Studies on Thioesters Related to Coenzyme A. A Kinetic Study of Aminolysis and Hydrolysis of β-(N-Methylacetamino)-ethyl Thioacetate, N,S-Diacetylaletheine and γ-Acetaminopropyl Thioacetate1
Building units for N-backbone cyclic peptides. Part 4.1 Synthesis of protected Nα-functionalized alkyl amino acids by reductive alkylation of natural amino acids
作者:Gal Bitan、Dan Muller、Ron Kasher、Evgenia V. Gluhov、Chaim Gilon
DOI:10.1039/a608389g
日期:——
A new method for the synthesis of protected
Nα-(Ï-Y-alkyl) amino acids (Y
is a thio, amino or carboxy group) and related compounds by reductive
alkylation of natural amino acids is reported. These new amino acids
serve as building units for the synthesis of backbone-cyclic peptides.
They are orthogonally protected at the α-amino position by
butoxycarbonyl (Boc) or 9-fluorenylmethoxycarbonyl (Fmoc), using
trimethylsilyl temporary protection, to allow for their incorporation
into peptides by solid phase peptide synthesis.
Structural analogues of decarboxylated S-adenosyl-L-methionine (dc-SAM), product of the reaction catalyzed by S-adenosyl-L-methionine decarboxylase (SAM-DC), with modifications in the side-chain portion of the molecule have been synthesized, and their ability to inhibit SAM-DC has been investigated. Mainly, compounds with a nitrogen atom in place of the sulfur were investigated. The data from these
Enantioselective Synthesis of <i>N</i>
,<i>S</i>
-Acetals by an Oxidative Pummerer-Type Transformation using Phase-Transfer Catalysis
作者:Souvagya Biswas、Koji Kubota、Manuel Orlandi、Mathias Turberg、Dillon H. Miles、Matthew S. Sigman、F. Dean Toste
DOI:10.1002/anie.201711277
日期:2018.1.8
Deuterium‐labelling experiments were performed to identify the stereodiscrimination step of this process. Further analysis of the reaction transition states, by means of multidimensional correlations and DFT calculations, highlight the existence of a set of weak noncovalent interactions between the catalyst and substrate that govern the enantioselectivity of the reaction.
A series of novel aliphatic tripodal trithioether ligands 4-6 differing in the lengths of the alkyl chains between central nitrogen atom and sulfur donor function has been synthesized. The neutral ligands 4-6 react with copper(I) under formation of the mononuclear complexes 7-9 featuring exclusive coordination of the metal center by the tertiary amine and the three thioether donor functions of the tripodal ligand. Molecular structures of 7 and 9 show a direct influence of the spacer lengths between central and terminal donor functions on the geometry of the tetracoordinated complex cations. Substitution of one ethylene by a propylene spacer leads to a larger bite angle between the amine and thioether donor functions and effects a tetrahedral distortion for the complex cation in 7. For the copper(I) compound 9 with a ligand possessing exclusively propylene spacers this effect is increased leading to a tetrahedral geometry of the complex cation. (C) 2010 Elsevier B.V. All rights reserved.