Stereoselective Reduction of β-Hydroxy Ketones with Aldehydes <i>via</i> Tishchenko Reactions Catalyzed by Zirconocene Complexes<sup>1</sup>

Umekawa, Y.; Sakaguchi, Satoshi; Nishiyama, Yutaka; Ishii, Yasutaka

doi:10.1021/jo970031l

Cited by 34 publications

(7 citation statements)

References 23 publications

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“…7 Alternatively, a samarium-catalyzed Tishchenko reduction has been developed by Evans et al which gives rise to 1,3-anti-diol monoesters with exceptional levels of diastereoselectivity (>98% de) and furnishes monoprotected and thus differentiated 1,3-diols in one step. 8 A binuclear aluminum alkoxide, 9 a zirconocene complex, 10 and Sc(OTf) 3 11 have also been reported as catalysts for this reaction. Apart from hydride reagents one-electron reducing agents such as SmI 2 have been employed in conjunction with proton sources to effect the highly anti-diastereoselective reduction of b-hydroxy ketones.…”

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confidence: 99%

Zr(Ot-Bu)₄-Catalyzed Tishchenko Reduction of β-Hydroxy Ketones

Schneider¹,

Klapa²,

Hansch³

2004

Synlett

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Zr(OtBu) 4 was found to catalyze the Tishchenko reduction of b-hydroxy ketones giving rise to differentiated 1,3-anti-diol monoesters in high yields and excellent stereoselectivity.The diastereoselective reduction of b-hydroxy ketones is a fundamental synthetic operation in the stereoselective synthesis of 1,3-dioxygenated compounds such as polyacetate-or polypropionate-derived natural products. 1 A large number of methods have been developed for the selective synthesis of either 1,3-syn-or 1,3-anti-diols. 2 Most prominent among the syn-selective methods is the Narasaka-Prasad protocol employing NaBH 4 /Et 2 BOMe, 3 which is based upon an external hydride delivery onto a preformed boron chelate and furnishes 1,3-syn-diols typically with >96% de. In addition, Zn(BH 4 ) 2 , 4 DIBALH 5 and combinations of TiCl 4 and various reductants 6 have also been shown to reduce b-hydroxy ketones to 1,3-syndiols, albeit with occasionally diminished diastereoselectivity. The most widely employed method to obtain 1,3-anti-diols was developed by Evans et al. and involves the use of Me 4 NBH(OAc) 3 , which delivers the hydride intramolecularly with anti/syn ratios of 95:5 or better. 7 Alternatively, a samarium-catalyzed Tishchenko reduction has been developed by Evans et al. which gives rise to 1,3-anti-diol monoesters with exceptional levels of diastereoselectivity (>98% de) and furnishes monoprotected and thus differentiated 1,3-diols in one step. 8 A binuclear aluminum alkoxide, 9 a zirconocene complex, 10 and Sc(OTf) 3 11 have also been reported as catalysts for this reaction. Apart from hydride reagents one-electron reducing agents such as SmI 2 have been employed in conjunction with proton sources to effect the highly anti-diastereoselective reduction of b-hydroxy ketones. 12 We have recently shown that Zr(Ot-Bu) 4 is a powerful catalyst for the aldol-Tishchenko reaction of ketone aldols such as diacetone alcohol (Scheme 1). 13 The reaction presumably proceeds via retro-aldol cleavage of the thermodynamically unstable ketone aldol, furnishing a zirconium enolate which then undergoes the aldol-Tishchenko reaction in good yield and excellent diastereoselectivity. These observations suggested that Zr(Ot-Bu) 4 may be employed as catalyst solely for the Tishchenko step of this sequence starting directly from b-hydroxy ketones. Accordingly, a systematic investigation was undertaken to devise optimal conditions for the Zr(Ot-Bu) 4 -catalyzed Tishchenko reduction of b-hydroxy ketones.Scheme 1

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confidence: 99%

Zr(Ot-Bu)₄-Catalyzed Tishchenko Reduction of β-Hydroxy Ketones

Schneider¹,

Klapa²,

Hansch³

2004

Synlett

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“…The Tishchenko-type reaction was also achieved in the presence of a catalytic amount of bidentate aluminum alkoxides 91 or Cp 2 ZrH 2 to form the corresponding diol monoesters with high levels of stereoselectivity under mild conditions. 92 Scott and co-workers reported the use of a catalytic amount of scandium triflate for stereoselective Tishchenko reduction of b-hydroxyketones (Scheme 42). 93 Scheme 42 Reduction of aromatic hydroxyketones with isobutyraldehyde in the presence of 10 mol% Sc(OTf) 3 .…”

Section: Scheme 37mentioning

confidence: 99%

Stereoselective Synthesis of 1,3-Diols

Bode¹,

Wolberg²,

Müller³

2006

Synthesis

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Many polyketide-derived natural products contain a synor anti-1,3-diol unit. No general and simple approach exists for the flexible synthesis of polyols and other polyketide-derived structural units, therefore a multitude of methods for the stereoselective synthesis of 1,3-diols has been developed. Asymmetric homogeneous and heterogeneous hydrogenation and diastereoselective reduction, chain elongation, enzymatic and nonenzymatic desymmetrization, or dynamic kinetic resolution are some of these methods. The development of different methods to synthesize these 1,3-diols stereoselectively is important, as often small structural changes in a molecule result in low yields or low stereoselectivity with a known method. This review article highlights some of the recent developments in this field.

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“…One method to prepare chiral 1,3-diol is the reduction of β-hydroxyketones, and various metal hydride reagents have been applied to the syntheses of biologically active compounds using this method. Recently, acetalization of a β-hydroxy group with an aldehyde followed by a hydride shift to the carbonyl carbon, the so called Evans-Tishchenko reduction ( Scheme 1 ) [ 3 , 4 , 5 ], has received much attention because it does not require the use of metal hydride reagents. Although the literature contains numerous examples using the Evans-Tishchenko reduction in the synthesis of biologically active compounds [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ], the enantioselective Evans-Tishchenko reduction of an achiral β-hydroxyketone had not been reported prior to our preliminary study [ 14 ].…”

Section: Introductionmentioning

confidence: 99%