Iodoarene-Mediated α-Tosyloxylation of Ketones with MCPBA and p-Toluenesulfonic Acid
作者:Hideo Togo、Ayumi Tanaka、Katsuhiko Moriyama
DOI:10.1055/s-0030-1260948
日期:2011.8
Alkyl aryl ketones and dialkyl ketones could be converted into the corresponding α-tosyloxy ketones by the reaction with MCPBA and p-toluenesulfonic acid monohydrate (PTSAËH2O) in the presence of a catalytic amount of molecular iodine (I2) in a mixture of acetonitrile and 2,2,2-trifluoroethanol, although the yields were dependent on the ketones (method A). The same conversion of alkyl aryl ketones and dialkyl ketones into the corresponding α-tosyloxy ketones could be smoothly carried out by the reaction with MCPBA and PTSAËH2O in the presence of catalytic amounts of iodine and tert-butylbenzene in a mixture of acetonitrile and 2,2,2-trifluoroethanol (method B). In those reactions, p-iodotoluene and 4-tert-butyl-1-iodobenzene were formed at first in method A and method B, respectively, and then they were converted into p-[(hydroxy)(tosyloxy)]iodotoluene and 4-tert-butyl-1-[(hydroxy)(tosyloxy)iodo]benzene by the reaction with MCPBA and PTSAËH2O. p-[(Hydroxy)(tosyloxy)]iodotoluene and 4-tert-butyl-1-[(hydroxy)-(tosyloxy)iodo]benzene worked as an α-tosyloxylation reagent of ketones.
4-MeC6H4I-Mediated Efficient α-Tosyloxylation of Ketones with Oxone® and p-Toluenesulfonic Acid in Acetonitrile
作者:Hideo Togo、Ayumi Tanaka
DOI:10.1055/s-0029-1218370
日期:2009.12
Various alkyl aryl ketones, dialkyl ketones, and cycloheptanone were efficiently converted into the corresponding α-tosyloxy ketones in good yields by using Oxone® and p-toluenesulfonic acid monohydrate in the presence of p-iodotoluene in acetonitrile. 4-Methoxyacetophenone and 2-acetylthiophene bearing an electron-rich aromatic group could be also converted into the corresponding α-tosyloxyketones smoothly in good yields with the present method. Here, p-iodotoluene works as catalyst and p-[(hydroxy)(tosyloxy)]iodotoluene is formed in situ as a reactive species for the α-tosyloxylation of ketones. However, one equivalent of p-iodotoluene was required to obtain α-tosyloxyketones in good yields and was recovered in 80-20% yields, depending on the reaction conditions.
room-temperature ionic liquid (RTIL) supported [hydroxy(tosyloxy)iodo]benzene (ion-supported HTIB) reagent was synthesised by three kinds of effective methods in high yields, which combined the advantages of ionic liquids and the hypervalent iodine. Ion-supported HTIB was an effective reagent for one-step conversion of ketones to the corresponding α-tosyloxylated ketones in the ionic liquid [emim]BF4or acetonitrile
A Novel One-Pot Method for α-Tosyloxylation of Ketones Using a Catalytic Amount of Ammonium Iodide
作者:Jie Yan、Jiantao Hu、Min Zhu、Yuan Xu
DOI:10.1055/s-0031-1289750
日期:2012.4
A novelone-pot procedure was designed for the preparation of various α-tosyloxy ketones in good yields by the reaction of ketones with m-chloroperoxybenzoic acid and p-toluenesulfonic acid monohydrate in the presence of catalytic amounts of ammoniumiodide and benzene in a mixture of acetonitrile and 2,2,2-trifluoroethanol (8:2) at room temperature for 24 hours. α-tosyloxylation - α-tosyloxy ketones
Effect of Substituents on the Regioselectivity of the Reaction of α-Tosyloxyketones with Thioureas in Acidic Medium: Access to 2-Aminothiazoles and 2-Imino-2,3-dihydrothiazoles
作者:Ranjana Aggarwal、Rajiv Kumar、Dionisia Sanz、Rosa M. Claramunt
DOI:10.1002/jhet.1676
日期:2014.5
Regioselective condensation of α‐tosyloxyacetophenones 1 and N‐substituted thioureas 2 in acidicmedium to give regioisomers 2‐aminothiazoles I and 2‐imino‐2,3‐dihydrothiazoles II is largely influenced by the substituents present on 1 and 2. A mechanism, supported by DFT calculations has been proposed to explain the observed regioselectively.