Synthesis and reactions of ethyl 6-aryl-3-ethoxy-6-oxo-2,4-hexadienoates

Article abstract of DOI:10.1248/cpb.44.885

Biologically interesting ethyl 6-aryl-3-ethoxy-6-oxo-2,4-hexadienoates (I) have been prepared by the Wittig reaction of [3-(ethoxycarbonyl)-2-ethoxy-2- propenylidene]triphenylphosphoranes (3a and 3b) and -arsorane (3c) with glyoxal monohydrates (5) and by oxidation of 6-aryl-3-ethoxy-6-hydroxy-2,4- hexadienoate (9) with activated manganese (IV) oxide supported by silica. Reaction of la with 3c gave 3-(4-chlorobenzoyl)-1,2-trans (and cis)-bis(1- ethoxy-2-ethoxycarbonylethenyl)cyclopropanes (6 and 7). When l a was treated with a 1: 5 mixture of concentrated HCI and tetrahydrofuran at room temperature, 3-hydroxy-6-oxo-2,4-hexadienoate (10a) was obtained in 46% yield. Treatment of 1b with trifluoroacetic acid Rave 5,6-dihydro-2H-pyran- 2-one (12) in 53% yield together with [0b in 28% yield. When la was treated with 1 N ethanolic potassium hydroxide, 12 and 2H-pyran derivative (13) were obtained in 33% and 28% yields, respectively. Reaction of la with ammonium hydroxide and primary amines in the presence of a proton acid gave 2-oxo- 1,2,5,6-tetrahydropyridines; (14) in good yields. The mechanism of the formation of 6, 12, 13, and 14 is discussed.

Full text of DOI:10.1248/cpb.44.885

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