THE REACTION OF LITHIUM TRIALKYLVINYLBORATES AND ALDEHYDES AS APPLIED TO THE SYNTHESIS OF 1,3-DIOLS, γ-CHLOROALCOHOL, AND CYCLOPROPANE
作者:Kiitiro Utimoto、Keiichiro Uchida、Hitosi Nozaki
DOI:10.1246/cl.1974.1493
日期:1974.12.5
Reaction of lithium trialkylvinylborates with aldehydes gives non-isolable boron compounds, 1,2-oxaborolane-bases borates (II) whose oxidative work-up furnishes 1,3-diols (III) smoothly. Successive treatment of a cyclic borate with phosphorus pentachloride and aqueous alkali provides a cyclopropane.
β-Hydroxy ketones can be reduced to the corresponding 1,3-diols in high yields and with excellent diastereoselectivity by carrying out the reaction with BH3·pyridine in CH2Cl2 at −78 °C in the presence of TiCl4. This protocol is general and chemoselective: excellent results are obtained when the substituents are primary, secondary, tertiary alkyl chains or aromatic moieties. The presence of reducible
β-羟基酮可以通过在-78 °C 和 TiCl4 存在下与 BH3·吡啶在 CH2Cl2 中进行反应,以高产率和优异的非对映选择性还原为相应的 1,3-二醇。该方案是通用的且具有化学选择性:当取代基为伯、仲、叔烷基链或芳族部分时,可获得优异的结果。可以很好地容忍可还原的官能团如溴、硝基和氰基的存在。
The reaction of trialkylvinylborates with aldehydes as applied to syntheses of 1,3-alkanediols, 1-chloro-3-heptanol and a cyclopropane derivative
作者:K. Utimoto、K. Uchida、H. Nozaki
DOI:10.1016/0040-4020(77)80382-7
日期:1977.1
R2BCHR-CH2-CH(OLi)R' (2) or its borate form (3). Oxidation of the adducts with alkaline hydrogen peroxide gives ca. 1:1 mixture of diastereomeric 1,3-alkanediols in good yields. On the other hand, the reaction of BrMg[R3BCHCH2] with R'CHO affords less satisfactory results. Successive treatment of 2 (R = n-Bu, R' = H) with PCl5 and alkaline H2O2 gives HOCHBu-CH2-CH2Cl (6). Treatment of Et2BCHEt-CH2-CHCl-Ph