Nucleophilic Addition to Electron-Rich Heteroaromatics: Dearomatizing Anionic Cyclizations of Pyrrolecarboxamides
摘要:
Despite its electron-rich nature, a pyrrole ring is susceptible to intramolecular nucleophilic attack by organolithiums. The resulting dearomatizing anionic cyclization yields new 5- or 7-membered heterocyclic rings. Formation of a new 5-membered ring, by cyclization of an N-benzylpyrrolecarboxamide, is accompanied by ring opening of the original pyrrole to yield 3-aminovinylpyrrolinones. Formation of a new 7-membered ring, by cyclization of an N-allyl pyrrolecarboxamide, yields bicyclic pyrroloazepinones.
Nucleophilic Addition to Electron-Rich Heteroaromatics: Dearomatizing Anionic Cyclizations of Pyrrolecarboxamides
摘要:
Despite its electron-rich nature, a pyrrole ring is susceptible to intramolecular nucleophilic attack by organolithiums. The resulting dearomatizing anionic cyclization yields new 5- or 7-membered heterocyclic rings. Formation of a new 5-membered ring, by cyclization of an N-benzylpyrrolecarboxamide, is accompanied by ring opening of the original pyrrole to yield 3-aminovinylpyrrolinones. Formation of a new 7-membered ring, by cyclization of an N-allyl pyrrolecarboxamide, yields bicyclic pyrroloazepinones.
β-Lactams or γ-lactams by 4-exo-trig or 5-endo-trig anionic cyclisation of lithiated acrylamide derivatives
作者:Jonathan Clayden、David W. Watson、Madeleine Helliwell、Mark Chambers
DOI:10.1039/b308029c
日期:——
Substituted acrylamide derivatives of benzylamine are lithiated α to nitrogen by LDA. The benzyllithium thus formed undergoes either 5-endo-trig anionic cyclisation, formally by intramolecular conjugate addition to the acrylamide, to yield 5-membered lactams, or, if the acrylamide bears a β-electron withdrawing group, 4-exo-trig cyclisation to a β-lactam.
Nucleophilic Addition to Electron-Rich Heteroaromatics: Dearomatizing Anionic Cyclizations of Pyrrolecarboxamides
作者:Jonathan Clayden、Rachel Turnbull、Ivan Pinto
DOI:10.1021/ol0364071
日期:2004.2.1
Despite its electron-rich nature, a pyrrole ring is susceptible to intramolecular nucleophilic attack by organolithiums. The resulting dearomatizing anionic cyclization yields new 5- or 7-membered heterocyclic rings. Formation of a new 5-membered ring, by cyclization of an N-benzylpyrrolecarboxamide, is accompanied by ring opening of the original pyrrole to yield 3-aminovinylpyrrolinones. Formation of a new 7-membered ring, by cyclization of an N-allyl pyrrolecarboxamide, yields bicyclic pyrroloazepinones.