Total synthesis of phenazinomycin and its enantiomer via high-pressure reaction

Aerobic Dehydrogenation of N-Heterocycles with Grubbs Catalyst: Its Application to Assisted-Tandem Catalysis to Construct N-Containing Fused Heteroarenes

An aerobic dehydrogenation of nitrogen-containing heterocycles catalyzed by Grubbs catalyst is developed. The reaction is applicable to various nitrogen-containing heterocycles. The exceptionally high functional group compatibility of this method was confirmed by the oxidation of an unprotected dihydroindolactam V to indolactam V. Furthermore, by taking advantage of the oxygen-mediated structural change of the Grubbs catalyst, we integrated ring-closing metathesis and subsequent aerobic dehydrogenation to develop the novel assisted-tandem catalysis using molecular oxygen as a chemical trigger. The utility of the assisted-tandem catalysis was demonstrated by the concise synthesis of N-containing fused heteroarenes including a natural antibiotic, pyocyanine.

A Practical, Enantiospecific Synthesis of (S)-Trans-γ-Monocyclofarnesol

An expedient and concise synthesis of (S)-trans-γ-monocyclofarnesol is here described. The aforementioned sesquiterpene was prepared starting from enantioenriched (S)-γ-dihydroionone, which was in turn obtained from racemic α-ionone through the combined use of two previously developed processes. Key steps of the presented synthesis are the stereoselective Horner-Wadsworth-Emmons reaction between triethyl phosphonoacetate and γ-dihydroionone and the effective fractional crystallization of the γ-monocyclofarnesol-3,5-dinitrobenzoate esters. By these means the target compound was obtained in good yield and with very high stereoisomeric purity.