SPIROLACTONES OF TYROSINE - SYNTHESIS AND REACTION WITH NUCLEOPHILES

Several quinonoidal spirolactones (1-oxaspiro[4,5]deca-6,9-diene-2,8-d iones) 12 have been synthesized chemically or electrochemically by oxi dation of the corresponding tyrosine phenols 3. The spirolactones are of considerable value in peptide chemistry, because they react as acti ve esters with amino acid esters to give dipeptides. In the latter, th e side chain of the tyrosine moiety is present as a quinol (4-hydroxyc yclohexa-2,5-dien-1-one) system, which can be reduced to the genuine t yrosyl dipeptide. Unsubstituted spirolactones also react as active est ers but give dipeptides only in modest yields.