914226-26-9Relevant articles and documents
Palladium(II)-Catalyzed highly enantioselective C-H arylation of cyclopropylmethylamines
Chan, Kelvin S. L.,Fu, Hai-Yan,Yu, Jin-Quan
supporting information, p. 2042 - 2046 (2015/03/04)
C-H arylation via a Pd(II)/Pd(IV) catalytic cycle has been one of the most extensively studied C-H activation reactions since the 1990s. Despite the rapid development of this reaction in the past two decades, an enantioselective version has not been reported to date. Herein, we report a Pd(II)-catalyzed highly enantioselective (up to 99.5% ee) arylation of cyclopropyl C-H bonds with aryl iodides using mono-N-protected amino acid (MPAA) ligands, providing a new route for the preparation of chiral cis-aryl-cyclopropylmethylamines. The enantiocontrol is also shown to override the diastereoselectivity of chiral substrates.
ANTIVIRAL COMPOUNDS AND USE THEREOF
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Page/Page column 32, (2009/12/02)
The invention relates to compounds, pharmaceutical compositions and methods useful for treating viral infection.
Preparation and structure of β-peptides consisting of geminally disubstituted β2,2- and β3,3-amino acids: A turn motif for β- peptides
Seebach, Dieter,Abele, Stefan,Sifferlen, Thierry,Haenggi, Martin,Gruner, Sibylle,Seiler, Paul
, p. 2218 - 2243 (2007/10/03)
We report on the synthesis of new and previously described β-peptides (1-6), consisting of up to twelve β2,2- or β3,3-geminally disubstituted β-amino acids which do not fit into any of the secondary structural patterns of β-peptides, hitherto disclosed. The required 2,2- and 3,3-dimethyl derivatives of 3-aminopropanoic acid are readily obtained from 3-methylbut-2-enoic acid and ammonia (Scheme 1) and from Boc-protected methyl 3-aminopropanoate by enolate methylation (Scheme 2). Protected (Boc for solution-, Fmoc for solid-phase syntheses) 1- (aminomethyl)cycloalkanecarboxylic-acid derivatives (with cyclopropane, cyclobutane, cyclopentane, and cyclohexane rings) are obtained from 1- cyanocycloalkanecarboxylates and the corresponding dihaloalkanes (Scheme 3). Fully 13C- and 15N-labeled 3-amino-2,2-dimethylpropanoic-acid derivatives were prepared from the corresponding labeled precursors (see asterixed formula numbers and Scheme 4). Coupling of these amino acids was achieved by methods which we had previously employed for other β-peptide syntheses (intermediates 18-23). Crystal structures of Boc-protected geminally disubstituted amino acids (16a-d) and of the corresponding tripeptide (23a), as well as NMR and IR spectra of an isotopically labeled β-hexapeptide (2a*) are presented (Figs. 1-4) and discussed. The tripeptide structure contains a ten-membered H-bonded ring which is proposed to be a turn-forming motif for β-peptides (Fig. 2).