9-Methyl-4-imino-477-pyrido

When 4-imino-9-methyl-4//-pyrido[l, 2-a]pyrimidine-3-nitrile reacted with sodium azide in a solvent at 60-70°C for 3-6 hours, ring-opened 3 - [(3 - methyl-2- py ridy l)amino]-2- (1 -H- tetrazol-5- yl)-2- propenenitrile was obtained, but the bicyclic 4-imino-9-methyl-3-(l//-tetrazol-5-yl)-4//-pyrido[l,2-a]pyrimidine could be isolated when the reaction was carried out in acetic acid at 115°C (90EUP385634). The latter product was also obtained from the ring-opened product by heating in IN hydrochloric acid at 100°C for 1 hour, or in IN potassium hydroxide at 100°C for 3.5 hours. Reaction in acetic acid was also extended to 9-phenoxymethyl, 9-(4-acetyl-... 

Diazacycl[3,3,3]azines (125 and 126) were prepared by the reaction of l-imino-8-methyl-lH-pyrido[l,2-c]pyrimidines (124) with ethoxymethy-lenemalononitrile and acetic anhydride, respectively (74CPB2765 78YZ623). In the latter cases, the hydrolysis of the imino group also occurred to give 4-0X0 derivatives of 124 (78YZ623). 

The 3-formyl group of 8-substituted 3-formyl-2-hydroxy-4//-pyrido[l,2-n]pyrimidin-4-one was reacted with (cyanomethyl)- and (terr-butoxycarbo-nylmethylene)triphenylphosphorane in THF, and with 5-aminotetrazole in boiling MeOH for 9h to yield ( )-3-propenenitrile, terr-butyl ( )-3-propenoate and 3-[(2//-tetrazol-5-yl)imino]methyl derivatives, respectively (OlMIPl). 

Reaction of 2-aminopyridine with ethyl 2-cyano-3-ethoxy-3-methyl-, -3-ethyl-, -3-phenylacrylates and ethyl 2-ethoxycarbonyl-3-ethoxy-3-methyl-, -3-phenylacrylates in boiling xylene yielded 2-substituted 4/f-pyrido[l,2-u]pyrimidine-3-carbonitriles and -3-carboxylates (99MI7). Similar reactions of 2-aminopyridine with 2-cyano-3-ethoxyacrylonitrile and its 3-methyl, 3-ethyl, -3-phenyl derivatives in boiling MeCN afforded 4-imino-4//-pyrido[l,2-u]-pyrimidine-3-carbonitrile and its 2-substituted derivatives. 

Stereostructures of a co-crystal of (li )-l- 4-[(9aA)-perhydropyrido[l,2- ]pyrazin-2-yl]phenyl -2-phenyl-7-hydroxy-l, 2,3,4-tetrahydroisoquinoline with ERa-LBD301-553/C — S triple mutant <2005JME364> and iV-[2-(4-hydroxyphenyl)ethyl]-a-propyl-3-[(4-hydroxyphenyl)methyl]-l,4-dioxo-l,2,3,4,ll,l la-hexahydro-67/-pyrazino[l,2- ]isoquinoline-3-acetamide with fructose-1,6-biphosphatase <2003JBC51176> were determined by X-ray crystallography. The structure of a complex formed from 3-[( -methylphenyl)amino]-4-[(4-methylphenyl)imino]-4//-pyrido[l,2-tf]pyrazine with sodium bis(trimethylsilyl)amide and (norbornadiene)Mo(CO)4 in THF was characterized by single crystal X-ray diffraction <1995JPR38>. 

Reactions of stable N-substituted iminopropadienones with 2-methylaminopyridine in CH2C12 yielded 1 -methyl-2-(iV-substituted imino)-l,2-dihydropyrido[l,2- ]pyridinium-5-ium-4-olates <2002JOC2619>. Reactions of N-substituted iminopropadienones with 2-aminopyridines provided 2-(substituted aruino)-l//-pyrido[ 1, Z-a pyrimi-din-4-ones, which were accompanied by a small amount of isomeric 4-(substituted arnino)-2/7-pyrido[ 1,2- ]pynrnidin-2-ones. In refluxing toluene, a larger amount of the 2-oxo isomers formed. In the case of 2-amino-3-methylpyridine and... 

The 4-imino group of 3-cyano-4-imino-2-methylthio-4//-pyrido[ 1,2-a]-pyrimidine was transformed to the 4,4-diamino group with amines and to the 4-methylimino group with methyl iodide in dimethylformamide in the presence of potassium carbonate.268 On the action of dimethyl acetylenedi-carboxylate in dimethylformamide at 150°C, the 1,4-diazacycl [3,3,3] azine (234 R = CH3S) was formed.314... 

Substituted-4-oxo-4//-pyrido[l,2-a]pyrimidines of type 74 (6-R H) are transformed to l,4-dihydro-4-oxo-l,8-naphthyridines on the action of heat.bl)-71-7l, 1 29 1 33 323 325 Ring transformation is facilitated by the nearly coplanar disposition of the 4-CO group and the 6-substituent of the pyrido-[l,2-u]pyrimidines. The steric interaction of these groups is shown by the relatively long C-4—N-5 bond (e.g., 147 pm for ethyl 6-methyl-4-oxo-4/f-pyrido[l,2-u]pyrimidine-3-carboxylate, as determined by X-ray study326). The strain caused by this interaction is relieved when the C-4—N-5 bond cleaves. Ring transformation probably takes place via the reactive imino-ketene intermediate (75).130... 

Cycloaddition of methyl propiolate to 4-imino-4//-pyrido[ 1,2-a]py-rimidin-4-imine 481 in the presence of 5% palladium-on-charcoal catalyst as dehydrogenating agent yielded cyclazine derivative 482 in 12% yield (Scheme 27) (87YZ344). A similar reaction with dimethyl acetylenedicar-boxylate gave a mixture of addition (483), cycloaddition (484), and dehydrogenated (485) products in 16%, 23%, and 37% yields, respectively. 

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