Selective Formal Transesterification of Fluorinated 2-(Trimethylsilyl)ethyl α-Imino Esters Mediated by TBAF
作者:Santos Fustero、María Sánchez-Roselló、Vanessa Rodrigo、Amador García、Silvia Catalán、Carlos del Pozo
DOI:10.1021/jo800567a
日期:2008.7.1
The scope of the transesterification reaction between β-fluorinated α-imino esters and various electrophiles in the presence of TBAF as fluorine source is described. The reaction is highly selective for alkyl iodides, bromides, and mesylates, while alkyl chlorides react at a significantly slower rate and tosylates do not react under the reaction conditions. This methodology represents a simple and
A new and general synthesis of N-substituted fluorinated β-iminosulfoxides
作者:Santos Fustero、Antonio Navarro、Amparo Asensio
DOI:10.1016/s0040-4039(97)01051-4
日期:1997.7
Reaction of fluorinated imidoyl chlorides 1 with lithium enolates of chiral non-racemic methyl p-tolyl sulfoxide or racemic methyl phenyl sulfoxide 2 gave N-substituted γ-fluorinated β-iminosulfoxides 3 in excellent yields as the major tautomer with Z geometry.
New Strategies for the Synthesis of Fluorinated Vinylogous Amidines and β-Enamino Ketones
作者:Santos Fustero、Marta García de la Torre、Belén Pina、Antonio Simón Fuentes
DOI:10.1021/jo990392w
日期:1999.7.1
imidoyl chlorides 3 with ketimines 1a provides fluorinated 1,3-diimines, which were exclusively isolated as vinylogous amidine tautomers 2beta, with good yields. Fluorinated beta-enamino ketones 4 are obtained by regioselective hydrolysis of 2. Complementary methods for the synthesis of regioisomeric beta-enamino ketones 4 and 5 are also reported. These methods include the reaction of azaenolates of
Reaction of fluorinated and nonfluorinated N-substituted imidoyl chlorides 1 with lithium derivatives of enantiopure methyl p-tolyl sulfoxide 2a (or racemic methyl phenyl sulfoxide 2b) gave a wi;ie variety of chiral N-substituted beta-imino sulfoxides 4 in good to excellent yields. The title compounds (R)-4 were also prepared by aza-Wittig reaction of gamma-fluoro-beta-keto sulfoxides (R)-5 and N-aryl iminophosphoranes 6. The imino-enamino equilibrium was studied, showing, in all instances, the imino form as the predominant tautomer independent of the nature of the N-substituent. The configuration of the C=N double bond was found to be Z for both N-alkyl and N-aryl derivatives on the basis of H-1 NMR NOE difference experiments performed over several compounds. Ab initio calculations (HF/6-31G*) carried out on several representative examples of 1 and 4 are, in general, consistent with the experimental results.