Synthesis of 1,6-dihalogeno-2,3,4,5-tetracarba-nido-hexaborane(6) derivatives
摘要:
1,4,6,9-Tetraalkyl-3,8-diethyl-2,7-bis(diethylboryl[4.4]mona-1,3,6,8-tetraenes (alkyl = Pt (2a), Pr (2b), Pr-i (2c), ''Bu (2d)) react with four equivalents of boron tribromide to give 2,3,4,5-tetraalkyl-1,6-dibromo-2,3,4,5-tetracarba-nido-hexaboranes(6) (3a-d) in high yield. By monitoring the progress of the reactions using C-13 NMR spectroscopy, 2,5-diboryl-substituted 3-borolenes (10) were identified as intermediates that rearrange to the carboranes via elimination of ethylboron dibromide. Treatment of 2 with boron triiodide affords the analogous 1,6-diodo-substituted carboranes 4. The reaction of 2 with an excess of boron trichloride proceeds rather slowly, again with a 3-borolene (9) as intermediate, and leads finally to a mixture of the carboranes 5 and 6 as a result of elimination of EtBCl(2) or BCl3. Treatment of 2 with BF3 leads to decomposition without any defined products. The carboranes 3 react stepwise with Li[Et(3)BH] to give first the monohydride with a B(6)-H bond (17) and the dihydride with B(6)-H and B(1)-H bonds (18).
Oxidative coupling of tetraalkynyltin with aldehydes leading to alkynyl ketones
作者:Andrey S. Levashov、Nicolai A. Aksenov、Inna V. Aksenova、Valeriy V. Konshin
DOI:10.1039/c7nj01376k
日期:——
The reaction of tetraalkynyltin with aldehydes was studied for the first time. The reaction was shown to proceed as a tandem process of nucleophilic addition of tin acetylide to aldehyde followed by Oppenauer-type oxidation of produced tin alcoholates, and may be used as a convenient one-pot approach to acetylenic ketones. The advantages and limitations of the proposed method are discussed.
Lewis acid promoted reaction of tetraalkynylstannanes with acyl chlorides: An effective approach towards alkynyl ketones
作者:Andrey S. Levashov、Dmitrii S. Buryi
DOI:10.1016/j.tetlet.2017.10.035
日期:2017.11
Tetraalkynylstannanes were found to be atom-economical nucleophilic reagents for the synthesis of α,β-acetylenic ketones. The scope and some limitations of the method are discussed.
Monoalkyltrialkynyl- and dialkyldialkynyltin compounds can be selectively synthesized by transmetalation of tetraalkynyltin compounds with Grignard reagents; an example is given in Equation (1). This reaction provides a route to mono- and dialkyltin compounds that avoids the use of strongly electrophilic reagents. The labile tin-alkynyl bonds allow the transmetalation products to be converted into alkyltin oxides, chlorides, and alkoxides.