Bojan Vercek

An “One-Pot” Synthesis of Substituted 3-Benzoylamino-5-oxo-5, 6, 7, 8-Tetrahydrocoumarins

Abstract A new simple “one-pot” synthesis of some 3-benzoylamino-5-oxo-5, 6, 7, 8-tetrahydrocoumarins from 1, 3-cyclohexanediones, hippuric acid, acetic anhydride and triethyl orthoformate or other one-carbon synthetic equivalent is described.

Cyanoamino compounds in synthesis syntheses of some heterocycles

Transformations of some heterocyclic cyanoamino compounds leading to various heterocyclic systems are described.s-Triazolo (1,5-α)azines are obtained either in a direct synthetic approach or via the substituted aminotetrazoles, substituted 3-amino-5-oxo-1,2,4-oxadiazolines, and fromN-ethoxycarbonylN′-heteroaryl thioureas orN-heteroarylN′-hydroxyguanidine. The cyanoamino group reacts also witho-difunctional benzenes to give the corresponding substituted derivatives of benzimidazole, benzoxazole or benzothiazole.ZusammenfassungUmwandlungen von einigen heterocyclischen Cyanoamino-Verbindungen in verschiedene heterocyclische Systeme werden beschrieben.s-Triazolo-(1,5-a)azine konnten in einem direkten Syntheseschritt oder über die substituierten Aminotetrazole, substituierten 3-Amino-5-oxo-1,2,4-oxadiazoline und ausN-Ethoxycarbonyl-N′-Heteroaryl-Thioharnstoffen oderN-Heteroaryl-N′-Hydroxyguanidin erhalten werden. Die Cyanoamino-Gruppe reagiert auch mit einigeno-disubstituierten Benzolderivaten; es wurden damit Derivate von Benzimidazol, Benzoxazol oder Benzothiazol dargestellt.

4-Ethoxymethylene-2-phenyl-5(4H)-oxazolene as a Synthon for the synthesis of Some 2H-Pyran-2-ones

Treatment of 4-ethoxymethylene-2-phenyl-5(4H)-oxazolone with activated methylene compounds under acidic or basic conditions leads to 2H-pyran-2-ones and fused pyran-2-ones. On the other hand, methyl (3-benzoylamino-5-methoxycarbonyl-2-oxo-2H-pyran-6-yl)-acetate (4) has also been prepared by a one-pot synthesis from dimethyl 1,3-acetonedicarboxylate, diethoxymethyl acetate, hippuric acid and acetic anhydride

Pyrano [3,2-c]azepine, a new heterocyclic system. A new approach to pyrido [3,2-c]azepines

3-Benzoylamino-7,7-dimethyl-5-oxo-5,6,7,8-tetrahydrocoumarin (1a) was used as a synthon in the preparation of the first derivatives of the pyrano[3,2-c]azepine system 2 and in two approaches to pyrido[3,2-c]azepines 4

Neighbouring group participation in formation of condensed azines. Formation of pyrazolo(3,4-b)pyrazines, isoxazolo(4,5-b)pyrazines and isothiazolo(5,4-b)pyridine

Pyrazine- and pyridinecarboxamidoximes with an amino, potentially tautomeric hydroxy or mercapto group inortho position could be transformed in the appropriate condensed azines. In this manner, representatives of pyrazolo(3,4-b)pyrazine, isoxazolo(4,5-b)pyrazine and isothiazolo(5,4-b)pyridine ring system were synthesized and some transformations investigated.ZusammenfassungMit einer Amino-, potentiell tautomerer Hydroxy- oder Mercaptogruppe wurdenortho-substituierte Pyrazin- oder Pyridincarboxamidoxime in die entsprechenden kondensierten Azine umgewandelt. Auf diese Weise wurden Derivate des Pyrazolo(3,4-b)pyrazin, des Isoxazolo(4,5-b)pyrazin und Isothiazolo(5,4-b)pyridin dargestellt und einige Umwandlungen studiert.

Simple Procedure for the Synthesis of Pyridinecarbohydroximoyl Chlorides and Bromides

Abstract A convenient synthesis of 2-, 3- and 4-pyridine-carbohydroximoyl chlorides and bromides is described, This method involves reaction of appropriate amide oxime with sodium nitrite in the presence of hydrochloric or hydrobromic acid.

SYNTHESIS OF BENZOYLAMINOMETHYL AND AMINOMETHYL SUBSTITUTED FUSED 1,2,4-TRIAZOLES

The use of N-[2-(heteroarylhydrazono)ethyl]benzamides in the synthesis of benzoylaminomethyl and aminomethyl substituted fused 1,2,4-triazoles is reported.

Transformation of 5-Oxo Substituted Fused Pyran-2-ones. Lactam Versus Hydrazone Formation

Abstract 6, 7-Dihydrocyclopenta[b]pyran-2, 5-dione 1 was converted with hydrazines to fused pyridine-2(1H)-ones of type a. In contrast, 2H-1-benzopyran-2, 5-diones 2–4 gave under the same reaction conditions 5-hydrazonobenzopyrans of type b. Calculated heats of formation matched experimental findings.

A novel approach to [1,2,3]triazolo[1,5-a]pyrazines

A simple method for the preparation of [1,2,3]triazolo[1,5-a]pyrazines involving the cyclization of alkyl 2-benzoylamino-(4,5-dicyano-1H-1,2,3-triazol-1-yl)propenoates (5) is reported.

The synthesis of pyrimidine 1-oxides : a new transformation of amide oximes

Abstract The title N-oxides were prepared from several carboxamide oximes on treatment with 1,3-dicarbonyl derivatives.