Olefin hydroboration catalyzed by an iron-borane complex.

The well-defined iron(0) complex [(iPrDPBPh)Fe2-(µ-1,2-N2)] (A) reacts with HBpin to afford the complex [(η3-H2iPrDPB)Fe(η3-H2Bpin)] (B) via oxidative addition of the H-B bond. Complex A is an effective pre-catalyst for the hydroboration of a range of olefins in synthetically useful yields (typically >80%) under neat conditions.

1,3-Carboboration of iodonium ylides.

Herein, we disclose the utilisation of iodonium ylides to access a range of boron dienolates. Heating of acyclic iodonium ylides in the presence of different aryl boranes leads to the formation of rare 1,3-carboboration products. This methodology could not be expanded to cyclic iodonium ylides which instead formed a Lewis acid-base adduct. Products proved to be remarkably stable under a wide range of conditions allowing for their long term storage.

Asymmetric ketone hydroboration catalyzed by alkali metal complexes derived from BINOL ligands.

The ability of alkali metal complexes featuring functionalized BINOL-derived ligands to catalyze ketone hydroboration reactions was explored. The reduced products were formed in excellent yields and with variable enantioselectivities dependent upon the nature of the ligand and the alkali metal cation.

Streamlined Synthesis of C(sp3)-Rich N-Heterospirocycles Enabled by Visible-Light-Mediated Photocatalysis.

We report a general visible-light-mediated strategy that enables the construction of complex C(sp3)-rich N-heterospirocycles from feedstock aliphatic ketones and aldehydes with a broad selection of alkene-containing secondary amines. Key to the success of this approach was the utilization of a highly reducing Ir-photocatalyst and orchestration of the intrinsic reactivities of 1,4-cyclohexadiene and Hantzsch ester. This methodology provides streamlined access to complex C(sp3)-rich N-heterospirocycles displaying structural and functional features relevant to fragment-based lead identification programs.

Mechanistic investigation into the C(sp3)-H acetoxylation of morpholinones.

The study of a selective palladium(ii)-catalyzed C(sp3)-H acetoxylation reaction on a class of cyclic alkyl amines is reported. Computational modelling and kinetic studies were used to provide support for a mechanism involving selective C-O bond formation from a γ-aminoalkyl-Pd(iv) intermediate. The C-O bond forming step was computed to occur by a dissociative ionization mechanism followed by an SN2 process involving external acetate attack at the C-Pd(iv) bond. This pathway was computed to be of lowest energy with no competing C-N products observed. Additionally, with a few modifications to reaction conditions, preliminary studies showed that this process could be rendered enantioselective in the presence of a non-racemic BINOL-phosphoric acid.

A general catalytic ß-C-H carbonylation of aliphatic amines to ß-lactams.

Methods for the synthesis and functionalization of amines are intrinsically important to a variety of chemical applications. We present a general carbon-hydrogen bond activation process that combines readily available aliphatic amines and the feedstock gas carbon monoxide to form synthetically versatile value-added amide products. The operationally straightforward palladium-catalyzed process exploits a distinct reaction pathway, wherein a sterically hindered carboxylate ligand orchestrates an amine attack on a palladium anhydride to transform aliphatic amines into ß-lactams. The reaction is successful with a wide range of secondary amines and can be used as a late-stage functionalization tactic to deliver advanced, highly functionalized amine products of utility for pharmaceutical research and other areas.

ZrCl2(η-C5Me5)2-AlHCl2·(THF)2: efficient hydroalumination of terminal alkynes and cross-coupling of the derived alanes.

Stabilized AlHCl(2)·(THF)(2) hydroaluminates RC≡CH with exceptional chemo-, regio- and stereoselectivity under efficient ZrCl(2)(η-C(5)Me(5))(2) catalysis (2-5 mol%). The resulting vinyl alanes undergo palladium cross-coupling with a wide range of sp(2) electrophiles (aryl, heteroaryl and vinyl halides/pseudohalides) in good to excellent yields.