Palladium-Catalyzed Oxalyl Amide Directed Silylation and Germanylation of Amine Derivatives
Palladium-catalyzed direct ortho-silylation of oxalyl amide-protected phenylmethanamine and phenethylamine with commercially available disilanes is reported. Germanylation products were also produced under the same reaction conditions. This protocol tolerated oxalyl amide-protected aliphatic amines, which gave-C-H silylation products.
Pd-catalyzed coupling of γ-C(sp3)-H bonds of oxalyl amide-protected amino acids with heteroaryl and aryl iodides
Pd-catalyzed regioselective coupling of γ-C(sp3)-H bonds of oxalyl amide-protected amino acids with heteroaryl and aryl iodides is reported. A wide variety of iodides are tolerated, giving the corresponding products in moderate to good yields. Various oxalyl amide-protected amino acids were compatible in this C-H transformation, thus representing a practical method for constructing non-natural amino acid derivatives.
Practical syntheses of both enantiomers of cyclopropylglycine and of methyl 2-cyclopropyl-2-N-Boc-iminoacetate
A facile three-step synthesis of racemic cyclopropylglycine in multigram quantities from inexpensive cyclopropyl methyl ketone has been elaborated. Enzymatic hydrolysis of the N-Boc-protected methyl ester of cyclopropylglycine 9 with the inexpensive enzyme papain from Carica papaya affords both enantiomers of cyclopropylglycine (8) with enantiomeric excesses of 99% or better after deprotection under acidic conditions. Furthermore, the new cyclopropyl group-containing building block methyl 2-cyclopropyl-2-N-Boc-iminoacetate (13) was prepared by N-chlorination and subsequent dehydrochlorination with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). Addition of nucleophiles to 13 offers a ready access to an unusual, orthogonally bisprotected α,α-diamino acid derivative and interesting components of rigid peptide backbones.
Larionov, Oleg V.,De Meijere, Armin
p. 1071 - 1078
(2007/10/03)
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