Studies on conjugated heterodiene system and synthesis of some potential bioactive molecules

Abstract

Introduction:- A brief review on the chemistry of heterodine sytem Illustration of new concepts and strategies with special emphasis on heteroatom at no-1 position Pages - 1-11. Key words- Conjugated heterodiene system 1)Newer strategy towards the synthesis of heterosteroids 1a) Conversion of conjugated oximes into pyridines Strategies towards synthesis of heterosteroids, and their biological impo-rtance are reviewed. A new strategy towards synthesis of substituted pyrid-ine under Vilsmeier reaction condition is described., Pages 12-55 Key words- conjugated oxime, Vilsmeier reaction, substituted pyridine. 1b)A facile one pot synthesis of pyrazole using hydrazine-iodine system A review is made on novel pathways towards synthesis of pyrazoles. A novel discovery has been made in which hydrazine hydrochloride and iodine are utilised to synthesize steroidal as well as aliphatic pyrazoles. Pages - 56-85. Key words- Cycloaddition, Pyrazole 2) Intramolecular cycloaddition in steroids A review is made on the common characteristics of of the intramolecula cycloaddition with special emphasis on the nitrone and nitrile oxide cycload-ditions. Steroidal molecule 16-DPA is successfully transformed into D - ring fused isoxazolidine, isoxazoline and isoxazole. Pages - 86-109 Key words- stereoselectivity, intra molecular 1,3-dipolarcycloaddition, Nitone, nitrile oxide. 3) Vilsmeier reagent as an effective geminal dichlorinating agent Synthesis of geminal dichloride and its utility in organic chemistry is reviewed Reaction of enamino formyl steroid towards Vilsmeier reagent is studied. Pages 110-134. Key words - formyl enamide, Vilsmeier reagent , geminal dichloride. 4) Facile ring cleavages of steroidal D- ring. A brief study on enediynes and recent development on ring cleavage reactions are reviewed. Three new procedures are dev-eloped for facile opening of steroidal D-ring via C16-C17 single bond cleavage. One of the product is found to be important intermediate for novel class of steroidal diyne. Pages 135-159 Key words -...