Synthesis of 2,7-naphthyridines by the recyclization of trimethylformyl-piperidone

The Chemistry of α-Haloketones and Their Utility in Heterocyclic Synthesis

“…Some of the most interesting derivatives of thiophenes are 3-aminothieno[2,3- b ]pyridines, in view of their wide spectrum of high biological activities and valuable pro-perties in many applications [ 202 , 203 , 204 ]. It is noteworthy that investigators [ 205 , 206 , 207 , 208 , 209 , 210 , 211 , 212 , 213 , 214 , 215 , 216 , 217 , 218 , 219 , 220 , 221 , 222 , 223 , 224 , 225 , 226 , 227 , 228 , 229 ] have de-voted considerable attention in recent years to the synthesis of thieno[2,3- b ]pyridines 101 via S -alkylation of 3-cyanopyridine-2(1 H )-thiones 99 with α-haloketones ( Scheme 28 ).…”

Synthesis of pyrrolo[2,3-c]2,7-naphthyridine derivatives by cascade heterocyclization reaction of 2-amino-4-cyanomethyl-6-dialkylamino-3,5-pyridinedicarbonitriles

“…17 -25 An alternative approach, including ring annulations to the readily available 2,7-naphthyridine, was applied for thieno derivatives only. 26 importance in heterocyclic chemistry, 29 -32 since they allow creation of two or more rings at once at the expense of sequential chemical transformations induced one by another. It seems to be the most economical method for condensed heterocycles preparation.…”

Naphthyridines. Structure, physicochemical properties and general methods of synthesis

“…107 Similar treatment with sodium ethoxide of thioethers 32, prepared by the reaction of 1,2,5,6,7,8-hexahydro-1,6-naphthyridine-2-thiones 33 with halo ketones, esters, amides or nitriles, resulted in the synthesis of thieno [2,3- The reaction of 6,7,8a-trimethyl-1-oxo-3-thio-1,2,3,5,6,7,8,8aoctahydro-2,7-naphthyridine-4-carbonitrile (35) with 4-bromophenacyl bromide or N-cyanochloroacetamidine in the presence of a base gives thieno[2,3-c]-2,7-naphthyridines 36. 110 Cyclocondensation of 3-ethoxycarbonylmethylthio-2,7-naphthyridine 37 on heating in anhydrous ethanol in the presence of an equimolar amount of sodium ethoxide affords thienonaphthyridine 38. The dihydrochloride of the compound 38 possesses a mutagenic activity.…”

“…The compound 35 is the product of a cascade type reaction comprising acidic cleavage according to Claisen, the Michael intramolecular addition, the interaction between the thioamide and ester groups and dehydrogenation. 110 The cyclocondensation of piperidone 270 with cyanoacetamide in the presence of diethylamine gives 1,6-naphthyridinone 271, which reacts with POCl 3 to give chloro derivative 272. 217 The compound 272 was also prepared by condensation of enamine 273 with ethoxymethylidenemalononitrile followed by cyclisation of intermediate 274.…”