Cross-Metathesis of Methallyl Halides: Concise Enantioselective Formal Total Synthesis of (-)-Presphaerene.

The cross-metathesis (CM) of methallyl halides catalyzed using four different ruthenium-based complexes-Grubbs catalyst, Grubbs second-generation catalyst, Hoveyda-Grubbs second-generation catalyst, and Stewart-Grubbs catalyst-was investigated. When methallyl chloride or bromide was reacted with a model substrate containing a benzyl ether group, the Grubbs catalyst, and Grubbs second-generation catalyst did not promote the reaction well. However, the Hoveyda-Grubbs second-generation catalyst and Stewart-Grubbs catalyst afforded the corresponding products in moderate to good yield with moderate E/Z selectivity. Accordingly, several functionalized methallyl halides were prepared by CM. Various functional groups were well-tolerated in this system when the Stewart-Grubbs catalyst was used. To demonstrate the practical utility of our method, methallyl halide CM was successfully employed for the formal total synthesis of a natural product (-)-presphaerene, in which the precursor of the key cyclopentanecarboxylate intermediate was efficiently prepared in three steps.

Identification of a new M-ALPHA analog and MDMA in an illegal health product.

The widespread abuse of illicit psychoactive substances is one of the most serious public health and social problems. A suspicious airmail package was seized by Korean customs, and two psychoactive substances in the grayish-green pills in the package were detected by ultra-performance liquid chromatography. The structures of the two substances were elucidated by a combination of liquid chromatography quadrupole time-of-flight mass spectrometry, nuclear magnetic resonance spectroscopy, and comparison with reported or newly generated spectral data of the suggested structures. One of the psychoactive substances proved to be MDMA (commonly known as "Ecstasy"), and the other compound was an M-ALPHA analog bearing a hydroxyl group and an N-methylcarboxamide group. The new M-ALPHA analog was determined as 3-(benzo[d][1,3]dioxol-5-yl)-2-hydroxy-N,2-dimethyl-3-(methylamino)propanamide and named as M-ALPHA-HMCA, wherein HMCA denotes hydroxymethylcarboxamide. Although psychoactivity of this compound has not been assessed, M-ALPHA-HMCA should be considered a potential new psychoactive substance and/or a by-product of MDMA.