Naturally Occurring Quinazolines

The chemistry of quinazoline alkaloids is being continuously updated in the specialist periodicals entitled The Alkaloids which are published by The Chemical Society (London). The sections on quinazoline alkaloids are thorough and should be consulted not only for information published prior to 1976, but also for future data in subsequent volumes. Other reviews 

Groeger, in Biosynthesis der Alkaloide (K. Mothes, ed.), p. 551. VEB Dsch. Verlag. Wiss., Berlin, 1961 S, Johne and D. Groeger, Pharmazie 25, 22 (1970). 

Tremor-inducing mycotoxins were isolated from the mold Aspergillus clavatus, which infests rice. The mycotoxins were tetrapeptides of anthranilic acid (source of the quinazolin-4-ones), trypotophan, valine, and methyl-alanine or alanine. They were named tryptoquivaline (116 = OH, 

4-Methyl-, 2,4-dimethyl-, 2-ethyl-4-methyl-, 2-hydroxymethyl-4-methyl-, and 2-carbamoyl-4-methyl-quinazoline were isolated from Pseudomonas aeruginosa. (S)-Tryptophan was shown to be the precursor of these quinazo-lines by using the 14C-labeled amino acid in a new pathway of tryptophan biosynthesis73 (see Section III,A). 

Tremor-inducing mycotoxins were isolated from the mold Aspergillus clavatus, which infests rice. The mycotoxins were tetrapeptides of anthranilic acid (source of the quinazolin-4-ones), trypotophan, valine, and methyl-alanine or alanine. They were named tryptoquivaline (116 R1 = OH, R2 = R3 = Me X = H, OAc) and nortryptoquivalone (116 R =OH R2 = Me R3 = H X = O). The structures of the metabolites were deduced from spectral data, from the X-ray crystallographic analysis of the p-bromo-phenylurethan derivative of a transformation product of tryptoquivaline, and from chemical studies.259 

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Naturally Occurring PvRROLo[2,l-ft]QuiNAzoLiNEs and Pyrido[2,1-I ]quinazolines... 

Although position 3 remains the preferred site for chemical methylation in this type of compound 83,218), the naturally occurring quinazolinones, more often than not, contain alkyl groups at position 1. Furthermore, while one of the lactam forms (13a) and (13b) is less favored 83, 157) in N-1 unsubstituted quinazolin-4-ones [quinazolin-4-one and (5)], it has been... 

The quinazoline alkaloids form a small but important group of naturally occurring bases, which were isolated from a number of different families in the plant kingdom. Witt and Bergman [21] review the chemistry of quinazoline alkaloids, viz. chiysogine, luo-tonine A, tryptanthrin, febrifugine, and rataecarpine. The only non-alkaloid naturally... 

Quinazoline derivatives are one of the most important sbc-membered nitrogen-containing heterocyclic compounds as many naturally occurring and pharmaceutical compounds contain quinazoline moiety as the core unit. It has been used for the treatment of high blood pressiue as adrenergic blockers, anxiety, and panic disorder (Prazosin) and has... 

Methoxyquinazoline and methyl iodide give the salt 72 (Y = 0), and, although the route for this reaction has not been investigated, there is a suggestion that the reaction occurs at N-3. A final decision concerning the nature of electronic and steric influences on quater-nization in the quinazoline ring must clearly await further work. 

There are few general methods for the direct functionalization of quinazolines and quinazolinones because of their deactivated nature. TTierefore, these compounds are more commonly constructed from acyclic precursors. For those examples that do exist, SeAr reactions generally take place on the benzene ring, while nucleophilic substitution reactions generally occur on the diazine ring and are selective for the C4 position due to the electropositive nature of this position. Reactions can take place at the C2 position, but generally only if the C4 position is already occupied. 

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