6.7- Dihydro-277-pyrimido isoquinolines, catalytic reduction

Catalytic reduction of l-cyano-6,7-dihydro- and l-cyano-3,4,6,7-tetrahydro-2//-pyrimido[6,l-a]isoquinolines or of l-cyano-3-acetoxy-... 

Catalytic hydrogenation of 3,4-dihydro-2//-pyrimido[2,l-a]isoquinoline-2,4-diones (93) and 3,3-diethyl-9,10-dimethoxy-3,4,6,7-tetrahydro-2//-pyrimido[2,l-a]isoquinoline-2,4-dione (94) over Pt02 and Pd/C catalysts gave l,3,4,6,7,llb-hexahydro-2/7-pyrimido[2,l-a]isoquinoline-2,4-diones (95) [69YZ649 71JPP71/09466]. From the mother liquid of compounds 93 (R = H, R1 = Et and R = R1 = Et) 3-ethyl-2-hydroxy-6,7-dihydro-and -8,9,10,1 l-tetrahydro-4//-pyrimido[2,l-a]isoquinolin-4-ones, and 3,3-diethyl-l,3,4,llb-tetrahydro-2//-pyrimido[2,l-a]isoquinoline-2,4-dione, also could be isolated as minor products. Reduction of 3,3-diethyl-l,3,4,6,7,llfo-hexahydro-2//-pyrimido[2,l-a]isoquinoline-2,4-dione (95, R = R1 = Et, R2 = H) with LAH in tetrahydrofuran at 70°C for 9 h afforded 3,3-diethyl-l,3,4,6,7,llb-hexahydro-2//-pyrimido[2,l-a]isoquinoline (96). 

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