Cyclic Model for the Asymmetric Conjugate Addition of Organolithiums with Enoates
作者:Kiyoshi Tomioka、Katsumi Nishimura、Naoshi Fukuyama、Mitsuaki Yamashita、Takaaki Sumiyoshi、Yasutomo Yamamoto、Ken-ichi Yamada
DOI:10.1055/s-0034-1380702
日期:——
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。