Reactivity of Ring Carbon Atoms

Treatment of 4-phenyl-2,3-dihydro-l//-pyrido[l,2-c]pyrimidine-l,3-dione with POCI3 in the presence of A,A-dimethylaniline gave 3-chloro- 

2-Benzyl-l,2,3,5,6,7-hexahydropyrido[3,2,l-iy]quinazolin-7-one was acy-lated at position 9 by heating in acetic acid (72MI1). 

Treatment of l-imino-4-cyano-3-methylthio-l/7-pyrido[l,2-c]pyrimidine (105) with morpholine afforded the 1-amino-l-morpholine derivative (106). Reaction of the 1-imino derivative (105) with dimethyl acetylenedicarboxy-late gave the diaza[3,3,3]azine derivative (107) (75YZ13). Treatment of 105 with concentrated H2SO4 or with acetic acid yielded 4-aminocarbonyl-3-methylthio- l//-pyrido[l, 2-c]pyrimidin-l-one and 4-cyano-3-methylthio-l//-pyrido[l,2-c]pyrimidin-l-one, respectively. Reaction of the latter derivative with morpholine afforded the 3-morpholino derivative (75YZ13). Hydrolysis of 4-cyano-3-imino-2,3,5,6,7,8-hexahydro-l//-pyrido[l,2-c] pyrimidine-l-(thi)ones or their 3-(aminocarbonyl)imino derivatives in boiling 70% HCl gave 3-oxo derivatives (78MI1). 

Methylation of 4,4a,5,6,7,8-hexahydro-3//-pyrido[l,2-c]pyrimidin-3-one (108, R = H) with methylmagnesium chloride in the presence of CU2I2 or Cu2Br2 gave l-methylperhydropyrido[l,2-c]pyrimidin-3-one 

Treatment of 4-phenyl-2,3-dihydro-l//-pyrido[l,2-c]pyrimidine-l,3-dione with POCI3 in the presence of iV,N-dimethylaniline gave 3-chloro-4-phenyl-l//-pyrido[l,2-c]pyrimidin-l-one. The 3-chloro atom could be substituted by amino and alkoxy groups. Treatment of the 3-chloro derivative with thiourea afforded 4-phenyl-3-thioxo-2,3-dihydro-l//-pyrido[l,2-c]pyrimidin-l-one (57HCA1319). 

Heating 3-acetoxy-l-cyano-9,10-dimethoxy-3,4,6,7-tetrahydro-2H-pyri-mido[6,l-u]isoquinoline yielded the 6,7-dihydro derivative by elimination of acetic acid (81CB61 84MI3). 

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