- Protection of the carbonyl group as 1,2,4-trioxane and its regeneration under basic conditions
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(Chemical Equation Presented) An experimental protocol demonstrating the protection of the carbonyl group as 1,2,4-trioxane, the stability of the protecting group under a variety of reaction conditions, and the regeneration of the carbonyl group with Triton B in THF at room temperature is presented. The method provides a useful alternative for the protection of carbonyl compounds having acid-sensitive moieties.
- Singh, Chandan,Malik, Heetika
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p. 5673 - 5676
(2007/10/03)
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- A stereocontrolled route to cyclohexylethanoid natural products
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Rengyol and seven related cyclohexylethanoid natural products have been synthesized in a stereocontrolled manner from a common starting material. In the present study the absolute configuration of the three chiral products has been determined and the first synthesis of a cyclohexylethanoid natural product bearing an oxetane ring has been accomplished.
- Honzumi, Masatoshi,Kamikubo, Takashi,Ogasawara, Kunio
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p. 1001 - 1003
(2007/10/03)
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- Chemoenzymatic synthesis of rengyoside-A, -B, isorengyoside and synthesis of their aglycones
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The chemoenzymatic synthesis of a group of naturally occurring cyclohexylethanoids, rengyoside-A, -B and isorengyoside, has been performed by enzymatic glucosidation of their chemically synthesized aglycones, rengyol, rengyoxide and isorengyol.
- Soriente, Annunziata,Della Rocca, Anna,Sodano, Guido,Trincone, Antonio
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p. 4693 - 4702
(2007/10/03)
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- BIOGENESIS-LIKE TRANSFORMATION OF SALIDROSIDE TO RENGYOL AND ITS RELATED CYCLOHEXYLETANOIDS OF FORSYTHIA SUSPENSA
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Photooxygenation of salidroside (8) in methanol in presence of Rose Bengal afforded cornoside (9), which, on high pressure hydrogenation with 5percent palladium on activated carbon, yielded rengyoside B (6).Reduction of 6 with sodium borohydride gave rengyoside A(5) stereoselectively.By enzymatic hydrolysis, 9, 6 and 5 furnished rengyolone (4), rengyoxide (3) and rengyol (1), respectively. Similerly, p-hydroxyphenylethanol (10), the aglycone part of salidroside (8), was oxygenated photochemically to a dienone alcohol, which cyclized spontaneously to rengyolone (4).Hallerone (17) was obtained by the photooxygenation of p-hydroxyphenylethyl acetate (10b).Thus the plausible biosynthetic routes from salidroside (8) to rengyol (1) and the related natural cyclohexylethanoids were simulated chemically.
- Endo, Katsuya,Seya, Kazuhiko,Hikino, Hiroshi
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p. 3673 - 3682
(2007/10/02)
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- STRUCTURES OF RENGYOSIDES A, B AND C, THREE GLUCOSIDES OF FORSYTHIA SUSPENSA FRUITS
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Three new glucosides, rengyosides A, B and C, having as aglycones the reduced forms of phenylethanol, were isolated from Forsythia suspensa fruits.Chemical and spectroscopic studies established the structures of these natural products to be 2-(1,4-dihydroxycyclohexyl)ethyl β-D-glucopyranoside, 2-(1-hydroxy-4-ketocyclohexyl)ethyl β-D-glucopyranoside and 2-(1,4-dihydroxycyclohexyl)ethyl β-D-6-O-glucopyranoside, respectively.Saliroside, a possible biogenetic precursor of these glucosides, was also isolated. Key Word Index- Forsythia suspensa; Oleaceae; rengyoside A; rengyoside B; rengyoside C; cyclohexylethyl glucosides.
- Seya, Kazuhiko,Endo, Katsuya,Hikino, Hiroshi
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p. 1495 - 1498
(2007/10/02)
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