Abstract
Oxidation of 2-cis-α-ionylidene-ethanol (II) with active MnO2 afforded a mixture of 2-cis and 2-trans-α-ionylideneacetaldehydes (III and IV). Reduction of methyl epoxy-α- and -β-ionylideneacetates (Vb, Xb XXIb and XXIIb) with LiAlH4 gave the diols (VI, XI, XXIII and XXIV). The Wittig reaction of the hydroxyketones (XIII and XVIII) with carb-ethoxymethylenetriphenylphosphorane, followed by alkaline hydrolysis, yielded 5-(1'-and 2'-hydroxy-2', 6', 6'-trimethyl-l'-cyclohexyl)-3-methylpentadienoic acids (XIVa, XVa, XIXa and XXa). The reaction of α-cyclocitrylideneacetaldehyde (XXVII) and dihydro-a-ionone (XXXIII) with carbethoxymethylenetriphenylphosphorane afforded ethyl 3-demethyl-α-ionyli-deneacetate (XXVIIIb) and ethyl dihydro-α-ionylideneacetates (XXXIVb and XXXVb). Physiological activities of the above synthesized compounds on rice seedlings were examined.
