The diastereoselective ortho-lithiation of Kagan’s ferrocenyl acetal. Generation and reactivity of chiral 2-substituted ferrocenecarboxaldehydes

Mamane, Victor

doi:10.1016/j.tetasy.2010.03.012

Cited by 29 publications

(20 citation statements)

References 77 publications

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“…We finally turned our attention to Kagan’s method, which delivers enantiopure 2-substituted ferrocenecarboxaldehydes . In particular, 2-bromoferrocenecarboxaldehyde (( S Fc )- 36 ) was prepared and transformed to the alkyne ( S Fc )- 37 through a Seyferth–Gilbert homologation with Ohira–Bestmann reagent 38 .…”

Section: Results and Discussionmentioning

confidence: 99%

Disubstituted Ferrocenyl Iodo- and Chalcogenoalkynes as Chiral Halogen and Chalcogen Bond Donors

et al. 2020

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Asymmetric catalysis based on halogen and chalcogen bonds (XB and ChB) is in its infancy, and the search for new chiral XB and ChB donors represents a crucial step toward its development. In this context, we designed and prepared new motifs containing three key substructures: namely, regions of electron charge density depletion centered on iodine and chalcogen atoms, the ethynyl functionality, and the planar chiral ferrocenyl platform. Nine ferrocenyl iodoalkynes were prepared as pure enantiomers by asymmetric synthesis. The XB donor property of racemic ferrocenyl iodoalkynes was demonstrated in solution in two benchmark reactions: the Ritter reaction and the benzoxazole synthesis from thioamides. In contrast, the ferrocenyl chalcogenoalkynes were far less active in these reactions. The potential of racemic and enantiopure ferrocenyl iodoalkynes as XB donors was also confirmed by X-ray diffraction analysis, showing I•••C contacts between the electropositive σ-hole of the iodine atom and electron-rich π clouds for all crystal structures studied in the solid state.

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Section: Results and Discussionmentioning

confidence: 99%

Disubstituted Ferrocenyl Iodo- and Chalcogenoalkynes as Chiral Halogen and Chalcogen Bond Donors

et al. 2020

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“…Cleavage of the acetal as well as the SiMe 3 group is possible by hydrolysis in the presence of acid and fluoride, thus yielding (R p )-114 (Scheme 33). 228 Recently, Schmalz and coworkers presented another smart approach, leading to both enantiomers of 2-(oct-1-en-1-yl)formylferrocene starting from (S,S)-112. 229 Ferrocene (R p )-126 was obtained in consecutive reactions by ortho-directed lithiation of acetal (S,S)-112, introduction of a formyl functionality by treatment with DMF, Wittig olefination, and subsequent acetal cleavage.…”

Section: ■ Ortho-directed Metalationmentioning

confidence: 99%

“…A concise review covering this field of chemistry can be found elsewhere. 228 For other examples see ref 234.…”

Section: ■ Ortho-directed Metalationmentioning

confidence: 99%

Selective Syntheses of Planar-Chiral Ferrocenes

2013

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Planar-chiral ferrocenes are widely applied in catalytic asymmetric transformations in scientific research as well as in industry. A plethora of different methodologies have been developed to access these molecules with a high degree of regio- and stereoselectivity. The aim of this contribution is to give a comprehensive overview of this topic. The synthesis of 1,2- and 1,3-substituted ferrocenes by electrophilic aromatic substitution, ortho-directed metalation, kinetic resolution, and desymmetrization is discussed. Advantages and disadvantages are highlighted.

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“…Following the same procedure as for 12, the compound was purified by flash chromatography using EtOAc-hexane (1 : 1) and the pure product was recovered as an orange oil in 85.7% yield (0.92 g, 1.55 mmol). (14). Compound 4 (0.74 g, 1.81 mmol), t BuLi (1.7 M) (1.6 mL, 2.7 mmol, 1.5 eq.)…”

Section: Experimental Section General Conditionsmentioning

confidence: 99%

“…[8][9][10] Among ferrocenyl ligands, planar chiral 1,2-disubstituted ones emerge as the most prolific, and are often built by sequential, diastereoselective, directed ortho-metalation (DoM) and functionalization of ferrocenes containing a chiral ortho-directing group (CDG). 8,[11][12][13][14][15][16][17][18][19][20] Ideally, following diastereoselective abstraction of the desired cyclopentadienyl hydrogen and ipso-substitution by a new group, such CDGs should allow further transformation into new desirable structures. Indeed several known CDGs allow further transformations, giving rise to a variety of planar chiral ferrocenes.…”

Section: Introductionmentioning

confidence: 99%

Another side of the oxazaphospholidine oxide chiral ortho-directing group

et al. 2012

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A new ferrocenyl oxazaphospholidine oxide 3 was synthesized together with its P-epimer 2 in the reaction of ferrocene lithium with phosphoramidite chloride 1. 3 was successfully derivatized into planar chiral 1,2-ferrocenes, including phosphine ligands, via highly diastereoselective ortho-lithiation and subsequent functionalization; these compounds display opposite planar chirality to those obtained from 2. Some of these 1,2-ferrocenes were further lithiated, allowing for the introduction of a free phosphine group at the oxazaphospholidine ring. The X-ray structures of the compounds 2 and 3 as well as those of the new 1,2-ferrocenes 4 and 7 have been determined.

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The diastereoselective ortho-lithiation of Kagan’s ferrocenyl acetal. Generation and reactivity of chiral 2-substituted ferrocenecarboxaldehydes

Cited by 29 publications

References 77 publications

Disubstituted Ferrocenyl Iodo- and Chalcogenoalkynes as Chiral Halogen and Chalcogen Bond Donors

Disubstituted Ferrocenyl Iodo- and Chalcogenoalkynes as Chiral Halogen and Chalcogen Bond Donors

Selective Syntheses of Planar-Chiral Ferrocenes

Another side of the oxazaphospholidine oxide chiral ortho-directing group

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