- Amberlyst-15-catalyzed intramolecular S(N)2' oxaspirocyclization of secondary allylic alcohols. Application to the total synthesis of spirocyclic ethers theaspirane and theaspirone
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A variety of substituted 1-oxaspiro[4.4]non-6-ene. 1-oxaspiro[4.5]dec-6- ene, 6-oxaspiro[4.5]dec-1-ene and 1-oxaspiro[5.5]undec-7-ene systems have been prepared by utilizing Amberlyst-15-catalyzed intramolecular S(N)2' oxaspirocyclizations of secondary allylic alcohols under mild reaction conditions in quantitative yields. This oxaspirocyclization was applied to the total synthesis of theaspirane and theaspirone from β-ionone in five steps. (C) 2000 Elsevier Science Ltd.
- Young, Jenn-Jong,Jung, Liarng-Jyur,Cheng, Kuang-Ming
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p. 3415 - 3418
(2007/10/03)
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- A NOVEL SELENIUM-MEDIATED SPIROANNELATION: ONE-STEP PREPARATION OF d1-THEASPIRANE FROM α-DIHYDROIONOL
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dl-Theaspirane (1) was prepared by the selenium-mediated electrochemical oxidation of α-dihydroionol (2), via a novel selenium-mediated spiroannelation.
- Uneyama, Kenji,Fujibayashi, Shoji,Torii, Sigeru
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p. 4637 - 4638
(2007/10/02)
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- AN ELECTROCHEMICAL CHLORINATIVE ENE-TYPE REACTION OF ISOPRENOIDS
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The chlorinative ene-type reaction of isoprenoids (12) has been performed by electrolysis in CH2Cl2-H2O-NaCl system.The reaction provides useful allylic chlorides 2 for terpene synthesis in high yields and is affected strikingly by the nature of halide ions and solvents. dl-Theaspirane 21 was prepared from α-dihydroionol via the electrolysis.
- Torii, Sigeru,Uneyama, Kenji,Nakai, Toshiyuki,Yasuda, Tsuneo
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p. 2291 - 2294
(2007/10/02)
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- Isolation, tentative identification, and synthesis studies of the volatile components of the hairpencil secretion of the monarch butterfly
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The major volatile components of the hairpencil secretion of the male monarch butterfly have been identified as benzyl caproate and either 1, 5, 5, 9-tetramethyl-10-oxabicyclo[4.4.0]-3- decen-2-one(1), or 2, 2, 6, 8-tetramethyl-7-oxabicyclo[4.4.0]-4-decen-3-one(2). One sequence designed to synthesize 1 yielded two isomeric products of structure 1 whose spectra are very similar to each other but distinctly different from those of the natural product; this sequence also yielded a tricyclic ketal (9). A second sequence gave two epimeric spiro compounds (12) and a third sequence gave a [4.3.0] ring system (14).
- Bellas,Brownlee,Silverstein
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p. 2267 - 2271
(2007/10/07)
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- 147. Model reactions for the biosynthesis of damascone-related compounds and their preparative application
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We report a new general synthesis of damasconcs. In the presence of acids, 7, 8-dehydro-β-ionole (10) or the related diols 11 are converted into a mixture of β-damascone (2) and the 7, 8-dehydrotheaspiranes (19). In the same way the 6-hydroxy-7, 8-dehydro-α-ionoles 12 are transformed into a mixture of β-damascenone (3) and the 8-oxatheaspiranes (20). The reaction provides access to damascone derivatives 4-7 which have been found in nature. These synthetic experiments lend support to our hypotheses concerning the biogenesis of damascones from suitable carotenoids or their metabolites.
- Ohloff, Guenther,Rautenstrauch, Valentin,Schulte-Elte, Karl H.
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p. 1503 - 1513
(2007/10/10)
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