Palladium-Catalyzed Enantioselective Isodesmic C-H Iodination of Phenylacetic Weinreb Amides.

Isodesmic reactions represent mild alternatives to other chemical transformations that require harsh oxidizing agents or highly reactive intermediates. However, enantioselective isodesmic C-H functionalization is unknown and enantioselective direct iodination of inert C-H bond is very rare. Rapid synthesis of chiral aromatic iodides is of significant importance for synthetic chemistry. Herein, we report an unprecedented highly enantioselective isodesmic C-H functionalization to access chiral iodinated phenylacetic Weinreb amides via desymmetrization and kinetic resolution with PdII catalysis. Importantly, further transformations of the enantioenriched products are readily available at the iodinated or the Weinreb amide position, paving the way of related studies for synthetic and medicinal chemists.

Formal C-H/C-I Metathesis: Site-Selective C-H Iodination of 2-Aryl Benzoic Acid Derivatives Using Aryl Iodide.

C-H functionalization via functional group metathesis is extremely rare. A protocol of remote site-selective C-H iodination of 2-aryl benzoic acid derivatives via formal C(sp2)-H/C(sp2)-I metathesis using readily available 1-iodo-4-methoxy-2-nitrobenzene as the mild iodinating reagent was reported herein. A range of 2-aryl benzoic acid derivatives including 2-(naphthalen-1-yl)benzoic acids and [1,1'-binaphthalene]-2-carboxylic acids were iodinated under mild conditions to give valuable iodinated products in a site- and chemo-selective fashion.

Formal C-H/C-I Metathesis: Site-Selective C-H Iodination of Anilines Using Aryl Iodides.

Functional group metathesis has the potential to render mild reaction conditions for C-H functionalization. Protocols for the meta- and ortho-C-H iodination of aniline derivatives via formal C(sp2)-H/C(sp2)-I metathesis using 2-nitrophenyl iodides as mild iodinating reagents are reported herein. These protocols led to the production of a range of valuable iodinated aniline derivatives. These results demonstrate the potential of developing novel site-selective C-H activation reactions with electron-rich compounds, since mild reagents can often been utilized in functional group metathesis reactions.

Comparative analysis of hissing calls in five tit species.

Nest predation often leads to breeding failure and is an important component of natural selection that affects the evolution of nest defense behavior in birds. Many tit species give a hissing call as nest defense, but there are few studies of interspecific variation in hissing calls, and whether these are related to nest predation and nesting success. In this study, we compared the hissing calls of five tit species including cinereous tits (Parus cinereus), marsh tits (Poecile palustris), varied tits (Sittiparus varius), willow tits (Poecile montanus), and coal tits (Periparus ater) in Saihanba National Forest Park in Hebei and Xianrendong National Nature Reserve in Liaoning. In Saihanba of Hebei, the proportion of cinereous, willow, and coal tit individuals giving a hissing call differed significantly but the rate of nest predation was similar. It was also true for the three tit species (cinereous, varied, and marsh tits) in Xianrendong of Liaoning. Cinereous and varied tits showed no differences in clutch size, date of the first egg, nest predation and nesting success between individuals that gave and those that did not give a hissing call. These results indicate that for tit species that breed in nest boxes distributed within the same area, there is interspecific variation in hissing calls but this variation is not significantly correlated with nest predation risk.