The synthesis of methyl 2-(benzyloxycarbonyl)amino-3-dimethylaminopropenoate.: The synthesis of trisubstituted pyrroles, 3-amino-2H-pyran-2-ones, fused 2H-pyran-2-ones and 4H-pyridin-4-ones

Methyl 2-(benzyloxycarbonyl)amino-3-dimethylaminopropenoate (2) was prepared from methyl N-(benzyloxycarbonyl)glycinate (1) and t-butoxybis(dimethylamino)methane, and used as a reagent for preparation of substituted 3-(benzyloxycarbonyl)amino-4H-quinolizin-4-ones 5 and 6, -2H-pyran-2-ones 17-19, -2H-1-benzopyran-2-ones 28-31, and -naphthopyrans 32-35, -2H-pyrano[3,2-c]pyridine-2,5-dione 46, -pyrano[4,3-b]pyran-2,5-dione 47, -pyrano[3,2-c]benzopyran-2,5-dione 48, -pyrano[2,3-c]pyrazol-6-ones 49 and 50, -pyrano[2,3-d]pyrimidin-7-ones 51 and 52 derivatives. In the reaction of 2 with 1,3-diketones trisubstituted pyrroles 14-16 were formed. Selective removal of benzyloxycarbonyl group was achieved by catalytic transfer hydrogenation with Pd/C in the presence of cyclohexene to afford free 3-amino compounds 7, 8, 20, 36-38 and 53-57 in yields better than 80%.