A Novel Route to Coenzyme Qn

Synthesis of natural product-like polyprenylated phenols and quinones: Evaluation of their neuroprotective activities

Twenty-seven natural product-like polyprenylated phenols and quinones were synthesized and their neuroprotective activity was tested using human monoamine oxidase B (MAO-B) and SH-SY5Y cells. Eight compounds inhibited MAO-B (IC₅₀ values < 25 μM) and the inhibition mode and molecular docking of two (8c and 16c) were investigated. Compounds inhibiting MAO-B activity were additionally tested for their ability to protect SH-SY5Y cells from peroxide injury. Three derivatives (3c, 8c and 16c) exhibited both MAO-B inhibitory and neuroprotective activity. A structure activity-relationship study showed that a phenolic hydroxyl group and a longer side chain are important for both activities.

Nickel-catalyzed Heck-type reactions of benzyl chlorides and simple olefins

Nickel-catalyzed intermolecular benzylation and heterobenzylation of unactivated alkenes to provide functionalized allylbenzene derivatives are described. A wide range of both the benzyl chloride and alkene coupling partners are tolerated. In contrast to analogous palladium-catalyzed variants of this process, all reactions described herein employ electronically unbiased aliphatic olefins (including ethylene), proceed at room temperature, and provide 1,1-disubstituted olefins over the more commonly observed 1,2-disubstituted olefins with very high selectivity.

A Green and Efficient Synthesis of 1-Chloromethyl -2,3,4,5-Tetramethoxy-6-Methylbenzene

The title compound, a key intermediate for preparing coenzyme Q analogues, was prepared in excellent yield by a reaction sequence starting from the commercially available 3,4,5-trimethoxybenzadehyde via Wolff–Kishner reduction, selective bromination, methoxylation and Blanc chloromethylation reaction.

Alternative Synthesis of 5-Chloromethyl-2,3-Dimethoxy-6-Methyl-1,4-Benzoquinone: A Key Intermediate for Preparing Coenzyme Q Analogues

The title compound, a key intermediate for preparing Coenzyme Qn family, was prepared in high yield by a reaction sequence starting from the commercially available 3, 4, 5-trimethoxy-benzadehyde via Wolff–Kishner reduction, Vilsmeier–Haack reaction, Blanc chloromethylation reaction, Dakin reaction and oxidation.

Controlling Regiochemistry in Negishi Carboaluminations. Fine Tuning the Ligand on Zirconium

The species on the zirconocene catalyst is changed from two Cp's to the Brintzinger ligand and catalytic amounts of MAO are used to usually effect a >99% regiocontrol of Negishi carboaluminations of 1-alkynes in toluene.

An Improved Synthesis of the “Miracle Nutrient” Coenzyme Q10

[reaction: see text] A new route to the key coupling partner, chloromethylated CoQ0 (1), allows for direct formation of CoQ10 (3) via nickel-catalyzed cross-coupling with the side chain in the form of an in situ-derived vinyl alane (2).

Efficient Pd-Catalyzed Heterobenzylic Cross-Coupling Using Sulfonium Salts as Substrates and (PhO)(3)P as a Supporting Ligand

S-(2-Furanylmethyl)tetramethylenesulfonium hexafluorophosphate, S-(2-thienylmethyl)tetramethylenesulfonium hexafluorophosphate, S-(3-thienylmethyl)tetramethylenesulfonium hexafluorophosphate, and S-(N-tert-butoxycarbonyl-2-pyrrolylmethyl)tetramethylenesulfonium hexafluorophosphate have been conveniently prepared from the corresponding alcohols. These stable heterobenzylic sulfonium salts participate in palladium-catalyzed Stille cross-couplings with organostannanes. All but the last mentioned sulfonium salt are also active participants in palladium-catalyzed cross-coupling reactions with boronic acids and organozinc halides. Because the heterobenzylic cross-coupling reactants are potent alkylating agents, they scavenge the typical phosphines and arsines that otherwise could be used to stabilize the palladium catalyst over extended reaction times. This problem was overcome by the use of (PhO)(3)P as a unique supporting ligand for the palladium-catalyzed cross-coupling of heterobenzylic sulfonium salts.