Cascade condensation, cyclization, intermolecular dipolar cycloaddition by multi-component coupling and application to a synthesis of (±)-crispine A
作者:Iain Coldham、Samaresh Jana、Luke Watson、Nathaniel G. Martin
DOI:10.1039/b822743h
日期:——
A general approach for the synthesis of various nitrogen-containing heterocyclic compounds is described using an intermolecular dipolarcycloaddition reaction of azomethine ylides and nitrones. Stabilized and non-stabilized azomethine ylide dipoles or the related nitrones were generated by condensation of 4-, 5- or 6-halo-aldehydes with a readily available amino-acid, amino-ester or hydroxylamine to
A Three-Component, One-Pot Synthesis of Indolizidines and Related Heterocycles via the [3+2] Cycloaddition of Nonstabilized Azomethine Ylides
作者:William H. Pearson、Patrick Stoy、Yuan Mi
DOI:10.1021/jo030334h
日期:2004.3.1
for a one-pot, three-componentsynthesis of indolizidines. The (2-azaallyl)stannanes tolerate enolizable hydrogens in these cycloadditions, while (2-azaallyl)silanes do not. The mechanism of the cycloaddition cascade is clarified by a series of control experiments. The same (2-azaallyl)stannanes may be transmetalated by n-butyllithium to generate 2-azaallyllithiums, which also may undergo a [3+2] cy
通过分子内的N-烷基化/脱金属级联反应,可以由(2-氮杂烯丙基)锡烷和(2-氮杂烯丙基)硅烷产生不稳定的偶氮甲亚胺(即仅带有氢或烷基的那些)。所得的伊利德与贫电子或富电子双极性亲和性化合物进行[3 + 2]环加成反应,可高产率产生吲哚并立定和相关的1-氮杂[ m .3.0]双环烷烃体系。原位实验方案允许一锅,三组分合成吲哚并立定。在这些环加成反应中,(2-氮杂烯丙基)锡烷可耐受可氢化的氢,而(2-氮杂烯丙基)硅烷则不容许。一系列控制实验阐明了环加成级联反应的机理。相同的(2-氮杂烯丙基)锡烷可能被n重金属化-丁基锂生成2-氮杂烯丙基锂,它们也可能会经历[3 + 2]环加成反应/ N-烷基化级联反应形成吲哚并咪唑。