Arylation of Cyclopropanol with Pyrrole: Asymmetric Synthesis of Indolizidine 167B, Indolizidine 209D, and Monomorine I.

A Fe(NO3)3-mediated ring-opening arylation of cyclopropanol with the electron-rich pyrrole has been developed, which might proceed through oxidative radical ring opening of cyclopropanol followed by cyclization to the pyrrole motif and then aromatization. This method enables direct arylation of cyclopropanol without prefunctionalization and thus allows rapid access to a diverse array of chiral 5,6,7,8-tetrahydroindolizines from easily available chiral amino acid esters. The synthetic utility has been demonstrated by the asymmetric synthesis of alklaoids (-)-indolizidine 167B, (+)-indolizidine 209D, (+)-monomorine I, and a natural product analogue.

Asymmetric Total Synthesis of Sarpagine and Koumine Alkaloids.

We report here a concise, collective, and asymmetric total synthesis of sarpagine alkaloids and biogenetically related koumine alkaloids, which structurally feature a rigid cage scaffold, with L-tryptophan as the starting material. Two key bridged skeleton-forming reactions, namely tandem sequential oxidative cyclopropanol ring-opening cyclization and ketone α-allenylation, ensure concurrent assembly of the caged sarpagine scaffold and installation of requisite derivative handles. With a common caged intermediate as the branch point, by taking advantage of ketone and allene groups therein, total synthesis of five sarpagine alkaloids (affinisine, normacusine B, trinervine, Na -methyl-16-epipericyclivine, and vellosimine) with various substituents and three koumine alkaloids (koumine, koumimine, and N-demethylkoumine) with more complex cage scaffolds has been accomplished.

Investigation of reactive oxygen species produced by microwave electrodeless discharge lamp on oxidation of dimethyl sulfide.

Microwave electrodeless discharge lamp (MEDL) has been regarded as a powerful light source of photoreaction. Four kinds of chemicals, nitrogen (N2), oxygen (O2), water (H2O) and dimethyl sulfide (DMS), were used as molecular probes to explore the generation process of reactive oxygen species (ROS) and their photo-oxidation performances on the photodegradation of organic pollutants with application of an exterior MEDL system. ROS such as O (3P), O3, O (1D) and 1O2 were generated via irradiation of O2 and H2O except dry N2 by MEDL. They were transformed to other ROS including ·OH and H2O2 with increase of relative humidity. The ROS productivity was inhibited evidently by humidity and ·OH became the major active species at high humidity. An optimal mineralization rate of 23.6% for DMS photodegradation was reached in dry air compared with 8.74% at high humidity, which indicated that O (1D) and 1O2 were more powerful oxidants than O3 and OH. The results showed that the higher mineralization rate of organic pollutants was obtained by increasing the generation efficiency of ROS of O (1D) and 1O2. Furthermore, the results provided an alternative to develop intensification technology on photodegadation of organic pollutants with MEDL system and an optimal operation process including photocatalyst and humidity.