- Halogenated Terpenoids. XXII. Uroterpenol. The C8 Stereochemistry
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The two diastereoisomeric p-menth-1-ene-8,9-diols (uroterpenols) have been separated and crystallized.A crystallographic analysis of a dibromo derivative enables relative and absolute configurations to be assigned throughout the series.
- Carman, Raymond M.,Greenfield, Kay L.,Robinson, Ward T.
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- INTERCONVERSION AND CYCLIZATION OF ACYCLIC ALLYLIC PYROPHOSPHATES IN THE BIOSYNTHESIS OF CYCLIC MONOTERPENOIDS IN HIGHER PLANTS
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Key Word Index - Biosynthesis; interconversion; cyclization; acyclic allylic pyrophosphates; cyclic monoterpenoids; higher plants.The biosynthesis of cyclic monoterpenoids has been investigated in both intact plants and cell-free extracts of several higher plants.The participation of a non-redox process in the biosynthesis of the cyclic monoterpenoids was indicated by the retention of all the tritium labels originating from mevalonic acid and geranyl, neryl and linalyl pyrophosphates.The cell-free extract catalysed the non-redox interconversions of geranyl, neryl and linalyl pyrophosphates to each other.By contrast, in both intact plants and cell-free extracts, the incorporation of linalyl pyrophosphate into the cyclic monoterpenoids occurred preferentially to the incorporation of neryl and geranyl pyrophosphates.These observations suggest the involvetment of a teriary allylic compound and/or its equivalent as a key intermediate, not only in the interconversion of the acyclic allylic pyrophosphates, but also in the formation of the cyclic monoterpenoids.
- Suga, Takayuki,Hirata, Toshifumi,Aoki, Tadashi,Shishibori, Tsuyoshi
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p. 2769 - 2776
(2007/10/02)
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- Selective Bromination of Polyenes by 2,4,4,6-tetrabromocyclohexa-2,5-dienone
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2,4,4,6-Tetrabromocyclohexa-2,5-dienone (TBCO) liberates bromonium ion when treated with polyenes to form brominated products.The results of the reaction of TBCO with simple olefins are presented.The analogous bromo-ketones, 4-bromo-2,4,6-trichloro- and 2,4,6-tribromo-4-methyl-cyclohexa-2,5-dienone, (4) and (5) respectively, afford the same products (3a), (6), and (7) when treated with geranyl cyanide (1; R = CN).The evidence suggests that formation of the dibromide (3a) may be due to sequential reactions.TBCO in the presence of cetyltrimethylammonium bromide serves as an excellent reagent for selective bromination of polyenes under very mild conditions.
- Kato, Tadahiro,Ichinose, Isao
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p. 1051 - 1056
(2007/10/02)
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