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Takuya Hashimoto Dr. Kazuki Sakata Keiji Maruoka Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(27):5014-5017
Going through the phases : The title reaction was found to proceed by an initial base‐mediated isomerization to allenyl esters and subsequent phase transfer catalyzed alkylation at the α position of the ester (see scheme).
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Dhevalapally B. Ramachary Prof. Dr. Rajasekar Sakthidevi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(18):4516-4522
A practical and sustainable chemical process for the synthesis of highly substituted aldol?lactol products was achieved for the first time through the asymmetric Barbas–List aldol (BLA) reaction of 2‐hydroxybenzaldehydes with acetone in the presence of a catalytic amount of trans‐4‐OH‐L ‐proline (see scheme).
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Huan Wang Dr. Chuan Zhao Dr. Anand I. Bhatt Dr. Douglas R. MacFarlane Prof. Jia‐Xing Lu Prof. Alan M. Bond Prof. 《Chemphyschem》2009,10(2):455-461
Electrode‐dependent potential windows (see picture, GC=glassy carbon) are determined for five dialkylammonium carbamate (dialcarb) room‐temperature ionic liquids in a systematic study of their physical and electrochemical properties. The viscosity and conductivity of the dialcarb ionic liquids, which are “distillable” at low temperature, are comparable to those of some conventional room‐temperature ionic liquids.
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Eric S. Schmidtmann Dipl.‐Chem. Martin Oestreich Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(25):4634-4638
Once difficult to obtain , the title compounds can be prepared in virtually enantiomerically pure form with a bis(triorganostannyl) zinc reagent (see scheme). Subsequent diastereoselective thermal (left) and Lewis acid promoted reactions (right) illustrate the synthetic potential of these compounds.
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Xue‐Yi Chen Charles Barnes Dr. Jerry R. Dias Prof. T. C. Sandreczki Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(9):2041-2044
Triethylamine hydroiodide crystals were formed during Sonogashira reactions; after complete reaction the solution retains a characteristic light color (see picture). Very sluggish Sonogashira reactions of electron‐enriched aryl diiodides have been carried out in high yield in an oxygen‐free, two‐chamber reaction system. The formation of triethylamine hydroiodide crystals was monitored to determine the completion of reaction.
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Lei Gong Dr. Zhening Chen Yumei Lin Xumin He Prof. Dr. Ting Bin Wen Prof. Dr. Xin Xu Prof. Dr. Haiping Xia Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(25):6258-6266
Osmabenzenes can be easily synthesized from two η2‐coordinated olefin osmacycles in the presence of benzonitrile by means of facile hydrogen‐transfer conversions (see graphic). Mechanisms for the formation of osmabenzenes are proposed based on DFT calculations.
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Yi‐Fei Sheng Gong‐Qiang Li Qiang Kang Dr. An‐Jiang Zhang Prof. Dr. Shu‐Li You Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(14):3351-3354
Slowly does it! By adding the substrate by a syringe pump, a highly efficient Friedel–Crafts reaction of 4,7‐dihydroindoles with nitroolefins was realized with 0.5 mol % of a chiral phosphoric acid. The Friedel–Crafts alkylation, together with a subsequent oxidation of the product, led to 2‐substituted indoles in excellent enantiomeric excesses, which can be easily transformed to enantioenriched tetrahydro‐γ‐carbolines.
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Qiufeng Huang Dr. Ruimao Hua Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(15):3817-3822
Economical atoms : 2‐Cyclopenten‐1‐ones, 5‐alkylidenefuran‐2(5 H)‐ones and indan‐1‐ones have been synthesized by atom‐economic reductive cyclocarbonylation of internal alkynes with carbon monoxide catalyzed by [{RhCl(CO)2}2]/CO(NH2)2 in the presence of water (see scheme).
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Xiaogen Huang Dr. Teresa de Haro Cristina Nevado Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(24):5904-5908
Change the ligand, change the stereochemistry : 2,3‐Bis(acetoxy)‐1,3‐dienes are obtained in a stereocontrolled manner by a novel tandem 1,2‐/1,2‐bis(acetoxy) rearrangement (see scheme, R1 and R2 are δ+ stabilizing). Upon stabilization of the reaction intermediates, the ligand attached to gold controls the stereochemistry of the alkene in the second acetate migration, that is, N‐heterocyclic carbenes (NHC) favor cis alkenes, whereas phosphine ligands selectively afford trans olefins.
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Liana M. Klivansky Gayane Koshkakaryan Dennis Cao Yi Liu Dr. 《Angewandte Chemie (International ed. in English)》2009,48(23):4185-4189
Cage me! A linear dumbbell‐shaped bipyridinium molecule can template cage formation around itself through sixfold imine bond formation to give an interlocked [2]rotaxane as the single product (see picture). This highly efficient [2+3] clipping occurs despite the symmetry mismatch between the template and the formed macrobicycle.
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Hoi‐Yan Shiu Tak‐Chung Chan Dr. Chi‐Ming Ho Dr. Yungen Liu Dr. Man‐Kin Wong Dr. Chi‐Ming Che Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(15):3839-3850
Enriched cleavage : An efficient chemoselective cysteine modification of unprotected peptides and proteins has been developed by using electron‐deficient alkynes in aqueous media. Interestingly, terminal alkynone‐modified peptides could be converted back into the unmodified peptides by cleavage by adding thiols under mild conditions (see scheme).