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Chapter – 4 Studies on different types of reactions….. used while differently substituted β-keto esters have also been used for the synthesis of diversified dihydropyrimidine derivatives via Biginelli reaction. Use of 4-hydroxycoumarin in the synthesis of dihydropyrimidine synthesis is not much reported. The tautomeric form (1) of 4-hydroxycoumarin acts as a cyclic β-keto ester (Fig. 4.27) and condenses with aldehydes in the presence of urea / thiourea under acidic conditions and gives rise to the expected coumarin fused pyrimidines. Fig. 4.27 Brambhatt et. al. 305 reported synthetic method for the fused benzopyranopyrimidine derivatives. They reported the poor yielded synthetic procedure with the longer time period. Microwave assisted green chemical approach was applied to the synthesis of benzopyranopyrimidines by Kidwai et. al. 306 This method not only gave better yield with reduced reaction time but also eliminated the need of an external acid due to the usage of acidic solid support. Since the reaction takes place under acidic conditions, the effect of three different acidic inorganic support viz. acidic alumina, montmorillonite K10 clay and silica gel was explored. The same reaction was also carried out in solution phase under MW. A conventional method with basic alumina in oil bath maintained at 110– 120°C was also attempted, but the reaction took from 4 to 6 h to give the required product in about 39–60 % yield. This clearly indicates that the coupling of microwaves with the solid supported reagent is more than simple thermal effects. Furthermore They 307 eliminated the use of inorganic solid support and condensed all the three components i.e. 4-hydroxycoumarin, aromatic aldehydes and urea / thiourea, neat under microwave irradiation. Department of Chemistry, Saurashtra University, Rajkot – 360 005 215
Chapter – 4 Studies on different types of reactions….. 4.6 AIM OF CURRENT WORK This chapter contains four different schemes. Different types of reactions have been carried out on pyrazole aldehydes in each and every scheme. The synthesis of pyrazoles remain of great interest owing to the wide applications in pharmaceutical and agrochemical industry due to their herbicidal, fungicidal, insecticidal, analgesic, antipyretic, anti inflammatory, anti bacterial, anti parasitic and anti diabetic properties. Earlier, from this laboratory, some indolinone derivatives were prepared and tested for anti cancer activity on colon cancer cell line (SW 620), which showed good results. c In continuation of our previous work, few differently substituted pyrazole aldehydes were developed and new indolinone derivatives to observe their anti cancer activity. Similarly, chalcones of 3-acetyl-4-hydroxycoumarin with differently substituted benzaldehydes were prepared and tested for anti viral activity which showed good results. In continuation, new chalcones of 3-acetyl-4hydroxycoumarin with pyrazole aldehydes were synthesized and evaluated for their antiviral activity. Recently much attention has been devoted towards dihydropyrimidine derivatives due to their significant therapeutic and medicinal properties. Literature survey revealed that differently substituted benzaldehydes are fused with 4-hydroxycoumarin and urea / thiourea to synthesize coumarin fused pyrimidines but in place of substituted benzaldehydes, pyrazole aldehydes are not approached, which inspired us to synthesize some new coumarin fused pyrimidines. In the present work, the keto tautomeric form of 4-hydroxy-coumarin acts as a cyclic β-keto ester and condenses with pyrazole aldehydes in the presence of urea / thiourea under acidic conditions and gives rise to the expected coumarin fused pyrimidines. c V. Virsodia, A. Manvar, K. Upadhyay, R. Loriya, D. Karia, M. Jaggi, A. Singh, R. Mukherjee, M. S. Shaikh, E. C. Coutinho and A. Shah; Eur. J. Med. Chem., 2008, 1-8 (In press) Department of Chemistry, Saurashtra University, Rajkot – 360 005 216
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Saurashtra University Re - Accredit
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Statement under O. Ph. D. 7 of Saur
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ACKNOWLEDGEMENT It is a moment of g
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Jignesh Lunagariya, Hitesh Sarvaiya
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CONTENT Content General Remarks 6 A
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Content 3.2 Reaction scheme 149 3.3
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5.14 Conclusion 313 5.15 Spectral r
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MF Molecular Formula MW Molecular W
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GABA Gamma Amino Butyric Acid MES M
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PART - A STUDIES ON 2-METHYL INDOLI
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Part-A Studies on 2-methyl indoline
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CHAPTER - 1 PREPARATION AND YIELD O
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Chapter - 1 Preparation and Yield o
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Chapter - 2 Microwave assisted simp
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Part - B Studies on isatin derivati
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CHAPTER - 3 PREPARATION OF SMALL LI
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Chapter - 3 Preparation of small li
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Chapter - 5 Synthesis and Character
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Chapter - 6 Biological evaluation o
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Summary Synthesis and biological pr
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Summary Synthesis and biological pr
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Conferences / Seminar / Workshop At
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