Synthesis of boron substituted stannacyclohexadienes by a competitive metathesis

Victoria Volkis, Moris S. Eisen*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The reaction of phenyl borondibromide (PhBBr2) with 1,1-n-dibutylstanna-2,5-cyclohexadiene (8) produces, along with the expected phenylbora-2,5-cyclohexadiene (1), a mixture of boron substituted stannacyclohexadiene compounds 2 and 3 in a ratio of 1:2 respectively. Compounds 2 and 3 are in equilibrium at room temperature. The initial formation of either 2 or 3 is presumably the result of a metathesis reaction of the PhBBr2 with the double allylic C-H bond of the starting 1,1-n-dibutylstanna-2,5-cyclohexadiene (8), yielding compound 2, or with the allylic C-H bond of the 1,3-hydrogen isomerized starting stannacycle 8 (1,1-n-dibutylstanna-2,4-cyclohexadiene), yielding compound 3. The pseudo-first order rate of conversion from 2 ⇒ 3 was measured by an NMR spin population transfer technique to be k1 = 7.18 s-1 (2, 0.034M; T1 =1.6 s) while k-1 = was found to be 3.29 s-1 (T1 = 1.5 s), yielding an equilibrium constant of 2.18 at 298 K. The coalescence rate constant was calculated to be 235 s-1 which was not reached by heating the sample up to 383 K.

Original languageEnglish
Pages (from-to)293-299
Number of pages7
JournalMain Group Metal Chemistry
Volume20
Issue number5
DOIs
StatePublished - 1997
Externally publishedYes

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