One-Pot Selective Homodimerization/Hydrogenation Strategy for Sequential Dicarba Bridge Formation

The installation of interlocked dicarba bridges into peptide sequences requires the development of a regioselective and chemoselective methodology. This manuscript describes a one-pot, chemoselective synthesis of three 2,7-diaminosuberic acid derivatives from an alkyne, a cobalt–carbonyl protected alkyne, and an alkene using metathesis and homogeneous hydrogenation catalysis

Cross-Metathesis Approach to the Tricyclic Marine Alkaloids (−)-Fasicularin and (−)-Lepadiformine A

A cross-metathesis protocol has been developed to provide facile access to highly hindered trisubstituted α-branched olefins, which when coupled with a cationic azaspirocyclization reaction, generates the marine alkaloids (−)-fasicularin <b>2</b> and a pro-forma synthesis of (−)-lepadiformine A <b>1</b>

Divergent Approach to a Family of Tyrosine-Derived Ru–Alkylidene Olefin Metathesis Catalysts

A simple and generic approach to access a new family of Ru–alkylidene olefin metathesis catalysts with specialized properties is reported. This strategy utilizes a late stage, utilitarian Hoveyda-type ligand derived from tyrosine, which can be accessed via a multigram-scale synthesis. Further functionalization allows the catalyst properties to be tuned, giving access to modified second-generation Hoveyda–Grubbs-type catalysts. This divergent synthetic approach can be used to access solid-supported catalysts and catalysts that function under solvent-free and aqueous conditions

A Formal Synthesis of (−)-Perhydrohistrionicotoxin Using a Cross Metathesis–Hydrogenation Approach

The development of an efficient, high yielding six-step convergent synthesis of the semisynthetic alkaloid (−)-perhydrohistrionicotoxin is described. The key transformations include the cross metathesis of a Brønsted-acid masked primary homoallylic amine with a vinyl cyclohexenone and a regioselective palladium catalyzed hydrogenation. This sequence generated the advanced Winterfeldt spirocyclic precursor in 47% overall yield, with a longest linear sequence of five steps

Long-Time-Period, Low-Temperature Reactions of Green River Oil Shale

Reactions of water-washed chunks of a deeply buried Green River oil shale (2880–2920 ft, well below the water table) have been carried out in N₂–H₂O and CO–H₂O for up to 28 days at temperatures in the range of 280–370 °C. Large variations in yields of liquid products were observed for reactions below 330–340 °C. These were attributed to varying mineralogy in the chunks because the variations disappeared for reactions of ground samples or reactions above 330–340 °C, at which point the chunks disintegrated. Liquid-product yields of up to 70 wt % dry mineral matter free could be obtained from the chunks at temperatures as low as 320 °C, provided that long reaction times of 14 or 28 days were used. In particular, at lower temperatures, yields were higher under N₂ than under CO, but the quality of the CO–H₂O petroleum or oil/gas products tended to be better than that of N₂–H₂O products. The liquid products contained 1–2 wt % nitrogen, were high in aliphatic material, and contained significant amounts of heavily substituted aromatic rings