Current Organic Chemistry - Volume 7, Issue 7, 2003

Nitrogen-containing polyheteroaromatic derivatives are an important class of compounds involved in many fields of chemistry. The present report gives an overview on the recent synthetic methods developed to prepare compounds containing formally a pyridine ring and another (di)azine or non bipyridinic symmetrical bisazines. Ring construction as well as homocoupling and cross-coupling reactions are then presented.

Having demonstrated that nonsymmetric cephalostatin analogues are superior in biological activity to their symmetric counterparts we here report on further possibilities for desymmetrization of the readily available diketone 4.Since monoenolates had been prepared at an earlier stage, we describe here the selectivity of phenyl-iodosyldiacetate oxidations under basic conditions and as an example of selective nucleophilic attack, the Wittigmethylenation at the 12-ketogroup followed by a hydroboration is documented.

Recent developments in the chemistry of quinazolines and quinazolinones are discussed. The chemistry of quinazoline alkaloids is reviewed featuring chrysogine, luotonin A, tryptanthrin, febrifugine, and rutaecarpine.

Conveniently substituted flavones, chalcones and quinolones are highly attractive derivatives due to their therapeutic potential. The substitution pattern of these compounds is crucial for their biological activity. Literature survey regarding the structure-activity relationship of flavone, indicates that: azaflavones are highly active molecules; the 5 and 7 positions are the most important; hydroxyls, methoxy and amino groups are the most beneficial. In this manuscript, we report a general methodology to synthesize conveniently substituted azaflavones: (aminoflavones, 2-phenyl-4-quinolones, 3-phenyl-4- quinolones, aminochalcones and azaaurones) which fulfill these structural criteria. The methodology described implies the same starting and commercially available material: 3,5-dimethoxyaniline. Finally, we report some unusual reactivity behavior of amides derived from 3,5-dimethoxyaniline.