Generation of Magnesium Pentafluoropropen-2-olate from Hexafluoroisopropanol and Synthesis of 2,2,4,4,4-Pentafluoro-3,3-dihydroxyketones
摘要:
2,2,4,4,4-Pentafluoro-3,3-dihydroxyketones are valuable precursors to difluoroenolates following fragmentation during the release of trifluoroacetate; however, there are few synthetic strategies to prepare this unique class of compound. We addressed this issue and report a mild, two-step synthesis of 2,2,4,4,4-pentafluoro-3,3-dihydroxyketones from aldehydes. Specifically, aldehydes are treated with pentafluoropropen-2-olate, generated from a new fragmentation of hexafluoroisopropanol with a mixed Mg/Li amide, to give pentafluoroalcohols. A subsequent oxidation with Dess-Martin periodinane provides the targets in good isolated yields.
Conversion of methyl ketones and methyl sulfones into α-deutero-α,α-difluoromethyl ketones and α-deutero-α,α-difluoromethyl sulfones in three synthetic steps
作者:Munia F. Sowaileh、Changho Han、Robert A. Hazlitt、Eun Hoo Kim、Jinu P. John、David A. Colby
DOI:10.1016/j.tetlet.2016.12.018
日期:2017.2
Deuterodifluoromethyl ketones and sulfones were assembled in three synthetic steps from methylketones and sulfones, respectively. The key synthetic transformation is the deuteration of the difluorocarbanion generated by the release of trifluoroacetate from highly α-fluorinated gem-diols. High levels of deuterium on the "CF2D" group were routinely observed. This strategy is mild and versatile and it
Microwave-Assisted Copper Catalysis of α-Difluorinated <i>gem</i>-Diol toward Difluoroalkyl Radical for Hydrodifluoroalkylation of <i>para</i>-Quinone Methides
gem-diols by single electron oxidation. Under microwave irradiation, a catalytic amount of oxidant Cu(OAc)2 succeeds in the formation of transient difluoroalkyl radicals in situ, for the first time. The reaction features a simple protocol, short reaction time, scalability, and high yield. The synthetic utility of this new methodology was also explored for the synthesis of difluoroalkylated spiro-cyclohexadienones
A visible light promoted C(sp3)–H difluoromethylation of tetrahydroisoquinolines that uses stable and easily prepared α,α-difluorinated gem-diol as the CF2 source is disclosed.
Generation of formaldehyde and formaldehyde-d<sub>2</sub> for hydroxymethylations and hydroxydeuteromethylations of difluoroenolates and difluorobenzyl carbanions
作者:Hari R. Khatri、Changho Han、Reem A. Alkhodier、Amna T. Adam、Baharul Islam、David A. Colby
DOI:10.1039/d2cc01518h
日期:——
A method for the in situ production of formaldehyde from dimethylsulfoxide, bromine, and cesium carbonate is reported for reactions with difluoroenolates and difluorobenzyl carbanions. This process also generates formaldehyde-d2 for the production of 2,2-difluoro-1,1-deuteroethanols. Mechanistic and computational studies further characterize the production of hydroxymethylated and hydroxydeuteromethylated
iododifluoromethyl ketones with α, β-unsaturatedketones, which provides an obviously significant route to access 1,2-addition product with excellent regioselectivity. This method has a wide range of substrate scope, good efficiency, and mild reaction conditions. In addition, this method was applied to the synthesis of difluoro derivatives of biologically active molecules containing unsaturated ketone structures