19980-25-7Relevant articles and documents
Highly stereoselective oxazaborolidinium ion catalyzed synthesis of (Z)-silyl enol ethers from alkyl aryl ketones and trimethylsilyldiazomethane
Kang, Byung Chul,Shim, Su Yong,Ryu, Do Hyun
, p. 2077 - 2079 (2014/05/06)
Highly stereoselective (Z)-silyl enol ethers were prepared from alkyl aryl ketones and trimethylsilyldiazomethane (TMSD) using an oxazaborolidinium ion catalyst. In addition, ring-expanded silyl enol ethers were successfully constructed from cyclic ketones. Their synthetic utilities were shown by sequential Mukaiyama aldol and [2 + 2]-cycloaddition reactions.
A new method for the preparation of silyl enol ethers from carbonyl compounds and (trimenthylsily)diazomethane in a regiospecific and highly stereoselective manner
Aggarwal, Varinder K.,Sheldon, Chris G.,Macdonald, Gregor J.,Martin, William P.
, p. 10300 - 10301 (2007/10/03)
The reaction of lithium (trimethylsilyl)diazomethane with aldehydes and ketones has been investigated, and it has been found that quenching at low temperature with MeOH followed by addition of Rh2(OAc)4 gave silyl enol ethers in high yields. Quenching with other electrophiles (e.g., deuterium, MeI) gave terminal and substituted silyl enol ethers with complete control over regio- and stereochemistry. The mechanism of this novel process has been mapped out through a combination of deuterium labeling, ReactIR, and isolation of reaction intermediates. Copyright
α-nitration of ketones via enol silyl ethers. Radical cations as reactive intermediates in thermal and photochemical processes
Rathore, Rajendra,Kochi, Jay K.
, p. 627 - 639 (2007/10/03)
Highly colored (red) solutions of various enol silyl ethers and tetranitromethane (TNM) are readily bleached to afford good yields of α-nitro ketones in the dark at room temperature or below. Spectral analysis show the red colors to be associated with the intermolecular 1:1 electron donor-acceptor (EDA) complexes between the enol silyl ether and TNM. The formation of similar vividly colored EDA complexes with other electron acceptors (such as chloranil, tetracyanobenzene, tetracyanoquinodimethane, etc.) readily establish enol silyl ethers to be excellent electron donors. The deliberate irradiation of the diagnostic (red) charge-transfer absorption bands of the EDA complexes of enol silyl ethers and TNM at -40 °C affords directly the same α-nitro ketones, under conditions in which the thermal reaction is too slow to compete. A common pathway is discussed in which the electron transfer from the enol silyl ether (ESE) to TNM results in the radical ion triad [ESE?+, NO2?, C(NO2)3-]. A subsequent fast homolytic coupling of the cation radical of the enol silyl ether with NO2? leads to the α-nitro ketones. The use of time-resolved spectroscopy and the disparate behavior of theisomeric enol silyl ethers of α- and β-tetralones as well as of 2-methylcyclohexanone strongly support cation radicals (ESE?+) as the critical intermediate in thermal and photoinduced electron-transfer as described in Schemes 1 and 2, respectively.
