Synthesis of α-Amino ketones, acids, esters, nitriles and related compounds
Use of cinchona ligands with an anthraquinone (AQN) core, in place of the usual phthalazine (PHAL) core, in the asymmetric aminohydroxylation of cinnamates causes dramatic reversal of the regioselection, so that phenyl serines are obtained in high enantiomeric excess. Hence, the regioselectivity is controlled by the ligand and not the substrate.
B. Tao, G. Schlingloff, K. B. Sharpless, Tetrahedron Lett., 1998, 39, 2507-2510.
A mild and efficient monocarboxymethylation of a broad range of primary amines takes place under aqueous conditions at room temperature. Treatment of primary amines with two equivalents of glyoxylic acid leads to N-formyl glycine derivatives. Subsequent hydrolysis of the crude reaction solution gives monocarboxymethylated products in very good yield.
T. J. K. Gibbs, M. Boomhoff, N. C. O. Tomkinson, Synlett, 2007, 1573-1575.
A highly efficient copper-catalyzed asymmetric insertion of α-diazoesters into N-H bonds using chiral spiro bisoxazoline ligands affords α-amino acid derivatives in high yields with excellent enantioselectivities.
B. Liu, S.-F. Zhu, W. Zhang, C. Chen, Q.-L. Zhou, J. Am. Chem. Soc., 2007, 129, 5834-5835.
A new Cu/chiral bipyridine catalyst for the asymmetric insertion of α-diazocarbonyl compounds into the N-H bonds of carbamates generate an array of easily deprotected arylglycines in good ee.
E. C. Lee, G. C. Fu, J. Am. Chem. Soc., 2007, 129, 12066-12067.
A straightforward three-component reaction of preformed aromatic or in situ generated benzylic organozinc reagents with amines and ethyl glyoxylate allows the synthesis of a range of α-amino esters in very good yields. The procedure, which is characterized by its simplicity, allows the concise synthesis of esters bearing a phenylglycine or a phenylalanine scaffold.
C. Haurena, E. Le Gall, S. Sengmany, T. Martens, M. Troupel, J. Org. Chem., 2010, 75, 2645-2650.
A simple, commercially available iridium catalyst allows the use of sulfoxonium ylides as a carbene source for various intra- and intermolecular X-H bond insertions, including a practical ring-expansion strategy for lactams. The safety and stability of sulfoxonium ylides recommend them as preferable surrogates to traditional diazo ketones and esters.
I. K. Mangion, I. K. Nwamba, M. Shevlin, M. A. Huffman, Org. Lett., 2009, 11, 3566-3569.
The use of iodosobenzene (PhIO) as oxidant and p-toluenesulfonamide (TsNH2) as aminating reagent in the presence of a catalytic amount of perchlorate zinc hexahydrate enables a direct α-amination of β-dicarbonyl compounds. The reaction proceeds quickly at rt to provide the corresponding α-N-tosylamido β-dicarbonyl compounds very good yields.
J. Yu, S.-S. Liu, J. Cui, X.-S. Hou, C. Zhang, Org. Lett., 2012, 14, 832-835.
The intriguing Rh2(OAc)4 and chiral Brønsted acid cocatalyzed three-component Mannich-type reaction of a diazo compound, a carbamate, and an imine provides rapid and efficient access to both syn- and anti-α-substituted α,β-diamino acid derivatives with a high level control of chemo-, diastereo-, and enantioselectivity.
J. Jiang, H.-D. Xu, J.-B. Xi, B.-Y. Ren, F.-P. Lv, X. Guo, L.-Q. Jiang, Z.-Y. Zhang, W.-H. Hu, J. Am. Chem. Soc., 2011, 133, 8428-8431.
C-Acylimines undergo intermolecular amidation with amides to produce monoacyl gem-diamino acid derivatives in the presence of Cu(OTf)2 and PPh3 under mild conditions. This method provides an efficient access to gem-diamino acid equivalents with good to excellent yields.
S. Zhu, J. Dong, S. Fu, H. Jiang, W. Zeng, Org. Lett., 2011, 13, 4914-4917.
Chelated amino acid ester enolates react with aromatic nitro compounds in a 1,3-addition mode at the nitro group giving amino acids bearing an aryl(hydroxy)amino side chain. Two equivalents of enolate are necessary for complete conversion, because one equivalent is oxidized during the reaction.
D. Stolz, U. Kazmaier, R. Pick, Synthesis, 2006, 3341-3347.
Different aldehydes and amines react with acyl cyanides in the presence of a catalytic amount of the Schreiner thiourea catalyst to give the corresponding N-acyl amino nitriles in high yields. The scope of the reaction is broad and allows the use of both aromatic and aliphatic aldehydes and amines.
S. C. Pan, B. List, Synlett, 2007, 318-320.
The regio- and stereoselective aminochlorination of α,β-unsaturated ketones with N,N-dichloro-p-toluenesulfonamide (4-TsNCl2) and CuOTf as catalyst provides an easy access to vicinal haloamino ketones, with excellent regioselectivity and good yields. Aromatic and aliphatic enones give opposite regioselectivity.
D. Chen, C. Timmons, S. Chao, G. Li, Eur. J. Org. Chem., 2004, 3097-3101.
L-Proline-catalyzed asymmetric α-amination of ketones proceeds with various azodicarboxylates as the nitrogen source in high yields and excellent enantioselectivities. The scope and potential of the reaction are demonstrated by further transformation of the α-hydrazino ketones formed to both optically active syn and anti-α-amino alcohol derivatives.
N. Kumaragurubaran, K. Juhl, W. Zhuang, A. Gogevig, K. A. Jorgensen, J. Am. Chem. Soc., 2002, 124, 6254-6255.
Chiral tertiary α-hydroxy esters were transformed to α-azido esters by Mitsunobu reaction with HN3. Reactions proceed at room temperature with high chemical yield using 1,1-(azodicarbonyl)dipiperidine (ADDP) and trimethylphosphine (PMe3) with complete inversion of configuration at the α-carbon. Several α,α-disubstituted amino acids were synthesized in high overall chemical yield and optical purity.
J. E. Green, D. M. Bender, S. Jackson, M. J. O'Donnell, J. R. McCarthy, Org. Lett., 2009, 11, 807-810.
A novel enantioselective synthesis of α-amino acids has been developed, which is broad in scope, simple in application, and advantageous for many α-amino acids of interest in chemistry, biology, medicine.
E. J. Corey, J. O. Link, J. Am. Chem. Soc., 1992, 114, 1906-1908.
N-Sulfonyl-1,2,3-triazoles react with water in the presence of a rhodium catalyst to produce α-amino ketones in high yield. This transformation formally achieves 1,2-aminohydroxylation of terminal alkynes in a regioselective fashion in combination with a copper(I)-catalyzed 1,3-dipolar cycloaddition with N-sulfonyl azides.
T. Miura, T. Biyajima, T. Fujii, M. Murakami, J. Am. Chem. Soc., 2012, 134, 194-196.
A totally regioselective transformation of aromatic N-4-methoxyphenylaziridine 2-carboxamides into 2-aminoamides is promoted by active manganese (Mn*). α-Amino ketones can be readily obtained by reaction of morpholine-derived 2-aminoamides with organolithium compounds.
J. M. Concellón, H. Rodríguez-Solla, V. del Amo, P. Díaz, J. Org. Chem., 2010, 75, 2407-2410.
Structurally and functionally diverse N-carbamoylamino acids were obtained through the alkylation of monosubstituted parabanic acids followed by hydrolysis of the intermediate products in very good yields and excellent purity.
A. V. Bogolubsky, S. V. Ryabukhin, G. G. Pakhomov, E. N. Ostapchuk, A. N. Shivanyuk, A. A. Tolmachev, Synlett, 2008, 2279-2282.