NOVEL REARRANGEMENTS AND FORMATION OF 2,5-DIHYDRO-1,2,5-OXONIASTANNABORATOLES VIA METHANOLYSIS OF ZWITTERIONIC η²-(ALKYN-1-YLBORATE)ALKENYLTIN COMPOUNDS

Abstract

Organo-substituted 2,5-dihydro-1,2,5-oxoniastannaboratoles 3 were prepared by methanolysis of zwitterionic η²-(alkyn-1-ylborate)alkenyltin compounds 1. Analogously, the bis[η²-(alkyn-1-yl-borate)alkenyltin derivative 2 reacts with an excess of methanol to give a dimeric MeO-bridged 2,5-dihydro-1,2,5-oxoniastannaboratole (10a)₂. Various intermediates could be identified by NMR spectroscopy, and the molecular structure of (10a)₂ was determined by X-ray analysis. The structures of several products of the methanolysis indicate that protolysis of an Sn–C= bond occurs first, followed by an MeO/alkenyl exchange reaction.

Also published in Chemistry of Heterocyclic Compounds, 1999, 35 (9), pp 1041-1051

http://link.springer.com/article/10.1007/BF02251795