Pd-catalyzed γ-arylation of γ,δ-unsaturated <i>O</i>-carbamates <i>via</i> an unusual haptotropic rearrangement

Royal, Titouan; Baudoin, Olivier

doi:10.1039/c8sc05058a

Cited by 8 publications

(2 citation statements)

References 25 publications

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“…promoted chelation‐controlled deprotonation and effectively utilized this in cross‐coupling reactions [15–18] . More recently, Baudoin and co‐workers reported interesting enantioselective arylation reactions involving directed metallation and Negishi cross‐coupling reactions [19,20] …”

Section: Introductionmentioning

confidence: 99%

“…[15][16][17][18] More recently, Baudoin and coworkers reported interesting enantioselective arylation reactions involving directed metallation and Negishi cross-coupling reactions. [19,20] With the above precedence of a wide range of protocols for lithiation of carbamates and their applications, we sought to generate a relatively stable oxyallyl anion bearing a chiral oxazolidine template and investigate its ability to promote 1,2carbamoyl rearrangement. Interestingly, such direct diastereoselective deprotonation of carbamates has not been previously investigated.…”

Section: Introductionmentioning

confidence: 99%

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Asymmetric 1,2‐Carbamoyl Rearrangement of Lithiated Chiral Oxazolidine Carbamates and Diastereoselective Synthesis of α‐Hydroxy Amides

Ghosh

Basu

Hsu

et al. 2022

Chemistry A European J

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Asymmetric 1,2‐carbamoyl rearrangement of lithiated 2‐alkenyl carbamates has been investigated. Deprotonation of chiral 2‐alkenyl oxazolidine carbamates with sec‐butyllithium in ether at −78 °C followed by warming of the resulting 1‐lithio‐2‐alkenyl derivatives to room temperature resulted in 1,2‐carbamoyl rearrangement to provide α‐hydroxy amides. The rearrangement proceeded with excellent diastereoselectivity and in good to excellent isolated yield of the α‐hydroxy amide derivatives. The substrate scope of the reaction was investigated with a variety of 2‐alkenyl and benzyl oxazolidine carbamates. A stereochemical model is provided to explain the stereochemical outcome associated with the rearrangement. Acid‐catalyzed removal of the chiral oxazolidine afforded α‐hydroxy acid in high optical purity.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Asymmetric 1,2‐Carbamoyl Rearrangement of Lithiated Chiral Oxazolidine Carbamates and Diastereoselective Synthesis of α‐Hydroxy Amides

Ghosh

Basu

Hsu

et al. 2022

Chemistry A European J

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Enantioselective Intramolecular α‐Arylation of Benzylamine Derivatives: Synthesis of a Precursor to Levocetirizine

et al. 2023

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A practical, transition metal‐free method allows the enantioselective synthesis of α,α‐diarylmethylamines by asymmetric α‐arylation of benzylamines. Enantioselective lithiation of N′‐aryl‐N‐benzyl‐N‐isopropyl ureas using a chiral lithium amide base generates a benzyllithium that undergoes an unactivated stereospecific intramolecular nucleophilic aromatic substitution to generate an α,α‐diarylmethylamine in the form of its urea derivative, in up to >99 % ee. Treatment with acid induces an “azatropic shift” with retention of configuration, the product of which may be hydrolysed to the target amine.

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Enantioselective Intramolecular α‐Arylation of Benzylamine Derivatives: Synthesis of a Precursor to Levocetirizine

et al. 2023

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A practical, transition metal-free method allows the enantioselective synthesis of α,α-diarylmethylamines by asymmetric α-arylation of benzylamines. Enantioselective lithiation of N'-aryl-N-benzyl-Nisopropyl ureas using a chiral lithium amide base generates a benzyllithium that undergoes an unactivated stereospecific intramolecular nucleophilic aromatic substitution to generate an α,α-diarylmethylamine in the form of its urea derivative, in up to > 99 % ee. Treatment with acid induces an "azatropic shift" with retention of configuration, the product of which may be hydrolysed to the target amine.

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Pd-catalyzed γ-arylation of γ,δ-unsaturated O-carbamates via an unusual haptotropic rearrangement

Abstract: An unusual γ-selectivity was observed in the arylation of α-zincated γ,δ-unsaturated O-carbamates, which arose from the haptotropic rearrangement of the palladium–diene intermediate.

Cited by 8 publications

References 25 publications

Asymmetric 1,2‐Carbamoyl Rearrangement of Lithiated Chiral Oxazolidine Carbamates and Diastereoselective Synthesis of α‐Hydroxy Amides

Asymmetric 1,2‐Carbamoyl Rearrangement of Lithiated Chiral Oxazolidine Carbamates and Diastereoselective Synthesis of α‐Hydroxy Amides

Enantioselective Intramolecular α‐Arylation of Benzylamine Derivatives: Synthesis of a Precursor to Levocetirizine

Enantioselective Intramolecular α‐Arylation of Benzylamine Derivatives: Synthesis of a Precursor to Levocetirizine

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