REACTIONS OF <i>cis</i>-2-BORYL-1-STANNYLALKENES WITH CARBODIIMIDES, THIOCYANATES, ISOTHIOCYANATES, AND ISOCYANATES

Abstract

The reactions of (E)-2-diethylboryl-1-trimethylstannylbut-1-ene and (Z)-3-di-ethylboryl-2-trimethylstannylpent-2-ene with carbodiimides, methyl thiocyanate, thioisocyanates, and isocyanates were studied, and the products were characterised by multinuclear magnetic resonance spectroscopy (¹H, ¹¹B, ¹³C and ¹¹⁹Sn NMR). It was found that carbodiimides, bearing tert-butyl or trimethylsilyl groups at the nitrogen atoms do not react with (E)-2-boryl-1-stannylalkenes, in contrast to dicyclohexylcarbodiimide. There was also no reaction in the case of MeSCN. All other reactions proceed via a weak N^→B adduct formation in the initial step, followed by different rearrangements, depending on the structure of reagents as well as on the substitution pattern at the C=C bond in alkenes. New heterocycles are formed, in which the boron atom is either tricoordinated (1,2-azaborolenes, 1,2-azaborolanes), and one ethyl group has been transferred to the neighbour olefinic carbon atom, or the boron atom is tetracoordinated (1,2-azaboratoles, 1,2-oxoniaboratoles), and the trimethylstannyl group has migrated to one of the heteroatoms of the heterocumulenes.

How to Cite
Wrackmeyer, B.; Maisel, H. E.; Wagner, K. Chem. Heterocycl. Compd. 2001, 37, 1396. [Khim. Geterotsikl. Soedin. 2001, 1526.]

For this article in the English edition, see DOI https://doi.org/10.1023/A:1017955302461