Preparation and use of sterically hindered organobis(2,4,6-triisopropylphenyl)hydroborates and their polystyrene derivatives for the diastereoselective reduction of ketones
作者:Keith Smith、Gamal A. El-Hiti、Duanjie Hou、Gareth A. DeBoos
DOI:10.1039/a904260a
日期:——
benzyl and phenylbis(2,4,6-triisopropylphenyl)hydroborates [organoditripylhydroborates] are outlined. The lithium and potassium benzylditripylhydroborates reduce substituted cyclohexanones with diastereoselectivities comparable to those obtained with the most selective reagents known (e.g. 99% cis-4-methylcyclohexanol from 4-methylcyclohexanone). Lithium phenylditripylhydroborate also reduces ketones with
概述了苄基和苯基双(2,4,6-三异丙基苯基)氢硼酸酯[有机二三氢硼酸酯]的制备。苄基二三氢硼酸锂和钾硼酸钾可还原取代的环己酮,其非对映选择性可与已知的最具选择性的试剂(例如,来自4-甲基环己酮的99%顺式-4-甲基环己醇)相比较。苯基二三氢硼酸锂也以显着的选择性还原酮。例如,将4-甲基环己酮还原为顺式-4-甲基环己醇的纯度为88%。与大多数其他高选择性试剂不同,该反应在室温下进行,并具有额外的优势,即可以定量回收硼试剂。在萘二甲酸锂的存在下,Merrifield的树脂与二三氟烷基氟硼烷偶联,得到了(二三基硼烷基甲基)聚苯乙烯。类似地,bromopolystyrene与在存在ditripylfluoroborane耦合Ñ正丁基锂,得到(ditripylboryl)聚苯乙烯。这些聚合有机硼烷与t的反应-BuLi给出相应的聚合物负载的氢硼酸锂。二三烷基氢硼烷基甲基聚苯乙烯锂以与其非聚合对应物相