4-Methylene-3,4-dihydro-2//-pyrido

Recently, the X-ray structures of ocaperidone 8 [92AX(C)1827], risperidone 7 [93AX(C)1698], and 4-methylene-3,4-dihydro-4//-pyrido[ 1,2-a] pyrimidine 49 (90DOK619) were reported (see Table VII). 

Heating ethyl 5-fluoro-4-[cyano(ethoxycarbonyl)methyl]-2,3-dihydro-l-methyl-7-oxo-l//,7//-pyrido[3,2,l-i7]cinnoline-8-carboxylate (83, R = COOEt) in a mixture of cone. HCl and acetic acid gave the 8-carboxy-4-acetic acid derivative (92EUP470578). The acetic acid group was decarboxylated by heating in boiling ethanol in the presence of NEts to give the 4-methyl derivative. When the 4-[cyano(tert-butoxycarbonyl)methyl]-8-carboxylate 83 (R = COOrBu) was treated with trifluoroacetic acid in methylene chloride at room temperature, the 4-cyanomethyl-8-carboxylate 83 (R = H) was obtained. 

Reaction of 6-formyl-5,7,8,9-tetrahydro-ll//-pyrido[2,l-b]quinazolin-ll-one (135) with Clayfen [K-10 montmorillonite clay supported iron(III) nitrate] in boiling methylene chloride for 2.5 h gave a mixture of 6,6-dinitro-6,7,8,9-tetrahydro (136) and 6-formyl-8,9-dihydro-ll//-pyrido[2,l-6]-quinazolin-ll-ones (137) (90JOC6198). 

Hydroxy-3,4-dihydro-2H-pyrido[2,l-b][l,3]thiazin-5-ium chloride was formed when 2-hydroxy-3-(2-pyridylthio)propyl chloride was stirred in methylene chloride overnight (92JOC6335). When the reaction was carried out in methanolic sodium methylate, 3-(2-oxo-l,2-dihydro-l-pyridyl) thietane was obtained in 58% yield. 

Cyclocondensation of 2-amino-3-methylpyridine and allenephospho-nates 284 by stirring the reaction mixture in the absence of a solvent at 35-40°C for 48 hours afforded 4-methylene-3,4-dihydro-2//-pyrido[l,2-alpyrimidines 285 (90DOK619 91IZV473). The ethyl derivatives 285 (R = Et) were obtained as E and Z geometric mixtures. 

JA11707), 4-cyano-3-phenyl-3-trifluoromethyl-2,3-dihydro-lH-pyrido [l,2-c]pyrimidin-l-one (05MI1), and 10-(ferf-butyl)-3-methylene-3,4,4fl,5-tetrahydro-3H-[l,3]oxazino[3,4-b]isoquinolin-l-one (07EJ02015) under either acidic or basic conditions. 

Heating 10-(4-methyl-l-piperazinyl) and 10-fluoro-substituted derivatives of ethyl 9-fluoro-3-methylene-7-oxo-2,3-dihydro-7//-pyrido[l,2,3-de]-l,4-benzoxazine-6-carboxylate in a 1 1 mixture of cone. HC1 and AcOH afforded 3-hydroxy-3-methyl-6-carboxylic acid derivatives (92CCC216). 

A mixture of pyridinium N-imine hydriodide and 2-phenylazirine treated 4 days at room temp, with K-carbonate in methylene chloride 3-phenyl-l,9a-dihydro-2H-pyrido[l,2-b]-fl5 -triazine. Y 73%. F. e. s. A. Kakehi, S. Ito, and T. Manabe, J. Org. Chem. 40, 544 (1975) 41, 2739 (1976)... 

A mixture of phenylacetic acid, benzyl alcohol, and tri-n-butylamine in methylene chloride added under argon to a mixture of l-methyl-2-bromopyridinium iodide and methylene chloride, and refluxed 3 hrs. benzyl phenylacetate. Y 97%. F. e., also with l-methyl-2-chloropyridinium iodide, s. T. Mukaiyama et al., Chem. Lett. 1975, 1045 Bull. Chem. Soc. Japan 50, 1863 (1977) carboxylic acid amides from amines (cf. Synth. Meth. 26, 367) s. ibid. 1975, 1163 3,4-dihydro-2H-pyrido-[1,2-a]pyrimid-2-one as acid scavenger cf. ibid. 1976, 13, 57 lactones from hydroxycarboxylic acids (cf. Synth. Meth. 17, 320) with 2-chloropyridine methio-dide and triethylamine s. ibid. 1976, 49 esters with 2 halogeno-3-ethylbenzothia-zolium salts of ibid. 1976, 267 2-chloro-N-methylbenzothiazolium triflate as condensing agent s. F. Souto-Bachiller, G. S. Bates, and S. Masamune, Chem. Com-mun. 1976, 719. 

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