Synthesis of β-Substituted α-Amino Acids with Use of Iridium-Catalyzed Asymmetric Allylic Substitution

Kanayama, Takatoshi; Yoshida, Kazumasa; Miyabe, Hideto; Kimachi, Tetsutaro; Takemoto, Yoshiji

doi:10.1021/jo034638f

Cited by 108 publications

(32 citation statements)

References 47 publications

(19 reference statements)

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“…[266] The branched enones 276 were produced in a highly selective manner by the reaction of trimethylsilyl enol ethers of acyclic methyl ketones 274 with allyl carbonates 275 in the presence of chiral phosphoramidite ligand L198 (Scheme 89). [267] 4.1.…”

Section: Angewandte Chemiementioning

confidence: 99%

Metal‐Catalyzed Enantioselective Allylation in Asymmetric Synthesis

2007

Angew Chem Int Ed

1,361

431

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Metal-catalyzed enantioselective allylation, which involves the substitution of allylic metal intermediates with a diverse range of different nucleophiles or S(N)2'-type allylic substitution, leads to the formation of C-H, -C, -O, -N, -S, and other bonds with very high levels of asymmetric induction. The reaction may tolerate a broad range of functional groups and has been applied successfully to the synthesis of many natural products and new chiral compounds.

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Section: Angewandte Chemiementioning

confidence: 99%

Metal‐Catalyzed Enantioselective Allylation in Asymmetric Synthesis

2007

Angew Chem Int Ed

1,361

431

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“…With nBuLi as base and ZnCl 2 as additive, the alkylation product was isolated in 99% yield with 93% branched selectivity and 96% ee. Iridium complexes of another BINOL-derived phosphite containing a thioether substituent were shown to catalyze the alkylation of cinnamyl phosphates with a protected glycine nucleophile (Scheme 4) [56,57]. This reaction is particularly noteworthy because it occurs with high diastereoselectivity.…”

Section: Reactions Catalyzed By Iridium Complexes Of Chiral Phosphitementioning

confidence: 99%

“…3 occurred with good diastereoselectivity in the presence of iridium-phosphite catalysts (Sect. 3) [56,57]. …”

Section: Diastereoselectivity Of Iridium-catalyzed Allylic Substitutimentioning

confidence: 99%

Iridium-Catalyzed Allylic Substitution

Hartwig

Pouy

2010

Topics in Organometallic Chemistry

224

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Iridium-catalyzed asymmetric allylic substitution has become a valuable method to prepare products from the addition of nucleophiles at the more substituted carbon of an allyl unit. The most active and selective catalysts contain a phosphoramidite ligand possessing at least one arylethyl substituent on the nitrogen atom of the ligand. In these systems, the active catalyst is generated by a baseinduced cyclometalation at the methyl group of this substituent to generate an iridium metalacycle bound by the COD ligand of the [Ir(COD)Cl] 2 precursor and one additional labile dative ligand. Such complexes catalyze the reactions of linear allylic esters with alkylamines, arylamines, phenols, alcohols, imides, carbamates, ammonia, enolates and enolate equivalents, as well as typical stabilized carbon nucleophiles generated from malonates and cyanoesters. Iridium catalysts for enantioselective allylic substitution have also been generated from phosphorus ligands with substituents bound by heteroatoms, and an account of the studies of such systems, along with a description of the development of iridium catalysts is included.

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“…A conversion of 20.6 % was reached using a saturated KOAc solution versus 90.9 % conversion when solid KOAc was used. In literature other bases are reported, such as NaOAc, LiOAc, CsOAc, [77] Cs 2 CO 3 , Et 2 Zn, [78] KOH, and lithium diisopropylamide (LDA), [79] but most of the salts have a low solubility in the used solvents. Also the use of sodium salts of various nucleophiles, for example, diethyl 2-methylmalonate deprotonated with NaH, [52,80,81] is an often applied method but it suffers from a fast background reaction.…”

Section: Continuous Allylic Alkylation Reactionsmentioning

confidence: 99%

Molecular‐Weight‐Enlarged Multiple‐Pincer Ligands: Synthesis and Application in Palladium‐Catalyzed Allylic Substitution Reactions

et al. 2009

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Three different pincer ligand systems are synthesized via nucleophilic substitution reactions of polyaromatic benzyl bromides as support molecules and phenol derivatives as ligand precursors. Retention tests using a polymeric nanofiltration membrane show moderate to good retention in THF and CH(2)Cl(2). Concentration-dependent NMR spectroscopy gives no indication for the formation of aggregates in solution. The three ligand systems are active in both the allylic alkylation and allylic amination reactions and show high selectivity towards the linear trans products. An investigation of the kinetic parameters of the allylic amination reaction show that the reaction of cinnamyl acetate with morpholine is of zero order in cinnamyl acetate and of first order in morpholine. The order in catalyst is found to be one, and the rate constant k' is determined for a reaction under standard conditions. Moreover, one of the tri(pincer)-palladium complexes is used as soluble, molecular-weight-enlarged homogeneous catalyst in continuous allylic alkylation and amination reactions. The conversion of the allylic alkylation reaches a maximum of 30 %, while a maximum conversion of 80 % is reached in the allylic amination reaction. No palladium black was formed.

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Synthesis of β-Substituted α-Amino Acids with Use of Iridium-Catalyzed Asymmetric Allylic Substitution

Cited by 108 publications

References 47 publications

Metal‐Catalyzed Enantioselective Allylation in Asymmetric Synthesis

Metal‐Catalyzed Enantioselective Allylation in Asymmetric Synthesis

Iridium-Catalyzed Allylic Substitution

Molecular‐Weight‐Enlarged Multiple‐Pincer Ligands: Synthesis and Application in Palladium‐Catalyzed Allylic Substitution Reactions

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