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Chapter – 4 Studies on different types of reactions…..
4.13 RESULTS AND DISCUSSION
Four different schemes had been adopted to build up this chapter. This
chapter is mostly related to modification in the previous work done by our
group as well as others but the scaffolds reported here are new. Earlier
indolinone derivatives were known to be prepared by conventional method
using piperidine (base) in refluxing methanol or ethanol. Different 2-indolinone
derivatives have been prepared by adopting the conventional method.
Moreover, microwave assisted method was also employed to compare both
the methods in order to acquire best results. Microwave assisted method
found much faster than the conventional one and % yield found to be higher
than conventional but the purity was similar in both the methods.
It is very well known that C3 position of 4-hydroxycoumarin is highly
reactive. 3-acetyl-4-hydroxycoumarin was synthesized by acetylation on 4hydroxycoumarin
adopting cited literature method. Chalcones of 3-acetyl-4hydroxycoumarin
were prepared using substituted benzaldehydes using
piperidine (base) and chloroform which showed good anti viral activity j . In this
chapter, continuing previous work chalcones of 3-acetyl-4-hydroxycoumarin
using differently substituted pyrazole aldehydes were synthesized using the
same experimental protocol.
4-hydroxycoumarin and different pyrazole aldehydes were refluxed in
methanol under basic condition in order to prepare coumarin dimers but the 4hydroxycoumarin
tautomarize into 2H-chromene-2, 4(3H)-dione and due to
the in situ generation of active methylene group it gave arylidine at C3position.
Three component Biginelli reaction was used to prepare the coumarin
fused pyrimidine derivatives. Mixture of urea / thio urea, pyrazole aldehyde
j J. C. Trivedi, J. B. Bariwal, K. D. Upadhyay, Y. T. Naliapara, S. K. Joshi, C. C. Pannecouque,
E. De Clercq and A. K. Shah; Tet. Lett., 2007, 48(48), 8472.
Department of Chemistry, Saurashtra University, Rajkot – 360 005 252