An efficient one-pot protocol for the synthesis of (E)-nitroalkenes by reaction of aldehydes and nitroalkanes in the presence of polymer-bound triphenylphosphine, iodine and imidazole is described. Although the reaction works with similar efficiency with triphenylphosphine and its polymer-bound version, easy removal of the unwanted polymer-bound triphenylphosphine oxide and its recovery as triphenylphosphine provide the edge for practical application of the method. (C) 2013 Elsevier Ltd. All rights reserved.
Oxone® (2KHSO5·KHSO4·K2SO4) was used to promote the nitration of alkenes and alkynes with sodium nitrite (NaNO2) and potassium iodide (KI). This stable, easy-to-handle, and environmentally benign oxidant was used under mild conditions (room temperature) and provided short reaction times. Styrene derivatives that did not contain electron-donating groups afforded the corresponding nitro alkenes in moderate
A cyanide‐free platform technology for the synthesis of chiral nitriles by biocatalytic enantioselective dehydration of a wide range of aldoximes is reported. The nitriles were obtained with high enantiomeric excess of >90 % ee (and up to 99 % ee) in many cases, and a “privileged substrate structure” with respect to high enantioselectivity was identified. Furthermore, a surprising phenomenon was observed
A novelbifunctional organocatalyst library combining both aminocatalysis and phosphonicacid activation was used for the first time as an efficient tool for the stereoselectiveMichaeladdition of aldehydes with several aromatic nitroalkenes with good selectivities up to 95:5 dr and 93:7 er. Due to their high water solubility, the catalysts were easilyrecyclable and could be reused over several cycles
Indole-to-Carbazole Strategy for the Synthesis of Substituted Carbazoles under Metal-Free Conditions
作者:Shanping Chen、Yuxia Li、Penghui Ni、Huawen Huang、Guo-Jun Deng
DOI:10.1021/acs.orglett.6b02762
日期:2016.10.21
An efficient indole-to-carbazole strategy has been developed under metal-free conditions. This carbazole formation was highly promoted by NH4I with high regioselectivity through formal [2 + 2 + 2] annulation of indoles, ketones, and nitroolefins. It thus conveniently enabled the assembly of a large number of diversified carbazole products with good tolerance of a broad range of functional groups.