Thioether-directed Rh(III)-catalyzed peri-selective acyloxylation of arenes.

A thioether directed acyloxylation of arenes has been realized via Cp*Rh(III)-catalyzed C-H activation and subsequent coupling with carboxylic acids. This new method showed high functional group compatibility and broad substrate scope. Primary mechanistic studies have been conducted and a tentative reaction mechanism was proposed. It represents the first example of a thioether-directed Cp*Rh(III)-catalyzed C(sp2)-H acyloxylation reaction.

Access to acridones by tandem copper(I)-catalyzed electrophilic amination/Ag(I)-mediated oxidative annulation of anthranils with arylboronic acids.

An efficient and practical approach for the synthesis of medicinally important acridones was developed from anthranils and commercially available arylboronic acids by a tandem copper(I)-catalyzed electrophilic amination/Ag(I)-mediated oxidative annulation strategy. This new and straightforward protocol displayed a broad substrate scope (25 examples) and high functional group tolerance. What's more, a possible mechanistic proposal was also presented.

Cp*Co(III)-Catalyzed Annulations of 2-Alkenylphenols with CO: Mild Access to Coumarin Derivatives.

Cp*Co(III)-catalyzed annulations of 2-alkenylphenols with CO for the synthesis of coumarin derivatives have been developed. The reaction features mild reaction conditions, broad substrate scope, and good functional group tolerance. Preliminary mechanistic studies were conducted, suggesting that C-H activation is the turnover limiting step. Furthermore, the efficiency of this reaction was demonstrated by the rapid total synthesis of three natural products herniarin, xanthyletin, and seselin.

Cp*Rh(III) and Cp*Ir(III)-catalysed redox-neutral C-H arylation with quinone diazides: quick and facile synthesis of arylated phenols.

Cp*Rh(III)- and Cp*Ir(III)-catalysed direct C-H arylation with quinone diazides as efficient coupling partners is disclosed. This redox-neutral protocol offers a facile, operationally simple and environmentally benign access to arylated phenols. The reaction represents the first example of Cp*Ir(III)-catalysed C-H direct arylation reaction.

[Studies on the chemical constituents from Euphorbia chrysocoma].

OBJECTIVE: To study the chemical constituents from the aerial part of Euphorbia chrysocoma. METHODS: All compounds were isolated and purified by many methods, including siliga gel and reversed phase RP-18 column chromatographies, preparative thin layer chromatography, Sephadex LH-20, and recrystallization. Their structures were mainly elucidated by ESI-MS and NMR spectra and their physical characters. RESULTS: Six compounds were isolated from the petroleum ether section from 75% ethanol extraction of the material. Their structures were identified as taraxerol (1), epitaraxerol (2), beta-sistosterol (3), beta-sitostenone (4), jolkinolide E (5), and sesamin (6). CONCLUSION: Compounds 1, 2, 4, 5, and 6 are isolated from this plant for the first time.