We have found that either Bu 3 SnCl/PMHS/KF (aq) or the combination of tributyltin fluoride, PMHS, and catalytic quantities of tetrabutylammonium fluoride can serve as in situ sources of tributyltin hydride for both free radical and palladium-catalyzed hydrostannylation reactions. These methods are tolerant of a variety of functional groups, including silyl ethers. Furthermore, Me 3 SnCl is also reduced under these conditions, providing a relatively convenient and safe manner by which Me 3 -SnH can be formed and reacted. We have also observed that the Bu 3 SnCl/siloxane/fluoride combination offers improvements over the existing protocols for transforming 1-bromoalkynes into trans-1-(tributylstannyl)-1-alkenes. Specifically, the KF/PMHS methodology allows the 1-bromoalkyne to be formed and reacted in a single pot and with substoichiometric amounts of tin. Finally, alternative reductants such as Red-Sil are also amenable to the method.

In a fraction of the time required by conventional methods, microwave-accelerated one-pot hydrostannylation/Stille coupling allows 1-alkynes to be efficiently transformed into 1,3-dienes or styrenes.

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Microwave-Assisted One-Pot Hydrostannylation/Stille Couplings.-An efficient microwave-assisted one-pot hydrostannylation/Stille coupling protocol is developed. The hydrostannylation can be carried out under Pdcatalyzed or free-radical conditions. A variety of alkynes are coupled with aryl, benzyl and vinyl electrophiles in good yields after total of 8-13 min of microwave irradiation [extreme caution when heating: explosion risk]. -(MALECZKA JR., ROBERT E.; LAVIS, JEROME M.; CLARK, DAMON H.; GALLAGHER, WILLIAM P.; Org. Lett. 2 (2000) 23, 3655-3658; Dep. Chem., Mich. State Univ., East Lansing, MI 48824, USA; EN)

Application of Fluoride-Catalyzed Silane Reductions of Tin Halides to the in situ Preparation of Vinylstannanes -[14 refs.]. -(CLARK, DAMON H.; TERRELL, LAMONT R.; TERSTIEGE, INA; WHITEHEAD, SUSAN L.; MALECZKA JR., ROBERT E.; Proc. -NOBCChE 26 (1999) 73-78; Dep. Chem., Mich. State Univ., East Lansing, MI 48824, USA; EN)