The reduction of the carbonyl group in acylated trifluoroethyl alkanesulfonates follows the Felkin-Ahn selectivity, and the so-formed diastereomeric β-hydroxysulfonyl intermediates undergo syn- and anti-fragmentation, depending on the reaction conditions. In effect, isomeric E- and Z-alkenes are formed in a stereodivergent manner, which mimics the mechanistic manifold of the Peterson olefination.
Reductive couplings of acid chlorides mediated by SmI2
作者:J. Collin、F. Dallemer、J.L. Namy、H.B. Kagan
DOI:10.1016/s0040-4039(00)70710-6
日期:1989.1
Reductivecouplings of acidchlorides and of acidchlorides with aldehydes or ketones in presence of an excess of SmI2 produce ketones in moderate to good yields.
在过量的SmI 2的存在下,酰氯和酰氯与醛或酮的还原偶联以中等至良好的产率产生酮。
New Coupling Reactions of Some Acyl Chlorides with Samarium Diiodide in the Presence of Samarium: Carbinols from Three Acyl Units
A mixture of samarium(II) iodide and samarium can induce a coupling reaction of three molecules of alkanoyl halide to give trialkylcarbinols of 2-hydroxy-1,3-diones. When aliphatic, unbranched alkanoyl chlorides are used, this new coupling reaction provides trimeric products as the main reaction products. Tetrahydropyran (THP) proved superior as the solvent because no ring-opening and subsequent reaction
碘化钐 (II) 和钐的混合物可以诱导三分子烷酰卤的偶联反应,生成 2-羟基-1,3-二酮的三烷基甲醇。当使用脂肪族无支链烷酰氯时,这种新的偶联反应提供了三聚产物作为主要反应产物。四氢吡喃 (THP) 作为溶剂被证明是优越的,因为在反应条件下没有观察到开环和随后与烷酰卤的反应,这与使用 THF 时不同。
The reduction of α-silyloxy ketones using phenyldimethylsilyllithium
作者:Ian Fleming、Richard S. Roberts、Stephen C. Smith
DOI:10.1039/a709114a
日期:——
diol PhCH(OH)CH(OH)Ph 39. The reaction between phenyldimethylsilyllithium and the acyloin silyl ether 8d (R = But) does not give the ketone ButCH2COBut, but gives instead the anti-Felkin meso diol ButCHOHCHOHBut 40 also with high selectivity (Scheme 12). Silyllithium and some related reagents react with trifluoromethylketones 46 and 48 to give α,α-difluoro silyl enol ethers 47 and 49 (Scheme 14).
苯基二甲基甲硅烷基锂与酰氯甲硅烷基甲醚RCH(OSiMe 3)COR 8反应生成区域定义的甲硅烷基烯醇醚RCH C(OSiMe 2 Ph)R 9,并因此通过水解酮RCH 2 COR 10产生。收率可能很高,但通常是中等水平。建立这种减少的机制涉及布鲁克重排(方案6)而不是彼得森消除(方案1)。尽管在每种情况下机理似乎都是相同的,但甲硅烷基烯醇醚9的立体化学在芳族系列(R = Ph,方案7)和脂族系列(R =环己基,方案8)中在意义上是相反的,主要的芳族甲硅烷基烯醇醚是热力学上较不稳定的异构体E -PhCH C(OSiMe 2Ph)Ph E -9aa和主要的脂族甲硅烷基烯醇醚是热力学更稳定的异构体Z -cC 6 H 11 CH C(OSiMe 2 Ph)-cC 6 H 11 Z -9ba。这是芳族系列中反反费尔金攻击的结果。与甲硅烷基的反应醚卜吨CH(OSiMe 3)COPH图13b是在给予正常Ž
A novel photoinduced reduction system of low-valent samarium species: reduction of organic halides and chalcogenides, and its application to carbonylation with carbon monoxide
irradiation is found to enhance the reducing ability of samariumdiiodide (SmI2) dramatically. Organic halides (RCl, RBr, RI) and chalcogenides (RSPh, RSePh, RTePh) are smoothly reduced to the corresponding hydrocarbons by using this SmI2–hv system. The photoactivation can be also applied to ytterbium diiodide (YbI2) successfully. When the reduction of alkyl chlorides (RCl) by using the SmI2–hv system is conducted