CIS AND TRANS ISOMERISM OF β-ARYLGLUTACONIC ACIDS AND THEIR DERIVATIVES. PART I. FORMATION OF THE CIS AND TRANS FORMS OF β-COUMARYL-3-β-(4-METHOXYPHENYL)-ACRYLIC ACID

β-Arylglutaconic acids and their derivatives are ordinarily known to exist in the cis form. If, how­ever, the esters of these acids are condensed with salicylaldehyde, which contains a hydroxy group using piperidine as the condensing agent, β-coumaryl-3-β-arylacrylic acid and their eaten are obtained in cis and trans modifications. The present paper deals with the results obtained in the cage of β-(4-­methoxyphenyl)-, β-(4-methoxy-3 methylpherlyl)-, β-(2-methoxy-5 methylphenyl)-, β-(2-methoxy-4 methyl-phenyl)- and β-(4-methoxy-2 methyl-5 isopropylphenyl)-glutaconic acids