The asymmetric synthesis of phosphorus- and sulfur-containing tricarbonyl(η6-arene)chromium complexes using the chiral base approach

Ariffin, Azhar; Blake, Alexander J.; Ewin, Richard A.; Li, Wan‐Sheung; Simpkins, Nigel S.

doi:10.1039/a905610f

Cited by 29 publications

(10 citation statements)

References 14 publications

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“…Thus, double deprotonation of tricarbonyl[η 6 -(diphenylphosphinoyl)benzene]chromium(0) (15) with an excess of the chiral lithium amide 16 gave the intermediate dianion 17, which by reaction with chloro-trimethylsilane yielded the enantiomerically enriched disylilated tricarbonyl[η 6 -(diphenylphosphinoyl)benzene] chromium(0) (-)-18 (Scheme 4) [20]. [21].…”

Section: Deprotonation Of Aromatic Compoundsmentioning

confidence: 98%

Organodilithium Intermediates as Useful Dianionic Synthons: Recent Advances

Foubelo¹,

Yus

2005

COC

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Section: Deprotonation Of Aromatic Compoundsmentioning

confidence: 98%

Organodilithium Intermediates as Useful Dianionic Synthons: Recent Advances

Foubelo¹,

Yus

2005

COC

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“…They have been used to deprotonate the prochiral mono-substituted complexes 3, executing a directing group (DG) assisted, kinetically controlled asymmetric lithiation to give after electrophilic quench a wide range of orthosubstituted complexes 4 or ent-4 in moderate to high yields and enantioselectivities (Scheme 1). [8][9][10][11][12][13] In many cases, such as those that generate complexes (1pS)-7 14 and (1pR)-8, 15 a single recrystallisation of the product allowed the isolation of enantiomerically pure material.…”

Section: Non-racemic Chiral Base Mediated Synthesismentioning

confidence: 99%

“…Here, the bis-amide 19 proved to be highly efficient in discriminating between the benzylic methylene groups and complexes 20 (E = SiMe 3 , Me, Et, PhCH 2 , C 3 H 5 (allyl), CPh 2 OH, 2-naphthylmethyl) could be obtained in high chemical yields and in up to 95% ee. 15,22 The enantiomeric excess of some complexes (E = SiMe 3 , Me, CPh 2 OH, 2-naphthylmethyl) could be further improved to > 99% by recrystallisation. It is noteworthy that using amide 5 under identical conditions gave products in only about 5% ee.…”

Section: Non-racemic Chiral Base Mediated Synthesismentioning

confidence: 99%

Asymmetric catalysis using planar chiral arene chromium complexes

Gibson

Ibrahim

2002

Chem. Commun.

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“…Substrate 1 c contains an h 6bromostyrene ligand. As the bromo substituents in 1 c/2 c can be easily replaced by other functional groups by standard organic transformations (see below), [19] they serve as versatile precursors to various planar-chiral compounds. The reaction of rac-1 c under the optimized conditions afforded complex 2 c in 97 % ee and 47 % yield.…”

mentioning

confidence: 99%

“…[18] chiral chromium complexes are retained during the lithiation/ substitution sequence. [19] The levorotatory enantiomer (S)-(À)-2 c affords (+)-2 a and (À)-2 b, after the lithiation/ alkylation sequence, respectively. With these analyses, both (+)-2 a and (À)-2 b, which are the enantiomers that are preferentially cyclized in the Mo/(S)-L3-catalyzed ARCM, were identified as the S enantiomers.…”

mentioning

confidence: 99%

Kinetic Resolution of Planar‐Chiral (η⁶‐Arene)Chromium Complexes by Molybdenum‐Catalyzed Asymmetric Ring‐Closing Metathesis

Ogasawara

Arae

et al. 2012

Angew Chem Int Ed

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Planar-chiral (h 6 -arene)chromium complexes are useful chiral scaffolds in asymmetric synthesis, and have found widespread application as chiral ligands for asymmetric catalysis, or as chiral building blocks for natural product syntheses. [1] Typical methods for the preparation of enantiomerically enriched planar-chiral (arene)chromium species are based either on the optical resolution of racemates [2] or on stereoselective transformations, which include diastereoselective complexation, [3] diastereo-or enantioselective ortho-lithiation by utilizing a chiral directing group or a chiral base, [4] and diastereo-or enantioselective nucleophilic addition/hydride abstraction. [5] Whereas these methods require a stoichiometric amount of chiral reagents or auxiliaries, asymmetric catalysis is an attractive and effective alternative for preparing optically active (h 6 -arene)chromium complexes. Since the first report on such a catalytic process by Uemura et al. in 1993, [6] only a handful of examples of the desymmetrization of prochiral (arene)chromium substrates have been reported by Gotov and Schmalz, [7] Kündig and co-workers, [8,9] and Uemura and co-workers [10,11] .Recently, we reported the preparation of phosphinechelate (h 6 -arene)chromium complexes by Ru-catalyzed ringclosing metathesis. [12] We also demonstrated that Mo-catalyzed asymmetric ring-closing metathesis (ARCM) was highly effective for the asymmetric synthesis of the various planarchiral ferrocenes. [13] Thus, we are interested in controlling the planar chirality of (h 6 -arene)chromium complexes by ARCM. [14,15] Indeed, the kinetic resolution of racemic (h 6 -1,2-disubstituted benzene)chromium complexes proceeds efficiently in the presence of a chiral Mo-alkylidene species to give the planar-chiral chromium complexes with excellent enantiomeric purity. Furthermore, a highly enantiomerically enriched (h 6 -bromoarene)chromium complex that was prepared by using the present method is an excellent precursor to various planar-chiral (arene)chromium derivatives. A (phos-phinoarene)chromium species was derived from the (h 6bromoarene)chromium complex and applied as a chiral ligand in Rh-catalyzed asymmetric reactions, which achieved excellent enantioselectivity of up to 99.5 %.The (h 6 -arene)chromium complexes (rac-1) that were used in this study contain an h 6 -(2-substituted alkenylbenzene) ligand, which constructs the planar-chiral environment upon coordination to the chromium atom, and an alkenylphosphine ligand. The chiral catalysts were screened by using racemic [(h 6 -2-methylstyrene)Cr(CO) 2 (methallyldiphenylphosphine)] (1 a) as a prototypical substrate. The asymmetric reactions were carried out in benzene at 40 8C in the presence of an appropriate chiral Mo catalyst (10 mol %), which was generated in situ from the Mo precursor [(pyrrolyl) 2 Mo( = CHCMe 2 Ph)(=NC 6 H 3 -2,6-iPr 2 )] and an axially chiral biphenol derivative (Table 1). [16] Under these conditions, the Mo catalyst that was generated with (R)-L1 [17a] gave the ARCM product 2 a...

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The asymmetric synthesis of phosphorus- and sulfur-containing tricarbonyl(η6-arene)chromium complexes using the chiral base approach

Cited by 29 publications

References 14 publications

Organodilithium Intermediates as Useful Dianionic Synthons: Recent Advances

Organodilithium Intermediates as Useful Dianionic Synthons: Recent Advances

Asymmetric catalysis using planar chiral arene chromium complexes

Kinetic Resolution of Planar‐Chiral (η⁶‐Arene)Chromium Complexes by Molybdenum‐Catalyzed Asymmetric Ring‐Closing Metathesis

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The asymmetric synthesis of phosphorus- and sulfur-containing tricarbonyl(η6-arene)chromium complexes using the chiral base approach

Cited by 29 publications

References 14 publications

Organodilithium Intermediates as Useful Dianionic Synthons: Recent Advances

Organodilithium Intermediates as Useful Dianionic Synthons: Recent Advances

Asymmetric catalysis using planar chiral arene chromium complexes

Kinetic Resolution of Planar‐Chiral (η6‐Arene)Chromium Complexes by Molybdenum‐Catalyzed Asymmetric Ring‐Closing Metathesis

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Kinetic Resolution of Planar‐Chiral (η⁶‐Arene)Chromium Complexes by Molybdenum‐Catalyzed Asymmetric Ring‐Closing Metathesis