Terminal olefins to linear α,β-unsaturated ketones: Pd(II)/hypervalent iodine co-catalyzed Wacker oxidation-dehydrogenation.

Development of a mild (35 °C, no Brønsted acids) tandem Wacker oxidation-dehydrogenation of terminal olefins was accomplished using palladium(II) and hypervalent iodine co-catalysis. The reaction affords linear aryl and alkyl α,β-unsaturated ketones directly from readily available terminal olefins in good yields (average 75% per step) with excellent functional group tolerance and chemo- and stereoselectivities. The hypervalent iodine co-catalyst was found to be critical for dehydrogenation but was not effective as a stoichiometric oxidant.

Cafestol to Tricalysiolide B and Oxidized Analogues: Biosynthetic and Derivatization Studies Using Non-heme Iron Catalyst Fe(PDP).

The tricalysiolides are a recently isolated class of diterpene natural products featuring the carbon backbone of the well-known coffee extract, cafestol. Herein we validate the use of our non-heme iron complex, Fe(PDP), as an oxidative tailoring enzyme mimic to test the proposal that this class of natural products derives from cafestol via cytochrome P-450-mediated furan oxidation. Thereafter, as predicted by computational analysis, C-H oxidation derivatization studies provided a novel 2° alcohol product as a single diastereomer.

Directed metal (oxo) aliphatic C-H hydroxylations: overriding substrate bias.

The first general strategy for a directing effect on metal (oxo)-promoted C-H hydroxylations is described. Carboxylic acid moieties on the substrate overcome unfavorable electronic, steric, and stereoelectronic biases in C-H hydroxylations catalyzed by the non-heme iron complex Fe(PDP). In a demonstration of the power of this directing effect, C-H oxidation is diverted away from an electronically favored C-1 H abstraction/rearrangement pathway in the paclitaxel framework to enable installation of C-2 oxidation in the naturally occurring oxidation state and stereoconfiguration.

Diverting non-haem iron catalysed aliphatic C-H hydroxylations towards desaturations.

Carboxylate-ligated, non-haem iron enzymes demonstrate the capacity for catalysing such remarkable processes as hydroxylations, chlorinations and desaturations of inert, aliphatic C-H bonds. A key to functional diversity is the enzymes' ability to divert fleeting radicals towards different types of functionalization using active site and/or substrate modifications. We report that a non-haem iron hydroxylase catalyst [Fe(PDP)] can also be diverted to catalytic, mixed hydroxylase/desaturase activity with aliphatic C-H bonds.