- Protecting-Group-Free Amidation of Amino Acids using Lewis Acid Catalysts
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Amidation of unprotected amino acids has been investigated using a variety of ‘classical“ coupling reagents, stoichiometric or catalytic group(IV) metal salts, and boron Lewis acids. The scope of the reaction was explored through the attempted synthesis of amides derived from twenty natural, and several unnatural, amino acids, as well as a wide selection of primary and secondary amines. The study also examines the synthesis of medicinally relevant compounds, and the scalability of this direct amidation approach. Finally, we provide insight into the chemoselectivity observed in these reactions.
- Sabatini, Marco T.,Karaluka, Valerija,Lanigan, Rachel M.,Boulton, Lee T.,Badland, Matthew,Sheppard, Tom D.
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supporting information
p. 7033 - 7043
(2018/05/04)
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- Chiral primary amine catalyzed asymmetric direct cross-aldol reaction of acetaldehyde
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The first primary aminocatalytic direct cross-aldol reaction of acetaldehyde is presented. Among the various vicinal diamines screened, the L-tert-leucine derivative 1c in conjunction with (H4SiW 12O40)0.25 was identified as the optimal catalyst; good catalytic activity (up to 99% yield in 4 h), and high enantioselectivities (up to 92% ee) were achieved for a range of donors, including aromatic aldehydes and isatin derivatives. Aqueous acetaldehyde solution and paraldehyde can be conveniently applied in this system.
- Hu, Shenshen,Zhang, Long,Li, Jiuyuan,Luo, Sanzhong,Cheng, Jin-Pei
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experimental part
p. 3347 - 3352
(2011/08/03)
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- A new chiral synthesis of a bicyclic enedione containing a seven-membered ring mediated by a combination of chiral amine and Bronsted acid
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Several chiral amines bearing a heterocyclic moiety such as pyrrolidine, piperazine or tetrazole were prepared from l-phenylalanine. The enantioselectivity of the intramolecular asymmetric aldol reaction mediated by a combination of the synthetic chiral a
- Nagamine, Takashi,Inomata, Kohei,Endo, Yasuyuki
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experimental part
p. 1191 - 1204
(2009/06/28)
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- Design of an organocatalyst for the enantioselective Diels-Alder reaction with α-acyloxyacroleins
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We have realized the first enantioselective organocatalytic Diels-Alder reaction between α-substituted acroleins, such as α-acyloxyacroleins, and not only cyclic but also acyclic dienes. α-Acyloxyacroleins are useful as synthetic equivalents of α-haloacro
- Ishihara, Kazuaki,Nakano, Kazuhiko
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p. 10504 - 10505
(2007/10/03)
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