α-(Thiocyanatomethyl)benzylidenemalononitrile undergoes azo coupling with diazotized aromatic amines (ArNH2) to afford azo derivatives. The azo derivatives (Ar = Ph, 4-MeC6H4, 4-ClC6H4, 4-MeOC6H4) were readily cyclized on reflux in aqueous NaOH to 3(2H)-pyridazinimine derivatives. These latter compounds were transformed into the corresponding pyrrole derivatives on reflux in glacial acetic acid with Zn dust presumably via reductive cleavage of the N–N bond followed by recyclization with loss of ammonia. Under similar conditions the azo derivative (Ar = 2-NCC6H4) was cyclized into 6H-pyridazino[3,2-a]quinazolin-6-imine derivative which was easily transformed into the 6H-pyridazino[3,2-a]quinazolin-6-one on reflux in ethanolic HCl. This last compound was also obtained from the azo derivatives (Ar = 2-HOOCC6H4 and 2-MeOOCC6H4) by reflux in aq NaOH. The starting benzylidenemalononitrile reacts also with arylmethyleneamalononitrile or ethyl arylmethylenecyanoacetate (aryl = Ph, furyl, or thienyl) to afford substituted benzonitrile derivatives.

o-Bromoacetophenone reacts with the sodium salt of ethyl cyanoacetate to afford a-cyano-P-phenyl-A".Pbutenolide. This butenolide undergoes azo coupling with diazotized aromatic amines (ArNHJ to afford the hydrazo derivatives. These hydrazo derivatives (Ar= Ph, were transformed into the corresponding 3(2H)-pyridazinone derivatives on stirring in methanol in the presence of potassium hydroxide. These latter compounds were converted into the cowesponding 3-cyano-2,5-dihydroxy-4-phenyl-N-arylpyrrole derivatives on reduction with zinc dust in refluxing acetic acid, presumably via reductive cleavage of the N-N bond of the pyridazine followed by recyclization via loss of ammonia.In the context of our search for new simple syntheses of azoles, azines, and their fused derivatives [ 1-41 utilizing readily available starting materials, we have previously reported [5] that phenacyl thiocyanate (la) reacts with ethyl cyanoacetate (depending on the reaction conditions) to afford the Knovenagel condensation product 2a in relatively low yield (Scheme 1). In an attempt to improve the yield of 2a, we attempted to preDedicated to Prof Shigeru Oae on the occasion of hls seventyfifth birthda?To whom correspondence should be addressed

The thiophene derivative 1 reacts with the active methylene reagents 2a-c to afford the thieno[2,3-d]pyrimidine derivatives 6a,b and 8, respectively. 1 reacts with phenacyl bromide 2d to afford the N-alkylation product 9 and reacts with phenacyl thiocyanate 2e to afford the N-(thiazol-2-yl) derivative 10, which was further cyclized into thiazolo[3,2-a]thieno[2,3-d]pyrimidine derivative 12. Compound 1 reacts also with the cinnamonitriles 3a,b to afford the thieno[2,3-b]pyridines 15a,b, respectively. 1 undergoes either acetylation or hydrolysis to afford the thieno[2,3-b]pyridine derivative 19 and the thiophene derivative 22, respectively. Some of the new compounds show inhibitory effect to the production of mycotoxins and to fungal growth.

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1995 ring closure reactions ring closure reactions O 0130 -026Some Reactions with ω-Bromoacetophenone: Synthesis of δ. alpha.,β-Butenolide and Its Transformation into Pyrrole Derivatives.-Butenolide (III) undergoes azo coupling to yield hydrazo derivatives ( V) which are transformed into the corresponding pyridazinone derivatives (VI). Conversion into arylpyrroles (VII) proceeds via reductive cleavage of the N-N bond of the pyridazine followed by recyclization and loss of ammonia. -(ABDELRAZEK, F. M.; KANDEEL, Z. E.; SALAH, A. M.; Heteroat. Chem.