申请人:The Regents of the University of California
公开号:US05466798A1
公开(公告)日:1995-11-14
The present invention relates to novel, powerful reducing agents, lithium aminoborohydrides which are prepared by addition of BH.sub.3 .cndot.THF to the corresponding dialkylamine at 25.degree. C. to give the intermediate amineborane complex. Subsequent deprotonation by strong base, e.g. n-BuLi, yields the aminoborohydride quantitatively. Lithium aminoborohydrides are powerful reducing agents, comparable in strength to lithium aluminum hydride. The activity is determined by the dialkylamine. Lithium pyrrolidinoborohydride has unique activity and selectivity in its reducing properties. Esters, lactones and anhydrides are reduced cleanly at 25.degree. C. to give the corresponding alcohols, while carboxylic acids are not reduced. Test reductions show that lithium pyrrolidinoborohydride is also capable of reducing a wide range of functional groups including amides, epoxides, oximes, nitriles and halides.
本发明涉及一种新型的强还原剂——氨基硼氢化锂,该还原剂是通过将BH.sub.3 .cndot.THF 加到相应的二烷基胺中,在25℃下形成中间体胺硼烷络合物制备而成。随后通过强碱(例如n-BuLi)的去质子化反应,可以定量地得到氨基硼氢化锂。氨基硼氢化锂是一种强大的还原剂,其还原能力与氢化铝锂相当。其活性取决于二烷基胺的种类。吡咯烷基氨基硼氢化锂具有独特的还原活性和选择性。酯类、内酯和酐类在25℃下可以被干净地还原为相应的醇,而羧酸则不能被还原。测试还原反应表明,吡咯烷基氨基硼氢化锂还可以还原一系列官能团,包括酰胺、环氧化物、肟、腈和卤代物。