Chemoselective Reduction of Aldehydes in the Presence of Ketones Utilizing Raney Nickel

Barrero, Alejandro F.; Álvarez-Manzaneda, Enrique; Chahboun, Rachid; Meneses, R.

doi:10.1055/s-2000-6498

Cited by 30 publications

(26 citation statements)

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“…Chemical shifts are given on the δ scale in parts per million relative to signals of CHCl 3 as an internal standard (at 7.24 and 77.00 ppm, respectively). Signals in 13 C NMR spectra were assigned using the DEPT technique and comparison with spectra of known related compounds [3][4][5][6][11][12][13][14]. Specific rotation was measured in CHCl 3 on a Perkin-Elmer 241 polarimeter.…”

Section: Methodsmentioning

confidence: 99%

Synthesis of Drim-9(11)-en-8α- and -8β-ols from Drimenol

et al. 2005

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Drim-9(11)-en-8α-ol and drim-9(11)-en-8β-ol were synthesized in six steps from drimenol. Drimenol was oxidized by P 2 O 5 and DMSO to drimenal, which isomerized with p-TsOH into isodrimenal. Isodrimenal was reduced by NaBH 4 into isodrimenol, epoxidation of which by m-CPBA gave a mixture (3.4:1) of α-and β-epoxyisodrimenols. These reacted with tosyl chloride in Py to give a mixture of α-and β-epoxyisodrimenol tosylates. Treatment of the tosylate mixture with KI and then Ph 3 P produced a mixture of drim-9(11)-en-8α-and -8β-ols that was separated chromatographically. The overall yield was ~26%.The bicyclic sesquiterpenoids ent-drim-9(11)-en-8α-ol (1) and ent-drim-9(11)-en-8β-ol (2) occur in certain food products [1]. Several syntheses of the enantiomer of 2, drim-9(11)-en-8α-ol (3) [2-5] and drim-9(11)-en-8β-ol (4) [6,7], and the natural compound 1 [6] have been developed from available labdane and ent-labdane bicyclic diterpenoids.Herein we report the synthesis of 3 and 4 from the available drimane sesquiterpenoid drimenol (5) according to Scheme 1.Scheme 1

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Section: Methodsmentioning

confidence: 99%

Synthesis of Drim-9(11)-en-8α- and -8β-ols from Drimenol

et al. 2005

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“…The pathway is sterically hindered in both the dissociated and associated forms, although more so for the latter, and thus unlikely. Such selectivity has been observed for the addition of soft The final benzyl deprotection 15 was accomplished using LiAlH 4 in the presence of stoichiometric NiCl 2 , which after 11 h gave jaspaquinol 1 in 83% yield. The structure of 1 was confirmed by comparison with the natural product ( 1 H and 13 C NMR), which is identical and provides verification of the reported structure.…”

Section: Introductionmentioning

confidence: 93%

“…Reaction of 10 with arylstannane 12 15 in the presence of Pd 2 dba 3 AECHCl 3 and PPh 3 gave the S N 2 product 13 in 92% yield, whereas use of the bromide 11 gave the S N 2 product in a lower 81% yield.…”

Section: Introductionmentioning

confidence: 94%

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Synthesis of jaspaquinol and effect on viability of normal and malignant bladder epithelial cell lines

Demotie

Fairlamb

et al. 2004

Bioorganic & Medicinal Chemistry Letters

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“…1,2 Our recent studies have revealed that this reagent may also be very effective in carrying out the chemoselective reduction of organic halides.…”

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confidence: 99%

Raney Nickel: An Effective Reagent for Reductive Dehalogenation of Organic Halides

Barrero¹,

Álvarez-Manzaneda²,

Chahboun³

et al. 2001

Synlett

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Raney Nickel is an effective reagent to achieve the chemoselective reductive dehalogenation of organic halides. Fluorides and vinyl halides are unreactive under the used experimental conditions. The present authors have previously reported the effectiveness of Raney nickel to accomplish the chemoselective reduction of aldehydes in the presence of ketones and the reduction of conjugated olefins in a,b-unsaturated carbonyl compounds, which also contain isolated carboncarbon double bonds. 1,2 Our recent studies have revealed that this reagent may also be very effective in carrying out the chemoselective reduction of organic halides.The replacement of halogen by hydrogen has attracted great interest among organic chemists, stimulating considerable investigation, and a number of methods have been reported hitherto. 3 A variety of reducing agents are now available, and many of them are successfully applied to practical organic synthesis. Metallic zinc in acetic acid has been efficiently used for reductive dehalogenation. 4 The use of metal hydrides has also been found effective. Thus, lithium aluminum hydride reduces alkyl halides to the corresponding hydrocarbons, with good yields. 5 Sodium borohydride in aprotic polar solvents reduces primary, secondary, tertiary and benzyl halides, in the presence of nitro, ester or carboxylic groups, which remain unaltered. 6 Stannanes have been used extensively to replace halogen by hydrogen. 7 Tri-n-butyltin hydride is able to reductively replace iodides and bromides at room temperature, and chlorides under more extreme conditions; fluorides are not reactive. This reagent exhibits high chemoselectivity and is compatible with a variety of other functional groups. A drawback of this reagent is its toxicity.Catalytic hydrogenation has also been used to achieve the reductive dehalogenation of organic halides, the reaction rate being dependent on the structural feature and the halogen involved. For example, alkyl iodides and alkyl bromides are converted into the corresponding hydrocarbons by hydrogenation over palladium on carbon. 8 Williams et al. reported that the Raney nickel catalyst is readily deactivated by the halide during hydrogenation and, therefore, massive amounts of the catalyst are usually required in order to improve yields. 9,10 Recently, Yus et al.have described that NiCl 2 ·2H 2 O-Li-DTBB (cat.) reduces organic halides in high yields. 11During our research into the use of Raney nickel as a chemoselective reductor we found that activated Raney nickel is an effective reagent in the reduction of organic halides. Some representative examples are summarized in the table, which shows that benzyl halides (5a-8a) and a-halocarbonyl and related compounds (1a-3a, 9a-11a) are easily reduced after treating with Raney nickel in tetrahydrofuran at room temperature for 45 min-2 h. The treatment of a solution of bromolactone 4a in tetrahydrofuran with Raney nickel at room temperature for 5 min yielded g-lactone 4b in 80%; the carbon-carbon double bond was also reduced when the react...

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Chemoselective Reduction of Aldehydes in the Presence of Ketones Utilizing Raney Nickel

Abstract: Raney nickel is an effective reagent to achieve the chemoselective reduction of aldehydes in the presence of ketones, which takes place in high yield. Only highly hindered aldehydes do not undergo reduction.

Cited by 30 publications

References 9 publications

Synthesis of Drim-9(11)-en-8α- and -8β-ols from Drimenol

Synthesis of Drim-9(11)-en-8α- and -8β-ols from Drimenol

Synthesis of jaspaquinol and effect on viability of normal and malignant bladder epithelial cell lines

Raney Nickel: An Effective Reagent for Reductive Dehalogenation of Organic Halides

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