Catalytic Asymmetric Synthesis of anti-α,β-Diamino Acid Derivatives
A novel approach to chiral anti-α,β-diamino acid derivatives through tandem orthogonal organocatalysis has been developed. Chiral phosphoric acid catalysts control the chemo-, regio-, and stereoselective addition of hydroxylamines to alkylideneoxazolones, while a phosphine catalyst promotes the isomerization of Z- alkylideneoxazolones to the more reactive E- alkylideneoxazolones. (Chemical Equation Presented).
Izumi, Sanae,Kobayashi, Yusuke,Takemoto, Yoshiji
supporting information
p. 696 - 699
(2016/03/01)
Synthesis of di- and tri-substituted imidazole-4-carboxylates via PBu3-mediated [3+2] cycloaddition
Some new di- and trisubstituted imidazole-4-carboxylates were prepared from amidoacetic acids 3 in the present report. The key step to establish such imidazole- 4-carboxylates stemmed from the PBu3-mediated [3+2] cycloaddition between in situ-generated Δ2-oxazolinone 4 and ethyl cyanoformate6. Our results indicated that trisubstituted imidazoles 7-20 were afforded in better yields than those of disubstituted imidazoles 21-27. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications1 to view the free supplemental file. Copyright Taylor & Francis Group, LLC.
Hsu, Mei-Yuan,Dietrich, Justin,Hulme, Christopher,Shaw, Arthur Y.
p. 1538 - 1542
(2013/05/21)
E-Z ratio and stability of halogenated benzylidene derivatives formed during the detection of glycine conjugates
The orange fluorescing spot formed during the detection of halogenated hippuric acids with 4-N,N-Dimethylaminobenzaldehyde on TLC-plates consists of a E/Z-mixture of the corresponding benzyliden derivatives. Intermediates are the azlactones.
Oelschlaeger,Seeling,Radman,Bockhard
p. 825 - 828
(2007/10/03)
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