enantiomeric excesses and yields. The chiral diether ligand controlled asymmetric conjugate addition of organolithiums to nona-2,7-dienedioates preferentially proceeds via the s-cis conformation with coordination of the carbonyl oxygen atom to the lithium to give a lithium E-enolate intermediate. Subsequent intramolecular conjugate addition of the enolate also proceeds via a cyclic transition state involving
摘要 所述手性
配体的
二醚控制不对称共轭加成
有机锂的对壬-2,7- dienedioates优先经由前进小号-顺式构象的与羰基氧原子与
锂的协调,得到
锂ë -enolate中间。随后分子内共轭加成的烯醇化物也可通过涉及
锂和环状过渡状态前进小号-顺-enoate,产生反式,反式三取代
环己烷具有高对映体过量和产量。 所述手性
配体的
二醚控制不对称共轭加成
有机锂的对壬-2,7- dienedioates优先经由前进小号-顺式构象的与羰基氧原子与
锂的协调,得到
锂ë -enolate中间。随后分子内共轭加成的烯醇化物也可通过涉及
锂和环状过渡状态前进小号-顺-enoate,产生反式,反式三取代
环己烷具有高对映体过量和产量。