iii) and the 2H-1,3,2-diazaphosphole complex 7 in good to excellent yields, the latter complexes, 4–7, being formed regioselectively; the structure of the first ester-functionalized 2H-1,4,2-diazaphosphole complex 5 was established by X-ray analysis.