The 1-Phenylsulfonylallenyl Terminus in Intramolecular Diels-Alder Reactions: Tether Length and Reactivity
作者:James R. Bull、Richard S. Gordon、Roger Hunter
DOI:10.1055/s-1999-2675
日期:1999.5
Methods are described for the synthesis of 1-phenylsulfonylalka-1,2,(n + 4),(n + 6)-tetraenes 5 (n = 2-4), and preliminary findings on their thermally-induced intramolecular cycloaddition behaviour are reported. The reaction of 5 (n = 4) is slow, and engages the unactivated Ï-bond, whereas those of 5 (n = 2 & 3) proceed readily and exo-selectively with dienophilic participation of the activated terminal Ï-bond, to give the expected [4 + 2] cycloadducts. The reactivity of 5 (n = 2) is particularly noteworthy since cycloaddition proceeds under exceptionally mild conditions.
描述了1-苯磺酰基-1,2,(n+4),(n+6)-四烯5(n=2-4)的合成方法,并报道了它们热诱导的分子内环加成行为的初步研究结果。反应5(n=4)较慢,涉及未活化的π键,而5(n=2和3)的反应则迅速进行,且端位的活化π键参与亲双烯体作用,生成预期的[4+2]环加成产物。5(n=2)的反应活性特别值得注意,因为环加成反应在极为温和的条件下即可进行。