Protonation of acyl anion equivalents generated from acylphosphonates: nonhydride access to the aldehyde oxidation state from the carboxylic acid oxidation state
摘要:
Acylphosphonates, which are easily available from carboxylic acids, are potent acyl anion precursors and undergo cyanide ion promoted phosphonate-phosphate rearrangement to provide the corresponding acyl anion equivalents as reactive intermediates. The protonation of these acyl anion equivalents furnished cyanohydrin O-phosphates in good yields. For the high yield formation of cyanohydrin O-phosphates from arylphosphonates THF should be used and from alkylphosphonates DME was used. (c) 2006 Elsevier Ltd. All rights reserved.
Fe(OTf)3-catalyzed Friedel–Craftsreaction of 2,2-difluoro-1-arylethyl phosphates with electron-rich (hetero)arenes afforded difluoromethylated diarylmethanes. Control experiments showed that Fe(OTf)3 behaves as the Lewis acid, and that the phosphate leaving group and o- or p-alkoxy substituents on the substrates are necessary for the Fe(OTf)3-catalyzed reaction to proceed under mild conditions.
The first method for cyano-phosphorylation of aldehydes with diethyl cyanophosphonate in the presence of N-heterocyclic carbene prepared from 1,3-bis(2,4,6-trimethylphenyl)imidazolium chloride and KOt-Bu, as a nucleophilic catalyst, is described.