Monthly Archives: November 2012

Prof. Masaharu Nakamura Visited Our Lab

Prof. Masaharu Nakamura(Full professor at ICR, Kyoto University) visited our lab on 26th.Nov. In the morning, he gave us a wonderful lecture entitled with “C-C and C-N cross coupling reactions under High-oxidation-state Iron catalysis”, and after the lecture, he also discussed several questions with Prof. Aiwen Lei and students. We really learned a lot from Prof. Masaharu Nakamura’s lecture about iron catalysis.

New Paper:Spectroscopic observation of iodosylarene metalloporphyrin adducts and manganese(V)-oxo porphyrin species in a cytochrome P450 analogue

New Paper:Spectroscopic observation of iodosylarene metalloporphyrin adducts and manganese(V)-oxo porphyrin species in a cytochrome P450 analogue

Mian Guo,?Hang Dong,?Jie Li,?Ben Cheng,?Yun-qing Huang,?Yu-qi Feng?& Aiwen Lei

NATURE COMMUNICATIONS, 2012, Preview

DOI: 10.1038/ncomms2196

Abstract
Different metalloporphyrin model compounds have been synthesized to study the mechanisms of cytochrome P450s with various terminal oxidants, and numerous intermediates have been reported. However, the detailed mechanism of the oxygen atom transfer from iodosylarene to the substrates remains unclear. Here we report the direct ultraviolet-visible spectroscopic observation of the soluble iodosylarene-manganese porphyrin adduct following catalytic oxidation using 2,4,6-tri-tert-butylphenol as the reductant. When the reductant is changed to cis-stilbene, the rate-determining step also changes. Both the iodosylarene-manganese porphyrin adduct and [(porphyrin)Mn(V)=O] species may be simultaneously observed. In the absence of reductant, the adduct of iodosylarene with sterically hindered [Mn(meso-tetrakis(2,6-dichlorophenyl)porphinato)Cl] is immediately formed, and smoothly converted into a high-valent [(porpyrinato)Mn=O]. Electrospray ionization mass spectrometry analysis of the reaction further confirms the transformation between these species. This study provides an insight into the mechanism of oxygen transfer within the haem-containing enzymatic systems.?

 

New Paper:DDQ-Catalyzed Oxidative C-O Coupling Of sp3 C-H Bonds With Carboxylic Acids

New Paper:DDQ-Catalyzed Oxidative C-O Coupling Of sp3 C-H Bonds With Carboxylic Acids

Hong Yi, Qiang Liu, Jie Liu, Ziqi Zeng,Yuhong Yang, Prof. Aiwen Lei*

ChemSusChem 2012 Early View

DOI: 10.1002/cssc.201200458

http://onlinelibrary.wiley.com/doi/10.1002/cssc.201200458/abstract

Da-ddy, DDQ: By using catalytic amounts of DDQ combined with MnO2 as oxidant, an efficient oxidative C[BOND]O coupling of benzylic sp3 C[BOND]H bonds with carboxylic acids affords a series of carboxylic esters in 70–98 % yields. A wide range of functional groups and various carboxylic acids are tolerated. The reaction involves both C[BOND]H functionalization and C[BOND]O bond formation.

New Paper:Transition-Metal-Free Alkoxycarbonylation of Aryl Halides

New Paper

燭ransition-Metal-Free Alkoxycarbonylation of Aryl Halides

Hua Zhang, Renyi Shi, Anxing Ding, Lijun Lu, Borui Chen, and Aiwen Lei*

Angew. Chem. Int. Ed. 2012 Early View

DOI : 10.1002/anie.201206518

http://onlinelibrary.wiley.com/doi/10.1002/anie.201206518/abstract

Transitions: The title reaction has been developed for the synthesis of a variety of tert-butyl benzoates by employing 1,10-phenanthroline as an additive. Various functional groups were tolerated and heteroaryl iodides were also suitable substrates. Preliminary mechanism studies were conducted and indicate the participation of radical intermediates.