Radical Chain Reduction of Alkylboron Compounds with Catechols
作者:Giorgio Villa、Guillaume Povie、Philippe Renaud
DOI:10.1021/ja110224d
日期:2011.4.20
carboxylic acid at high temperature (>150 °C). We report here a mild radical procedure for the transformation of organoboranes to alkanes. 4-tert-Butylcatechol, a well-established radical inhibitor and antioxidant, is acting as a source of hydrogen atoms. An efficient chain reaction is observed due to the exceptional reactivity of phenoxyl radicals toward alkylboranes. The reaction has been applied to a wide
烷基硼烷向相应烷烃的转化通常通过烷基硼烷的质子分解进行。这个简单的反应需要使用严格的反应条件,即在高温(> 150 °C)下用羧酸处理。我们在这里报告了一种将有机硼烷转化为烷烃的温和激进程序。4-叔丁基儿茶酚是一种成熟的自由基抑制剂和抗氧化剂,是氢原子的来源。由于苯氧基自由基对烷基硼烷的特殊反应性,观察到有效的链式反应。该反应已应用于广泛的有机硼衍生物,例如 B-烷基儿茶酚硼烷、三烷基硼烷、频哪醇硼酸酯和烷基硼酸。此外,迄今为止,通过实验确定了仲烷基自由基和邻苯二酚衍生物之间的氢转移的难以捉摸的速率常数。有趣的是,它们在 80 °C 时比氢化锡慢不到 1 个数量级,这使得儿茶酚对涉及 CC 键形成的广泛转化特别有吸引力。
Platinum- and Gold-Catalyzed Rearrangement Reactions of Propargyl Acetates: Total Syntheses of (−)-α-Cubebene, (−)-Cubebol, Sesquicarene and Related Terpenes
作者:Alois Fürstner、Peter Hannen
DOI:10.1002/chem.200501299
日期:2006.4.3
the carbophilic transition-metal cation. Formal attack of the alkene moiety onto the resulting pi-complex engenders the formation of an electrophilic cyclopropyl carbene species which subsequently reacts with the adjacent acetate unit to give the final product. The alternative phasing of events, implying initial attack of the acetate (rather than the alkene moiety) onto the metal-alkyne complex, is
unexplored area for C−C bond formation. Herein 64 examples of β‐alkylated styrene derivatives, synthesized through the reactions of readily accessible feedstock olefins with β‐nitrostyrenes by ozone/FeII‐mediated radical substitutions, are reported. These reactions proceed with good efficiencies and high stereoselectivities under mild reaction conditions and tolerate an array of functional groups. Also demonstrated
烯烃C(sp 3)-C(sp 2)键的脱烯基烯基化作用一直是C-C键形成的未知区域。本文报道了64个β-烷基化苯乙烯衍生物的例子,这些例子是通过容易获得的原料烯烃与β-硝基苯乙烯通过臭氧/ Fe II介导的自由基取代反应而合成的。在温和的反应条件下,这些反应具有良好的效率和较高的立体选择性,并且可以耐受一系列官能团。还证明了该策略通过产品的几种合成转化以及天然产物异吗啡丁和药物(E)-美丹尼丁的合成的适用性。
Iminyl radicals: part II. ring opening of cyclobutyl- and cyclopentyliminyl radicals.
作者:Jean Boivin、Eric Fouquet、Samir Z. Zard
DOI:10.1016/s0040-4020(01)80850-4
日期:1994.1
Slow addition of tributylstannane to sulphenylimines 2 give the corresponding cycloiminyl radicals 3 which can undergo ring opening, a process that is easily incorporated into complex reaction sequences.
Asymmetric Synthesis using Organoboranes. Relative Effectiveness of the B-Halobis(terpenyl)boranes for the Enantioselective Halogenative Cleavage of Representative meso-Epoxides
作者:Chandra D. Roy、Herbert C. Brown
DOI:10.1071/ch07118
日期:——
A comparative study of the relative effectiveness of various Ter2BX, such as dEap2BX, lEap2BX, 2-dIcr2BX, 4-dIcr2BX, and lCleap2BX along with dIpc2BX for the asymmetric ring opening of three representative meso-epoxides (cyclohexene, cyclopentene, and cis-2,3-butene oxides) is reported. Among all the reagents studied, 2-dIcr2BCl (78–80%) demonstrated significant improvement in enantiomeric excess over