Reduction of natural enones in the presence of cerium trichloride

Luche, Jean‐Louis; Rodríguez‐Hahn, Lydia; Crabbé, Pierre

doi:10.1039/c39780000601

Cited by 318 publications

(171 citation statements)

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“…The direct dehydration of an alcohol to alkene is a major issue since it requires high temperature and acidic conditions leading to various side products (35). Thus, encouraged by the results obtained for dehydration of aldoximes to nitriles, dehydration of secondary alcohols to alkenes (Scheme 2) was also tested under the same set of reaction conditions ( Table 7).…”

Section: Green Chemistry Letters and Reviews 145mentioning

confidence: 99%

Silica supported heteropolyacid catalyzed dehydration of aldoximes to nitriles and alcohols to alkenes

Parghi

Satam

Jayaram

2011

Green Chemistry Letters and Reviews

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An expedient method of silica supported heteropolyacid (HPA) catalyzed liquid phase dehydration of aldoxime to nitrile and secondary alcohols to alkenes were developed. Supported HPA was prepared by wet impregnation method and characterized by various analytical techniques such as X-ray diffraction, FT-IR, and NH 3 -TPD analysis. HPW-SiO 2 was found to be the most efficient catalyst amongst the prepared HPA and was found to be reusable for dehydration reaction under mild operating conditions giving high yields of the desired products.

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Section: Green Chemistry Letters and Reviews 145mentioning

confidence: 99%

Silica supported heteropolyacid catalyzed dehydration of aldoximes to nitriles and alcohols to alkenes

Parghi

Satam

Jayaram

2011

Green Chemistry Letters and Reviews

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“…The mixture of diastereoisomers 6a and 6b were separated from 6c and 6d by column chromatography and both the mixtures were independently treated with NaBH 4 in ethanol (Scheme 3) in the presence of CeCl 3 .7H 2 O under Luche's reaction conditions 20 . 6a and 6b afforded a mixture of alcohols 12 (major), 13 (minor) and 14 (single isomer) in the ratio of 4:1:2 respectively in a combined yield of 88%, while 6c and 6d furnished 15 as an inseparable mixture of alcohols.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of pseudo saccharide precursors through ‘off template site’ Michael –Wittig reaction on sugar derived enal

Sharma¹,

Chander²,

Krishna³

et al. 2004

Arkivoc

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Abstract[3+3] Annulation protocol at an'off template site' on the sugar derived enal synthon effectively resulted in the formation of C-C linked pseudo saccharide precursors. Thus, the enolate of phosphorane generated from ethyl acetoacetate first undergoes a Michael reaction on the enal followed by a Wittig reaction to furnish the target saccharides, where the chirality is very effectively translated from the parent sugar.

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“…[13][14][15] A mixture of 10a and 10b was used in the next reaction without separation because of their * To whom correspondence should be addressed. -and trans-5,8-dihydroxy-5,6,7,8-tetrahydro-1,4-naphthoquinone (1a, 1b) were for the first time synthesized from 5,8-dihydroxy-1,4-naphthoquinone (naphthazazine) (6) as a starting material and racemic triol (3) was first synthesized from 7.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of cis- and trans-5,8-Dihydroxy-5,6,7,8-tetrahydro-1,4-naphthoquinone.

Arima

Yamada

Takeda

et al. 2001

CHEMICAL & PHARMACEUTICAL BULLETIN

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Sch 49210 (2) is a novel metabolite having antitumor and inhibitory phospholipase D activities and was isolated from a fungal culture broth by Chu et al. in 1994. 1) Compound 2 contains a unique structure, ketobisepoxydecalone with a spiroacetal linkage through a naphthalene moiety. CJ-12, 372 (4) isolated by Sakemi et al. 2) was shown to possess DNA gyrase inhibition activity and is a spiroacetal compound with 1,8-naphtalenediol (5) as compound 2. Recently, investigations of analogous compounds of 2 and 4 have been reported and the syntheses of a series of these naturally occurring spiroacetal-bridged compouds were published.3-11) The synthesis of bisepoxide 2 and naphthalene dimer 4 has not yet been published, however, we initially began to synthesize key compounds 1a and 3 for 2 and 4 (Chart 1). In this paper, we describe the first synthesis of cis -and trans-5,8-dihydroxy-5,6,7,8-tetrahydro-1,4-naphthoquinone (1a, 1b) by two routes, and also the first synthesis of racemic triol 3. Results and Discussion2,3-Dihydro-5,8-dihydroxy-1,4-naphthoquinone (7) was synthesized from naphthazazine (6) as the starting material by applying the procedure 12) developed by Pearson et al. Reduction of 6 by 20 eq of stannous chloride under acidic conditions gave dihydro compound 7 in 90% yield (Chart 2). Diol 7 was used in the following procedure without purification because 7 is unstable to air-oxidation and returns to starting material 6 easily. Diol 7 was then reduced by treatment with large excess (24 eq) of NaBH 4 in the presence of a catalytic amount of CeCl 3 13-15) in tetrahydrofuran (THF) at room temperature to afford a mixture of 8a and 8b. Oxidation of a mixture of 8a and 8b using ceric ammonium nitrate (CAN) [16][17][18] as an oxidant in acetonitrile gave a mixture of 1a (cis) and 1b (trans).19) The mixture was separated by column chromatography to give crystals 1a and oil 1b in 34 and 50% yields, respectively (Chart 2). The stereostructures of 1a and 1b were decided as follows. The determination whether 1a and 1b are the cis or trans isomer by 1 H-NMR spectra presented great difficulty because each spectrum exhibits a complicated coupling pattern. Therefore, X-ray analysis of 1a was performed. The ORTEP view of 1a showed a cis diol structure and exhibited interesting stereochemical features as shown in Fig. 1. The cyclohexane ring adopts a half-chair conformation and two carbonyl groups in quinone are above so that they are apart from each cis hydroxyl group. From these results, it was proved that 1a and 1b are correspondent to a cis and trans diol, respectively.In the procedure shown in Chart 2, separation of 1a and 1b by column chromatography was difficult because their Rf values are very close in spite of the short process. We therefore developed another method for 1a and 1b as shown in Chart 3. Methylation of 6 by treatment with Ag 2 O and CH 3 I afforded 9 in 76% yield according to the procedure developed by Pearson and co-workers. 12) At first LiAlH 4 was used as a reducing agent, but 1,4-dihydroxy-5,8-dim...

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Reduction of natural enones in the presence of cerium trichloride

Cited by 318 publications

References 0 publications

Silica supported heteropolyacid catalyzed dehydration of aldoximes to nitriles and alcohols to alkenes

Silica supported heteropolyacid catalyzed dehydration of aldoximes to nitriles and alcohols to alkenes

Synthesis of pseudo saccharide precursors through ‘off template site’ Michael –Wittig reaction on sugar derived enal

Synthesis of cis- and trans-5,8-Dihydroxy-5,6,7,8-tetrahydro-1,4-naphthoquinone.

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