Quinazoline-2-carboxaldehyde

Quinazoline-2-carboxaldehydes. A suspension of 3-acetoxy-7-chloro-2-methyl-amino-5-phenyl-3H-1,4-benzodiazepine in dil. HGl stirred and heated 10 min. at 85° 6-chloro-4-phenylquinazoline-2-carboxaldehyde. Y 49%. F. e. s. L. H. Sternbach et al., J. Org. Ghem. 29, 332 (1964). 

Another group of acid-catalyzed rearrangements involves cleavage of the 3,4-bond followed by cyclization between positions 2 and 4, for example the conversion of (218) to the quinazoline carboxaldehyde (219). Similar reactions are given by (220) and (221). 

In total, 185 substances were found in the wing-sac liquid of male S. bilineata from a Costa Rican population. For a more detailed analysis the relative peak area of thirteen focus compounds was compared (Table 14.1). Of these nine were male-specific substances (indole, indol-3-carboxaldehyde, indole-3-carboxylic acid, 2-aminoacetophenon, anthranilic acid, SHJOH-dipyrrolofl -aT -dJpyrazine-5,10-dione (pyrocoll), indolo[2,l-b]quinazoline-6,12-dione (tryptanthrin), 2,6,10-trimethyl-3-oxo-6,10-dodecadienolide, and a compound C15H24O2 of unknown structure), three were fatty acids (tetradecanoic acid, hexadecanoic acid, and octadecanoic acid), and one a steroid (cholesterol). On average, the cumulative peak area of these substances made up 62.5 20.7% of the whole chromatogram area. 

Oxidation of 8-hydroxymethyl-2-isopropyl-l 1 //-pyrido[2,l-b]quinazolin-11-one with pyridinium chlorochromate in methylene chloride gave the 8-carboxaldehyde, which was converted into its 8-aminomethyl derivatives by reacting with amines followed by reduction of the Schiff bases with sodium cyanoborohydride in acetic acid (87JOC2469). 

Cyclocondensation routes also provide access to pyrimidines. 2,3-Disubstituted pyrido[2,3-/i]-quinazolin-4(3//)-ones are obtained via cyclocondensation of 5-aminoquinoline-6-caiboxylic acid with acid chlorides <02SC235>. 5,6,8-Trialkyl-7-methoxy-2-aminoquinazolines are obtained from 1,3-dimethoxybenzenes via cyclocondensation of intermediate dihydrobenzenes with guanidine carbonate <02TL3295>. Diastereoselective intramolecular hetero Diels-Alder cyclization of a pyrazole carboxaldehyde condensed onto 1,3-dimethylbarbituric acid (101) gave polycyclic heterocycle 102 <02T531>. An efficient one-step synthesis of cyclobutene-annelated pyrimidinones 103 from methyl 2-chloro-2-cyclopropylideneacetate and amidines has been... 

The palladium(II)-assisted alkenylation of aromatic compounds has also been applied to the synthesis of heterocycles. A novel synthesis of pyrido[3,4-d] pyrimidines, pyrido[2,3-d]pyrimidines and quinazolines was developed by Hirota et al. [18] employing the palladium(ll)-promoted oxidative coupling of uracil derivatives and alkenes. l,3-Dimethyluracil-6-carboxaldehyde dimethylhydrazone (22), 6-dimethylaminomethylenamino-l,3-dimethyluracil (24) and ( )-6-(2-dimethylaminovinyl) uracil (26) all reacted with methyl acrylate in the presence of stoichiometric Pd(OAc)2, producing pyrido[3,4-ii]pyrimidine 23, pyrido[2,3-if]pyrimidine 25 and quinazoline 27, each apparently arising from direct arylation, 6ti electrocycliza-tion, and elimination of dimethylamine, in 67%, 89% and 64% yields respectively (Scheme 9.3). 

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