Antal Udvardy

Pd-tetrahydrosalan-type complexes as catalysts for sonogashira couplings in water: efficient greening of the procedure.

New sulfonated tetrahydrosalen-type ligands and their water-soluble palladium(II) complexes have been synthesized. The palladium(II) complexes catalyze the Sonogashira coupling (23 examples) of various aryl halides (including chloroarenes) with terminal alkynes, with good to excellent conversions under mild conditions (80°C, air, no Cu(I) cocatalyst) in aqueous-organic mixtures and turnover frequencies of up to 2790 h(-1) . Under optimized reaction conditions to minimize environmental contamination, diphenylacetylenes can be isolated in 76-98% yield. The aqueous catalyst solution can be recycled four times with decreasing activity; however, yields between 93 and 98% can still be achieved with extended reaction times. Several water-insoluble products can be isolated in excellent yield by simple filtration and purification by washing with water; this method is used, for the first time, for this type of C-C coupling procedure.

Synthesis and structure of stable water-soluble phosphonium alkanoate zwitterions derived from 1,3,5-triaza-7-phosphaadamantane

Abstract1,3,5-triaza-7-phosphaadamantane (PTA) was shown to form phosphonium alkanoate zwitterions with unsaturated dicarboxylic acids in water in the absence of strong acids. Solid-state structures of the phosphonium salt (1) derived from maleic or fumaric acids and that of the zwitterionic product (2) of the reaction of PTA with citraconic and mesaconic acids were determined by single-crystal X-ray diffraction. DFT calculations gave insight into the mechanism of the reaction, including the relative reactivity of the four dicarboxylic acids, and revealed the reasons for the lack of phosphonium salt formation by PTA in strongly acidic aqueous solutions.

Salutaridine and its derivatives as thebaine-equivalents in the synthesis of aporphines

AbstractHere we report the transformation of tetracyclic morphinan salutaridine (1) into 2,3,10,11-tetrasubstituted (R)-aporphines. This method serves as another chemical proof of the previously verified biosynthetic connection with pentacyclic morphinan-6,8-diene-type thebaine. In the presence of nucleophiles, this procedure could lead to pharmacologically interesting new tetrasubstituted aporphinoids. The enantioselective synthesis of 7S-salutaridinol (2) has been also achieved in order to investigate the acid-catalyzed reactions of this natural morphinan.

The first synthesis of 3-deoxyoripavine and its utilization in the preparation of 10-deoxyaporphines and cyprodime

AbstractThe synthesis of 3-deoxyoripavine (7) was realized as a novel and promising intermediate towards the synthesis of the important class of dopaminergic and/or serotonergic 10-deoxyaporphines and the special pharmacological tool µ opioid antagonist cyprodime. Generally, the preparation of these valuable biologically active compounds was achieved in remarkable yields.

Water-soluble phosphonium salts as supramolecular synthons

Water soluble aryl phosphonium salts are known as the product of reaction of sulphonated tertiary aryl phosphanes with unsaturated carboxylic acids in aqueous media under ambient conditions.[1] However, aliphatic phosphanes and their phosphonium salt derivatives are rather sensitive for oxygen and moisture. The small water soluble aliphatic phosphane, 1,3,5-triaza7-phospha adamantane (PTA) is an effective catalyst of the Morita-Baylis-Hillman (MBH) reaction i.e. coupling of aldehydes with activated olefins resulting the corresponding allyl alcohol derivative.[2] Phosphonium salts play intimate role in the phosphorous catalyzed MBH reaction and could have paramount importance in hydrogenation reactions catalyzed by platinum metal complexes of tertiary phosphanes, as well. We have managed to prepare a whole library of phosphonium salts under appropriate conditions by reacting PTA with activated olefins. The detailed analysis of the crystal structures of these phosphonium salts will be presented. The compounds are perfectly air stable in the solid state and their crystals are brittle. The structures are stabilized by strong ionic and weak van der Waals interactions as well as weak C-H...O / strong O-H...O hydrogen bonds.