Studies On The Synthesis Of Spiroheterocycles With A Fused Pyrimidine Ring Unit Via 1, 3-Dipolar Cycloaddition Reactions

This paper focuses on the synthesis of novel series of spiroheterocyclic compounds via 1,3-dipolar cycloaddition reactions.Bis(arylmethylene)cyclic ketones, the condensates of cyclopentanone, cyclo- heptanone or 1-benzylpiperidin-4-one and aryl aldehydes, reacted with thiourea to give 7-benzylidene-4-phenyl-1,2,3,4,6,7-hexahydro-5H-cyclopenta[1,2-d]pyrimidine -2-thione, 4-aryl-9-arylmethylene-1,2,3,4,6,7,8,9-octahydro-5H-cyclohepta[1,2-d] pyrimidine-2-thione and 6-benzyl-8-benzylidene-4-phenyl-1,2,3,4,5,6,7,8-octahydro- pyrido[4,3-d]pyrimidine-2-thione, respectively. These thioxopyrimidines reacted with chloroacetic acid and appropriate aryl aldehydes, in one pot, to give 22 dipolarophiles with two exocyclic double bonds including 5-aryl-2,8-bis(arylmethylene)-2,3,7,8- tetrahydro-5H,6H-cyclopenta[1,2-d]thiazolo[3,2-a]pyrimidine-3-ones, 5-aryl-2,10-bis (arylmethylene)-2,3,7,8,9,10-hexahydro-5H,10H-cyclohepta[1,2-d]thiazolo[3,2-a]pyr-imidine-3-ones and 2,9-bis(arylmethylene)-7-benzyl-5-phenyl-2,3,6,7,8,9-hexahydro- 5H-pyrido[4,3-d]thiazolo[3,2-a]-pyrimidin-3-ones.21 novel spiroheterocyclic compounds were synthesized by 1,3-dipolar cycloaddition reactions of self-synthesized fused pyrimidine ring compounds with exocyclic double bond and azomethine ylide derived from isatin and sarcosine by a decarboxylative route. Structures of novel compounds were determined by IR, 1H NMR, 13C NMR and mass spectra. The regio and stereochemistry of these 1,3-dipolar cycloaddition reactions was established by X-ray single crystal analyses.9 novel spiroheterocyclic compounds were synthesized by 1,3-dipolar cycloaddition reactions of self-synthesized dipolarophiles and 2,6- dichlorobenzonitrile oxide. Structures of novel compounds were determined by IR, 1H NMR, 13C NMR and mass spectra. The regio and stereochemistry of these 1,3-dipolar cycloaddition reactions was established by X-ray single crystal analyses.