The increasing importance of furano-fused heterocycles as biologically active compounds [1][2][3][4][5] has led to continuing development of new simple procedures for their synthesis. In the light of these findings and our continuing interest in the synthetic importance of the enaminones and synthesis of some functionally substituted heterocycles [6-9], we have investigated the behavior of some furans of the enaminone type towards cinnamonitriles.When arylidenemalononitriles 1a-c [10] were subjected to reaction with alkyl 4-oxo-2-phenylamino-4,5-dihydrofuran-3-carboxylates 2a,b [11] in refluxing 1-propanol in the presence of a catalytic amount of piperidine (Scheme 1), the 1-benzofuran derivatives 5a-c were obtained, instead of the expected furo-[3,2-b]pyrans 4a-c. Similar behavior has been reported previously [12][13][14][15][16].The NMR spectrum of compound 5a exhibited two one-proton singlets at 5.50 (CH benzyl) and  5.60 (OH) ppm. The mass spectrum of compound 5b showed the molecular ion at m/z 584.Formation of compound 5 could be explained by addition of two molecules of compound 1 to compound 2 to form the intermediate 3 via retro Knoevenagel reaction followed by cyclization and elimination of hydrogen cyanide. This reaction represents an interesting method for the construction and functionalization of the 1-benzofuran ring systems. In addition, this method has the advantages of ready accessibility of the reagents, good yields, and experimental simplicity.In view of the above findings and in connection with the present work aiming to explore the synthetic importance of enaminones, we studied the conversion of compound 2a into some new substituted furan derivatives.

Although β-aminoenones and β-nitroenamines are already established as synthetic intermediates, particularly, in heterocyclic chemistry [1][2][3][4][5], the utility of phenylhydrazones and oximes, which have closely related structures to them, is little studied [6][7][8]. In this paper we describe the reaction of cyanoolefins 1 with diphenylhydrazone 2 and dioxime 3 as a route to functionally substituted pyridazines and oxazines, respectively.The reaction of electrophiles such as compound 1 with nucleophiles such as compound 2 is of interest because it may occur either at the nitrogen atom of the NH group or at the carbon atom of the cyano group. Thus, condensation of diphenylhydrazone 2 [9] with activated cyanoolefins 1a-c in a molar ratio of 1:2 in refluxing ethanolic piperidine afforded 3,3'-carbonylbis(6-amino-4-aryl-5-cyano-1-phenylpyridazine) 4a-e (Scheme 1).The structure of compound 4 was established for the reaction product, and the structure 5 was excluded, based on analytical and spectral data (cf. Experimental). The 1 H NMR spectrum of compound 4c exhibited a four proton singlet at δ 5.55 (s, 2NH 2 ), a two-proton singlet at δ 4.42 due to H-4 of pyridazine, and eighteen proton multiplets at δ 7. . N N N N O C 6 H 5 C 6 H 5 NH 2 N H 2 CN NC Ph Ph m/z 273 m/z 301 4a The mass spectrum of compound 4a showed a molecular ion at m/z 573 [M + -H], m/z 273 [pyridazine], m/z 301 [pyridazine-CO], m/z 196 [pyridazine-C 6 H 5 ], and m/z 77 base peak [C 6 H 5 ].

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Base-mediated condensation of anilinodihydrothiophenes (I) and (IV) with arylidenemalononitriles provides unexpectedly the hitherto unknown ring systems (III) and (V), respectively, Reaction of (IV) with toluidine gives the expected amide (VII). -(HAMMOUDA, M.; ABOU ZEID, Z. M.; METWALLY*, M. A.; Phosphorus, Sulfur Silicon Relat. Elem. 180 (2005) 12, 2645-2651; Dep. Chem., Fac. Sci., Mansoura Univ., Mansoura 35516, Egypt; Eng.) -H. Toeppel

Ring closure reactions O 0130 Synthesis of Novel Functionally Substituted Pyridazines and Oxazines. -The reaction mechanism is discussed. -(HAMMOUDA, M.; ABOU ZEID, Z. M.; METWALLY, M. A.; Chem. Heterocycl. Compd. (N. Y.) 44 (2008) 8, 985-990; Dep. Chem., Fac. Sci., Mansoura Univ., Mansoura 34517, Egypt; Eng.) -H. Haber 23-042