133399-50-5Relevant academic research and scientific papers
Reaction of stannyl-substituted phosphorus ylides with boron trifluoride diethyl etherate: Evidence for formation of transient triphenylphosphonio-substituted stannaethenes
Grützmacher, Hansj?rg,Pritzkow, Hans
, p. 938 - 946 (2008/10/08)
The reaction of the stannyl-substituted phosphorus ylide Ph3PCH(SntBu2OiPr) (4) with boron trifluoride diethyl etherate yields [1,1,3,3-Tetra-tert-butyl-2,4-bis(triphenylphosphonio)-1,3-distannetane] bis(tetrafluoroborate) (11) in addition to Ph3PCH2SntBu2F+BF4 - (12) and boranyl-substituted phosphorus ylides (13). If the reaction is performed in the presence of benzophenone, (2,2-diphenylvinyl)triphenylphosphonium tetrafluoroborate (15) is isolated. The reactive intermediate in these experiments could be a triphenylphosphonio-substituted stannaethene (stannavinylphosphonium salt), Ph3PCH=SntBu2+BF4- (14), although reaction routes not involving a low-coordinate tin species are possible. A different reactivity is shown by the ylide Ph3PCCH3(SntBu2OiPr) (5), which reacts with boron trifluoride diethyl etherate with formation of a betaine, Ph3PCCH3(BF3) (SntBu2F) (22). If benzophenone is added as trapping reagent, reduction to diphenylcarbinol, Ph2CHOH, is observed and the vinylphosphonium salt Ph3P+(C=CH2)SntBu2FBF 4- (23) is isolated. This unusual reactivity is explained by a migration of a hydrogen atom from the methyl group in Ph3PCCH3=SntBu2+BF4 - (21a) to the low-coordinate tin center via a cyclic hydrogen-bridged intermediate with a three-center, 2-electron bond (21c). The reaction behavior of the assumed transient stannavinylphosphonium salts finds parallels in the well-known reactivity of silaethenes. The X-ray structures of the compounds Ph3PCH2(SntBu2F)+BF4 - (12), Ph3P(C=CH2)SntBu2F+BF 4- (23), and [(Ph3P)-CHSntBu2CH(PPh3)SntBu2 2+](BF4-)2 (11) are reported.
