Asymmetric synthesis of palitantin from the (5R)-tert-butyldimethylsiloxy-2-cyclohexenone

Hareau, Georges; Koiwa, Masakazu; Hanazawa, Takeshi; Sato, Fumie

doi:10.1016/s0040-4039(99)01549-x

Cited by 22 publications

(6 citation statements)

References 15 publications

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“…The trialkylsilyl-substituted cyclohexenones have been used for the synthesis of, e.g., Sarcodictyenone 3 and Nicandrenone NIC-10 4 . The 5-hydroxy-substituted cyclohexenones 2 have been employed in a number of syntheses, such as 19- nor -1α,25-dihydroxyvitamin D 3 5 , or Rugulosin 6 . , Furthermore, the silyl and hydroxy group in 1 and 2 , respectively, can be used to control the stereochemistry of transformations at adjacent double bonds. , …”

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confidence: 99%

Organocatalytic Asymmetric Synthesis of 5-(Trialkylsilyl)cyclohex-2-enones and the Transformation into Useful Building Blocks

2008

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A simple organocatalytic approach to highly attractive chiral building blocks is presented. By the reaction of beta-ketoesters with alpha,beta-unsaturated aldehydes using a chiral TMS-protected prolinol as the catalyst, optically active 5-(trialkylsilyl)cyclohex-2-enones are formed in good yields and with 98-99% ee. The applications of 5-(trialkylsilyl)cyclohex-2-enones for the formation of 5-(hydroxy)cyclohex-2-enones and the A-ring of 19- nor-1alpha,25-dihydroxyvitamin D3 are also presented.

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confidence: 99%

Organocatalytic Asymmetric Synthesis of 5-(Trialkylsilyl)cyclohex-2-enones and the Transformation into Useful Building Blocks

2008

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“…Although the mechanistic details for this elimination are still obscure at present, the absolute stereochemistry of the synthesized 5-cyclohex-2-enone was unambiguously determined by its conversion to the corresponding tert-butyldimethylsilyl ether 46, whose sign of optical rotation was equal to the sign of the reported literature value. 31 The silyl ether 46 was further transformed to the key intermediate 51 for an inositol phosphatase inhibitor as follows. (Scheme 8) Epoxidation of 46 with alkaline hydrogen peroxide gave the epoxide 47, stereoselectively, which, on reduction with NaBH4 gave a diastereomixture of alcohols 48 and 49, in a ratio of ca.…”

Section: Synthesis Of Lignan Lactones (-)-Hinokinin (-)-mentioning

confidence: 99%

Syntheses of Natural Products and Biologically Active Compounds by Means of Enantioselective Deprotonation Strategy.

Honda

2002

J. Syn. Org. Chem., Jpn.

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: Enantioselective deprotonation reactions of prochiral 4, 4-disubstituted cyclohexanone, 3-substituted cyclobutanones and 3, 5-dioxygenated cyclohexanones with a chiral lithium amide bases in the presence of silylating agents, were carried out to give the corresponding silyl enol ethers. The silyl enol ether obtained from 4-methyl-4-tolylcyclohexanone was converted to (+)-a-cuparenone.On the other hand , the silyl enol ethers derived from 3-substituted cyclobutanones were utilized in the synthesis of naturally occurring (-)-methylenolactocine and several kinds of lignan lactones, and also in the synthesis of medicinally important compound, (R)-( -)-r olipr am . Moreover, the silyl enol ethers prepared from prochiral 3 , 5-dioxygenated cyclohexanones were employed as the starting materials in the synthesis of biologically important compounds, such as HMG-CoA reductase inhibitor and antiobesity agent , tetrahydrolipstatin, with the opposite mode of asymmetric induction even by using the same chiral amide base. Finally, a synthetic procedure for enantiomerically enriched 5-hydroxycyclohex-2-enone was established by elimination of the alkoxide group in the chiral silyl enol ether, which was further transformed into an inositol phosphatase inhibitor.

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“…Enantiomerically enriched cyclohex-2-enone derivatives are extremely useful building blocks for the preparation of biologically active compounds, including natural products. − Among the various types of cyclohex-2-enone derivatives, 5-hydroxy- and 5-alkoxycyclohex-2-enones represent the most attractive and versatile chiral building blocks, − and several approaches for their synthesis have been proposed. , The two 5-siloxycyclohex-2-enones 1 and 2 and bicyclic compounds 3 and 4 are the only enantiomerically enriched 6-alkyl-substituted 5-hydroxycyclohex-2-enone derivatives reported thus far. …”

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Synthesis of Optically Active 5-Alkoxy-6-methylcyclohex-2-en-1-ones and 4-Alkoxy-5-methylcyclopent-1-enyl Benzoate

Turks

Vogel

2008

J. Org. Chem.

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The reaction of (-)-(1E,3Z)-2-methyl-1-((1S)-1-phenylethoxy)penta-1,3-dien-3-ol benzoate with allyltrimethylsilane in SO2 and in the presence of a catalytic amount of Tf2NTMS gives a silyl sulfinate intermediate that furnishes (-)-(6Z,1'S,4S,5S)-5-methyl-4-(1'-phenylethoxy)octa-1,6-dien-6-yl benzoate after acidic workup. The latter undergoes ring-closing metathesis producing (-)-(2S,3S)-2-methyl-3-((1S)-1-phenylethoxy)cyclopent-5-en-1-yl benzoate. It has been converted also into the corresponding trimethylsilyl enol ether. After oxidation, an enone is obtained that undergoes ring-closing metathesis giving (-)-(5S,6S)-6-methyl-5-((1S)-1-phenylethoxy)cyclohex-2-en-1-one.

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Asymmetric synthesis of palitantin from the (5R)-tert-butyldimethylsiloxy-2-cyclohexenone

Cited by 22 publications

References 15 publications

Organocatalytic Asymmetric Synthesis of 5-(Trialkylsilyl)cyclohex-2-enones and the Transformation into Useful Building Blocks

Organocatalytic Asymmetric Synthesis of 5-(Trialkylsilyl)cyclohex-2-enones and the Transformation into Useful Building Blocks

Syntheses of Natural Products and Biologically Active Compounds by Means of Enantioselective Deprotonation Strategy.

Synthesis of Optically Active 5-Alkoxy-6-methylcyclohex-2-en-1-ones and 4-Alkoxy-5-methylcyclopent-1-enyl Benzoate

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