Carotenoids and related compounds. Part XXXIV. Synthesis of violerythrin and other cyclopentenediones
Abstract
On treatment with manganese dioxide, carotenoid diosphenols are converted into 2-nor-analogues with a cyclopentenedione end group. Thus astacene (3,3′-dihydroxy-2,3,2′,3′-tetradehydro-β,β-carotene-4,4′-dione) yields the blue pigment violerythrin (2,2′-dinor-β,β-carotene-3,4,3′,4′-tetraone).