D. Latha

An efficient one step conversion of 3-formylchromones into 3-cyanochromones

3-Cyanochromones constitute an important class of intermediates because of their use in the synthesis of anti-allergic substances.’ The cyan0 group enhances the dienophilic nature of the carbon-carbon double bond of the cyclic enone system and thus 3-cyanochromones have been extensively used as dienophiles in the synthesis of compounds with selective acetylcholinesterase inhibiting activity? Several methods have been reported for the synthesis of 3cyanochromones (3) by dehydration of the corresponding aldoximes (2). These include refluxing for 12 hrs in alcohol in the presence of hydrochloric acid3 sodium formate in acetic acid4 and acetic anh~dride.~ Sulfuric acid promoted elimination of methanol from 0-methyloximes has also been reported for the synthesis of 3-cyanochromones.6 Most of these methods involve i) prior preparation of oximes’ and ii) dehydration, with the disadvantages of strongly acidic conditions,46 expensive reagents,6 long reaction times? tedious isolation of products and low overall yields. The synthetic potential and medicinal interest of 3-cyanochromones and the difficulties encountered in the synthesis of 3-cyanochromones prompted a search of a convenient method.

Synthesis of some new 4-Heteroaryl substituted 3-cyano coumarins starting from 3-formylchromones

A series of new 4-pyrazolyl/benzopyrano[4,3-6]pyridinyl/pyrazolo[l,5a]pyrimidinyl-3-cyanocoumarins (5, 6 & 7) have been synthesized starting from 3formylchromones (1).

SYNTHESIS OF 6-[(4-CHROMON-3-YL-BENZOPYRANO[4,3-b] PYRIDIN-2-YL)]-2H-[1,4]-BENZOXAZIN-3(4H)-ONES

YL)]-2H[ 1,4] -BENZOXAZIN-3(4H)-ONES G. Jagath Reddy *, D. Latha, C. Thirupathaiah and K. Srinivasa Rao R & D Laboratories, Dr. Jagath Reddys Heterocyclics, 81, S.V.Co-op Industrial Estate, Baianagar, Hyderabad 500 037, India, e-mail-jagathreddy@usa.net; Fax #91-40-23773487. and Md. Khalilullah Department of Chemistry, Jawaharlal Nehru Technological University, Hyderabad-500072, India. Abstract:

Synthesis of Pyrazolo[1,5-a]pyrimido[4,3-d] benzopyrans and 2-Pyrazolo[1,5-a]pyrimidinylphenols from the reaction of 5(3)-amino pyrazoles

A number of Pyrazolo[l,5-a]pyrimido[4,3-d]benzopyrans(4a-m) and 2(Pyrazolo[l,5-a]pyrimidinyl)phenols (7a-k) have been prepared from the reaction of 5(3)-aminopyrazoles 3. Introduction Several benzopyrans and benzopyrans fused with a heterocyclic ring at 3,4 positions such as pyridine, pyrazole and isoxazoles have been reported to possess and

MICROWAVE ASSISTED SYNTHESIS OF 5-ARYL-THIOPHENE-2-CARBOXYLATES

5-Arylthiophene-2-carboxylates can be synthesized by the reaction of either ßchlorovinyl aldehydes or l-chloropropen-3-ylideneimmonium salts with mercaptoacetates in presence of triethylamine in pyridine and in triethylamine/pyridine in presence of potassium hydroxide to effect spontaneous cyclization of the intermediate thioesters. Microwave assisted organic reactions have gained much importance during recent years, as they are completed in a short time with higher yields and purity when compared to conventional heating. In continuation of our interest, in synthesizing functionally substituted heterocycles by simple methods and using commonly available reagents, 10 we report here in a simple and rapid microwave assisted synthesis of 5-arylthiophene carboxylates from 3-chlorovinyl aldehydes and mercaptoacetic acid esters. Abstract

Synthesis of 7-Aryl / chromonyl substituted benzopyrano[4,3-d]pyrazolo[1,5-a]pyrimidines by reaction of 5(3)-Aminopyrazoles

A series of 7-Aiyl/chromonyl substituted benzopyrano[4,3-d]pyrazolo[l,5ajpyrimidines (3a-g and 5a-c) have been prepared by reaction of 5(3)Aminopyrazoles(2).

Synthesis of some new Ethyl 4-(1,3-Diarylpyrazol-4-yl)-6-methyl-2-thioxo-1,3,4-trihydropyrimidine-5-carboxylates

A series of some new 4-pyrazolyl-6-methyl-2-thioxo-l,3,4-trihydropyrimidine-5carboxylates (4a-h) have been synthesised.

A MILD AND FACILE METHOD FOR THE SYNTHESIS OF 3-CYANOCHROMONES FROM OXIMES DERIVED FROM 3-FORMYLCHROMONES USING DIMETHYLFORMAMIDE - THIONYLCHLORIDE COMPLEX

A mild and facile method for the synthesis of 3-cyanochromones (4) from oximes (2) derived from 3-formylchromones using Dimethylformamide-thionylchloride complex (1) is herein reported.