Andreas Heumann

Epoxidation with molecular oxygen in the presence of PdCl (NO2) (CH3CN)2

Abstract Several mono or non conjugated diolefins are submitted to the action of oxygen in presence of catalytic amounts of PdCl (NO2) (CH3CN)2. Depending on the olefin structures methylketones or epoxides are obtained.

Cyclopentene-regioselective palladium-catalyzed cycloisomerization under neutral and bis-cationic reaction conditions

A series of 1,6-dienes is cyclized to cyclopentene derivatives under neutral conditions with palladium chloride in ethanol or with in situ generated LPd2+ in acetonitrile.

Synthesis of enantiomerically pure (1S, 2R)-epoxy indane and cis-(1R,2S)-2-amino-1-indanol

Abstract Enantiomerically pure (1 S , 2 R )-epoxy indane and cis -(1 R , 2 S )-2-amino-1-indanol were synthesized via highly enantioselective lipase catalyzed transesterification of racemic trans -2-bromo-1-indanol.

Kinetic resolution of racemic alcohols with chiral car☐ylic acids and dicyclohexylcarbodiimide

The DCC-esterification method has been used to kinetically resolve racemic mixtures of alcohols. With simple chiral car☐ylic acids, such asO-aryl lactic acids, in the presence of various basic catalysts, mixtures of the enantiomerically enriched alcohols (e.e.<50%) and the corresponding esters (d.e.<70%) have been obtained.

Kinetic resolution of racemic carboxylic acids and alcohols with homochiral alcohols and carboxylic acids, respectively, and the Mukaiyama or Palomo reagents

Abstract The Mukaiyama and Palomo reagents have been used for the kinetic resolution of racemic carboxylic acids or alcohols with homochiral alcohols or carboxylic acids, respectively, in the presence of triethylamine. Thus, enantiomerically enriched carboxylic acids (e.e.

Lewis super-acid catalyzed cyclizations: a new route to fragrance compounds.

This review deals with the application of Lewis super acids such as AlIII, InIII, and SnIV triflates and triflimidates as catalysts in the synthesis of fragrance materials. Novel catalytic reactions involving CC and Cheteroatom bond‐forming reactions, as well as cycloisomerization processes are presented. In particular, SnIV and AlIII triflates were employed as catalysts in the selective cyclization of unsaturated alcohols to cyclic ethers, as well as in the cyclization of unsaturated carboxylic acids to lactones. The addition of thiols and thioacids to non‐activated olefins, both in intra‐ and intermolecular versions, was efficiently catalyzed by InIII derivatives. SnIV Triflimidates catalyzed the cycloisomerization of highly substituted 1,6‐dienes to gem‐dimethyl‐substituted cyclohexanes bearing an isopropylidene substituent. The hydroformylation of these unsaturated substrates, catalyzed by a RhI complex with a bulky phosphite ligand, selectively afforded the corresponding linear aldehydes. The olfactory evaluation of selected heterocycles, carbocycles, and aldehydes synthesized is also discussed.

Palladium catalyzed cyclization of 1,5-bismethylenecyclooctane application to one carbon ring enlargement

Abstract 1,5-Bismethylene cyclooctane 1 is transformed in a one pot multi step sequence to bridgehead substituted bicyclo [ 4. 3. 1 ] decane derivatives by a catalytical Pd II mediated oxidation reaction. A regioselective Wagner Meerwein rearrangement leading to ring enlargement is involved. The major product 5 can be fragmentated to a nine membered ring .

Kinetic resolution of racemic carboxylic acids with homochiral alcohols and dicyclohexylcarbodiimide

Abstract Racemic carboxylic acids have been kinetically resolved by means of homochiral alcohols using the DCC-esterification methodology. The best results were obtained with commercially available homochiral 1-(4-pyridyl)ethanol:

Palladium-Catalyzed Enantioselective Organic Transformations.

Many palladium-catalyzed organic reactions with tailored ligands, besides the princess of asymmetric catalysis, allylic alkylation, are suitable for enantioselective organic synthesis. This is clearly illustrated by the large number of promising examples such as the Heck reaction, and Wacker-type oxidations, cycloadditions, cycloisomerizations, carbonylations, and copolymerization of alkenes with carbon monoxide.

Epoxidation with O2 using PdClNO2(CH3CN)2 catalysts: reactivity of the C-Pd bond in the intermediate complex formed during oxidation of norbornene

The reactivity of di-p-chlorobis[3-(nitrosooxy)bicyclo[2.2.]] hept-2-yl-C,N]dipalladium II can be modified by added reagents. In presence of CuCl2, the thermal decomposition leading to epoxynorbornane is completely suppressed and an unequivocal rearrangement of the norbornane framework is observed.