Atsushi Kaga

Diastereoselective aminooxygenation and diamination of alkenes with amidines by hypervalent iodine(III) reagents.

Diastereoselective anti-aminooxygenation and anti-diamination of alkenes with amidines were enabled by hypervalent iodine(III) reagents such as PhI(OCOR)2 and PhI(NMs2)2, respectively. The present transformation offers diastereochemically pure dihydroimidazoles divergently from E- and Z-alkenes.

Diastereo‐Divergent Synthesis of Saturated Azaheterocycles Enabled by tBuOK‐Mediated Hydroamination of Alkenyl Hydrazones

Diastereo-divergent synthesis of saturated azaheterocycles has been achieved by tBuOK-mediated hydroamination of alkenyl hydrazones. DFT calculations suggested that the cation-π interactions between a potassium cation and aryl substituents on hydrazones give rise to 2,5-cis selectivity in pyrrolidines, which were synthesized by the reaction of γ,δ-unsaturated N-benzyl hydrazones. By contrast, 2,5-trans selectivity was observed when an isopropyl group was used as the substituent on hydrazones. An unusual 2,6-trans selectivity in piperidine formation was also realized using the present strategy.

Application of Vinyl Azides in Chemical Synthesis: A Recent Update

Among organic azides, vinyl azides have shown versatile chemical reactivities in the recent development of new synthetic methodologies mainly for nitrogen-containing molecules. This synopsis highlights and discusses recent advances on use of vinyl azides in chemical synthesis as a radical acceptor and an enamine-type nucleophile.

Synthesis of Fasicularin

The synthesis of a tricyclic marine alkaloid, fasicularin, was accomplished. Stereoselective synthesis of the aza-spirocyclic BC-ring precursor and ensuing construction of the A-ring with stereocontrolled installation of the C2 hexyl group feature prominently in the synthesis.

Hydroamination of alkenyl N-arylhydrazones mediated by t-BuOK for the synthesis of nitrogen heterocycles

The t-BuOK-mediated reactions of γ,δ-alkenyl N-arylhydrazones enabled intramolecular hydroamination with the outer nitrogen, affording tetrahydropyridazine derivatives. DFT calculations demonstrated a clear distinction in the chemical reactivity between hydrazones and analogous oximes in inorganic base-mediated hydroamination.