Chiral synthesis via organoboranes. 45. Asymmetric hydroboration of 1-cyclopentenol derivatives using diisopinocampheylborane. Synthesis of optically active cyclopentane-1,2-diol derivatives of high optical purity
作者:Herbert C. Brown、Dhanabalan Murali、Bakthan Singaram
DOI:10.1016/s0022-328x(99)00047-9
日期:1999.6
The asymmetric hydroboration of 1-cyclopentenol derivatives, such as ethers, acetate, silyl ether and borinate, was investigated using diisopinocampheylborane, dIpc2BH. The product trialkylboranes were treated with excess of acetaldehyde to give the corresponding diethyl boronate esters. These boronate esters on oxidation using alkaline hydrogen peroxide gave optically active trans-cyclopentane-1,2-diol
使用diisopinocampheylborane,d Ipc 2 BH研究了1-环戊烯醇衍生物(如醚,乙酸酯,甲硅烷基醚和硼酸酯)的不对称硼氢化。用过量的乙醛处理产物三烷基硼烷,得到相应的硼酸二乙酯。这些硼酸酯在使用碱性过氧化氢氧化后,以50-85%的对映体过量和高达95%的总收率得到了旋光性的反式-环戊烷-1,2-二醇衍生物。通过醚裂解将一些旋光的反式-2-烷氧基环戊醇转化为旋光的反式-(1 R,2 R)-环戊烷-1,2-二醇。3-甲氧基-2,5-二氢呋喃的不对称硼氢化反应以总产率的70%得到75%ee的反式-(3R,4R)-4-甲氧基四氢呋喃-3-醇。