Cyclic Allene Approach to the Manzamine Alkaloid Keramaphidin B.

We report an approach to the core of the manzamine alkaloid keramaphidin B that relies on the strain-promoted cycloaddition of an azacyclic allene with a pyrone trapping partner. The cycloaddition is tolerant of nitrile and primary amide functional groups and can be complemented with a subsequent retro-Diels-Alder step. These efforts demonstrate that strained cyclic allenes can be used to build significant structural complexity and should encourage further studies of these fleeting intermediates.

Arene C-H borylation strategy enabled by a non-classical boron cluster-based electrophile.

Introducing a tri-coordinate boron-based functional group (e.g., boronic ester) into an unactivated C-H bond in the absence of directing groups is an ongoing challenge in synthetic chemistry.

Sulfide Oxidation by 2,6-Bis[hydroxyl(methyl)amino]-4-morpholino-1,3,5-triazinatodioxomolybdenum(VI): Mechanistic Implications with DFT Calculations for a New Class of Molybdenum(VI) Complex.

Sulfide oxidation is accomplished by a new class of dioxomolybdenum(VI) catalyst () that uses the tridentate 2,6-bis[hydroxyl(methyl)amino]-4-morpholino-1,3,5-triazine ligand to form a five-coordinate molybdenum(VI) center. Resonance Raman spectra show that the dioxo groups on the Mo(VI) oxygens readily exchange with water in an acetonitrile media that allows O labeling of catalyst . The model oxidation reaction was the conversion of thioanisole () to the corresponding sulfoxide with 4% of using an equimolar amount of HO in MeCN-.