75 Genipinとアミノ酸より生成するPseudoazulene骨格をもつ青色々素の構造に関する研究

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Genipin (1) readily reacts with amino acids (or primary amines) in the presence of oxygen to give a mixture of blue polymeric pigments. we have carried out basic studies to elucidate the structure and formation mechanism of blue pigments using monomethylamine as a primary amine. The reaction of genipin (1) with monomethylamine in the absence of oxygen afforded nine red substances: two monomers (one monoterpene unit) 3 and 5, four dimers 6, 7, 8 and 9, two trimers 10 and 11, and one tetramer 12. The compounds 3 and 5 possess a pseudoazulene skeleton, whereas the compounds 6-12 consist of pseudoazulene and tetrahydropseudoazulene units. In addition, the reaction also yielded a yellow monomer which seems to be the primary intermediate leading to red and blue pigments. Measurement of the molecular weight of the polymeric pigment mixture as well as the comparison of its ^<13>C NMR spectrum with those of the above compounds suggested that the mixture has an average molecular weight of ca. 9000 and is composed of pseudoazulene and tetrahydropseudoazulene units. The chromophore of this polymeric mixture is presumably constituted of units like dimer 14, which can easily be derived from dimer 6. Also, there is some evidence to suggest that polymerization leading to pigment formation is caused by a radical reaction.
天然有機化合物討論会の論文
1983-09-15