Sulfur diimide anions
Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
Synthesis of 1,2,5-Azastannaborole Derivatives from Sulfur Diimide Anions and cis-Stannyl-boryl-alkenes - X-ray Crystallographic Study of Two 2,5-Dihydro-1-(imino-λ4-sulfanylidene)-1,2,5-azastannaboratoles(E)-3-(Diethylboryl)-2-(chlorodimethylstannyl)-2-pentene (1) reacts with the sulfur diimide anions 3 [R - NSN-K+, R=tBu (a), Me3Si (b), tBu2P (c)] in a 1:1 ratio, and with 4 (K+;-NSN-K+) in a 2:1 ratio, to give various heterocycles. The first products of the reaction between 1 and 3 [2,5-dihydro-1-(imino-λ4-sulfanylidene)-1,2,5-azastannaboratoles 5a, b, c] are isolated at -30°C and characterized by X-ray crystallography. The compounds 5a,b rearrange into the borole derivates 6a,b (with an additional N—Sn coordination) by transfer of an ethyl group from the boron to the sulfur atom. Ethylene is eliminated from compound 6a (not 6b) to give the diaminosulfane derivative 7a. The 2:1 reaction between 1 and 4 affords an unstable intermediate 8 with a fluxional structure, leading to 9 in which an EtS moiety bridges a borole ring (analogous to 6 but without the additional N - Sn coordination) and a boratole ring (analogous to 5). All compounds are characterized by 1H-, 11B-, 13C-, 15N- (in part), 29Si- and 119Sn-NMR spectra.
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