Polyenes. I. The Synthesis and Absorption Spectra of the

WILLIAM G. YOUNG,LAWRENCE J. ANDREWAND STANLEY 1.CRISTOL

520

[CONTRIBUTION FROM

THE

Vol. 66

DEPARTMENT OF CHEMISTRY, UNIVERSITY OF CALIFORNIA AT LOS ANCELES]

Polyenes. I. The Synthesis and Absorption Spectra of the Ionylideneacetones and Related Compounds',* BY WILLIAM G. YOUNG,LAWRENCE J. ANDREWS AND STANLEY J. CRISTOL In a study of synthetic methods for increasing the a-ionone had maxima at 227 mb, t 12850 and the polyene chain of @-ionone,/34onylideneacetone 296 mu, t 1950.a The reaction paths involved are has been prepared by two different procedures. as follows Because thk absorption maxiBrCH&OOCIHs KHSO4 mum of this ketone was found R-C=O ______) R-C(OH)CH&OOC2Hs to lie a t 285 mp instead of in Zn CH, CH3 the expected range of 300-320 mp, it seemed possible that IQ,P I I d during some stage in the alc. KOH PCls (CHs)nCd R--C=CH-COOH R--C=CH--COOC2Hs preparation of the sixteen I I carbon ketone the double CH3 bond in the @-iononering had IIIa,B rearranged to the position R-C=CH--C=O which it occupies in a-ionone. I I and CHa CHs Consequently, the preparation of a-ionylideneacetone Va,B from a-ionone by the same ,CiX CH, methods used to prepare the CN \COOCHs CN aq. NaOH p isomer was undertaken. A Ia,5 R--C=C/ "Y