Chandra Kanta Ghosh

Bio: Chandra Kanta Ghosh is an academic researcher from University of Calcutta. The author has contributed to research in topic(s): Benzopyran & Benzopyrans. The author has an hindex of 10, co-authored 53 publication(s) receiving 400 citation(s).

Chemistry of 4-Oxo-4H-[1]benzopyran-3-carboxaldehyde

Abstract: Cet article de synthese presente un examen approfondi de la synthese, des proprietes et des reactions de l'oxo-4 chromenecarbaldehyde-3 et de l'utilisation de ses condensats pour la preparation de divers systemes chimiques

Chemistry and application of 4-oxo-4H-1-benzopyran-3-carboxaldehyde

Abstract: The Chemistry and application of the title aldehyde and some simple derivatives thereof are reviewed.

Benzopyrans. Part 42 [1]. Reactions of 4-oxo-4H-1-benzopyran-3-carbaldehyde with some active methylene compounds in the presence of ammonia

Abstract: The title aldehyde 1 in the presence of ammonia gives the pyridine derivatives 9-11 respectively with acetylacetone, diethyl malonate and ethyl cyanoacetate, and ethyl (or methyl)-l-benzopyrano[4,3-b]pyri-dine-3-carboxylate 22 (or 23) with ethyl (or methyl) acetoacetate. Acetylacetone pretreated with ammonia condenses with 1 giving the fused pyridine 24. Ammonia converts the ester 6 to the pyridine 13 or 14. Chromic acid oxidation of 22 and 23 affords the coumarinopyridines 25 and 26, respectively.

Chemistry of 4-Oxo-4H-1-benzopyran-3-carbonitrile

Abstract: Of all the cyano substituted 1-benzopyran-4-ones [1], the title nitrile (trivial name: 3-cyanochromone) 1 is unique because of diverse functionalities being imbedded in it. Being an α,β-unsaturated nitrile as well as α,β-unsaturated ketone, it possesses three electron deficient sites viz. C-2, cyano carbon and carbonyl carbon, the last one having obviously the least electrophilicity compared to the other two. So an initial addition of a nucleophile to 1 and any subsequent transformation, if possible, of the adduct will depend on the nature of the nucleophile as well as the reaction conditions. The presence of two electron-withdrawing groups at the same end of the pyran 2,3-olefinic bond is likely to make this olefin a sufficiently active dienophile in [4+2]cycloaddition with dienes, and dipolarophile in [3+2]cycloaddition with 1,3-dipoles. Furthermore, the chromone 1 can be regarded as an intramolecular enol ether of the aldehyde 2 that can give rise to 2-amino-3formylchromone 4 via 3 (Scheme 1). So a nucleophilic 1,4addition to the α,β-unsaturated nitrile (or ketone) functionality of 1 with concomitant opening of the pyran ring followed by recyclisation is equivalent to the nucleophilic 1,2addition to the aldehyde function of 4; in other words, the nitrile 1 is ‘chemically equivalent’ to the aminoaldehyde 4 under certain reaction conditions. Because of its above stated characteristics, the reactions of the title nitrile 1 alone are the subject matters of many publications. The present review gives a comprehensive account of its synthesis and reactions reported up to 2004. In this review the 4-oxo-4H1-benzopyran-3-yl moiety is abbreviated as ‘Chr’ so that 1benzopyran-4-one having ‘X’ substitution at its 3-position may be represented by Chr-X.

The simple β-carboline alkaloids

Abstract: The simple β-carbolines are presented as a distinct group of alkaloids displaying structural modification of three basic ring systems. Their occurrence in plants is listed on a taxonomic basis and aspects of their metabolism, pharmacological properties and taxonomic significance are briefly summarized.

A versatile route to 2-alkyl-/aryl-amino-3-formyl- and hetero-annelated-chromones, through a facile nucleophilic substitution at C2 in 2-(N-methylanilino)-3-formylchromones

Abstract: The N-methylanilino group in 2-(N-methylanilino)-3-formylchromones, obtained in high yield by rearrangement of C(4-oxo-4H[1]-benzopyran-3-yl)-N-phenylnitrones to 2-anilino-3-formyl-chromones followed by N-methylation, undergoes facile nucleophilic substitution by a variety of nitrogen nucleophiles, thereby paving the way for synthesis of a variety of novel 2-substituted-3-formylchromone derivatives as well as hetero-annelated chromones.

Activation of the amide group by acylation hydroxy- and aminoacyl incorporation in peptide systems.

Abstract: A new reaction, the hydroxy- and aminoacyl incorporation in aliphatic and alicyclic N-hydrox-(amino)acl amides is described in detail. The reaction affording linear or cyclic peptides and depsipeptides proceeds via formation of cyclols. Its course depends on the nucleophilicity of the HO- and NH2-groups, the electrophilicity of the amide carbonyl and, with cyclic amides, on the size of the ring. The cyclols which sometimes can be isolated display a number of unique properties, in particular, a tendency to undergo transformation into acylamides or macrocycles. Hydroxy- and aminoacyl incorporation is significant in the synthesis of peptides and depsipeptides. For example, it has been utilized in the synthesis of the antibiotic serratomolide and its analogues. A discussion of the biochemical and biogenetic implications of the reaction is given.