Synthesis of β-amino ketones, aldehydes and derivatives
Weakly basic carbon nucleophiles add efficiently to a Fmoc-protected N,O-acetal. The new reactions shows the compatibility of the Fmoc protecting group with moderately basic reaction conditions and should serve as a model for the development of more efficient syntheses of Fmoc-protected amino acids.
A. E. Hartman, C. L. Brophy, J. A. Cupp, D. K. Hodge, T. J. Peelen, J. Org. Chem., 2009, 74, 3952-3954.
Bismuth triflate catalyzes the Mannich-type three component reaction of a variety of aldehydes and anilines (leading in situ to aldimines) with silyl enol ethers. The reaction proceeds rapidly and affords the corresponding protected β-amino ketones in high yields.
T. Ollevier, E. Nadeau, J. Org. Chem., 2004, 69, 9292-9295.
A highly stereoselective three-component direct Mannich reaction between aromatic aldehydes, p-toluenesulfonamide, and unfunctionalized ketones in the presence of a bifunctional quinidine thiourea catalyst gives the corresponding N-tosylated β-aminoketones in high yields and excellent diastereo- and enantioselectivities.
Q. Guo, J. C.-G. Zhao, Org. Lett., 2013, 15, 508-511.
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.
The use of zinc tetrafluoroborate as a catalyst in Mannich-type addition of silyl enol ethers to aldimines in aqueous THF provides β-amino ketones or β-amino esters in high yields. A one-pot reaction of an aldehyde, amine and silyl enolate also works well.
B. C. Ranu, S. Samanta, S. K. Guchhait, Tetrahedron, 2002, 58, 983-988.
Iodine efficiently catalyzes the three-component coupling of aromatic aldehydes, enolizable ketones or keto esters, and acetonitrile in the presence of acetyl chloride at room temperature to afford β-acetamido ketones in good yields.
B. Das, K. Ravinder Reddy, R. Ramu, P. Thirupathi, B. Ravikanth, Synlett, 2006, 1756-1758.
At room temperature, zirconium oxychloride efficiently catalyzes the direct Mannich-type three-component reaction of aldehydes and anilines with ketones under solvent-free conditions to afford the β-amino ketones in good yields with good stereoselectivities. The catalyst can be recycled for subsequent reactions without any appreciable loss of efficiency.
B. Eftekhari-Sis, A. Abdollahifar, M. M. Hashemi, M. Zirak, Eur. J. Org. Chem., 2006, 5152-5157.
An efficient catalytic and enantioselective method for Mannich reactions between trimethylsilyl enol ethers derived from acetone and acetophenone and aryl, alkenyl, alkynyl, and alkyl imines allows the synthesis of a various β-amino ketones in the presence of 1-5 mol % AgOAc and an inexpensive amino acid-derived phosphine.
N. S. Josephsohn, M. L. Snapper, A. H. Hoveyda, J. Am. Chem. Soc., 2004, 126, 3734-3735.
A catalytic, asymmetric conjugate addition of carbamates to enoyl systems provides a highly enantioselective two-step access to N-protected β-amino acids.
C. Palomo, M. Oiarbide, R. Halder, M. Kelso, E. Gómez-Bengoa, J. García, J. Am. Chem. Soc., 2004, 126, 9188-9189.
In the presence of a catalytic amount of Cu(OTf)2 and a chiral diamine ligand, various N-acylimino esters reacted smoothly with silyl enol ethers and alkyl vinyl ethers to afford the corresponding Mannich-type adducts in high yields with high diastereo- and enantioselectivities. The reaction mechanism is discussed.
S. Kobayashi, R. Matsubara, Y. Nakamura, H. Kitagawa, M. Sugiura, J. Am. Chem. Soc., 2003, 125, 2507-2515.
A highly efficient enantioselective aza-ene-type reaction of N-benzoylimines with enecarbamates has been developed. The reaction can be performed at extremely low loading of a chiral Brønsted acid catalyst without notable loss in enantioselectivity.
M. Terada, K. Machioka, K. Sorimachi, Angew. Chem. Int. Ed., 2006, 45, 2254-2257.
Pd-catalyzed enantioselective diborations of prochiral allenes followed by allylation reactions with primary imines provide vinyl boronates which may be oxidized to give nonracemic Mannich products. Alternatively, enantiomerically enriched homoallylic amine derivatives may be obtained by protonation and Suzuki cross-coupling of the vinyl boronate.
J. D. Sieber, J. P. Morken, J. Am. Chem. Soc., 2006, 128, 74-75.
An efficient enantioselective catalysis in the Mannich-type reactions of diketones and ketoester equivalents with aldimines was developed using a chiral combined salt of chiral 1,1′-binaphthyl-2,2′-disulfonic acid with 2,6-diarylpyridine, which acted as convenient chiral tailor-made Brønsted acid-base organocatalysts in situ.
M. Hatano, T. Maki, K. Moriyama, M. Arinobe, K. Ishihara, J. Am. Chem. Soc., 2008, 130, 16858-16860.
Direct catalytic, enantioselective, anti-selective Mannich-type reactions between unmodified ketones and α-imino esters using 5-10 mol % of (R)-3-pyrrolidinecarboxylic or (R)-β-proline as catalyst in 2-PrOH at room temperature gave products in good yields with high diastereo- and enantioselectivities.
H. Zhang, M. Mifsud, F. Tanaka, C. F. Barbas, III, J. Am. Chem. Soc., 2006, 128, 9630-9631.
Proline-catalyzed Mannich-type reactions of N-PMP-protected α-imino ethyl glyoxylate with a variety of unmodified ketones provided functionalized α-amino acids in high yields with excellent regio-, diastereo-, and enantioselectivities. In reactions involving ketone donors where diastereoisomeric products could be formed, two adjacent stereogenic centers were created simultaneously upon carbon-carbon bond formation with complete syn-stereocontrol.
A. Cordova, W. Notz, G. Zhong, J. M. Betancort, C. F. Barbas, III, J. Am. Chem. Soc., 2002, 124, 1842-1843.
Proline-catalyzed Mannich-type reactions of N-PMP-protected α-imino ethyl glyoxylate with a variety of unmodified aliphatic aldehydes provided functionalized α-amino acids in high yields with excellent enantioselectivities. The diastereoselectivity of the reaction increased with the bulkiness of the substituents of the aldehyde donor.
A. Cordova, W. Notz, G. Zhong, J. M. Betancort, C. F. Barbas, J. Am. Chem. Soc., 2002, 124, 1866-1867.
A direct highly anti-selective and enantioselective asymmetric Mannich reaction using a novel axially chiral amino trifluoromethanesulfonamide has been developed. Reactions between aldehydes and N-PMP-protected α-imino ethyl glyoxylate proceed smoothly to give β-amino aldehydes with high anti/syn ratio and enantioselectivity.
T. Kano, Y. Yamaguchi, O. Tokuda, K. Maruoka, J. Am. Chem. Soc., 2005, 127, 16408-16409.
(3R,5R)-5-methyl-3-pyrrolidinecarboxylic acid as catalyst for Mannich-type reactions afforded anti-products in good yields with excellent diastereo- and enantioselectivities under mild conditions and low catalyst loadings.
S. Mitsumori, H. Zhang, P. H.-Y. Cheong, K. N. Houk, F. Tanaka, C. F. Barbas, III, J. Am. Chem. Soc., 2006, 128, 1040-1041.
A highly chemoselective PPh3-catalyzed three-component reaction of an imine, alkyl vinyl ketone, and phthalimide or succinimide gives various highly functional adducts with high diastereoselectivities via aza-Morita-Baylis-Hillman reactions of aryl-substituted imines and alkyl vinyl ketones followed by Michael additions of imides and then epimerization.
S.-e. Syu, Y.-T. Lee, Y.-J. Jang, W. Lin, J. Org. Chem., 2011, 76, 2888-2891.