Two aspects of the desymmetrization of selected prochiral aromatic or vinylic dihalides: enantioselective halogen–lithium exchange and prochiral recognition in chiral liquid crystals

Fan, Chun-An; Ferber, Benoı̂t; Kagan, Henri B.; Lafon, Olivier; Lesot, Philippe

doi:10.1016/j.tetasy.2008.12.003

Cited by 29 publications

(15 citation statements)

References 62 publications

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“…In 2008, Kagan et al presented a synthesis starting with a monolithiation of ferrocene followed by reaction with (–)‐( S )‐menthyl p ‐tolylsulfinate . ortho ‐Lithiation of the formed sulfoxide followed by stannylation, dilithiation, distannylation, and iodination afforded 4 in 71 % overall yield, avoiding the use of mercury compounds , . When we used the above‐mentioned improved method for the synthesis of 3 starting from iodoferrocene ( 6 ) instead of 5 and replacing bromine by iodine, we obtained 1,2‐diiodoferrocene ( 4 ) in an excellent yield of 90 % (Scheme ).…”

Section: Resultsmentioning

confidence: 99%

Improved Syntheses of 1,2‐Disubstituted Ferrocenes

Werner

Butenschön

2016

Eur J Inorg Chem

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1,2-Disubstituted ferrocenes, in particular 1,2-dihaloferrocenes, are important starting materials. Herein, we describe significantly improved high-yielding syntheses of 1,2-disubstituted ferrocenes such as 1,2-dibromo-and 1,2-diiodoferrocene as well as 1-bromo-2-iodoferrocene, and 1-bromo-2-fluoroferrocene. DFT calculations show that 1,2-dihaloferrocenes do not differ much in their highest occupied molecular orbital (HOMO) energies; however, their lowest unoccupied molecular orbital (LUMO) energies -and thus the HOMO/LUMO gaps -correlate

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Section: Resultsmentioning

confidence: 99%

Improved Syntheses of 1,2‐Disubstituted Ferrocenes

Werner

Butenschön

2016

Eur J Inorg Chem

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“…The mixture could not be fully separated by chromatography. Treatment of this mixture with iodine in CH 2 Cl 2 21 gave, after chromatography with heptane as the eluent, bromoiodoferrocene ( S Fc )- 2 in 60% overall yield (based on 4 ). The molecular structure of ( S Fc )- 2 could be determined by X-ray diffraction and this confirmed not only its structural integrity but also its S absolute configuration (Figure 1, top left; for crystallographic data see the Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

Biferrocene-Based Diphosphine Ligands: Synthesis and Application of Walphos Analogues in Asymmetric Hydrogenations

et al. 2013

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A total of four biferrocene-based Walphos-type ligands have been synthesized, structurally characterized, and tested in the rhodium-, ruthenium- and iridium-catalyzed hydrogenation of alkenes and ketones. Negishi coupling conditions allowed the biferrocene backbone of these diphosphine ligands to be built up diastereoselectively from the two nonidentical and nonracemic ferrocene fragments (R)-1-(N,N-dimethylamino)ethylferrocene and (SFc)-2-bromoiodoferrocene. The molecular structures of (SFc)-2-bromoiodoferrocene, the coupling product, two ligands, and the two complexes ([PdCl2(L)] and [RuCl(p-cymene)(L)]PF6) were determined by X-ray diffraction. The structural features of complexes and the catalysis results obtained with the newly synthesized biferrocene-based ligands were compared with those of the corresponding Walphos ligands.

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“…52 An enantioselective halogen-lithium exchange reaction of 1,2-diiodoferrocene (39) was achieved by Kagan et al by treatment of 39 with butyllithium/(-)-sparteine giving (S p )-77 in 86% yield and 34% ee (Scheme 26). 53…”

Section: Lithiation Followed By Trapping With An Electrophilementioning

confidence: 99%

“…Enantioselective substitution of 39 53 1,1′-Dibromoferrocene (10) can be monolithiated selectively when treated with butyllithium in THF at -70 °C. This process has been exploited for the synthesis of 1,1′-heterodisubstituted ferrocenes by quenching with an electrophile followed by another lithiation and treatment with a different electrophile.…”

Section: Scheme 26mentioning

confidence: 99%

Haloferrocenes: Syntheses and Selected Reactions

Butenschön

2018

Synthesis

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Although haloferrocenes constitute important starting materials for many ferrocene-derived products with importance in a variety of fields such as materials science, medicinal chemistry and catalysis, only relatively few haloferrocenes out of the large number of possible examples have been prepared so far. The first part of this review summarizes the syntheses of all the homo- and heterohaloferrocenes known up to date. The second part summarizes typical reactions of haloferrocenes, namely lithiation followed by trapping with an electrophile, copper-mediated halogen substitution, coupling with formation of diferrocenyl derivatives, ortho-lithiation followed by trapping with an electrophile, palladium-catalyzed coupling reactions and finally miscellaneous reactions.1 Introduction2 Homohaloferrocenes2.1 Fluoroferrocenes2.2 Chloroferrocenes2.3 Bromoferrocenes2.4 Iodoferrocenes3 Heterohaloferrocenes4 Selected Reactions of Haloferrocenes4.1 Lithiation Followed by Trapping with an Electrophile4.2 Copper-Mediated Halogen Substitution4.3 Coupling with Formation of Diferrocenyl Derivatives4.4 ortho-Lithiation of Haloferrocenes4.5 Palladium-Catalyzed Reactions of Haloferrocenes4.6 Miscellaneous Reactions of Haloferrocenes5 Conclusions

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Two aspects of the desymmetrization of selected prochiral aromatic or vinylic dihalides: enantioselective halogen–lithium exchange and prochiral recognition in chiral liquid crystals

Cited by 29 publications

References 62 publications

Improved Syntheses of 1,2‐Disubstituted Ferrocenes

Improved Syntheses of 1,2‐Disubstituted Ferrocenes

Biferrocene-Based Diphosphine Ligands: Synthesis and Application of Walphos Analogues in Asymmetric Hydrogenations

Haloferrocenes: Syntheses and Selected Reactions

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