作者:Paul S. Hinchliffe、J. Matthew Wood、Andrew M. Davis、Rupert P. Austin、R. Paul Beckett、Michael I. Page
DOI:10.1039/b104923m
日期:——
The hydrolysis of N-acyl-β-sultams generally occurs with ring opening and S–N fission in contrast to the C–N fission observed in analogous acyclic N-acyl sulfonamides. Similar to other β-sultams, the N-acyl derivatives are at least 106 more reactive than N-acylsulfonamides. However, the α-substituted 4-isopropylidene β-sultam is relatively unreactive and undergoes alkaline hydrolysis with C–N fission leaving the strained 4-membered β-sultam ring intact. This reduction in reactivity is shown to be due to steric strain introduced in the transition state for attack at the sulfonyl centre. (Z)-4-Ethylidene-β-sultam shows similar behaviour with preferential C–N fission whereas the (E)-4-ethylidene isomer and 4-isopropyl-β-sultam revert to hydrolytic ring opening with S–N fission.
N-酰基-β-磺内酰胺的水解通常伴随开环和S-N裂变发生,这与在类似的无环N-酰基磺酰胺中观察到的C-N裂变相反。与其他 β-磺酰胺类似,N-酰基衍生物的反应性比 N-酰基磺酰胺至少高 106。然而,α-取代的 4-异亚丙基 β-磺内酰胺相对不活泼,会发生碱性水解并伴随 C-N 裂变,使应变的 4 元 β-磺内酰胺环保持完整。这种反应性的降低被证明是由于在过渡态中引入空间应变以攻击磺酰基中心。 (Z)-4-亚乙基-β-磺内酰胺显示出与优先 C-N 裂变相似的行为,而 (E)-4-亚乙基异构体和 4-异丙基-β-磺内酰胺则通过 S-N 裂变恢复到水解开环。