Cobalt/Salox-Catalyzed Enantioselective Dehydrogenative C-H Alkoxylation and Amination.

The past decade has witnessed a rapid progress in asymmetric C-H activation. However, the enantioselective C-H alkoxylation and amination with alcohols and free amines remains elusive. Herein, we disclose the first enantioselective dehydrogenative C-H alkoxylation and amination enabled by a simple cobalt/salicyloxazoline (Salox) catalysis. The use of cheap and readily available cobalt(II) salts as catalysts and Saloxs as chiral ligands provides an efficient method to access P-stereogenic compounds in excellent enantioselectivities (up to >99 % ee). The practicality of this protocol is demonstrated by gram-scale preparation and further derivatizations of the resulting P-stereogenic phosphinamides, which offering a flexible asymmetric alternative to access P-stereogenic mono- and diphosphine chiral ligands. Preliminary mechanistic studies on the enantioselective C-H alkoxylation reaction suggest that a cobalt(III/IV/II) catalytic cycle might be involved.

[The role of 9-cisRA in the regulation of pig preadipocyte differentiation].

RT-PCR,Oil red O staining, Oil red O staining extract and spectrometer were used to study the effect and mechanisms of different concentrations of 9-cis RA (0-10 micromol/L) on the differentiation of pig primary preadipocyte. The results showed that different concentrations of 9-cis RA had different effect on the differentiation of preadipocyte. Low concentrations of 9-cisRA (0-10 nmol/L) could promote the differentiation of preadipocyte and upregulate the expression of RXRalpha, PPARgamma mRNA and the activity of GPDH. High concentrations of 9-cisRA (100 nmol/L-10 micromol/L) could inhibit the differentiation of preadipocyte and downregulate the RXRalpha, PPARgamma mRNA and the activity of GPDH. These results showed that different concentrations of 9-cis RA could promote or inhibit the differentiation of pig preadipocyting by regulating the expressions of RXRalpha and PPARgamma.