High enantioselectivity in the intramolecular cyclopropanation of allyl diazoacetates using a novel rhodium(II) catalyst

Doyle, Michael P.; Pieters, Roland J.; Martin, Stephen F.; Austin, Richard E.; Oalmann, Christopher J.; Müller, Paul

doi:10.1021/ja00004a059

Cited by 191 publications

(42 citation statements)

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“…(1) 0108-2701/91/061345-03503.00 active carboxylic acid with (-)-menthol (Doyle, Pieters, Martin, Austin, Oalmann & Muller, 1991;Martin, Austin & Oalmann, 1990). Crystals of (1) were obtained by slow evaporation from a carbon tetrachloride-diethyl ether solution.…”

Section: Methodsmentioning

confidence: 99%

Determination of the absolute configuration of a novel dipeptide isostere

Lynch¹,

Austin²,

Martin³

et al. 1991

Acta Crystallogr C

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Abstract. { 1R-[1 a(1R*, (1) were obtained by slow evaporation from a carbon tetrachloride-diethyl ether solution. The data crystal was a large block of approximate dimensions 0.56 × 0.70 × 0.76 mm. Data were collected on a Nicolet R3 diffractometer using a graphite monochromator and a Nicolet LT-2 low-temperature delivery system. Lattice parameters were obtained from the leastsquares refinement of 40 reflections with 25.2 < 20 < 27.8 ° . Data were collected using the to-scan technique, with a 1.2 ° to scan at 4-8 ° min-~ and a 20 range from 4.0-55.0 ° (h = 0--, 11, k = 0--, 12, l --0---, 32). 3068 reflections were collected. Four reflections (334, 3,2,14, 3,2,14, 354) were remeasured every 96 reflections to monitor instrument and crystal stability. A smoothed curve of the intensities of these check reflections was used to scale the data. The scaling factor ranged from 0-995-1.01. Data were also corrected for Lp effects but not absorption. 608 reflections were considered unobserved, Fo < 4~r(Fo).Data reduction and decay correction were performed using the Nicolet XRD SHELXTL-Plus software package (Sheldrick, 1988). The structure was solved by direct methods and refined by full-matrix least squares (Sheldrick, 1988). In all, 399 parameters were refined. The non-H atoms were refined with anisotropic thermal parameters. All H-atom positions were obtained from a AF map and refined with isotropic thermal parameters. The bond lengths

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Section: Methodsmentioning

confidence: 99%

Determination of the absolute configuration of a novel dipeptide isostere

Lynch¹,

Austin²,

Martin³

et al. 1991

Acta Crystallogr C

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“…The enantiomeric Rh2(5R-MEPY)4, which is also readily accessible, gave identical % ee's but opposite chirality in cyclopropanation reactions, and reversed diastereomeric preferences were obtained from reactions with MDA. Since the trans isomer has C2 symmetry, the geometry of the Rh 2 (MEPY)4 catalysts could be established by NMR spectroscopy to be that of the cw-isomer 9. intramolecular cyclopropanation of 3-methyl-2-buten-l-yl diazoacetate (eq 2) occurs in high yield and with 92% enantiomeric excess (36). Chiral rhodium(II) oxazolidinones 5-7 were not as effective as Rh2(MEPY)4 for enantioselective intramolecular cyclopropanation, even though the steric bulk of their chiral ligand attachments (COOMe versus /-Pr or Cl^Ph) are similar.…”

Section: Chiral Catalystsmentioning

confidence: 94%

Chiral Rhodium(II) Carboxamides

Doyle

1993

ACS Symposium Series

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Dirhodium(II) tetrakis(carboxamides), constructed with chiral 2-pyrrolidone-5-carboxylate esters so that the two nitrogen donor atoms on each rhodium are in a cis arrangement, represent a new class of chiral catalysts with broad applicability to enantioselective metal carbene trans formations. Enantiomeric excesses greater than 90% have been achieved in intramolecular cyclopropanation reactions of allyl diazoacetates. In intermolecular cyclopropanation reactions with monosubstituted olefins, the cis-disubstituted cyclopropane is formed with a higher enantiomeric excess than the trans isomer, and for cyclopropenation of 1-alkynes extraordinary selectivity has been achieved. Carbon-hydro gen insertion reactions of diazoacetate esters that result in substituted γ -butyrolactones occur in high yield and with enantiomeric excess as high as 90% with the use of these catalysts. Their design affords stabiliza tion of the intermediate metal carbene and orientation of the carbene substituents for selectivity enhancement.A select number of transition metal compounds are effective as catalysts for carbenoid reactions of diazo compounds Their catalytic activity depends on coordination unsaturation at their metal center which allows them to react as electrophiles with diazo compounds. Electrophilic addition to diazo compounds, which is the rate limiting step, causes the loss of dinitrogen and production of a metal stabilized carbene. Transfer of the electrophilic carbene to an electron rich substrate (S:) in a subsequent fast step completes the catalytic cycle (Scheme I). Lewis bases (B:) such as nitriles compete with the diazo compound for the coordinatively unsaturated metal center and are effective inhibitors of catalytic activity. Although carbene complexes with catalytically active transition metal compounds have not been observed as yet, sufficient indirect evidence from reactivity and selectivity correlations with stable metal carbenes (4,5) exist to justify their involvement in catalytic transformations.Transition metal catalysts that are effective for carbenoid transformations include those of copper(I), palladium(II) or platinum(II), cobalt(II), and rhodium(II) (7-5, 6-8), but only copper and rhodium catalysts have been routinely employed.

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“…Excellent enantioselectivities have been reported in a series of allylic diazoacetates 25 (n = 1, Z = O) catalysed by Rh 2 (5S-MEPY) 4 (S-9a), and Rh 2 (5R-MEPY) 4 (R-9a) to give fused cyclopropyl lactones 26 (n = 1, Z = O) equation 4 (Doyle et al, 1991b(Doyle et al, , 1995c. Cyclopropanation of homoallylic diazoesters 25 (n = 2, Z = O) (Martin et al, 1992a) and N-tert-butyldiazoacetamides 25 (n = 2, Z = Nt Bu) equation 4 (Doyle et al, 1994e) proceeded with moderate to high enantioselectivities with the same catalysts.…”

Section: Intramolecular Processesmentioning

confidence: 98%

Dirhodium(II) Carbenes : The Chiral Product Cascade

Roos

Raab

Al-Hatmi

2000

SQU Journal for Science

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ABSTRACT:The last decade has witnessed enormous growth in the spectrum of highly efficient asymmetric synthetic transformations. One prominent example of this progress is the application of dirhodium (II) carbenes generated from diazoprecursors. Innovative construction of 'designer' catalysts has played a integral role in extending the breadth of the synthetic cascade of non-racemic products now available through the range of cyclopropanation, C-X insertion, aromatic cycloaddition-rearrangement, and ylide-based reaction types. This review deals briefly with an overview of the important catalytic systems and maintains as its primary focus the cascade of diverse optically enriched products that flow from their applications. ROOS, RAAB, and AL-HATMI 74 CONTENTS

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High enantioselectivity in the intramolecular cyclopropanation of allyl diazoacetates using a novel rhodium(II) catalyst

Cited by 191 publications

References 0 publications

Determination of the absolute configuration of a novel dipeptide isostere

Determination of the absolute configuration of a novel dipeptide isostere

Chiral Rhodium(II) Carboxamides

Dirhodium(II) Carbenes : The Chiral Product Cascade

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