Condensed oligocycles and a great number of heterocycles have been prepared from γ- and δ-oxocarboxylic acids by treatment with difunctional agents. In the reactions of aromates and cyclohexene-or norbornenedicarboxylic anhydrides (7 and 9) (Scheme 1), acylation and addition take place simultaneously, which yields different aryl-substituted oxocarboxylic acids. From these, with aminoalcohols, the isoindolobenzoxazinones (34 and 36) and methylene-bridged derivatives (35, 37 and 38) were synthesized (Scheme 11). Acylation of 7 and 9 yielded lactones (11 and 13) and ketal-lactones (10 and 14) (Schemes 2 and 3); these were applied to prepare bicyclic or tricyclic pyridazinones (16a,b, 17a,b, 18 and 19) (Schemes 4 and 6) with a hydroxy substituent on the (bi)cycloalkane ring. By intramolecular cyclization, the aroyl group of the oxocarboxylic acid was built to yield a benzocyclooctene skeleton; this was used for ring closure to obtain condensed 5-7-membered heterocycles (26-33) (Scheme 8). Levulinic acid with diendo-norbornane/eneamino acids gives condensed methyl-substituted tetracycles (47 and 48), whereas, the diexo analogues afforded pyrrolopyridinones (49 and 50) in Claisen condensations (Scheme 14). The transformation and ring closure of diendo-and diexo-aminonorbornenecarboxylic acids led to condensed heterocycles which, on heating to the melting point, decomposed with the loss of cyclopentadiene. The new method resulted in heteromonocycles: 2-substituted (56) and 2,3-disubstituted (57 and 58) pyrimidinones (Schemes 16 and 17), pyrimidinediones (59), thiouracils (61) (Schemes 19 and 20), 1,3-oxazin-6-ones (65) and isoindolobenzoxazinedione (67) (Schemes 21 and 22). From the reactions of hydrazides with oxoesters, the spirotricyclic pyrimidinones (74) were obtained (Scheme 23), while the reactions with aroylcyclohexanecarboxylic acid yielded pyrimidopyridazine (79), isoindolopyrimidine (81) and bisacylamides (77 and 78) (Scheme 24). By application of a double RDA process, the norbornenecarbohydrazides were reacted with an aminonorbornene carboxylic acid adduct containing both an exo and an endo aroyl group, when the bicyclic pyrimidopyridazine (82) was isolated (Scheme 25). The RDA method does not require special tools or rigorous conditions; accordingly, it is suitable for the synthesis of heterocycles which are difficult to obtain on a preparative scale by other routes.
|Number of pages||10|
|Journal||Magyar Kemiai Folyoirat, Kemiai Kozlemenyek|
|Publication status||Published - márc. 1 2004|
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