possessing internally-activated vinylic sulfone dienophilic groups undergo intramolecular Diels-Alder (IMDA) reaction with high or complete selectivity for the cis-fused products. Incorporation of silyloxy groups within the carbon tether linking the diene and dienophile results in increased IMDA reactivity. The stereochemical outcomes of these processes are rationalised in terms of the preference for an exooriented
一系列具有内部活化的
乙烯基砜二亲核基团的
三烯经过分子内Diels-Alder(I
MDA)反应,对顺式融合产物具有高或完全选择性。在连接二烯和亲二烯体的碳系链中并入甲
硅烷氧基基团会增加I
MDA反应性。这些方法的立体
化学结果根据对外向性苯基磺酰基的偏爱以及使甲
硅烷氧基和砜取代基之间的未键合相互作用最小化而合理化。