ChemInform Abstract: CONJUGATED HYDROSTANNYLATION REACTION OF ACETYLENIC COMPOUNDS

Abstract

Die disubstituierten Acetylene (I) und (V) geben Produkte der kombinierten Hydrostannylierung mittels Triäthylstannyl‐lithium (II) nur in Gegenwart von Wasserstoffdonatoren.

Synthesis of Tetrasubstituted Alkenes by Stereo- and Regioselective Stannyllithiation of Diarylacetylenes

“…According to a report in 1981, triethylstannyllithium in THF adds to diphenylacetylene in only 2% yield, 6,7 and in our case, trimethylstannyllithium in THF afforded the Z-adduct 2 in 31% yield. To our pleasant surprise, trimethylstannyllithium in hexane at 0 °C afforded after D 2 O quenching (2-deuterio-1,2-diphenylethenyl)stannane 4a in 97% yield with 100% Z selectivity (for all cases shown in Table 1) and with 100% deuterium incorporation.…”

Modular Synthesis of Functionalized Benzosiloles by Tin-Mediated Cyclization of (o-Alkynylphenyl)silane

“…First, there was a report that Et 3 SnLi in THF adds to diphenylacetylene only in 2% yield. 8 Second, while the successful cyclization implies the formation of an intermediate B instead of the less hindered one A, the same reaction in hexane suggested the intermediacy of A. Thus, the reaction in hexane instead of diethyl ether gave 2 after quenching with aqueous NH 4 Cl.…”

“…This was a surprise for two reasons. First, there was a report that Et 3 SnLi in THF adds to diphenylacetylene only in 2% yield . Second, while the successful cyclization implies the formation of an intermediate B instead of the less hindered one A , the same reaction in hexane suggested the intermediacy of A .…”