Pd(0)-Catalyzed Alkene Oxy- and Aminoalkynylation with Aliphatic Bromoacetylenes
摘要:
Tetrahydrofurans and pyrrolidines are among the most important heterocycles found in bioactive compounds. Cyclization-functionalization domino reactions of alcohols or amines onto olefins,constitute one of the most efficient methods to access them. In this context oxy- and aminoalkynylation are especially important reactions because of the numerous transformations possible with the triple bond of acetylenes yet these methods have been limited to the use of silyl protected acetylenes. Herein we report the first palladium-catalyzed oxy- and aminoalkynylation using aliphatic bromoalkynes which proceeded with high diastereoselectivity and functional group tolerance. A one-pot hydrogenation of the triple bond gave then access to alkyl-substituted tetrahydrofurans and pyrroldines. Finally a detailed study of the side products formed during the reaction gave a first insight into the reaction mechanism.
Enantiodivergent α-Amino C–H Fluoroalkylation Catalyzed by Engineered Cytochrome P450s
作者:Juner Zhang、Xiongyi Huang、Ruijie K. Zhang、Frances H. Arnold
DOI:10.1021/jacs.9b04344
日期:2019.6.26
engineered cytochrome P450 enzymes to catalyze this abiological reaction under mild conditions with total turnovers (TTN) up to 4070 and enantiomeric excess (ee) up to 99%. The iron-heme catalyst is fully genetically encoded and configurable by directed evolution so that just a few mutations to the enzyme completely inverted product enantioselectivity. These catalysts provide a powerful method for synthesis
Aerobic intramolecular aminothiocyanation of unactivatedalkenes has been developed by in situ generated iodine thiocyanate under open-flask conditions. This protocol provides a concise and efficient method for synthesizing SCN-containing pyrrolidine, piperidine and indoline derivatives with isolated yields of up to 87%. Furthermore, mixing iodine and sodium thiocyanate with oxygen afforded iodine
FeCl2-Promoted Cleavage of the Unactivated CC Bond of Alkylarenes and Polystyrene: Direct Synthesis of Arylamines
作者:Chong Qin、Tao Shen、Conghui Tang、Ning Jiao
DOI:10.1002/anie.201202464
日期:2012.7.9
efficient and convenient nitrogenation strategy involving CCbondcleavage for the straightforward synthesis of versatile arylamines is presented. Various alkyl azides and alkylarenes, including the common industrial by‐product cumene, react using this protocol. Moreover, this method provides a potential strategy for the degradation of polystyrene.
Use of (Cyclopentadienone)iron Tricarbonyl Complexes for C–N Bond Formation Reactions between Amines and Alcohols
作者:Thomas J. Brown、Madeleine Cumbes、Louis J. Diorazio、Guy J. Clarkson、Martin Wills
DOI:10.1021/acs.joc.7b01990
日期:2017.10.6
of a series of (cyclopentadienone)iron tricarbonyl complexes to “borrowing hydrogen” reactionsbetweenamines and alcohols was completed in order to assess their catalytic activity. The electronic variation of the aromatic groups flanking the C═O of the cyclopentadienone influenced the efficiency of the reactions; however, in other cases, the Knölker catalyst 1, containing trimethylsilyl groups flanking
aziridine to copper. ESI-MS analysis provided evidence of involvement of reactive Cu(II) intermediates in the catalytic cycle. Overall, our results indicate that the reaction proceeds at the hypervalent iodine moiety of Togni reagent, which is activated by Cu(II) species acting as a Lewis acid catalyst. On the basis of these mechanistic considerations, we developed an efficient synthesis of trifluoromethylated