Control of Synthetic Reactions by the Use of Organo Boron Compounds

6,8-二苯基-1-羟基-1,2,3,4-四氢-2-氧-1-硼萘，它有望与羟基化合物形成硼酸酯，并覆盖底物的一面以控制反应的选择性。例如，该硼化合物优先与2-脱氧核糖衍生物的β -异头体形成硼酸酯。将该化合物加入到5-苄基-2-脱氧核糖中，与-异头物发生优先酯化反应。该硼化合物成功地用于立体选择性还原无环和环-羟基酮。硼化合物和无环酮通过共沸脱水转化为相应的硼酸盐，所得到的硼酸盐用还原剂原位处理，几乎只得到syn 1,3-二醇。抗α取代-羟基酮也被还原成立体选择性抗1,3-二醇。此外，3-羟基-1-环戊酮还原得到顺式二醇，收率较高。以R-(+)-普乐酮为原料，经8步合成了手性增敏剂双氰苯薄荷醇衍生物。作为对照实验，在甲醇-乙腈中使用高压汞灯照射己基（三甲基硅基甲基）胺，在这种情况下，光化学氨基甲基化没有进行。而在相同条件下，具有增敏剂部分的手性巴豆酸酯非对映选择性地生成相应的γ -氨基甲酯（转化率58%，原产率40%）。在此基础上，发现了一种新的取代基效应。

6,8-Diphenyl-1-hydroxy-1,2,3,4-tetrahydro-2-oxa-1-boranaphthalene, which is expected to form boronate esters with hydroxyl compounds and to cover one face of the substrates to control the selectivities of the reaction, . was designed and synthesized For example, thi boron compound forms the boronate ester preferentially with the beta-anomer of 2-deoxyribose derivative. When this compound was added to tert-butyl 5-benzyl-2-deoxyribose, preferential esterification with the beta-anomer was observed. This boron compound is successfully employed for the stereoselective reduction of acyclic and cyclic beta-hydroxy detones. The boron compound and acyclic ketones were converted to the corresponding boronates by azeotropic removal of water, and the resulting boronates were treated in situ with reducing reagent to give syn 1,3-diol almost exclusively. Anti alpha-substituted beta-hydroxy ketones were also reduced to give anti, anti 1,3-diol stereoselectively. Furthermore, the reducton of 3-hydroxy-1-cyclopentanone gave a cis diol in high yield.Dicyanophenylmenthol derivative was synthesized from R-(+)-Pulegone in eight steps as a chiral sensitizer, . As a controlled experiment, phenylmenthyl crotonate was irradiated using high-pressure mercury lamp in the presence of diethy (trimethylsilylmethyl) amine in methanol-acetonitrile and in this case, photochemical aminomethylation did not proceed. However, under the same conditions, the chiral crotonate having a sensitizer part gave the corresponding gamma-aminomethyl ester diastereoselectively (conversion yield 58%, 40%d.e.). Based on this result, a novel substituent effect of the sensitizer was discovered.