Michał Achmatowicz

A simple synthesis of chiral macrocyclic tetraamides derived from α-amino acids

Abstract Bisamidation of oxalyl chloride using four l -α-amino acid esters afforded chiral diesters which were reacted with three α,ω-diamines under high-pressure conditions (10 kbar) to give macrocyclic tetramides of C 2 -symmetry.

The synthesis of l-proline derived hexaazamacrocyclic ligands of C3 symmetry via intramolecular methyl ester aminolysis

Abstract A convenient synthesis of enantiomerically pure 18-, 21-, and 24-membered hexaaza-crown ligands is presented. Linear α,ω-aminoesters, prepared from l -proline, undergo intramolecular aminolysis to afford the corresponding 18-, 21-, and 24-membered macrocyclic amides in satisfactory yields (42, 65, and 22%, respectively). These were subsequently transformed into the title macrocyclic hexamines via exhaustive reduction with a borane–dimethylsulfide complex. X-Ray structures of two larger macrocyclic amides are also presented.

Asymmetric syn-dihydroxylation of γ-substituted (2R)-N-(β,γ-enoyl)bornane-10,2-sultams

Abstract Various γ-substituted (2R)-N-(β,γ-enoyl)bornane-10,2-sultams have been examined in diastereoselective OsO4 syn-dihydroxylation. In contrast to the C(α)-atom, the bornane-10,2-sultam auxiliary exerts a very poor influence on the C(β)-carbon. Spontaneous stereoselective hydrolysis of the minor diastereoisomer (3S,4S)-5c opens the way to enantiomerically pure building blocks.

Preparation of a new type of homochiral l-proline derived cyclam and their nickel(II) complexes

Abstract A convenient and efficient synthesis of a novel class of chiral ligands able to form stable complexes with transition metal ions is presented. Nickel(II) complexes with three ligands of this type are characterized.

STEREOSELECTIVITY IN THE TICL4-CATALYZED 4+2 CYCLOADDITION OF CYCLOPENTADIENE TO (2R)-BORNANE-10,2-SULTAM DERIVATIVES OF FUMARIC ACID MONOESTERS

The [4+2] cycloaddition of cyclopentadiene to the (2R)-bornane-10,2-sultam derivative (−)-1b of fumaric monomethyl ester proceeds with high endo and π-facial diastereoselectivity in the presence of 0.5 mol-equiv. of TiCl4. The major diastereoisomer endo-(2R,3R)-2b, isolated in 87% yield by crystallization, was subjected to X-ray crystal-structure analysis. Steric influence of ethyl- and benzyl-ester analogues (−)-1c and (−)-1d, respectively, is also reported.

The Simple Synthesis of Chiral Polyazaoxacoronands Derived from α-Amino Acids

Abstract Bisamidation of oxaloyl chloride using L-amino acid methyl ester hydrochlorides afforded chiral diesters. The following reactions of diesters with 2,2-(ethylene-dioxy)diethylamine, afforded tetramides possessing C2 symmetry. Coupling of N-hydroxysuccinimide ester of N-benzyloxycarbonyl-L-alanine with 1,5-diamino-3-oxapentane, followed by cleavage of protecting groups, afforded an optically active diamine, which was transformed consequently into tetramide via the reaction with diglycolic acid dimethyl ester under high pressure conditions.