AsymmetricDiels-Alder Cycloadditions withC2-Symmetrical Chiral Carbamoylnitroso Dienophiles
作者:Albert Defoin、Agn�s Brouillard-Poichet、Jacques Streith
DOI:10.1002/hlca.19910740112
日期:1991.1.30
The C2-symmetrical chiral pyrrolidines 2 and 3 are of opposite helicity. The corresponding N-acylnitroso dienophiles 6 and 7 react in good yield with cyclohexadiene, leading thereby with excellent diastereoisomeric excess to the expected Diels-Alder cycloadducts (see Scheme). The [2.2.2] bicyclic moieties of the major diastereoisomers 9 and 11 proved to be of opposite configuration, as expected. Their
的c ^ 2 -symmetrical手性吡咯烷2和3是相反的螺旋性。相应的N-酰基亚硝基二亲二烯体6和7与环己二烯反应良好,从而导致非对映异构体过量,超过了预期的Diels - Alder环加合物(参见方案)。如预期的那样,主要的非对映异构体9和11的[2.2.2]双环部分被证明具有相反的构型。假定酰基亚硝基双亲亲分子在顺式中可以最好地解释它们的构型构象在过渡状态下,二烯的存在的方法内(参见图)。