Juergen Conrad

Double C-H activation: the palladium-catalyzed direct C-arylation of xanthines with arenes.

The novel Pd-catalyzed C(sp(2))-H/C(sp(2))-H cross-coupling of unactivated xanthines with unactivated arenes utilizing a combination of Ag(I) and O(2) as oxidants exclusively yields C-8 arylated xanthines in a single synthetic operation.

Cu(I)-catalyzed domino reactions: efficient and selective synthesis of 4H-chromenes and naphthalenes.

Depending on the ratio of the substrates and the reaction conditions, the Cu(I)-catalyzed domino reaction between bromobenzyl bromides and β-ketoesters exclusively yields either 4H-chromenes or naphthalenes.

Combined action of enzymes: the first domino reaction catalyzed by Agaricus bisporus

The enzymes tyrosinase and laccase from a crude extract of the button mushroom (Agaricus bisporus) can be employed to catalyze the domino reaction between phenol and various cyclic 1,3-dicarbonyls using atmospheric oxygen as the oxidizing agent and yielding annulated benzofuranes in a highly efficient and sustainable manner.

Laccase-catalyzed synthesis of catechol thioethers by reaction of catechols with thiols using air as an oxidant

The laccase-catalyzed reaction between catechols and thiols using aerial oxygen as the oxidant delivers the corresponding catechol thioethers with yields up to 96% under mild reaction conditions.

Synthesis of disulfides by laccase-catalyzed oxidative coupling of heterocyclic thiols

A new method employing a laccase–mediator system as the catalyst and aerial oxygen as the oxidant has been developed for the oxidative coupling of heterocyclic thiols to the corresponding disulfides with yields up to 95% under mild reaction conditions.

Laccase-catalyzed oxidative phenolic coupling of vanillidene derivatives

The laccase-catalyzed oxidative phenolic coupling of vanillidene derivatives using aerial oxygen as the oxidant has been developed. Depending on the substitution pattern of the vanillidene double bond of the substrate, either dilactones, dihydrobenzo[b]furans or biphenyls are formed.

Laccase-catalyzed oxidation of Hantzsch 1,4-dihydropyridines to pyridines and a new one pot synthesis of pyridines

The laccase-catalyzed oxidation of 1,4-dihydropyridines to pyridines using aerial O2 as the oxidant exclusively delivers pyridines with yields up to 95% under mild reaction conditions. Combination of the Hantzsch 1,4-dihydropyridine synthesis with the newly developed laccase-catalyzed oxidation forms the basis of a facile and environmentally benign method for the synthesis of pyridines in one pot.

Copper(I)-catalyzed intramolecular O-arylation for the synthesis of 2,3,4,9-tetrahydro-1H-xanthen-1-ones with low loads of CuCl.

As little as 0.5 mol % CuCl is sufficient to catalyze the intramolecular O-arylation of easily accessible 2-(2-bromobenzyl)cyclohexane-1,3-diones to provide the corresponding 2,3,4,9-tetrahydro-1H-xanthen-1-ones with yields ranging from 83% to 99%.

Laccase-Catalyzed Domino Reaction between Catechols and 6-Substituted 1,2,3,4-Tetrahydro-4-oxo-2-thioxo-5-pyrimidinecarbonitriles for the Synthesis of Pyrimidobenzothiazole Derivatives

The laccase-catalyzed domino reaction between catechols and 6-substituted 1,2,3,4-tetrahydro-4-oxo-2-thioxo-5-pyrimidinecarbonitriles using aerial O2 as the oxidant delivers new pyrimidobenzothiazole derivatives. The complete structure elucidation of the ring-proton deficient heterocyclic products and the unambiguous determination of the regioselectivity of the reactions have been achieved by extended NMR spectroscopic methods including HSQMBC, super long-range HMBC, and (15)N measurements.

Laccase-catalyzed stereoselective oxidative ring opening of 2,5-dialkylfurans into 2-ene-1,4-diones using air as an oxidant

The laccase-catalyzed ring opening of 2,5-dimethylfuran using air as an oxidant stereoselectively yields (Z)- or (E)-3-hexene-2,5-dione depending on the mediator employed: with TEMPO the (Z)-3-hexene-2,5-dione is formed, while a combination of TEMPO and violuric acid gives (E)-3-hexene-2,5-dione. The (Z)-selective ring cleavage was extended to a variety of symmetrical and unsymmetrical 2,5-dialkylfurans.