Journal ArticleDOI
An Expedient New Synthesis of Substituted Carbazoles via α-Oxoketene Acetals through Heteroaromatic Annelation Methodology
TLDR
In this paper, a new general method for substituted carbazoles was developed involving base induced conjugate addition-elimination sequence of indole-3-acetonitriles 1 to various α-oxoketene S,S-,O,S- and N,Sacetals 2a-x followed by cyclization of the intermediates 3 with p -toluenesulfonic acid in refluxing benzene.About:
This article is published in Tetrahedron Letters.The article was published on 1997-04-28. It has received 17 citations till now.read more
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Journal ArticleDOI
[3+3] Benzannulations of benzenoid- and heteroaromatic-ring systems
Journal ArticleDOI
Heteroaromatic Annulation of 2-Methyl/2-Cyanomethylbenzimidazole Dianions with α-Oxoketene Dithioacetals: A Highly Regioselective Synthetic Protocol for 1,2- and 2,3-Substituted/Annulated Pyrido[1,2-a]benzimidazoles†
TL;DR: The dianion 2A derived from 2-methylbenzimidazole has been shown to undergo regioselective 1,2-addition with various alpha-oxoketene dithioacetals derived from acyclic and cyclic ketones to afford various carbinol acetals in high yields.
Journal ArticleDOI
Aromatic and heteroaromatic annelation studies on 3-[bis(methylthio)methylene]-1-methyloxindole: synthesis of carbazoles and an efficient route to pyrido[2,3-b]indoles
TL;DR: In this paper, a cycloaromatization with allyl and methallyl magnesium chlorides to afford substituted carbazoles was proposed for 3-[bis(methylthio)methylene]-1-methyloxindole.
Journal ArticleDOI
A new regiospecific method for the synthesis of substituted phenanthridines and benzo[j]phenanthridines via aromatic annelation of 1-N-benzenesulfonyl-3-[bis(methylthio)methylene]-1,2,3,4-tetrahydroquinoline-4-one
TL;DR: In this paper, a new efficient method for the synthesis of substituted phenanthridines, benzo[j]phenanthridine and naphtho[2,1-j]-phenanthidines is described.
Journal ArticleDOI
α-Oxoketene dithioacetals mediated heteroaromatic annulation protocol for benzoheterocycles: an efficient regiocontrolled synthesis of highly substituted and annulated indazoles
TL;DR: An efficient regiocontrolled synthesis of highly substituted and annulated indazoles involving base induced addition-elimination of 1,3-diphenyl-5-cyanomethylpyrazole to a variety of acyclic and cyclic α-oxoketene, followed by acid assisted cycloaromatization of the resulting conjugate adducts has been reported.
References
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Journal ArticleDOI
α-Oxoketene-S,S-, N,S- and N,N-acetals: Versatile intermediates in organic synthesis
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Efficient Syntheses of Substituted Carbazoles and Cyclopent[b]indoles from 1-Methyl-3-(benzotriazol-1-ylmethyl)indole.
TL;DR: NMR study is described to discriminate between structures of types 6 and 8 on the basis of (1)H-(13)C long-range correlation to give 1-functionalized cyclopent[b]indoles 15 and 16 with a high degree of stereoselectivity.
Journal ArticleDOI
α-Oxoketene Dithioacetals as Intermediates for Aromatic Annelation
TL;DR: In this paper, the α-oxoketene dithioacetals of general formula 1 (Scheme 2), undergo regioselective 1,2-addition with allyl anions to afford the corresponding carbinol acetals 6 in quantitative yields, which on treatment with BF3.Et2O in refluxing benzene yield the corresponding aromatic systems.