Synthesis of 3-Methylenecyclohexan-1-ols by Lewis Acid Catalyzed Cyclization of (Epoxy-allyl)silanes
作者:Francisco J. Pulido、Asunción Barbero、Pilar Castreño
DOI:10.1002/ejoc.200901263
日期:2010.3
A newroute for the synthesis of (epoxy-allyl)silanes bearing the PhMe 2 Si group has been developed and their acid-catalyzed cyclization studied. The so-called normal products derived from 5-exo or 6-endo attack were never obtained. On the contrary, an interesting tandem rearrangement/cyclization process was observed, which selectively led to 3-methylenecyclohexan-1-ols. A mechanism is proposed to
已经开发了一种合成带有 PhMe 2 Si 基团的(环氧-烯丙基)硅烷的新途径,并研究了它们的酸催化环化。5-exo 或 6-endo 攻击衍生的所谓正常产物从未得到过。相反,观察到了一个有趣的串联重排/环化过程,它选择性地产生了 3-亚甲基环己-1-醇。提出了一种机制来解释这种串联反应。环化过程的立体选择性取决于催化剂的性质。
TROST, B. M.;COPPOLA, B. P., J. AMER. CHEM. SOC., 1982, 104, N 24, 6879-6881
作者:TROST, B. M.、COPPOLA, B. P.
DOI:——
日期:——
2-Bromo-3-trimethylsilylpropene. An annulating agent for five-membered carbo- and heterocycles
作者:Barry M. Trost、Brian P. Coppola
DOI:10.1021/ja00388a112
日期:1982.12
degradation product from any mechanism other than that proceeding directly through [3.3] shifts (e.g., 1 4 b 5 3b). The observed ratios in Table I are clearly incompatible with the generation of 3a, and hence 2 and/or 7, but show admirable coincidence with the values calculated for the direct sigmatropicshift sequence. These results constitute a truly surprising experimental manifestation of the theoretical
如果 2 是中间体(“[2 + 2 + 2]”),则 0:2:1 如果重排涉及 4 b 和 5(但不是 7)(“[3.3]”),并且 2:6:7 如果7 很容易获得(“spir0[3.3]”)。*~ 如果所有环碳上的标签以某种方式打乱(“随机”),该比例将为 1:10:7。检查未标记丁二酮的母峰包络 atm / e 86-8821 可以通过考虑 90% 13C 标记掺入和未富集位置中天然丰度标记的存在来预测上述选项的预期峰值比(表 I )。也许最明显的是,除了直接通过 [3.3] 转换(例如,1 4 b 5 3b)之外的任何机制形成双标记降解产物的必要性。表 I 中观察到的比率显然与 3a 的生成不相容,因此 2 和/或 7,但与为直接 sigmatropic 移位序列计算的值显示出令人钦佩的重合。这些结果构成了理论预测的真正令人惊讶的实验表现,即热 [2 + 2 + 21 炔烃环加成在动