Generation of (2-Nitroethyl)benzene and related benzenoids from L-Phenylalanine; flower scents of the Japanese Loquat Eriobotrya japonica [Rosales: Rosaceae]

(2-Nitroethyl)benzene, methyl 4-methoxybenzoate and 4-methoxybenzaldehyde have been known as major scent components in flowers of the Japanese loquat Eriobotrya japonica [Rosales: rosaceae], together with 13 related benzenoids, including Z- and E-2-phenylacetaldoxime and benzyl alcohol. The scents air-trapped from a flowering panicle during 24 h incubation with d 8 -L-phenylalanine were composed of 15 deuterium labeled compounds {d 6 -styrene, d 5 -benzaldehyde, d 7 -2-phenylacetaldehyde, methyl d 5 -benzoate, d 7 − 2-phenylethanol, d 7 -2-phenylacetonitrile, d 4 -1,4-dimethoxybenzene, d 7 -Z-2-phenylacetaldoxime, d 4 -4-methoxybenzaldehyde, d 7 -E-2-phenylacetaldoxime, d 4 -4-methoxybenzyl alcohol, d 7 -(2-nitroethyl)benzene, methyl d 4 -4-methoxybenzoate, methyl d 6 -cinnamate and ethyl d 4 -4-methoxybenzoate}. On the other hand, hexane extracts of the flower petal incubate with a mixture of d 5 -Z- and d 5 -E-2-phenylacetaldoxime after 24 h indicated generation of six d 5 -labeld components {d 5 -benzaldehyde, d 5 -benzyl alcohol, d 5 -2-phenylacetaldehyde, methyl d 5 -benzoate, d 5 -2-phenylethanol, and d 5 -(2-nitroethyl)benzene}. By comparing those results, (2-nitroethyl)benzene was concluded as a product directly generated from a mixture of Z- and E-2-phenylacetaldoxime together with six minor benzenoids, while two major compounds (4-methoxybenzaldehyde and methyl 4-methoxybenzoate) together with three minors from L-phenylalanine, presumably via L-tyrosine. The other two minor components were derived from L-phenylalanine. Generation of (2-Nitroethyl)benzene and Related Benzenoids from L-Phenylalanine; Flower Scents of the Japanese Loquat Eriobotrya japonica [Rosales: Rosaceae]