TETRABUTYLAMMONIUM DIFLUOROTRIPHENYLSTANNATE AS A NEW ANHYDROUS SYNTHETIC EQUIVALENT TO TBAF

Tetrabutylammonium difluorotriphenylstannate (1) is the first hypervalent complex of tin acting as a fluorinating agent. In contrast to TBAF and TASF, this crystalline complex is relatively stable up to 210-degrees-C and is not hygroscopic or hydrated. Enolsilylether alkylations with alkyl bromides proceeded in good to quantitative yields in the presence of (1), which was kept for years unprotected from moisture. Relative rate studies indicated that nucleophilic fluorination of benzyl bromide proceeded 18 times faster than with dried cesium fluoride in refluxing CH3CN.