DIRECTED REDUCTION OF BETA-HYDROXY KETONES EMPLOYING TETRAMETHYLAMMONIUM TRIACETOXYBOROHYDRIDE
DIRECTED REDUCTION OF BETA-HYDROXY KETONES EMPLOYING TETRAMETHYLAMMONIUM TRIACETOXYBOROHYDRIDE
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DOI：
10.1021/ja00219a035
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发表时间：
1988-05-25
影响因子：
15
通讯作者：
CARREIRA, EM
中科院分区：
文献类型：
--
作者：
EVANS, DA;CHAPMAN, KT;CARREIRA, EM
温和的还原剂三乙酰氧基硼氢化四甲基铵以高的非对映选择性将无环双羟基酮还原为相应的反式二醇.α-烷基取代不显著影响这些还原的立体选择性。在所有检查的情况下，获得良好至优异的非对映异构体均质二醇的产率。这些减少的机制涉及酸促进的配体交换乙酸酯为底物醇的三乙酰氧基硼氢化物阴离子。所得的氢化物中间体，推测为烷氧基二乙酰氧基硼氢化物，
The mild reducing agent tetramethylammonium triacetoxyborohydride reduces acyclicß-hydroxy ketonesto their corresponding anti diols with high diastereoselectivity. a-Alkyl substitution does not significantly affect the stereoselectivity of these reductions. In all cases examined, good to excellent yields of diastereomerically homogeneous diols were obtained. The mechanism of these reductions involves an acid-promoted ligand exchange of acetate for substrate alcohol by the triacetoxyborohydride anion. The resultant hydride intermediate, presumably an alkoxydiacetoxyborohydride, reduces proximal