Phosphine-mediated sequential annulations of allenyl ketone and isocyanide: a bicyclization strategy to access a furan-fused eight-membered ring and a spirocycle
Phosphine-mediated cascade annulations of allenyl ketone and isocyanide have been disclosed. Two molecular allenyl ketones work as different four-carbon synthons to form two rings, respectively, and thus enables the efficient synthesis of a furan-fused eight-membered ring and a spirocycle.
catalyzed carbonylation of allenyl ketones has been investigated. Carbonylative dimerization predominantly proceeded to afford bis(3-furanyl)methanones 2 as the major products. The use of DMSO strikingly changed the course of the reaction, affording methyl 3-furancarboxylates 3 as the major products. DFT calculations revealed that DMSO stabilized the methanol-coordinated intermediate, leading to methoxycarbonylation
catalyzed carbonylation of 1,2-allenyl ketones 1 in the presence of p-benzoquinone (1 equiv) under a CO atmosphere (balloon) afforded difuranylketones 4 in moderate to good yields. Mechanistically, the electron-withdrawing nature of the acyl group should enhance the electrophilicity of the acylpalladium species B, and thus promote the oxypalladation of an additional molecule of 1, leading to the difuranyl
A bicyclization reaction with two molecular allenyl ketones and isocyanides: synthesis of a lactone-containing azaspirocycle derivative
作者:Hongdong Yuan、Chongrong Tang、Shikuan Su、Lei Cui、Xueshun Jia、Chunju Li、Jian Li
DOI:10.1039/c9cc02785h
日期:——
A novel bicyclization reaction of twomolecular allenyl ketones and isocyanides has been disclosed. This strategy allows for the construction of structurally complex spirocyclic lactam–lactone systems in an efficient manner. This protocol also demonstrates other advantages such as high synthetic efficiency, atom economy, and broad substrate scope under mild conditions.
An efficientsynthesis of substituted indolizine and its benzo derivatives, pyrrolo[1,2-a]quinolines and pyrrolo[2,1-a]isoquinolines, by the reaction of allenyl ketones with α-bromo carbonyl compounds and pyridines (quinoline or isoquinoline) under mild conditions without an added oxidant other than molecular oxygen from air was developed. Notably, allenyl ketones with or without a substituent attached