Isolation and Characterization of β-Methylene-l-(+)-norvaline from Lactarius helvus

An unsaturated free amino acid, C6H11NO2, present in sporophores of the mushroom, Lactarius helvus, has been isolated in pure, crystalline form by chromatographic techniques. On the basis of its chemical and physical properties, its activity with l- (but not d-) amino acid oxidase, its oxidative cleavage by periodate-permanganate reagent to formaldehyde, propionic acid and ammonia, and the formation of an equimolar mixture of isoleucine and alloisoleucine on catalytic hydrogenation, the structure β-methylene-l-(+)-norvaline is proposed. Confirmation of this assignment has been provided by a Strecker synthesis of the desired racemate from α-ethylacrolein.