Novel one-pot three-component synthesis of fused dihydropyrimido-thiadiazole compounds of biological interest

Abstract

Multi-component reaction allow the creation of several bonds in a single operation and are attracting increasing attention as one of the most powerful emerging synthetic tools for the reaction of molecular diversity and complexity . Multi-component one-pot reaction is the simplest and the most economical methods for the synthesis of biologically important and pharmacologically useful dihydro-thiadiazol quinozoline derivatives . Without using catalyst under thermal condition is proven efficient method for a one-pot synthesis of dihydro- thiadiazole-quinazolin derivatives in excellent yields from thiadiazole , dimedone and aldehydes in presence of ethanol solvent . The present environmentally benign procedure for the synthesis of dihydro-thiadiazole-quinazolin derivatives is suitable for library synthesis and it will find application in the synthesis of biologically active molecules . The process presented here in operationally simple environmentally benign and has excellent yield . Furthermore , the reaction time is very short within an hour under steam bath reflux condition .

Reaction scheme

In Vitro Bactericidal Profiles of compounds in Terms of Zone of Inhibition

The P-2 compound showed bactericidal moderate activity against S . aureus , B . subtilis , P. aeruginosa . Noticeably , all the compounds showed the antibacterial activity against B . subtilis . P . aeruginosa E . coli , S . aureus , C . freundii . Among them P-1 showed very good activity against B . subtilis , P . aeruginosa , E . coli , S . aureus . P-3 compound showed very good activity against C . freundii . P-1 , P-2 and P-3 compounds showed the antifungal activity against both T . harzianum and A . niger .

Comp. Bacterial species Fungal Species Gram positive Gram negative S.a B.s E.c P.a S.t C.f T.h A.n P-1 25 23 26 22 18 32 9 7 P-2 11 15 10 9 13 15 6 13 P-3 20 20 15 7 10 25 13 7

Antibacterial activity against S .a Antibacterial activity against P. a

Antifungal activity aganist T. h

20 Inhibition zone 10 (mm) 0

p-1 p-2 p-3 Compounds no