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Hitherto unknown functionalized 2 imino 3 (N cyclohexylcarbamoyl) 2,5 dihydrofurans were synthesized by the reactions of tertiary α hydroxy ketones with N cyclohexyl(cyano acetamide). Several reactions of thus synthesized compounds at the imino group were carried out.Functionalized 2 imino 2,5 dihydrofurans 1 and 2,5 dihydrofuran 2 ones 2-5 are the promising hetero cyclic compounds and of practical and scientific interest. Synthesis of these compounds is an important problem.In continuation of our research on condensation of tertiary α hydroxy ketones with compounds bearing the active methylene group, 1 in the present work we involved N cyclohexyl(cyanoacetamide) (1) in the condensations with α hydroxy ketones (Scheme 1). At an equimolar reactant ratio, the reaction of α hydroxy ketones 2a-c with compound 1 in MeOH in the presence of MeONa at 40 °C for 5 h resulted in 2 imino 3 (N cyclohexyl carbamoyl) 4 methyl 5,5 dialkyl 2,5 dihydrofurans 3a-c in high yields.Hydrolysis of the resulting imino derivatives 3a-c un der weakly acidic conditions (pH 4-5) at 85-90 °C for 3 † Deceased. h furnished the corresponding 2,5 dihydrofuran 2 ones 4a-c (Scheme 2). Scheme 2R 1 = R 2 = Me (a); R 1 = Me, R 2 = Et (b); R 1 + R 2 = (CH 2 ) 4 (c) i. H 2 O, HCl, pH = 4-5, 85-90 °C Bubbling of gaseous HCl through a benzene solution of 2 imino 2,5 dihydrofurans 3a-c afforded the corre sponding hydrochlorides 5a-c in quantitative yields (Scheme 3). The resulting hydrochlorides 5a-c can readily be converted into the starting 2 imino derivatives 3a-c by treatment with 0.1 M NaOH or aqueous K 2 CO 3 solution. Aqueous hydrolysis of hydrochlorides 5a-c at 85-90 °C for 2 h resulted in 2,5 dihydrofuran 2 ones 4a-c.With the aim of synthesizing of dicyanomethylidene dihydrofuran derivatives bearing the chromophores, we performed the reactions of 2 iminoderivatives 3a-c with malononitrile (Scheme 4). These reactions carried out at an equimolar reactant ratio in anhydrous EtOH at room temperature gave the corresponding 2 dicyano methylidene 2,5 dihydrofurans 6a-c with quantitative yields (the reactions completed when the evolution of ammonia ceased).Methylation of 2 imino 2,5 dihydrofurans 3a-c with dimethyl sulfate in the presence of Na 2 CO 3 at room Scheme 1 R 1 = R 2 = Me (a); R 1 = Me, R 2 = Et (b); R 1 + R 2 = (CH 2 ) 4 (c)

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The diones (IV) may be regarded as analogues of the natural alkaloid cerpegin.