摘要:
The stannylcupration of terminal alkynes 4a,b with cuprates 1-3 proceeds rapidly and reversibly above -35-degrees-C to afford vinylcuprate intermediates 5a,b and 6a,b. These intermediates have been characterized by H-2 and C-13 NMR labeling experiments. Corroborating evidence for this reversible addition comes from further chemical tests and cross-over experiments that show the thermodynamic favorability of the adducts. Further comparative study of reaction products and byproducts shows 2 to be the stannylcuprate of choice for the preparation of vinylstannanes from terminal alkynes.