Asymmetric, Catalytic Phenyl Transfer to Aldehydes: Enantioselective Synthesis of Diarylmethanols

Bolm, Carsten; Hermanns, Nina; Jp, Hildebrand; Muñiz, Kilian

doi:10.1002/1521-3773(20001002)39:19<3465::aid-anie3465>3.0.co;2-4

Cited by 145 publications

(87 citation statements)

References 38 publications

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“…[28Ϫ30] Enantioselective syntheses of diarylmethanols use either asymmetric catalytic hydrogenation of diarylketones [31,32] or enantioselective addition of arylzinc reagents to benzaldehydes in the presence of chiral catalysts. [33] Asymmetric monosubstitution of 1,3-dioxolanes provides a simple route to enantioenriched neobenodine (17), although the absence of an o-substituent in the required acetal precursor 5a is detrimental to the enantioselectivity of the procedure. Nevertheless, treatment of 5a with p-tolyllithium in the presence of the chiral ligand (R,R)-7 afforded 6c in 82 yield and 49% ee.…”

Section: Asymmetric Synthesis Of (S)-neobenodinementioning

confidence: 99%

Asymmetric Nucleophilic Substitution of Acetals

Müller¹,

Nury²,

Bérnardinelli³

2001

Eur. J. Org. Chem.

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Section: Asymmetric Synthesis Of (S)-neobenodinementioning

confidence: 99%

Asymmetric Nucleophilic Substitution of Acetals

Müller¹,

Nury²,

Bérnardinelli³

2001

Eur. J. Org. Chem.

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“…8 The results provide a unified view of oxygentransfer pathways, for example, in osmium-catalyzed olefin dihydroxylation methods developed in the last nine decades. [4][5][6][7] The oxidation of dioxoosma-2,5-dioxolane to the trioxo species requires an oxidant with a higher TOP than that of trioxo-/dioxoosma-2,5-dioxolane (TOP ) -36). 9 Perchlorate (TOP ) -24) was used in Hofmann's pioneering work 6a and N-methylmorpholine N-oxide (TOP ) -17 for Me 3 NO/NMe 3 ) is the terminal oxidant in the Upjohn process.…”

mentioning

confidence: 99%

From Evolution to Green Chemistry: Rationalization of Biomimetic Oxygen-Transfer Cascades

Deubel

2004

J. Am. Chem. Soc.

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The accumulation of O 2 in the earth's atmosphere began approximately two billion years ago, after the molecular oxygen that was liberated from photosynthetic bacteria had oxidized most of the iron(II) resources in the oceans to ferric minerals. 1 Although a powerful oxidant had become available, the low reactivity of O 2 to typical organic fuel molecules was a major obstacle in evolution. Nature circumvented the unfavorable kinetics of direct oxidations by designing the aerobic respiratory chain, which proceeds in the inner mitochondrial membrane of eukariotic cells. 2 The feasibility of each electron-transfer step in respiration depends on the difference of the electron-transfer potential, E, for the corresponding pairs of redox couples Ox/Red -. Electron-transfer potentials are typically measured relative to the H + / 1 / 2 H 2 reference couple and are connected to the reaction free energy ∆G r of reaction 1.Chemists learned from nature to improve the efficiency of catalytic oxidation processes. 3 Protocols using the green terminal oxidant hydrogen peroxide are of particular interest because water is the only waste product. The Beller 4 and Bäckvall 5 laboratories recently reported environmentally benign oxygen-transfer chains for the Sharpless dihydroxylation, 6,7 where the oxidation of the fivemembered metallacycle of osmium(VI) (dioxoosma-2,5-dioxolane) to the osmium(VIII) species is a crucial step (Figure 1). Whereas experimental electron-transfer potentials from textbooks 1,2 reflect the electron flow in the redox reactions of respiration (see Supporting Information), a quantitative rationalization of the design of oxygen-transfer chains has not been achieved. In this work, we define and predict the thermodynamic oxygen-transfer potential (TOP, in kcal/mol) for a couple XO/X as the reaction free energy ∆G r of reaction 2.The oxidation of X is thermodynamically more favorable than that of Z (or X may be oxidized by ZO) if TOP (XO/X) < TOP (ZO/Z). Figure 2 displays TOP values for a variety of oxidants and substrates calculated using density functional theory (DFT) at the B3LYP level. 8 The results provide a unified view of oxygentransfer pathways, for example, in osmium-catalyzed olefin dihydroxylation methods developed in the last nine decades. [4][5][6][7] The oxidation of dioxoosma-2,5-dioxolane to the trioxo species requires an oxidant with a higher TOP than that of trioxo-/dioxoosma-2,5-dioxolane (TOP ) -36). 9 Perchlorate (TOP ) -24) was used in Hofmann's pioneering work 6a and N-methylmorpholine N-oxide (TOP ) -17 for Me 3 NO/NMe 3 ) is the terminal oxidant in the Upjohn process. 6c For Bäckvall's recent method 5c of olefin dihydroxylation with H 2 O 2 in the presence of methyltrioxorhenium(VII) (MTO), 10 the chiral tertiary amine (DHQD) 2 PHAL, and osmium tetraoxide, the TOPs in Figure 2 demonstrate the likely oxygen-transfer cascade from the rhenium peroxide (TOP ) 1) via the amine (TOP ) -17 for Me 3 NO/NMe 3 ) to the osmium metallacycle (TOP ) -36; see orange bars in Figure 2).Since the TOP val...

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“…Yields in the phenylation reaction with DAIB ranged from 53% to 91%. In contrast to the phenylation of ketones, several highly enantioselective catalysts have been developed for the asymmetric addition of phenyl groups to aldehydes (14)(15)(16)(17)(18)(19)(20).…”

mentioning

confidence: 99%

Catalytic asymmetric addition of diphenylzinc to cyclic α,β-unsaturated ketones

García

Walsh

2004

Proc. Natl. Acad. Sci. U.S.A.

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We have examined the use of our bis(sulfonamide) diol ligand (1) in the asymmetric addition of phenyl groups to cyclic ␣,␤-unsaturated ketones. Good to excellent enantioselectivities have been obtained with cyclic enones bearing alkyl substituents in the 2 position (71-97% enantiomeric excess). Furthermore, excellent enantioselectivities have been observed in the asymmetric phenylation of cyclic enones with 2-iodo and 2-bromo substituents. The results of this study broaden the scope of the asymmetric additions to ketones promoted by the titanium catalyst derived from ligand 1.alkylation ͉ tertiary alcohols ͉ zinc ͉ titanium ͉ asymmetric catalysis W e recently developed a highly enantioselective titanium catalyst based on the bis(sulfonamide) diol ligand 1 (Fig. 1) for the asymmetric addition of alkylzinc reagents to ketones (Eq. 1; ref. 1). When cyclic ␣,␤-unsaturated ketones were used as substrates, we found that the asymmetric addition reaction could be coupled with a diastereoselective epoxidation by using molecular oxygen as the oxidant to provide a one-pot synthesis of epoxy alcohols with high enantio-and diastereoselectivity (Eq. 2; ref. 2). These studies provide a solution to a long-standing problem in synthetic organic chemistry: the catalytic synthesis of tertiary alcohols from ketones with high enantioselectivity. Unlike related additions of dialkylzinc reagents to aldehyde substrates, which are promoted by hundreds of catalysts (3, 4), only a few systems will catalyze alkyl additions to ketones (1, 2, 5-8), and most of them use high catalyst loadings and long reaction times (6-8).The successful use of ligand 1 in the alkyl additions to ketones led our group (9) and Yus and coworkers (10) to examine the enantioselective phenylation of acyclic ketones with ZnPh 2 . The only previous results in the catalytic asymmetric phenylation of ketones were reported by Dosa and Fu in 1998 (11). In this pioneering work, these authors used Noyori's amino alcohol ligand, (ϩ)-3-exo-(dimethylamino)isoborneol [(ϩ)-DAIB] (12, 13), and diphenylzinc (3.5 eq). Initially, the reaction gave low yields and moderate enantioselectivities. It was found, however, that addition of 1.5 eq of methanol to the diphenylzinc resulted in formation of a mixed alkoxy phenyl zinc reagent that led to increased yields and enantioselectivities (Eq. 3) (11). Under these conditions, excellent enantioselectivities were obtained with substituted propiophenones [86-91% enantiomeric excess (ee)], and acetophenone derivatives afforded enantioselectivities as high as 80%. In the case of cyclohexyl methyl ketone and 3-methyl-2-butanone, the reaction proceeded with 75% and 60% enantioselectivities, respectively. Yields in the phenylation reaction with DAIB ranged from 53% to 91%. In contrast to the phenylation of ketones, several highly enantioselective catalysts have been developed for the asymmetric addition of phenyl groups to aldehydes (14-20).In our initial study on the addition of diphenylzinc to acyclic ketones with ligand 1, we found that enantio...

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Asymmetric, Catalytic Phenyl Transfer to Aldehydes: Enantioselective Synthesis of Diarylmethanols

Cited by 145 publications

References 38 publications

Asymmetric Nucleophilic Substitution of Acetals

Asymmetric Nucleophilic Substitution of Acetals

From Evolution to Green Chemistry: Rationalization of Biomimetic Oxygen-Transfer Cascades

Catalytic asymmetric addition of diphenylzinc to cyclic α,β-unsaturated ketones

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