A series of air-stable, nitrile-ligated (cyclopentadienone)iron dicarbonyl compounds was synthesized and their activities as catalysts in the transfer reduction of acetophenone were explored. While all were active catalysts, the acetonitrile adduct was chosen for further study and was found to be active in the transfer reduction of aldehydes and ketones and in the Oppenauer-type oxidation of secondary alcohols. The acetonitrile catalyst exhibited activities similar to those of an analogous air-sensitive iron hydride, but unlike the iron hydride it was unreactive in carbonyl reductions using hydrogen gas.

We describe a cobalt-catalyzed hydroacylation of 1,3-dienes with non-chelating aldehydes. Aromatic aldehydes provide 1,4-addition products as the major isomer, while aliphatic aldehydes favor 1,2-hydroacylation products. The kinetic profile supports an oxidative cyclization mechanism involving a cobaltacycle intermediate that undergoes transformation with high regio- and stereoselectivity.

Over the past 40 years, intramolecular hydroacylation has favored five-membered rings, in preference to four membered rings. Herein, we report a catalyst derived from earth-abundant cobalt that enables preparation of cyclobutanones, with excellent regio-, diastereo-, and enantiocontrol, under mild conditions (2 mol % catalyst loading and as low as 50 °C).

General transfer hydrogenation procedure S6 Conversion monitoring of 4-phenyl-2-butanol dehydrogenation S7 General transfer dehydrogenation procedure S8 Product inhibition experimental details S8-S9 NMR experiments S9-S10 N-Benzylideneaniline reduction procedure S10-S11 References S11 NMR Spectra S12-S25 S2 General Methods. Compound 3 was prepared according to the literature procedure. S1 All commercially available chemicals and anhydrous solvents were used as received, and all reactions were done under an atmosphere of nitrogen unless otherwise noted. Reagent grade isopropanol and acetone (for the transfer hydrogenations and dehydrogenations) were degassed by bubbling N2 through them for at least 15 minutes prior to use, but no attempt was made to remove residual water. NMR spectra were recorded at rt (approx. 22 °C) unless otherwise noted on a Bruker Avance 400 MHz FT-NMR spectrometer. 13 C NMR spectra (100 MHz) were all proton decoupled. Chemical shifts are reported in parts per million (ppm) downfield from tetramethylsilane (TMS) with reference to TMS for 1 H NMR and 13 C NMR spectra. Multiplicities are abbreviated as follows: singlet (s), doublet (d), triplet (t), quartet (q), quintet (quint), sextet (sext), septet (sept), multiplet (m), and broad (br). IR spectra were collected on a Nicolet IR200 attenuated total reflectance FT-IR spectrometer and only diagnostic peaks are given. IR bands are given in cm-1 and peak intensities correspond to weak (w), medium (m), strong (s), and broad (br). High resolution mass spectrometry data were collected at the Johns Hopkins University Mass Spectrometry Facility. Analytical thin-layer chromatography (TLC) was performed using silica gel 60 F254 precoated plates (0.25 mm thickness) with a fluorescent indicator. Visualization was performed with UV light. Flash column chromatography was performed using silica gel 60 (230-400 mesh). Gas chromatograms were collected on a Thermo Scientific Trace 1300 gas chromatograph with an AI 1310 autosampler and an FID. A TR-5 (5% phenyl methylpolysiloxane) column (30 m length x 0.25 mm ID x 0.25 μm film thickness) was used under the following method conditions: 110 °C for 5 min, ramp 20 °C/min to 250 °C, hold at 250 °C for 2 min. The carrier gas was helium, used at a constant flow rate of 1 mL/min. A sample volume of 1 μL was added to the 300 °C injector at a 30:1 split ratio, and the FID temperature was 250 °C. Retention times (4.7 min for acetophenone, 4.5 min for 1-phenylethanol, 7.6 min for 4-phenyl-2-butanol, 7.4 min for 4-phenyl-2-butanone, 11.2 min for Nbenzylideneaniline, 11.5 min for N-benzylamine, and 9.0 min for biphenyl) were determined using pure samples. Synthesis of Iron Compounds Scheme S1. Synthesis of 4. (2,3,4,5-Tetraphenylcyclopentadienone)iron tricarbonyl (4). S2 A solution of 2,3,4,5tetraphenylcyclopentadienone S3 8a (3.0 g, 7.8 mmol) and iron pentacarbonyl (2.0 mL, 3.0 g, 15 mmol) in 35 mL degassed toluene in a thick-walled round-bottom flask with a PTFE screw cap was heated to 140 °C for 24 h. After cooling to rt,...

A Rh-catalyzed desymmetrization of α,α-bis(allyl)aldehydes occurs by enantioselective isomerization followed by olefin-directed hydroacylation.