Pyrimido quinolines, formation

Ar-quinolin-2-yl)imino]propionates by injection or sublimation at 530°C yielded a mixture of 3-amino- and 3-ethoxy-l//-pyrimido[l,2-rz]quinolin-l-ones <2004AJC577>. An oxidative cascade for the biomimetic formation of the pyoverdine chromophore was supported by incubation of 2-[(4-hydroxyphenyl)- and 2-[(2-(3,4-dihydroxipheny-l)ethyl]-l,4,5,6-tetrahydropyrimidines with polyphenol oxidase or Pseudomonas extract to afford a mixture of 8,9-dihydroxy-2,3-dihydro- and -2,3,5,6-tctrahydro-l //-pyrimido[ 1,2- ]quinolines <20030L2215>. Oxidation of 2-[(2-(3,4-dihydroxiphenyl)ethyl]-l,4,5,6-tetrahydropyrimidine with MnOz gave a similar result. 

The analogous reaction to that described in Equation (42) using paraformaldehyde in equimolar amount to dimedone (instead of a large excess) was irradiated for 3 min to yield pyrimido[4,5- ]quinoline-4,6-dione 591 via formation of intermediate adduct 590 <2006TL27>. The 5-aryl-5,6,7,8,9,10-hexahydropyrimido[4,5-/ ]quinolines 592 were also prepared by the cyclocondensation reaction of 6-aminopyrimidine 460 with dimedone and 4-sub-stituted benzaldehydes by boiling in absolute ethanol for 30 min <1998JHC231>. 

A number of unusually fused heterocyclic compounds have been reported by Tu and co-workers [118]. The three-component domino reaction of an aldehyde, an enaminone 72 and malononitrile resulted in the formation of polysubstituted imi-dazo[l,2-a]quinazolines 73 and pyrimido[l,2-a]quinolines 74. (Scheme 56) When enaminone 75 was reacted using the same reaction conditions, this resulted in the formation of quinolino[l,2-a]quinazolines 76 in good yields. In this one-pot reaction, up to five new bonds were formed accompanied by the generation of the lactam group. Interestingly, the volume of ethylene glycol used seems to influence the yield of the product (Scheme 57). 

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