Nucleophilic fluorination of β-ketoester derivatives with HBF4
作者:Raffaele Pasceri、Hannah E. Bartrum、Christopher J. Hayes、Christopher J. Moody
DOI:10.1039/c2cc37284c
日期:——
Treating readily available α-diazo-β-ketoesters with HBF4 results in nucleophilic fluorination by the usually inert and stable tetrafluoroborate anion. The resulting α-fluoro-β-ketoesters are highly versatile synthetic intermediates, for example in the preparation of fluoro-heterocycles, as illustrated by the direct formation of fluoro-pyrimidines, -pyrazoles and -coumarins in a single step.
The selective and direct introduction of the fluorine atom into the α-position of β-dicarbonylcompounds was electrochemically achieved using iodotoluene difluoride as the mediator. The resulting α-fluoro-β-dicarbonyl compounds are important building blocks for biologically active compounds.
Acylation of fluorocarbethoxy-substituted ylides: a simple and general route to .alpha.-fluoro .beta.-keto esters
作者:Alagappan Thenappan、Donald J. Burton
DOI:10.1021/jo00001a052
日期:1991.1
(Fluorocarbethoxymethylene)tri-n-butylphosphorane (3) reacts with acid chlorides and anhydrides to form the corresponding carbon acylated phosphonium salts 4, and hydrolysis of 4 under mild basic conditions provides RCOCFHCOOEt (8) in moderate yields. The reaction is applicable to primary, secondary, tertiary, cyclic, aromatic, and ester-substituted acid chlorides. Acylation with ethyl chloroformate and ethyl chlorothioformate leads to the diesters CFH(COOEt)2 and EtSCOCFHCOOEt. Extension of this reaction sequence to perfluorinated and partially fluorinated acid chlorides did not proceed cleanly to give the expected phosphonium salts. However, the anion derived from (EtO)2P(O)CFHC(O)OEt reacts with R(F)COCl to form the corresponding C-acylated phosphonates 10, and hydrolysis of 10 gives R(F)COCFHCOOEt.
An expedient synthesis of α-fluoro-β-ketoesters
作者:Alagappan Thenappan、Donald J. Burton
DOI:10.1016/s0040-4039(01)93318-0
日期:——
A Facile P-C Bond Cleavage of 2-Fluoro-2-Phosphonyl-1,3-Dicarbonyl Compounds on Silica Gel
作者:Dae Young Kim
DOI:10.1080/00397910008087140
日期:2000.4
alpha-Fluoro-beta-keto esters and alpha-fluoromalonates were prepared by the P-C bond cleavage of 2-fluoro-2-phosphonyl-1,3-dicarbonyl compounds on wet silica gel.