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Sz&tnmmyThe ergot pigments, ergochrysin A, the secalonic acids A, B, C, and D, and ergoxanthin have 2,2'-linkages between the biphenyl residues.

Ozonolysis of ergochrysin A, C2,H2,012(C02Me), one of the pigments of ergot, yields hemiergoflavin-2-carboxylic acid (VIII), pyrolysis forms the benzoate (IV; R = Me), and fusion with alkali gives the acid (IV; R = H) with the biphenyl (V; R1 = COMe, R2 = H). Vigorous acetylation of ergochrysin A forms the hemiergoflavin (VI; R1 = R2 = Ac), which is degraded by acid to carbon dioxide, the acid (IV; R = H), and the hemiergoflavin (VII; R = H).Tri-O-methylergochrysinone A (X) , formed by oxidation of tri-O-methylergochrysin A (I; R2 = R3 = H, R1 = Me), gives the biphenyl (XI) upon degradation with alkali.Ergochrysin A undergoes mutarotation in pyridine to yield an isomer, isoergochrysin A. These and other observations are rationalised in terms of the structures (I; R2 = R3 = H, R1 = Me) for tri-O-methylergochrysin A and ( I ; R1 = R2 = R3 = H) or ( 111) for ergochrysin A.Constitutions are derived for the closely related colouring matters, secalonic acid A and secalonic acid B.The biosynthesis of the ergot pigments is discussed. c o -~o r k e r s . ~ Secalonic acids B and C have been i ~o l a t e d . ~ The term chrysergonic acid, when used in the present Paper, refers to the mixture of secalonic acid A and secalonic acid B isolated by Stoll et aZ.ll Chrysergonic acid Part XLVI, preceding Paper.

A Friedel-Crafts reaction between 2,6-dimethoxybenzoyl chloride and benzene yields 2.6-dimethoxybenzophenone and 3-benzoyI-2,2',4,6'-tetramethoxybenzophenone, and under milder conditions, 3-carboxy-2,2',4.6'-tetramethoxybenzophenone. A synthesis and the degradation under acid conditions of 3-benzoyI-Z,2',4,6'-tetramethoxybenzophenone are described.

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