One-Pot Eschenmoser Episulfide Contractions in DMSO: Applications to the Synthesis of Fuligocandins A and B and a Number of Vinylogous Amides
摘要:
Practical total syntheses of the natural products fuligocandin A (2a) and fuligocandin B (3) have been achieved through a convergent strategy depending on the Eschenmoser episulfide contraction as a key step. Conducting the reaction in DAIS proved to be an efficient and general method for the synthesis of a variety of vinylogous amides, such as azepan-2-ylidenepropan-2-one.
12-Tungstophosphoric acid (H3PW12O40) is found to be an efficient and recyclable catalyst in promoting a chemo- and regioselective condensation of hydrazines/hydrazides, diamines, and primary amines with various 1,3-dicarbonyl compounds in pure water at room temperature to afford pyrazoles, diazepines, and enaminones/enamino esters, respectively, in high yields.
Room-Temperature Synthesis of Pyrazoles, Diazepines, <font>β</font>-Enaminones, and <font>β</font>-Enamino Esters Using Silica-Supported Sulfuric Acid as a Reusable Catalyst Under Solvent-Free Conditions
highly efficient regio- and chemoselective condensation of hydrazines/hydrazides, diamines, and primary amines with various β-dicarbonyl compounds at room temperature to afford pyrazoles, diazepines, and β-enaminones/β-enaminoesters under solvent-free conditions within 5–15 min.
Reactions of Lithium Silylcuprates with Pyrazolium and Indazolium Salts
作者:Ana M. González-Nogal、Mariola Calle、Purificación Cuadrado
DOI:10.1002/ejoc.200700742
日期:2007.12
Although pyrazoliumsalts have been shown to be unreactive toward lithium carbocuprates, these substrates were opened by lithium silylcuprate reagents to give versatile N-silylated β-enaminoimines stabilized by coordination of the silyl group with both nitrogen atoms. In contrast, the behaviour of indazolium salts on treatment with the same reagents is more complex. Depending on the substitution patterns
Practical total syntheses of the natural products fuligocandin A (2a) and fuligocandin B (3) have been achieved through a convergent strategy depending on the Eschenmoser episulfide contraction as a key step. Conducting the reaction in DAIS proved to be an efficient and general method for the synthesis of a variety of vinylogous amides, such as azepan-2-ylidenepropan-2-one.