Zoltán Hell

A simple synthesis of 2-substituted oxazolines and oxazines

Abstract β-Aminoalcohols react with carboxylic acids in the presence of a zeolite, Ersorb-4, resulting in the formation of oxazoline derivatives in good yields. Similarly, 3-aminopropanol and benzoic acid gave the corresponding 2-phenyloxazine.

A simple method for the preparation of propargylamines using molecular sieve modified with copper(II)

A new, heterogeneous, 4 A molecular sieve-supported copper(ii) catalyst was developed and was used successfully in the A(3) coupling of alkynes, aldehydes and amines under simple reaction conditions.

Convenient one-pot heterogeneous catalytic method for the preparation of 3,4 -dihydropyrimidin -2 (1H) -ones

Abstract A new, simple, environmentally friendly synthesis of dihydropyrimidinones from aromatic and aliphatic aldehydes, ethyl acetoacetate, and urea or thiourea using a small‐pore‐size zeolite as catalyst is described. Compared with the classical Biginelli reaction conditions, this method has the advantage of high yield, shorter reaction time, and recyclable and reusable catalyst.

Single electron transfer induced elemental steps in the transformation of iodomalonic esters and related CH-acids under solid-liquid PTC conditions. Preparation of electrophilic cyclopropanes

Abstract Single electron transfer induced elemental steps have been shown to occur during the transformation of iodomalonic esters and related CH-acids to cyclopropane derivatives under solid-liquid phase transfer catalytic conditions. The iodo derivatives are formed from iodine and CH-acids “in situ”, in the same pot in which the transformations to cyclopropane derivatives take place. A number of electrophilic cyclopropanes with a wide range of substituents have been synthetised by this route.

Heterogeneous Catalytic Method for the Conversion of Aldoximes into Nitriles Using Molecular Sieve Modified with Copper(II)

Abstract A simple heterogeneous metal-catalyzed method was developed for the transformation of aldoximes into nitriles. Molecular sieve (4 Å) modified with copper(II) proved to be an efficient catalyst for the conversion. Supplemental materials are available for this article. Go to the publishers online edition of Synthetic Communications® to view the free supplemental file. GRAPHICAL ABSTRACT

Zeolite-catalyzed simple synthesis of isochromans via the oxa-Pictet–Spengler reaction

The modified small pore size zeolite E4a has been found to be an efficient catalyst for the synthesis of isochromans via the oxa-Pictet–Spengler reaction. This method is simple, cheap, environmentally-friendly and gives the isochromans in high yield.

Microwave-assisted conversion of oximes into nitriles in the presence of a zeolite

Aromatic aldoximes were converted to the corresponding nitriles in a microwave oven in the presence of a molecular sieve-type modified zeolite, Ersorb, under solvent-free conditions. The yields depended on the substituent of the oxime.

Zeolite-catalyzed environmentally friendly synthesis of benzimidazole derivatives

Abstract A simple and environmentally friendly synthesis of substituted benzimidazoles was developed using a small‐pore‐size zeolite. The similar reaction was not applicable to the preparation of 2‐substituted imidazolines.

Reaction of non-activated olefins with CH-acids; a novel method for the preparation of electrophilic cyclopropanes

Abstract Reaction of non-activated olefines with active methylene compounds was accomplished under solid-liquid phase-transfer conditions, in the presence of iodine, to give electrophilic cyclopropanes of a wide range of substituents. Several data to the mechanism of the reaction are also given.

Mg-Al 3:1 hydrotalcite catalyst in the synthesis of cyclopropane carboxylic acid derivatives

Abstract The non-activated Mg-Al 3:1 hydrotalcite is a suitable basic catalyst both in the intramolecular cyclization reaction of malonic acid allylic esters into bicyclic cyclopropane carboxylic acid lactones and the intermolecular cyclization reaction of dibromoethane and diethyl malonate into cyclopropane dicarboxylic acid diester. The optimal reaction conditions of the intramolecular cyclization were determined using a 2 4 factorial design. An interesting effect on the diastereoselectivity of the intramolecular cyclization was observed compared with the diastereoselectivity of this cyclization using solid potassium carbonate as base.