Asymmetric induction in kinetically controlled zirconium‐catalysed Meerwein‐Ponndorf‐Verley reductions

Krohn, Karsten; Knauer, Birgit

doi:10.1002/recl.19961150206

Cited by 15 publications

(2 citation statements)

References 38 publications

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“…Consistent with aggregation of the catalyst is the concentration-dependence and inverse temperature-dependence of induction, with different enantiomers being preferentially produced at 0 "C and -23 "C. The optimum catalyst 17 was found to give 87 YO ee for the reaction of cinnamaldehyde and ketene acetal 10. The same catalyst gave 80:20 anti:syn selectivity from the reaction of benzaldehyde and the ketene acetal 22 where the major anti isomer was produced with YO YO ee. Finally, it was observed that catalyst 17 was ineffective at producing a reaction between aldehydes and ketene acetal25 (Sch.…”

Section: Aldol Reactionsmentioning

confidence: 99%

“…Slightly higher induction was observed with chiral alkoxides derived from erbium iso-propoxide but the reactions were still not synthetically useful. Finally, Krohn and Knauer have reported that a catalyst prepared from a TADDOL ligand and aluminum tert-butoxide failed to give any asymmetric induction in a MeerweinPonndorf-Verley reduction [22] Asymmetric reduction of carbonyls has also been achieved by Dupas and coworkers by reaction of achiral NADH equivalents mediated by chiral aluminum Lewis acids [23]. They reduced methyl benzoyl formate with the dihydropyrido[2,3-b]indole 86 and chiral aluminum Lewis acids whose structures are drawn and 89 and 90 (Sch.…”

Section: Carbonyl Additions and Reductionsmentioning

confidence: 99%

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Chiral Aluminum Lewis Acids in Organic Synthesis

Wulff

2000

Lewis Acids in Organic Synthesis

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The earliest report of a reaction mediated by a chiral three coordinate aluminum species describes an asymmetric Meerwein-Ponndorf-Verley reduction of ketones with chiral aluminum alkoxides which resulted in low induction in the alcohol products [1]. Subsequent developments in the area were sparse until over a decade later when chiral aluminum Lewis acids began to be explored in polymerization reactions, with the first report describing the polymerization of benzofuran with catalysts prepared from and ethylaluminum dichloride and a variety of chiral compounds including /3-phenylalanine [2]. Curiously, these reports did not precipitate further studies at the time because the next development in the field did not occur until nearly two decades later when Hashimoto, Komeshima and Koga reported that a catalyst derived from ethylaluminum dichloride and menthol catalyzed the asymmetric Diels-Alder reaction shown in Sch. 1 [3,4]. This is especially curious because the discovery that a Diels-Alder reaction could be accelerated by aluminum chloride was known at the time the polymerization work appeared [5]. Perhaps it was because of this long delay, that the report of this asymmetric catalytic Diels-Alder reaction was to become the inspiration for the dramatic increase in activity in this field that we have witnessed in the twenty years since its appearance. It is the intent of this review to present the development of the field of asymmetric catalytic synthesis with chiral aluminum Lewis acids that includes those reports that have appeared in the literature up to the end of 1998. This review will not cover polymerization reactions or supported reactions. The latter will appear in a separate chapter in this handbook. 15 rnol % catalyst 4 toluene, -78 OC, 3 h 0 2 1.1 equiv 3 69 % yield exo : endo = 98 : 2 72 % ee 1 EtAlC12 . OAIC12 A A 5 4 Scheme 1

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Section: Aldol Reactionsmentioning

confidence: 99%

Section: Carbonyl Additions and Reductionsmentioning

confidence: 99%

Chiral Aluminum Lewis Acids in Organic Synthesis

Wulff

2000

Lewis Acids in Organic Synthesis

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Zirconium Alkoxides in Catalysis

2001

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This paper presents recent advances in the reactions catalyzed by zirconium alkoxide. Catalytic asymmetric reactions with chiral zirconium catalysts and redox reactions are first discussed. The diverse characteristics of zirconium alkoxides as Lewis acids, Brönsted bases, and nucleophiles, are key for promoting these unique reactions. Our recent development of novel reactions, one-pot synthesis of trans-1.2-diol derivatives and trans-beta-cyanohydrins from olefins, is also described. These reactions cannot be produced using other metals.

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Meerwein‐Ponndorf‐Verley Reduction

2010

Comprehensive Organic Name Reactions and Reagents

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It is an aluminum alkoxide‐catalyzed reduction of carbonyl compounds (ketones and aldehydes) to corresponding alcohols using another alcohol (e.g., isopropanol) as the reducing agent or hydride source. This reaction is generally referred to as the Meerwein–Ponndorf–Verley reduction (MPV) or Meerwein–Ponndorf–Verley reaction. Later several improvements have been incorporated for this reaction. This reaction has various advantages and does not affect other double bonds or triple bonds as well as other enolizable carbonyl compounds. All the steps of the reaction and suitable catalyst have been discussed. The study finds that the yields of reduction can be further enhanced by using freshly prepared nonaggregated aluminum alkoxide or by a slow addition of carbonyl compounds into the aluminum alkoxide solution, in addition, this reaction has been modified to reduce carbonyl compounds enantioselectively.

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Asymmetric induction in kinetically controlled zirconium‐catalysed Meerwein‐Ponndorf‐Verley reductions

Cited by 15 publications

References 38 publications

Chiral Aluminum Lewis Acids in Organic Synthesis

Chiral Aluminum Lewis Acids in Organic Synthesis

Zirconium Alkoxides in Catalysis

Meerwein‐Ponndorf‐Verley Reduction

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