Synthesis of β-Amino Acids and Derivatives
Mannich-rype reactions of secondary amines, aldehydes and ketene silyl acetals were efficiently promoted by catalytic amounts of diarylborinic acid esters, affording β-amino esters selectively with no formation of the corresponding β-hydroxy esters.
Y. Tanaka, T. Hasui, M. Suginome, Synlett, 2008, 1239-1241.
Aminoboranes are highly efficient and mild iminium ion generators in the Mannich-type aminative coupling of aldehydes with silyl ketene acetals. The use of diisopropylaminoboranes enables a three-component Mannich reaction of free secondary amines with aldehydes and silyl ketene acetals.
M. Suginome, L. Uehlin, M. Murakami, J. Am. Chem. Soc., 2004, 126, 13196-13197.
A highly efficient Mukaiyama aldol reaction is catalyzed by sodium phenoxide-phosphine oxides as simple homogeneous Lewis base catalysts, which minimized competing retro-aldol reaction. Various aromatic ketones and aldimines, aldol and Mannich-type products with an α-quaternary carbon center were obtained in good to excellent yields.
M. Hatano, E. Takagi, K. Ishihara, Org. Lett., 2007, 9, 4527-4530.
The Hf(OTf)4-catalyzed Mannich-type reaction of an enol silyl ether or a ketene silyl acetal with an N,O-acetal allows the preparation of amino acid derivatives. In particular, use of the N,O-acetal having a bis(trimethylsilyl)amino group directly produced N-unprotected aspartic acid derivatives after a standard aqueous workup.
N. Sakai, A. Sato, T. Konakahara, Synlett, 2009, 1449-1452.
Addition of in situ generated samarium acetamide and chloroacetamide enolates to aldimines afforded 3-aminoamides and 3-amino-2-chloroamides in high yields. A mechanism is proposed to explain the synthesis and reactivity of samarium enolates of primary amides.
J. M. Concellón, H. Rodríguez-Solla, C. Concellón, C. Simal, N. Alvaredo, Synlett, 2010, 2119-2121.
N-Benzyldiphenylphosphinamides are deprotonated at the NCα position diastereospecifically upon treatment with t-BuLi in diethyl ether at low temperature. Reaction of the anions with various electrophiles and subsequent cleavage of the P-N linkage affords 1,2-amino alcohols and α-, β-, and γ-amino acids.
P. O. Burgos, I. Fernández, M. J. Iglesias, S. García-Granda, F. L. Ortiz, Org. Lett., 2008, 10, 537-540.
A highly efficient general strategy for the synthesis of 2-amino acids by homologation of α-amino acids, involving the Reformatsky reaction with a Mannich-type imminium electrophile is reported.
R. Moumne, S. Lavielle, P. Karoyan, J. Org. Chem., 2006, 71, 3332-3334.
Sonication of diazo ketones derived from Fmoc-protected amino acids in dioxane in the presence of silver benzoate and water results in clean formation of the corresponding β-amino acid derivatives. The degree of racemization was examined using capillary zone electrophoresis. No substantial epimerization occured except for phenylglycine.
A. Müller, C. Vogt, N. Sewald, Synlett, 2006, 837-841.
A one-pot, three-component reaction between an aromatic aldehyde, an enolizable ketone or a β-keto ester, and a nitrile in the presence of acetyl chloride is accomplished efficiently using cyanuric chloride in an aqueous medium to give the corresponding β-acetamido ketone or ester in high yield.
B. Das, M. Srilatha, B. Veeranjaneyulu, B. R. Rao, Synthesis, 2010, 803-806.
In a highly enantioselective direct Mannich-type reaction of aldimines with dialkyl malonates, an inexpensive Mg(II)-BINOLate salt can activate both aldimines and malonates as a cooperative acid-base catalyst. Various β-aminoesters and α-halo-β-aminoesters could be synthesized in high yields and with high enantioselectivities even in gram-scale.
M. Hatano, T. Horibe, K. Ishihara, Org. Lett., 2010, 12, 3502-3505.
A highly enantioselective Mannich reaction with in situ generation of carbamate-protected imines from stable α-amido sulfones catalyzed by an organic catalyst provides a concise and highly enantioselective route converting aromatic and aliphatic aldehydes into optically active aryl and alkyl β-amino acids.
J. Song, H.-W. Shih, L. Deng, Org. Lett., 2007, 9, 603-606.
Li(I) BINOLate salts as Lewis acid-Brønsted base catalysts offer high catalytic activity toward 1,3-dicarbonyl compounds such as diketone, ketoester, ketothioester, ketoamide, and ketolactone. Mannich-type reaction of aldimines with 1,3-dicarbonyl compounds proceeded at -78 °C within 1-2 h in the presence of 1−10 mol % catalyst highly enantio- and diastereoselectively.
M. Hatano, T. Horibe, K. Ishihara, J. Am. Chem. Soc., 2010, 132, 56-57.
A base-catalyzed Michael-type addition of sodium diethyl malonate to N-Boc-α-amidoalkyl-p-tolyl sulfones in tetrahydrofuran followed by hydrolysis of the adducts in refluxing 6 M aqueous hydrochloric acid affords β3-amino acid hydrochlorides in high yield and excellent purity.
M. Nejman, A. Śliwińska, A. Zwierzak, Tetrahedron, 2005, 61, 8536-8541.
Efficient carbon-carbon bond formation of N-carbobenzyloxy amines with 1,3-dicarbonyl compounds at the α-position of nitrogen was established by a one-pot oxidative Mannich reaction using N-tert-butylbenzenesulfinimidoyl chloride as an oxidant.
J-I. Matsuo, Y. Tanaki, H. Ishibashi, Org. Lett., 2006, 8, 4371-4374.
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.
Catalytic asymmetric direct Mannich-type reactions of α-substituted nitroacetates using a new bench-stable homodinuclear Ni2-Schiff base complex gave Mannich products in high ee, that serve as precursors for anti-α,β-diamino acids with an α-tetrasubstituted carbon stereocenter. The Ni complex was also applicable to direct Mannich-type reactions of malonates and β-keto ester.
Z. Chen, H. Morimoto, S. Matsunaga, M. Shibasaki, J. Am. Chem. Soc., 2008, 130, 2170-2171.
An axially chiral dicarboxylic acid has been applied to a highly enantioselective Mannich reaction of arylaldehyde N-Boc imines and diazo compounds as a new class of chiral hydrogen-bonding catalyst.
T. Hashimoto, K. Maruoka, J. Am. Chem. Soc., 2007, 129, 10054-10055.