Synthesis of β,γ-unsaturated amino acid derivatives by alkyne carbometalation-palladium catalyzed coupling with 2-aza-π-allyl palladium complexes

O’Donnell, Martin J.; Li, Min; Bennett, William D.; Grote, Todd M.

doi:10.1016/s0040-4039(00)78548-0

Cited by 19 publications

(17 citation statements)

References 23 publications

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“…Isopropyl (acetyloxy)[(diphenylmethylene)amino]acetate (1b): yield 37%; white crystals; mp 92.5-93.5 °C; IR (KBr) 1738, 1629, 1241, 1103, 699 cm -1 ; 1 H NMR (CDCl3) δ 1.24 (dd, 6H, J ) 3.0, 3.0 Hz), 2.17 (s, 3H), 5.05 (dq, 1H, J ) 6.0 Hz), 6.13 (s, 1H), 7.30-7.69 (m, 10H); 13 C NMR (CDCl3) δ 21. 0,21.6,69.9,84.4,127.9,128.1,128.4,129.2,129.3,131.3,135.5,138.6,166.3,169.9,174.3.…”

Section: Methodsmentioning

confidence: 99%

Efficient Catalytic Enantioselective Reaction of a Glycine Cation Equivalent with Malonate AnionsviaPalladium Catalysis

O’Donnell¹,

Chen²,

Zhou³

et al. 1997

J. Org. Chem.

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The enantioselective alkylation of Schiff base acetates 1 with malonate types of stabilized carbon nucleophiles in the presence of a stable palladium source Pd(OAc) 2 and the chiral ligand (+)-BINAP was developed. The product 2, a protected -carboxyaspartic acid (ASA), was obtained in up to 85% enantiomeric excess by varying the ester protecting group on the substrate. The nature of the nucleophile has a significant effect on the enantioselectivity in this (2-aza-π-allyl)palladium system. While a rapid chemical conversion was achieved with Schiff base benzoates 5, the enantioselectivity was insensitive to the leaving group used. An optically active substrate (51% ee) gave the same level of enantioselectivity as that obtained from the racemate. Temperature effects on the reaction were also studied; the best selectivity was obtained at 0°C. A laboratoryscale reaction of the reactive nucleophile KCH(COOCH 3 ) 2 with the tert-butyl ester substrate 1c gave, following a single recrystallization, product 2c with 95.5% ee in an overall chemical yield of 62%. 3962

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Section: Methodsmentioning

confidence: 99%

Efficient Catalytic Enantioselective Reaction of a Glycine Cation Equivalent with Malonate AnionsviaPalladium Catalysis

O’Donnell¹,

Chen²,

Zhou³

et al. 1997

J. Org. Chem.

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“…This concept was extended to coupling of a hard nucleophile (vinylalanes, 71) as a route to β,γ-unsaturated amino acid derivatives (vinylglycines, 12ca-cd) (Scheme 40). 101,102 The vinylalane 81 was prepared by Cp 2 ZrCl 2 -catalyzed carboalumination of alkynes with Me 3 Al. The coupling reaction of 7b and 81 with a catalytic amount of (Ph 3 P) 4 Pd in dioxane at room temperature gave tri-or tetrasubstituted vinylglycines in moderate yields.…”

Section: Cationic Glycine: Malonate Anion Enantioselective (Binap) Anmentioning

confidence: 99%

“…The methodology was refined by the introduction of a TEMPO-catalyzed oxidation that was selective for the primary alcohol in the presence of two secondary alcohols, obviating the need for Mom-protection, and providing 99 in 8 steps in an overall yield of 20%. Other amino sugars (101) and aza-sugars (102) were synthesized using the same methodology. 114,115…”

Section: Nitrogen Alkylation For the Preparation Of N-alkyl Amino Acimentioning

confidence: 99%

Benzophenone Schiff bases of glycine derivatives: Versatile starting materials for the synthesis of amino acids and their derivatives

O’Donnell

2019

Tetrahedron

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This review focuses on the introduction and early development, in solution, of phase-transfer catalyzed (PTC) reactions to afford racemic or enantioenriched natural and unnatural amino acids. To form monosubstituted amino acids alkylation reactions are performed on the benzophenone Schiff base of glycine. For α,α-disubstituted amino acids the activated intermediate is an aldimine derivative of the monosubstituted amino acid. Enantioenriched products are produced by organocatalysis using derivatives of Cinchona alkaloids as the phasetransfer catalyst. Selectivity for monoalkylatation and lack of product racemization depend on the acidities of the glycine imines, and dialkylated products are formed from aldimine esters of monoalkyl amino acids. The racemic and catalytic enantioselective reactions of a cationic glycine equivalent with organoboranes, organometallics and malonate anion are discussed as are other reactions of these versatile Schiff bases derivatives. Keywords Amino Acid Synthesis Unnatural Amino Acids Phase-Transfer Catalysis (PTC) Asymmetric Synthesis Benzophenone Schiff Bases Imines of Amino Acid Derivatives Organocatalysis Racemic and Stereoselective Reactions Glycine and Other Amino Acid Anion Equivalents Glycine Cation Equivalents Contents 10 9. Synthesis of α-methyl histidine by two complementary routes 11 10. PTC mono-or dialkylation with potassium carbonate 12 11. Intra-and intermolecular PTC dialkylations of a glycine equivalent 12 12. Acidities (pKa) of imine derivatives of glycine: Insights into alkylations 13 ___________________________________________________________________ This is the author's manuscript of the article published in final edited form as: O'Donnell, M. J. (2019). Benzophenone Schiff bases of glycine derivatives: Versatile starting materials for the synthesis of amino acids and their derivatives. Tetrahedron.

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“…In addition to malonate nucleophiles, O'Donnell's group also disclosed that vinylalanes readily coupled with the 2-aza-π-allylPd(II) intermediates generated from α-acetoglycinate 249b (Table 10). 171 The requisite vinylalane reagents were first generated by the zirconium-catalyzed syn-methylalumination of various terminal (entries 1−4) or symmetrical internal (entry 5) alkynes with Me 3 Al before combining with 2-azaallyl cation precursor 249b and Pd(PPh 3 ) 4 as a catalyst. Whereas the polar aprotic solvent acetonitrile was optimal for the transformations involving malonate nucleophiles, the Pdcatalyzed vinylation of 249b performed best in the nonpolar solvent 1,4-dioxane.…”

Section: -Azaallyl Cationsmentioning

confidence: 99%

2-Azaallyl Anions, 2-Azaallyl Cations, 2-Azaallyl Radicals, and Azomethine Ylides

et al. 2018

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This review covers the use of 2-azaallyl anions, 2-azaallyl cations, and 2-azaallyl radicals in organic synthesis up through June 2018. Particular attention is paid to both foundational studies and recent advances over the past decade involving semistabilized and nonstabilized 2-azaallyl anions as key intermediates in various carbon–carbon and carbon–heteroatom bond-forming processes. Both transition-metal-catalyzed and transition-metal-free transformations are covered. Azomethine ylides, which have received significant attention elsewhere, are discussed briefly with the primary focus on critical comparisons with 2-azaallyl anions in regard to generation and use.

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Synthesis of β,γ-unsaturated amino acid derivatives by alkyne carbometalation-palladium catalyzed coupling with 2-aza-π-allyl palladium complexes

Cited by 19 publications

References 23 publications

Efficient Catalytic Enantioselective Reaction of a Glycine Cation Equivalent with Malonate AnionsviaPalladium Catalysis

Efficient Catalytic Enantioselective Reaction of a Glycine Cation Equivalent with Malonate AnionsviaPalladium Catalysis

Benzophenone Schiff bases of glycine derivatives: Versatile starting materials for the synthesis of amino acids and their derivatives

2-Azaallyl Anions, 2-Azaallyl Cations, 2-Azaallyl Radicals, and Azomethine Ylides

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