Chiral auxiliary-promoted asymmetric nucleophile additions to arene-manganese tricarbonyl complexes

Pearson, Anthony J.; Gontcharov, Alexander; Zhu, Ping Y.

doi:10.1016/s0040-4020(97)00006-9

Cited by 22 publications

(10 citation statements)

References 24 publications

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“…The increase in diastereoselectivity when a methyl substituent is present in the position para to the chiral auxiliary is fairly significant. We made a similar observation with arenemanganese complexes and explained it by suggesting a nucleophile approach trajectory shifting closer to the chiral auxiliary due to steric repulsion between the nucleophile and the methyl group . On the basis of this observation, one could speculate that a further increase in steric hindrance at the para position (e.g., by replacing the methyl group by trimethylsilyl) would increase the diastereoselectivity of nucleophilic addition.…”

Section: Resultssupporting

confidence: 60%

Asymmetric Conversion of Arenechromium Complexes to Functionalized Cyclohexenones: Progress toward Defining an Optimum Chiral Auxiliary

Pearson

Gontcharov

1998

J. Org. Chem.

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An investigation into the asymmetric synthesis of 5-substituted cyclohexenones via nucleophile addition to (alkoxyarene)chromium tricarbonyl complexes is described. Diastereoselectivity during the nucleophile addition step was achieved using alkoxy substituents derived from terpenoid substrates as chiral auxiliaries. Selectivities as high as 24:1 were obtained when 2-phenylisoborneol was used as the chiral auxiliary and as high as 17:1 using 3,3-(ethylenedioxy)isoborneol. The absolute stereochemistry of the major products was assigned by Mosher's method, after their conversion to the corresponding cyclohexenol. A study of the temperature dependence of the nucleophile addition to alkoxytoluene complexes revealed a thermodynamic preference for addition ortho to the ether substituent.

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Section: Resultssupporting

confidence: 60%

Asymmetric Conversion of Arenechromium Complexes to Functionalized Cyclohexenones: Progress toward Defining an Optimum Chiral Auxiliary

Pearson

Gontcharov

1998

J. Org. Chem.

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“…This represented a promising application to differentiate two diastereotopic meta positions even if the parameters governing this selectivity were not yet understood (Scheme 6). 27 We have used another representation of the h 5 -cyclohexadienyl unit for clarity reasons with five Mn-C bonds.…”

Section: + Complexesmentioning

confidence: 99%

Planar chiral (η5-cyclohexadienyl)- and (η6-arene)-tricarbonylmanganese complexes: synthetic routes and application

Rose‐Munch

Rose

2011

Org. Biomol. Chem.

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Planar chiral arenetricarbonylchromium complexes have been intensively investigated and they have been applied as valuable building blocks for asymmetric synthesis and as ligands for asymmetric catalysis. In contrast, in the field of the isoelectronic cationic [(η(6)-arene)Mn(CO)(3)](+) complexes, until these last 10 years, very few studies were published involving nonracemic planar chiral cationic complexes and their potential applications, certainly because of the difficult access to enantiopure starting material. In 2009, however, the discovery of the first resolution of such compounds opened a new area for their application in the field of organic as well as of organometallic enantioselective syntheses. We felt it important to write a review on this subject to give an up-to-date summary of the methodologies used to prepare enantiomerically pure planar chiral neutral [(η(5)-cyclohexadienyl)Mn(CO)(3)] and cationic [(η(6)-arene)Mn(CO)(3)](+) complexes as well as their potential in enantioselective synthesis.

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“…A chiral auxiliary can also be positioned on the arene ring itself [96,141,142]. Addition of nucleophiles then proceeds regioselectively away from the metal and on the side not blocked by the methyl group of this auxiliary.…”

Section: Addition/oxidation With Arene-mn(co) 3 Cation Complexesmentioning

confidence: 99%

(Arene)Cr(CO)3 Complexes: Aromatic Nucleophilic Substitution

Semmelhack

Chlenov

2004

Topics in Organometallic Chemistry

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Transition metals coordinated to the pi system of arenes function as strong electronwithdrawing groups and favor nucleophilic addition to the arene to give cyclohexadienyl-metal complexes. The regioselectivity of addition is influenced in subtle and indirect ways, compared to the powerful effect on both reactivity and regioselectivity of electron-withdrawing groups attached to the sigma bond system of the arene. The intermediate cyclohexadienyl complexes can be processed in several ways, leading to several distinct synthesis methods. Useful reactivity is known for several metal systems and each is discussed for specific reaction types. The presence of a fluoro or chloro substituent on the arene allows an effective analog of classical S N Ar reactivity, with a wide range of nucleophiles including simple amines, alkoxides, and carbon anions. Another general process is the addition/protonation protocol, where a hydrogen substituent on the arene is replaced by a nucleophile. This opens new questions of regioselectivity since the typical arene ligand has several hydrogens which are candidates for substitution. The formation of five-and six-membered rings by both general mechanisms are known. Less general indirect mechanisms (e.g., tele substitution) have also been defined.

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Chiral auxiliary-promoted asymmetric nucleophile additions to arene-manganese tricarbonyl complexes

Cited by 22 publications

References 24 publications

Asymmetric Conversion of Arenechromium Complexes to Functionalized Cyclohexenones: Progress toward Defining an Optimum Chiral Auxiliary

Asymmetric Conversion of Arenechromium Complexes to Functionalized Cyclohexenones: Progress toward Defining an Optimum Chiral Auxiliary

Planar chiral (η5-cyclohexadienyl)- and (η6-arene)-tricarbonylmanganese complexes: synthetic routes and application

(Arene)Cr(CO)3 Complexes: Aromatic Nucleophilic Substitution

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