Janos Pitlik

Solution-phase synthesis of a combinatorial monocyclic β-lactam library: Potential protease inhibitors

Abstract A 126-member library of monocyclic β-lactams was generated in parallel fashion by solution-phase Ugi four-component condensation reaction between β-amino acids, aldehydes, and isocyanides. The library was designed to identify potential human leukocyte elastase inhibitors. The approach is also capable of optimizing the lead compounds generated in the original library.

Asymmetric Synthesis of 3-(Isoxazolin-5-yl)cephalosporins

Abstract Novel C-3 substituted cephalosporins 2a-d were prepared from 3-vinylcephalosporins 1 via asymmetric silyl nitronate cycloaddition reactions.

1,3-Dipolar cycloadditions of 3-methylenecephams with diazoalkanes

Abstract The 3-methylenecephams underwent 1,3-dipolar cycloaddition reactions with diazomethane to give spiropyrazolinocephams in a completely stereo- and regioselective manner. Thermal breakdown of these 1-pyrazolines led to spirocyclopropane and vinyl derivatives.

Cycloaddition reactions of vinylcephalosporins with diazoalkanes

Abstract In the reaction of a vinylcephalosporin (2) with diazoalkanes the initially formed 3-pyrazolinocephalosporins (3) underwent further reactions leading either to bispyrazolinocephalosporins (5) or to cyclopropylcephalosporins (6).

Stereoselective formation of tricyclic cephalosporins in reactions to cephem phosphorus ylides and ketoaldehydes

Abstract Novel tricyclic cephalosporins ( 3a–d ) and cephem 3-α,β-unsaturated ketones ( 2c–f ) were obtained in a Wittig-type approach with cephalosporin C-3 phosphorus ylides and keto-substituted aldehydes in completely stereoselective reactions. The product ratio was found to be a function of the substituent on the aldehyde. Structure elucidation of the products was carried out by means of NMR methods and molecular mechanics.

A New and Convenient Reduction of Cephalosporin Sulphoxides

Abstract A new, convenient and good yield reduction of cephalosporin S (β)-sulphoxides to the corresponding sulphides was achieved upon treatment with iodotrimethylsilane (TMSI) in dichloromethane.

Efficient syntheses of multiply 2H‐ and 13C‐labeled acrylic acid, glyceric acid, glycidic acid and glycerol

Syntheses of multiply 2 H- and 13 C-labeled C-3 carbohydrates have been carried out from commercially available [1,2- 13 C 2 ]bromoacetic acid. The syntheses are illustrated for [1,2- 13 C 2 ]acrylate, [2,3,3- 2 H 3 , 1,2- 13 C 2 ]acrylate, [1,2- 13 C 2 ]glycerate, [2,3,3- 2 H 3 , 1,2- 13 C 2 ]glycerate, [1,2- 13 C 2 ]glycidate and [1,1- 2 H 2 , 1,2- 13 C 2 ]glycerol..

Synthesis and transformations of 3-vinylcephalosporins. Part 6. Reactions of cephalosporin phosphoranes with bifunctional carbonyl compounds

Cephalosporin C-3-phosphoranes have been converted into the corresponding 3-alkenylcephems and novel tricyclic derivatives on treatment with different bifunctional carbonyl compounds. The effect of substituents on the product ratio has been examined. The stereoselectivity of the ringclosure is explained on the basis of theoretical considerations.