6- quinazolin-l 1 -one

Solubilities of different 1,2,3,4- and 1,2,3,4,6,7,8,9-octahydro-llH-pyrido-[2,1 -6]quinazolin-l 1 -ones have been determined in water, ethanol, and n-octanol (83MI2). Octahydro derivatives were more water soluble than tetrahydro derivatives. 

The 9-methyl group on 6,7,8,9-tetrahydro- and 1,2,3,4,6,7,8,9-octahydro-117/-pyrido[2,l-6]quinazolin-l 1-ones occupies a quasi-axial position due to the 1-3 allyl-type strain, which would develop between the 9-methyl group and the neighboring C(11)=0 carbonyl group if the methyl group were in a quasi-equatorial position (87JHC1045). 

Nitration of 6,7,8,9-tetrahydro-117/-pyrido[2,l-6]quinazolin-l 1 -one (7) with a 1 1 mixture of cone, nitric acid and cone, sulfuric acid at -5°C for... 

Cyclocondensation of cis- and trans-2-amino-4-cyclohexene-l-carboxylic acid with 2-methoxy-3,4,5,6-tetrahydropyrimidine in boiling chlorobenzene for 6 h gave ds-4a,lla-H- and trani-4a,lla-H-l,4,4a,6,7,8,9,lla-octahydro-1 l//-pyrido[2,l-6]quinazolin-l 1-ones (75 and 78) (90PHA109). 

Chloromethyl- and 6-methoxymethyl-5a-trifluoromethyl-5a,5,6,7,8,9-hexahydro-1 l//-pyrido[2,l -6]quinazolin-l 1 -ones (331 and 332) were prepared from 5a-trifluoromethyl-5,5a,6,7,8, 9-hexahydro-ll//-5,6-(methano)-pyrido[2,l-b]quinazolin-ll-one (330) by ring opening in boiling methanol with hydrogen chloride and boron trifluoride etherate, respectively (86CPB3672). Treatment of the chloromethyl derivative (331) with potassium hydroxide in boiling ethanol yielded tetracyclic derivative 330. 

The reaction of methyl anthranilate and 3-amino-2-chloropyridine in 1,2,4-trichlorobenzene in the presence of KOt-Bu at 50 °C gave 5,11 -dihydro-6//-pyrido[2,3-/)]benzodiazepin-6-one and 6-amino-11H-pyr-ido[2,l-6]quinazolin-l 1-one as a by-product (99BMCL3031). 

Reaction of 1 -methylene-1,2,3,4-tetrahydro-5//-pyrazino[2,1 -Z)]quina-zoline-3,6-diones (435) with PhLi and MeMgBr in THE at —78°C gave a mixture of 1 l//-pyrido[2,l-Z)]-quinazolin-l 1-ones 435-439 (01T1987). 

The octanol-water (pH 5) partition coefficients of 1,2,3,4-tetrahydro-and 1,2,3,4,6,7,8,9-octahydro-llH-pyrido[2,l-Z>]quinazolin-l 1-ones and their 6-, 7-, 8-, and 9-methyl derivatives were determined and the Hansch it values of the methyl substituents were also calculated (84MI5). The oc-tahydro derivatives were more hydrophilic than the tetrahydro compounds. 

Arylhydrazono-6,7,8,9-tetrahydro- and 6-arylhydrazono-l,2,3,4,6,7,8,9-octahydro-11 //-pyrido[2,l -ft]quinazolin-l 1 -ones (25) exhibit solvent-dependent E-Z isomerism (Table II) (84JHC1301 87JHC1045). 

Amino-6,7,8,9-tetrahydro-l l//-pyrido[2,l -b]quinazolin-l 1 -one was prepared by catalytic hydrogenation of the 3-nitro derivative over Raney nickel in ethanol [91KFZ(11)28]. 

Reactions of 6,7,8,9-tetrahydro-ll//-pyrido[2,l-b]quinazolin-l 1-one (7), its 2-ethoxycarbonyl derivative (120, R = 2-COOEt), and 1,2,3,4,6,7,8,9-octahydro-ll//-pyrido[2,l-b]quinazolin-ll-one with diethyl oxalate in ethanol in the presence of sodium ethoxide at ambient temperature for 12 h gave 6-ethoxalyl derivatives (23 and 24) [89JCS(P2)1613]. 

The amino group of 8-amino-l 1 //-pyrido [2,1 -b]quinazolin-l 1 -one was acylated with nicotinoyl chloride (89MI1). The nitro group of 2-nitro-6,7,8,9-tetrahydro-ri//-pyrido[2,l-6]quinazolin-ll-one (120, R = 2-N02) was reduced to an amino group which was acylated to give 2-acetamido and 2-benzamido derivatives [85IJC(B)336],... 

MI1, 84MI3). 6-[2-(4-Methyl-l-piperazinyl)acetamido]-ll//-pyrido[2,l-b]quinazolin-l 1-one (329) was isolated from a mixture of crude 11-chloroacetyl-5,11 -dihydro-6 7/-pyrido[2,3-b][l, 4]benzodiazepin-6-one (327, R = COCH2Cl)) and excess 1-methylpiperazine in boiling benzene as a byproduct with pirenzepine (328) (88CCC1820 89JHC1229). 

Condensation of 6,7,8,9-tetrahydro-l17/-pyrido[2,l-Z>]quinazolin-l 1-one and PhCHO in boiling Ac20 for 48 h yielded a 6-phenylmethylene derivative (01H(55)1555). 

Hexahydro-117/-pyrido[2,l-b]quinazoline alkaloid was obtained in 70% yield when l-(2 -nitrobenzyl)-2-cyanopiperidine was reduced with Zn in acidified EtOH at 78 °C (99SL1383). 6,7,8,9-Tetrahydro-1 l//-pyrido[2, l-b]quinazolin-l 1-ones (426) were synthesized by azidoreductive cyclization of /V-(2-azidobenzoyl)-2-piperidones 425 using TMSCl-Nal and bakers yeast (01JOC997). 

The reduction of cis- and frrw.s-l,4,4a,6,7,8,9,lla-octahydropyrido[2,l-h]quinazolin-l 1-one with platinum/hydrogen has also been described39. 

Cyclization of 2-(4-hydroxypentyl)quinazolin-4(37/)-ones 422 under Mitsunobu s conditions afforded only linearly fused 6,7,8,9-tetrahydro-ll/f-pyrido[2,l- ]quinazolin-l 1-ones 423 without angularly fused 1,2,3,4-tetrahydro-6/f-pyrido[l,2-a]quinazolin-6-ones 424 (98CPB928). 

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