Mario Fernández-Zertuche

Diastereoselective reduction of β-ketophosphonates derived from amino acids. A new entry to enantiopure β-hydroxy-γ-aminophosphonate derivatives

Abstract The reduction of γ-N,N-dibenzylamino-β-ketophosphonates 4 derived from readily available (S)-tribenzylated amino acids was achieved with catecholborane at –20°C affording γ-amino-β-hydroxyphosphonates 5 in high diastereoselectivity and good chemical yield. These reactions provide a new entry to enantiomerically pure γ-amino-β-hydroxyphosphonates.

Preparation of (R)- and (S)-γ-amino-β-hydroxypropylphosphonic acid from glycine

Abstract An efficient synthesis of both enantiomers of γ-amino-β-hydroxypropylphosphonic acid, an analogue of GABOB, has been achieved for the first time starting from glycine, through the resolution of dimethyl (±)-3-( N , N -dibenzylamino)-2-hydroxypropylphosphonate 7 with ( S )- O -methylmandelic acid.

An Amphotericin B Derivative Equally Potent to Amphotericin B and with Increased Safety

Amphotericin B is the most potent antimycotic known to date. However due to its large collateral toxicity, its use, although long standing, had been limited. Many attempts have been made to produce derivatives with reduced collateral damage. The molecular mechanism of polyene has also been closely studied for this purpose and understanding it would contribute to the development of safe derivatives. Our study examined polyene action, including chemical synthesis, electrophysiology, pharmacology, toxicology and molecular dynamics. The results were used to support a novel Amphotericin B derivative with increased selectivity: L-histidine methyl ester of Amphotericin B. We found that this derivative has the same form of action as Amphotericin B, i.e. pore formation in the cell membrane. Its reduced dimerization in solution, when compared to Amphotericin B, is at least partially responsible for its increased selectivity. Here we also present the results of preclinical tests, which show that the derivative is just as potent as Amphotericin B and has increased safety.

Allylic strain effects on the stereochemistry of the alkylation reaction of mycophenolic acid chiral enolates

An attempted enantioselective synthesis of all the four individual diastereomers of α,β-dimethylated mycophenolic acid using Evans chiral auxiliaries is reported. The 1,3-allylic strain effect on the enolates used favor the formation of the syn acids.

Microwave-Assisted Improved Synthesis of Oxazolidin-2-ones, Oxazolidine-2-thiones and Thiazolidine-2-thione Chiral Auxiliaries

A microwave assisted method for the synthesis of some typical 4-substituted oxazolidinone chiral auxiliaries used in asymmetric synthesis is reported in this work. Under these conditions, treatment of (S)-phenylalaninol, (S)-phenylglycinol, (S)-valinol and (1S, 2R)-norephedrine with ethyl carbonate or carbon disulfide under the appropriate and specific microwave reaction conditions, led to an efficient synthesis of some oxazolidin-2-ones, oxazolidine-2-thiones and thiazolidine-2-thiones. The methodology reported in this paper provides these chiral auxiliaries with improved yields and a remarkable reduction on the reaction times, particularly in the case of thiazolidine-2-thiones, as compared with the conventional methods. All the auxiliaries prepared here show spectroscopic data in full agreement with those previously reported in the literature.

Synthesis of cis- and trans-3-aminocyclohexanols by reduction of β-enaminoketones.

We describe a protocol developed for the preparation of β-enaminoketones derived from 1,3-cyclohexanediones, and their subsequent reduction by sodium in THF-isopropyl alcohol to afford cis- and trans-3-aminocyclohexanols.

Novel-Substituted Heterocyclic GABA Analogues. Enzymatic Activity against the GABA-AT Enzyme from Pseudomonas fluorescens and In Silico Molecular Modeling

γ-Aminobutyric acid (GABA) is the most important inhibitory neurotransmitter in the central nervous system, and a deficiency of GABA is associated with serious neurological disorders. Due to its low lipophilicity, there has been an intensive search for new molecules with increased lipophilicity to cross the blood-brain barrier to raise GABA concentrations. We have designed and evaluated in vitro and in silico some new analogues of GABA, where the nitrogen atom at the γ-position is embedded in heterocyclic scaffolds and determined their inhibitory potential over the GABA-AT enzyme from Pseudomonas fluorescens. These modifications lead to compounds with inhibitory activity as it occurs with compounds 18a and 19a. The construction of Pseudomonas fluorescens and human GABA-AT models were carried out by homology modeling. Docking assays were done for these compounds over the GABA-AT enzyme models where 19a showed a strong interaction with both GABA-AT enzymes.

Practical and efficient synthesis of (E)-α,β-unsaturated amides bearing (S)-α-methylbenzylamine from 2-phosphonamides via Horner-Wadsworth-Emmons reaction

The highly stereoselective synthesis of (E)-α,β-unsaturated amides bearing (S)-a-methylbenzylamine was achieved from 2-phosphonamides via Homer-Wadsworth-Emmons reaction. The starting phosphonamides are easily prepared in two steps with excellent yields via the standard Arbuzov reaction of trimethylphosphite and α-bromoamides.