Preparation of N-unsubstituted β-ketoamides by Rhodococcus rhodochrous-catalysed hydration of β-ketonitriles

L-Cysteine-Catalysed Hydration of Activated Alkynes

Hydration reactions consist of the introduction of a molecule of water into a chemical compound and are particularly useful to transform alkynes into carbonyls, which are strategic intermediates in the synthesis of a plethora of compounds. Herein we demonstrate that L-cysteine can catalyse the hydration of activated alkynes in a very effective and fully regioselective manner to access important building blocks in synthetic chemistry such as β-ketosulfones, amides and esters, in aqueous media. The mild reaction conditions facilitated the integration with enzyme catalysis to access chiral β-hydroxy sulfones from the corresponding alkynes in a one-pot cascade process in good yields and excellent enantiomeric ratios. These findings pave the way towards establishing a general method for metal-free, cost-effective, and more sustainable alkyne hydration processes.

Synthesis of functionalised β-keto amides by aminoacylation/domino fragmentation of β-enamino amides

Ethylenediamine-derived β-enamino amides are used as equivalents of amide enolate synthons in C-acylation reactions with N-protected amino acids. Domino fragmentation of the obtained intermediates leads to functionalised β-keto amides, bearing a protected amino group in their side chain.

Selective Cleavage of Inert Aryl C-N Bonds in N-Aryl Amides

A highly selective, IBX-promoted reaction has been developed for the oxidative cleavage of inert C(aryl)-N bonds on secondary amides while leaving the C(carbonyl)-N bond unchanged. This metal-free reaction proceeds under mild conditions (HFIP/H₂O, 25 °C), providing facile access to various useful primary amides, some of which would be otherwise unattainable using conventional aminolysis and hydrolysis approaches.

An expeditious method to synthesize difluoroboron complexes of β-keto amides from β-keto nitriles and BF3·OEt2

An expeditious and convenient method has been developed to synthesize difluoroboron complexes of β-keto amides from β-keto nitriles and BF₃·OEt₂.

Chlorophosphines as auxiliary ligands in ruthenium-catalyzed nitrile hydration reactions: application to the preparation of β-ketoamides

The utility of chlorophosphines as auxiliary ligands in metal-catalyzed nitrile hydration reactions has been demonstrated, along with their application in the preparation of β-ketoamides.

Nitrile, amide and temperature effects on amidase-kinetics during acrylonitrile bioconversion by nitrile-hydratase/amidase in situ cascade system

In this study the amidase kinetics of an in situ NHase/AMase cascade system was explored as a function of operational parameters such as temperature, substrate concentration and product formation. The results indicated that controlling amidase inactivation, during acrylonitrile bioconversion, makes it possible to recover the intermediate product of the two-step reaction in almost a pure form, without using purified enzyme. It has been demonstrated, in long-term experiments performed in continuous stirred UF-membrane bioreactors, that amidase is kinetically controlled by its proper substrate, depending on the structure, and by acrylonitrile. Using acrylamide, AMase-stability is temperature dependent (5°C, kd=0.008 h(-1); 30°C kd=0.023 h(-1)). Using benzamide, amidase is thermally stable up to 50°C and no substrate inhibition/inactivation occurs. With acrylonitrile, AMase-activity and -stability remain unchanged at concentrations <200 mM but at 200 mM, 35°C, after 70 h process, 90% irreversible inactivation occurs as no AMase-activity on benzamide revives.

De NovoParallel Design, Synthesis and Evaluation of Inhibitors against the Reverse Transcriptase of Human Immunodeficiency Virus Type-1 and Drug-Resistant Variants

We used molecular modeling to design de novo broad-range inhibitors against wild type and drug-resistant variants of the reverse transcriptase (RT) of human immunodeficiency virus type-1 (HIV-1). First, we screened for small fragments that would interact with each one of four RT structures (one wild type and three mutants). Then, these fragments were linked to build a scaffold molecule. Out of 27 different compounds that were synthesized, four inhibited the DNA polymerase activity of RT with IC50 values below 10 microM. Compound 5f inhibited RT with an IC50 value of about 3.5 microM, while inhibiting drug-resistant RT variants more efficiently than the clinically used drug, nevirapine (11-cyclopropyl-5,11-dihydro-4-methyl-6H-dipyrido[3,2-b:2',3'-e][1,4]diazepin-6-one). 5f also inhibited the RT ribonuclease H activity with an IC50 of 20 microM and therefore, unlike nevirapine, targets both RT activities. Accordingly, 5f can serve as lead for developing novel inhibitors against RT that may be used to suppress HIV-1 growth.

Bacterial Preparation of Enantiopure Unactivated Aziridine-2-carboxamides and Their Transformation into Enantiopure Nonnatural Amino Acids and vic-Diamines

[reaction: see text] Enantiopure (1R,2S)-1-benzyl- and 1-arylaziridine-2-carboxamides were obtained by kinetic resolution of their racemates by Rhodococcus rhodochrous IFO 15564 catalyzed hydrolysis. Several regio- and enantioselective nucleophilic ring openings of (1R,2S)-1-benzylaziridine-2-carboxamide or its LAH-reduced product led to a series of enantiopure products, such as O-methyl-l-serine and some vicinal diamines.