- Regioselective and enantiospecific rhodium-catalyzed allylic alkylation reactions using copper(I) enolates: Synthesis of (-)-sugiresinol dimethyl ether
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The transition metal-catalyzed allylic alkylation represents a fundamentally important cross-coupling reaction for the construction of ternary carbon stereogenic centers. We have developed a regioselective and enantiospecific rhodium-catalyzed allylic alk
- Evans, P. Andrew,Leahy, David K.
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p. 8974 - 8975
(2007/10/03)
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- Conjugate addition of arylmetal reagents to an α,β-unsaturated ketone. Short syntheses of (-)-agatharesinol dimethyl ether and (-)-sugiresinol dimethyl ether
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(-)-Agatharesinol dimethyl ether and (-)-sugiresinol dimethyl ether, derivatives of (-)-agatharesinol and (-)-sugiresinol isolated from Agathis australis and Cryptomeria Japonica, respectively were synthesized starting from a protected D-glyceraldehyde in
- Matsuo, Keizo,Ono, Yuji,Seki, Atsutaka,Kuwajima, Hiroshi,Nishiwaki, Keiji
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p. 2553 - 2560
(2007/10/03)
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- Synthesis of (-)-sugiresinol dimethyl ether utilizing (-)-quinic acid
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(-)-Sugiresinol dimethyl ether, a derivative of (-)-sugiresinol isolated from Cryptomeria japonica, was synthesized through 1,4-conjugate addition of arylmetal reagent to a substituted chiral 2-cyclohcxcn-1-one derived from (- )quinic acid.
- Matsuo, Keizo,Sugimura, Wakiko,Shimizu, Yumiko,Nishiwaki, Keiji,Kuwajima, Hiroshi
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p. 1505 - 1513
(2007/10/05)
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- Asymmetric endoselective [4+2] heterocycloadditions of styrene dienophiles with chiral benzylidenepyruvic esters. Total synthesis of (-)-O-dimethylsugiresinol
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Eu(fod)3 catalyzed [4+2] heterocycloadditions of para-methoxystyrene 7 with esters 8a-f of benzylidenepyruvic acids (deriving from various chiral alcohols) furnished endo adducts 9a-f with variable diastereoselective ratios (from 58/42 to 86/14). Interestingly, the benzylidenepyruvic esters 8g and 8h, deriving from a new chiral vector, the α-O-silyl ether 6 of (D)-(-)-erythronolactone 5, gave the corresponding endo adducts 9g and 9h with a high diastereoselective ratio (dr ≤95/5). The adduct 9h was used as a precursor in a five-step synthesis of 'natural' (-)-dimethylsugiresinol (1b).
- Dujardin, Gilles,Maudet, Mickael,Brown, Eric
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p. 1555 - 1558
(2007/10/03)
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- Lignans.19. Total synthesis of (-)-O-dimethylsugiresinol, involving asymmetric [4+2] heterocycloaddition of a styrene with a benzylidenepyruvic ester of an α-O-silyl derivative of (D)-erythronolactone
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α-O-t-Butyldiphenylsilyl-(D)-erythronolactone [(+)-25] (a new chiral vector) was esterified with 4-methoxybenzylidene pyruvic acid (19). Eu(fod)3 catalyzed [4+2] heterocycloaddition of the latter 1-oxabutadiene with 4- methoxystyrene (as the dienophile), afforded high yields of the endo adduct 23c with 95/5 diastereofacial ratio. Five further steps led to enantiomerically pure natural (-)-O-dimethylsugiresinol (-)-2 in 12% overall yield from the acid 19.
- Brown, Eric,Dujardin, Gilles,Maudet, Mickael
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p. 9679 - 9694
(2007/10/03)
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- Enantioselective total synthesis of the di-O-methyl ethers of (-)-agatharesinol, (+)-hinokiresinol and (-)-sugiresinol, characteristic norlignans of Coniferae
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Facile enantioselective syntheses of the di-O-methyl ethers of the norlignans, (-)-agatharesinol (-)-1a, (+)-hinokiresinol (+)-2a and (-)-sugiresinol (-)-3a are described. Grignard addition of vinylmagnesium bromide to an aldimine (-)-13, prepared from the tert-butyl ester 11 and 4-methoxycinnamaldehyde 12, afforded a homochiral vinyl aldehyde, (-)-3-(4-methoxyphenyl)pent-4-enal (-)-14 in > 95% ee, which was converted into a diastereoisomeric mixture of 1,3-bis(4-methoxyphenyl)pent-4-en-1-ols (3R)-6 by a second Grignard reaction with 4-methoxyphenylmagnesium bromide. Sharpless' asymmetric dihydroxylation of the vinyl alcohols (3R)-6 proceeded diastereoselectively to give the triol of desired relative stereochemistry (2S,3S)-7. This, upon dehydration, afforded (-)-di-O-methylsugiresinol (-)-3b, the subsequent acid-catalysed cyclization of which gave (-)-di-O-methyl agatharesinol (-)-1b. (+)-Di-O-methylhinokiresinol (+)-2b was readily obtained by the dehydration of the vinyl alcohols (3R)-6.
- Muraoka, Osamu,Zheng, Bao-Zhong,Fujiwara, Noriyuki,Tanabe, Genzoh
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p. 405 - 411
(2007/10/03)
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- First asymmetric synthesis of (-)-sugiresinol dimethyl ether
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Efficient enantioselective synthesis of (-)-sugiresinol dimethyl ether was accomplished based upon two asymmetric processes: asymmetric β-alkylation of α,β-unsaturated aldimines and enantioselective dihydroxylation of olefins.
- Muraoka,Fujiwara,Tanabe,Momose
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p. 357 - 358
(2007/10/02)
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