The Alkaloids of Senecio jacobaea L. II. The structures of the acids, and the relationship between Jacobine and Jaconine

Abstract

A study has been made of the "necic" acids formed by hydrolysis from the pyrrolizidine bases of Senecio jacobaea L., in particular jaconecic acid and its derivatives, and certain tentative conclusions have been reached concerning the structure of these compounds. Jacobine and jaconine are interconvertible by addition and loss of hydrogen chloride, which is accompanied by reversal in sign of optical rotation. It is suggested that jacobine contains an ethylene oxide ring and jaconine is the corresponding chlorohydrin. Jacoline on alkaline hydrolysis yields retronecine and an oily acid which forms a solid dilactone acetate. Jacozine has been hydrolysed to jacozinecic acid which appears to be new.