3-Acetyl-2-hydroxy-4//-pyrido

The relative stereostructure of 9-acetyl-7-hydroxy-l,2-dimethyl-7-meth-oxycarbonyl-4-phenyl-6-oxo-l, 4,7,8-tetrahydro-6/7-pyrido[l, 2-u]pyri-midine-3-carboxylate 122 was justified by an X-ray diffraction analysis (97JOC3109). The stereochemistry and solid state structure of racemic trans-6,9-//-l, 6-dimethyl-9 z-ethoxy-9-hydroxy-4-oxo-l,6,7,8,9,9 z-hexahydro-4//-pyrido[l,2- z]pyrimidine-3-carboxylate (123), adopting a cw-fused conformation, were determined by X-ray investigations (97H(45)2175). 

Cyclocondensations of benzylidenemalononitrile with pyridinethiones 210 and 211 afforded the amino derivatives of pyrido[2,l-h][l,3]thiazines 212 and 213, respectively (90MI2 92MI6). Reaction of 5-acetyl-3-cyano-6-methyl-4-phenyl-3,4-dihydropyridine-2(lfl)-thione with epichlorohydrin in the presence of potassium hydroxide and sodium methylate gave 7-acetyl-3-hydroxy-6-methyl-8-phenyl-2,3,4,8-tetrahydropyrido[2,l-h][l,3]-thiazine-9-carbonitrile (94KGS139). 

Hydroxy-4-oxo-4//-pyrido[l,2-a] pyrimidines have been O-alkyl-ated46,54,59,78,88,138,140 and O-acetylated.58,78 O-Acetylation of a 9-hydroxy-6,7-dihydro derivative has also been reported.316... 

Hydroxy-2-oxo-3,4-dihydropyrido[l,2-a]pyrimidine was O-acetylated with acetic anhydride and dehydrated to 2-oxo-2//-pyrido[l,2-u]pyrimidine (18) with phosphorus pentoxide.200... 

Acetyl-2-phenyl-4-hydroxy-4tf-pyrido[l,2-a]pyrimidine was oxidized with chloranil to the 4-oxo compound.168... 

Reaction of 9-bromomethyl-4-oxo-4//-pyrido[ 1,2-a]pyrimidine-3-carboxylates 505 and their homologs with 2,4-dihydroxy-3-propyl-and -3-allyl-acetophenone 506 in boiling methyl ethyl ketone in the presence of potassium carbonate afforded 9-(4-acetyl-3-hydroxy-2-substituted phenoxymethyl) derivatives (507) [87EUP242230 88JAP(K)88/246375]. 

Acetyl-4-phenylamino-2if-pyrido[l, 2-a]pyrimidin-2-one (285) was obtained when A-(2-pyridyl)acetoacetamide 332 (R = H) was first treated with PhNCS in the presence of K2CO3 and BnEtsNCl, then with Mel and NEt3, and then the reaction mixture was heated rapidly to 80 °C (95MI2). Reaction of A-(2-pyridyl)acetoacetamides 332 with CS2 in the presence of K2CO3 and a catalytic amount of BnEt3NCl, then with 1 or 2 equiv of Mel afforded 3-acetyl-2-hydroxy-4Ef-pyrido[l,2-<2]pyrimidine-4-thiones 333 and 3-acetyl-4-methylthio-2i/-pyrido[l,2-a]pyrimidin-2-one (334), respectively (96MI22). 

Dimethyl-l-(phenyl-acetyl)- E8b, 432 (2,4-Pentandion + Ar — CH2-CO-NH-NH2) Pyrido 4,3-d -l,3-oxazol 6-Methyl-2-phenyl-4,5,6,7-tetrahydro- E8a, Pyrimidine 4-Hydroxy-S-isopropyl-2-phenyl- E9b/2, 100 (R-CH = CH-NR2 + Ar-CO-NCO)... 

Acetyl-4-hydroxy-3-methyl-1-phenyl- H- (pyrido 2,3-c]-pyrazol) 70% ... 

Streptomyces spp. B1848 Streptomyces spp. B6005 Flavobacterium Bio215 Bacteria Biomass 1-acetyle-P-carboline perlolyrin l-[5-(hydroxymethyl)furan-2-yl]-9H-pyrido[3,4-b] indole-3-carboxylic acid (Flazin) l-(9/f- -carbolin-1 -yl) - 3 -hydroxy-propan-1 -one [5]... 

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