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Chapter – 4 Studies on different types of reactions…..
Comparative results of method (A) and method (B) are summarized as under.
Code
No.
Reaction Condition % Yield
Method (A) Method (B)
Temp.
(°C)
Time
(hrs.)
Watt
(W)
Temp.
(°C)
Time
(min.)
Method
(A)
Method
(B)
DNJ-701 90-95 5.0 400 110 3.0 48 81
DNJ-702 90-95 5.5 400 110 3.1 50 80
DNJ-703 90-95 6.0 400 110 3.3 52 85
DNJ-704 90-95 7.0 400 110 3.0 49 79
DNJ-705 90-95 4.0 400 110 3.2 55 83
4.9.5 GENERAL PROCEDURE FOR THE PREPARATION OF DNJ-801 TO
DNJ-805
0.01 mole of 3-acetyl-4-hydroxycoumarin and 0.01 mole of an
appropriately substituted pyrazole-4-carboxaldehyde were dissolved in 30 ml
of chloroform. A catalytic amount of piperidine was added and the reaction
mixture was refluxed for 4 hours. The progress and the completion of the
reaction were checked by silica gel-G F254 thin layer chromatography using
hexane : ethyl acetate (6 : 4) as a mobile phase. The chloroform was distilled
out and the residue was washed with methanol and dried to give desired
product in moderate yield which was recrystallized by DMF. (Physical data of
the synthesized end products are summarized in the table 4.10.2)
4.9.6 GENERAL PROCEDURE FOR THE PREPARATION OF DNJ-901 TO
DNJ-905
METHOD – (A) CONVENTIONAL APPROACH
0.01 mole of 4-hydroxycoumarin was dissolved in 30 ml of methanol
into 100 ml round bottom flask. 0.01 mole of an appropriately substituted
pyrazole-4-carboxaldehyde was added to the above flask along with few
drops of piperidine. The reaction mixture was heated on water bath for 4-5
hours. The progress and the completion of the reaction were checked by silica
gel-G F254 thin layer chromatography using hexane : ethyl acetate (6 : 4) as a
Department of Chemistry, Saurashtra University, Rajkot – 360 005 227