Synthesis of 7H-8, 9-Dihydro-4,8-Dimethyl-Pyrano[2,3-e]Indol-2-Ones

The synthesis of pyrrolocoumarins viz., 7H-8,9-dihydro-4,8-dimethyl-pyrano[2,3-e]indol-2-ones, a new tricyclic system (5), have been achieved from 7-amino-4-methylcoumarin (1) by tosylation, allylation and neat pyrolysis. A plausible mechanism involving amino-Claisen rearrangement followed by [3:3] sigmatropic shift has been presented.     

The Rearrangement of 3, 4-Dihydro-2, 2-Dimethy-2H, 5H-Pyrano [2, 3-b][1] Benzopyran-5-Ones With DDQ

A novel rearrangement of 3, 4-dihydro-2, 2-dimethyl-2H, 5H-pyrano [2, 3-b] [1] benzopyran-5-ones (dihydropyranochromones) has been observed during the dehydrogenation with DDQ. The products obtained are found to be 2, 2-dimethyl-2H, 5H-pyrano [3, 2-c] [1] benzopyran-5-ones (pyranocoumarins).     

Synthese von einigen 2H-Pyran-2-on-Derivaten

The Synthesis of Some 2H-Pyran-2-one Derivatives Derivatives of 6-unsubstituted 2H-pyran-2-one have been synthesized by several different methods. The 4-chloro-2H-pyran-2-one ( 9 ) is the most important, since it serves as starting material for the synthesis of different 4-substituted 2H-pyran-2-ones (Scheme 2). Also described are simple transformations of cumalic-acid derivatives producing 5-(2,2-dichlorovinyl)-2H-pyran-2-one ( 23 ), 2-oxo-2H-pyran-2-carbonitrile ( 26 ), and 4,5-bis(trifluoromethyl)-2H-pyran-2-one ( 32 ) (Scheme 3 and 4).     

Über die Reaktion einiger 2H-Pyran-2-on-Derivate mit primären Aminen

On the Reaction of Some 2H-Pyran-2-one Derivatives with Primary Amines The versatile reactivity of 6-unsubstituted 2H-pyran-2-ones towards aliphatic and aromatic amines has been studied. It was found that the result of the reaction depends not only on the substitution of 2H-pyran-2-ones and on the structure of amines, but also on the stoichiometric ratio of reacting compounds.     

One-pot synthesis of some 2H-Pyran-2-one derivatives

A one-pot synthesis of various 2H-pyran-2-one derivatives 5–19 starting from methyl ketones 1 , N,N-dimethylformamide dimethyl acetal and N-acylglycines 3 in acetic anhydride is described.     

A Convenient Synthesis of 2H-Pyran-2-one Derivatives

A simple procedure for the synthesis of 2H-pyran-2-ones 1 is described: selective Wittig olefination of keto aldehydes at the aldehyde group followed by a cyclization in acidic medium.     

1,2,3,4-Tetrahydropyrimido[1,2-a]benzimidazol-2- and -4-Ones

We have studied the reaction of 2-aminobenzimidazole with esters of substituted cinnamic acids and arylidene derivatives of Meldrum's acid, and have established the direction of formation of the tetrahydrooxopyrimidine ring. We have conducted an X-ray diffraction study of 2-phenyl-1,2,3,4-tetrahydropyrimido[1,2-a]benzimidazol-4-one.     

Some Cyclization Reactions with 2-Ethoxycarbonylmethylidene-4,5-Dihydro-4-Thiazolinone

2-Ethoxycarbonylmethylidine-4,5-dihydro-4-thiazolinone (1) was condensed with bis aromatic aldehydes such as terephthalaldehyde or 4,4′-bisformyl-diphenylether (2a,b) (2:1 molar ratio) and furnished bis-4-thiaozlidinones (3a,b). The reaction of (3a,b) with malononitrile and aromatic aldehydes (1:2:2 molar ratio) gave bis thiazolopyridines (4a–d). Bis-(thiazolopyridine) derivative (6) was obtained by reaction of 4-thiaozlinone (5c) with bis aldehyde (2b) in refluxing ethanol containing piperidine. Cyclization of 4-thiazolinones (5a,b) with different α-cyanocinnamonitriles gave thiazolo[3,2-a]pyridines (7a–d). Compound 9 was produced via the reaction of 8 with thioglycolic acid, which reacted with p-chlorobenzaldehyde to produce 10. Compound 10 was condensed with hydrazine hydrate and afforded 11. Compounds 12 and 16a,b were produced by the reaction of 9 with isatin and α-ethoxycarbonylcinnamonitriles, respectively.     

A Convenient Synthesis of 4-Arylidene- 2-Phenyloxazol-5-Ones Catalyzed by KF-Alumina

A series of 4-arylidene-2-phenyloxzol-5-ones were synthesized by cyclodehydration-condensation of hippuric acid, aromatic aldehydes and acetic anhydride catalyzed by KF-Alumina.     

Synthesis,Properties, and Biological Activity of 4-Hydroxy-2H-Pyran-2-ones and Their Derivatives

The review summarizes published data on the methods for preparation, chemical properties, and biological activity of 4-hydroxy-2H-pyran-2-ones and their derivatives.     

One Pot Synthesis of 7-[1, 2-Dihydro-4-Hydroxy-1-Methyl/Phenyl-2-OXO-3-Quinolinyl]-5, 7-Dihydro-5-Methyl/Phenyl-6H-[1]-Benzo Pyrano [3, 2-c] Quinolin-6-Ones

The reaction of two moles of 4-hydroxy quinotin-2-ones (1) with one mole of salicylaldehydes (2) furnished 6H-benzo-pyrano-[3, 2-c] quinolin-6-ones (3a-j).     

A Facile Synthesis of 2-Mino-3H-Quinazolin-4-Ones with Tandem Aza-Wittig Reaction

2-Amino-3H-quinazolin-4-ones 8 were prepared from tandem aza-Wittig reaction of iminophosphorane 5 with aromatic isocyanate and nucleaphilic reagent HY in mild condition.     

A Convenient Synthesis of Chiral Oxazolidin-2-Ones and Thiazolidin-2-Ones and an Improved Preparation of Triphosgene

Oxazolidin-2-ones and thiazolidin-2-one are conveniently prepared by condensation of L-serine, L-threonine and L-cysteine, respectively with triphosgene. The corresponding methyl esters may be subsequently obtained by quenching the reaction mixture with methanol, without prior need for the isolation of the free acids. An improved procedure for preparation of triphosgene using an internal cooling system is described.