... The pre- dominance of a free-radical mechanism or of a stepwise (2) Negishi, E. Organometallics in Organic Synthesis; Wiley: New York, 1980; p 410. ... Page 2. Hydrostannylation of Propargyl Alcohols J. Org. Chem., Vol. 53, No. 4, 1988 821 k' ' ' R' BusSn R '+OH R' Scheme I1 ...