Co-reporter:Gemma C. Geary, Eric G. Hope, Kuldip Singh and Alison M. Stuart
RSC Advances 2015 vol. 5(Issue 21) pp:16501-16506
Publication Date(Web):22 Jan 2015
DOI:10.1039/C4RA15733H
The isolation of iodonium ylide 8, from the reaction of fluoroiodane 1 with ethyl 3-oxo-3-phenylpropanoate 5 in the presence of potassium fluoride, provides strong evidence that 1,3-dicarbonyl compounds undergo an addition reaction with fluoroiodane 1 to form an iodonium intermediate which can be deprotonated to generate an iodonium ylide. In the presence of TREAT-HF, however, the iodonium intermediate reacts to form the 2-fluoro-1,3-dicarbonyl product and we propose that fluoroiodane 1 simulates electrophilic fluorination via an addition/substitution mechanism. Further evidence to support this mechanism was obtained by successfully reacting the isolated iodonium ylide 8 with TREAT-HF, hydrochloric acid, acetic acid and p-toluenesulfonic acid to form the 2-fluoro-, 2-chloro-, 2-acetyl- and 2-tosyl-1,3-ketoesters respectively.
Co-reporter:Gemma C. Geary; Eric G. Hope ;Dr. Alison M. Stuart
Angewandte Chemie International Edition 2015 Volume 54( Issue 49) pp:14911-14914
Publication Date(Web):
DOI:10.1002/anie.201507790
Abstract
A new class of fluorinated lactones was prepared by the intramolecular fluorocyclizations of unsaturated carboxylic acids by using the stable fluoroiodane reagent in combination with AgBF4. This unique reaction incorporates a cyclization, an aryl migration, and a fluorination all in one step. The fluoroiodane reagent, prepared easily from fluoride, can also be used without a metal catalyst to give moderate yields within just 1 hour, thus demonstrating that it is a suitable reagent for developing new 18F-labelled radiotracers for PET imaging.
Co-reporter:Gemma C. Geary; Eric G. Hope ;Dr. Alison M. Stuart
Angewandte Chemie 2015 Volume 127( Issue 49) pp:15124-15127
Publication Date(Web):
DOI:10.1002/ange.201507790
Abstract
A new class of fluorinated lactones was prepared by the intramolecular fluorocyclizations of unsaturated carboxylic acids by using the stable fluoroiodane reagent in combination with AgBF4. This unique reaction incorporates a cyclization, an aryl migration, and a fluorination all in one step. The fluoroiodane reagent, prepared easily from fluoride, can also be used without a metal catalyst to give moderate yields within just 1 hour, thus demonstrating that it is a suitable reagent for developing new 18F-labelled radiotracers for PET imaging.
Co-reporter:Gemma C. Geary, Eric G. Hope, Kuldip Singh and Alison M. Stuart
Chemical Communications 2013 vol. 49(Issue 81) pp:9263-9265
Publication Date(Web):16 Aug 2013
DOI:10.1039/C3CC44792H
The air and moisture stable fluoroiodane 8, readily prepared on a 6 g scale by nucleophilic fluorination of the hydroxyiodane 7 with TREAT-HF, has been used as an electrophilic fluorinating reagent for the first time to monofluorinate 1,3-ketoesters and difluorinate 1,3-diketones in good isolated yields.
Co-reporter:Michal Fornalczyk, Kuldip Singh and Alison M. Stuart
Chemical Communications 2012 vol. 48(Issue 29) pp:3500-3502
Publication Date(Web):02 Feb 2012
DOI:10.1039/C2CC17985G
The first enantioselective Reformatsky-type reaction of ethyl iodofluoroacetate has been accomplished with alkyl aryl ketones. High diastereoselectivities and excellent enantioselectivities for the major diastereomer (93–95% ee) were achieved with large alkyl groups. For smaller alkyl groups the diastereoselectivities were moderate, but excellent enantioselectivities were obtained for both diastereomers (79–94% ee).
Co-reporter:Michal Fornalczyk, Kuldip Singh and Alison M. Stuart
Organic & Biomolecular Chemistry 2012 vol. 10(Issue 16) pp:3332-3342
Publication Date(Web):23 Feb 2012
DOI:10.1039/C2OB25081K
Two approaches have been developed for the enantioselective Reformatsky reaction of ethyl iododifluoroacetate with ketones to form a quaternary carbon centre using (1R,2S)-1-phenyl-2-(1-pyrrolidinyl)-1-propanol as the chiral ligand. Good yields and high enantioselectivities (80–91% ee) were achieved with a range of alkyl aryl ketones in a convenient one-pot protocol using ethyl iododifluoroacetate and diethylzinc to form the difluorinated Reformatsky reagent homogeneously. In the traditional two-step Reformatsky reaction using the preformed Reformatsky reagent generated from ethyl iododifluoroacetate and zinc dust, good yields and good enantioselectivities (75–84% ee) were also obtained.
Co-reporter:Daniel Duncan, Eric G. Hope, Kuldip Singh and Alison M. Stuart
Dalton Transactions 2011 vol. 40(Issue 9) pp:1998-2005
Publication Date(Web):24 Jan 2011
DOI:10.1039/C0DT01004A
A new fluorous PCP pincer ligand has been coordinated to Ni(II), Pd(II) and Pt(II). The air stable palladium complex, which promotes Heck reactions between methyl acrylate and either aryl bromides or iodides, can be recovered intact by fluorous solid-phase extraction and was reused four times in the Heck reaction between methyl acrylate and 4-bromoacetophenone without loss in catalytic activity.
Co-reporter:Nicolas Audic;Philip W. Dyer;Eric G. Hope;Alison M. Stuart;Samuel Suhard
Advanced Synthesis & Catalysis 2010 Volume 352( Issue 13) pp:2241-2250
Publication Date(Web):
DOI:10.1002/adsc.201000196
Abstract
New perfluoroalkylated polystyrene resins have been prepared by the suspension polymerisation of 4-(perfluoro-n-octyl)styrene. The evaluation of these highly fluorinated insoluble materials as catalyst supports for rhodium-catalysed hydrogenation of styrene and palladium-mediated Suzuki–Miyaura carbon-carbon bond forming reactions with 4-bromoacetophenone and 4-bromoanisole revealed improvements in the recycling of the perfluoroalkylated catalysts as compared to that achieved using fluorous reverse-phase silica gel.
Co-reporter:Benoit Gourdet, Kuldip Singh, Alison M. Stuart, José A. Vidal
Journal of Fluorine Chemistry 2010 Volume 131(Issue 11) pp:1133-1143
Publication Date(Web):November 2010
DOI:10.1016/j.jfluchem.2010.06.002
A series of dibenzo-18-crown-6 lariat ethers containing two C7H15 (11), (CH2)2C6F13 (14), (CH2)2C8F17 (15), NHC7H15 (18) and NHCH2C6F13 (19) sidearms were prepared and the single crystal X-ray structure of cis-4,4′-di(1H,1H,2H,2H-perfluorodecyl)-dibenzo-18-crown-6 (15a) is reported. The “light fluorous” dibenzo-18-crown-6 ether (14) has emerged as a stable and robust PTC catalyst, which can be recycled efficiently by fluorous solid-phase extraction, and gives better PTC catalytic activity compared to the parent, non-fluorinated PTC catalyst, dibenzo-18-crown-6, and the alkylated derivative (11) in aliphatic and aromatic nucleophilic substitutions.The “light fluorous” crown ether can be recycled efficiently by fluorous solid-phase extraction and it gives better PTC catalytic activity than dibenzo-18-crown-6 in aliphatic and aromatic nucleophilic substitutions.
Co-reporter:Charlotte Emnet;Kathleen M. Weber;José A. Vidal;Crestina S. Consorti;Alison M. Stuart;J. A. Gladysz
Advanced Synthesis & Catalysis 2006 Volume 348(Issue 12-13) pp:
Publication Date(Web):11 AUG 2006
DOI:10.1002/adsc.200606138
The fluorous tertiary phosphine [Rf6(CH2)2]3P [Rfn=CF3(CF2)n−1] and excess PhCH2Br, CH3(CH2)3OSO2CF3, or Rf6(CH2)2OSO2CF3 react (CF3C6H5, 45–110 °C) to give the phosphonium salts (PhCH2)[Rf6(CH2)2]3P+ Br− (2, 71 %), [CH3(CH2)3][Rf6(CH2)2]3P+ CF3SO3− (3, 65 %), or [Rf6(CH2)2]4P+ CF3SO3− (4, 83 %). The phosphines [Rf6(CH2)2]2[Rf8(CH2)2]P and [Rf8(CH2)2]3P are similarly elaborated with Rf6(CH2)2I, Rf8(CH2)2I, or Rf8(CH2)2Br (DMF, 115 °C) to [Rf8(CH2)2]4-x[Rf6(CH2)2]xP+ I− (x=3, 7; 2, 8; 1, 9; 0, 10) or [Rf8(CH2)2]4P+ Br− (80–60 %). The salts exhibit melting points between 110 °C and 43 °C, with lower values favored by less symmetrical cations, Rf6 segments, and triflate and bromide anions. Solubilities decrease in the solvent sequence CF3C6F5 (all salts at least moderately soluble, room temperature)>acetone>THF>CF3C6H5>CF3C6F11>CH3C6H5, Et2O, CH2Cl2, hexane (all salts insoluble at elevated temperatures); some appreciably increase upon heating. Partition coefficients are very biased towards fluorous phases (>93:<7). The salts can be quite efficient at extracting picrate from water into CF3C6F5 (97–86 % for 2, 4, 9, 10) or CF3C6H5 (85–66 % for 2-4), demonstrating their potential for phase transfer catalysis. A CF3C6F5 solution of Rf8(CH2)3I and aqueous NaCl react at 100 °C in the presence (but not the absence) of 9 to give Rf8(CH2)3Cl.
Co-reporter:Daniel Duncan, Eric G. Hope, Kuldip Singh and Alison M. Stuart
Dalton Transactions 2011 - vol. 40(Issue 9) pp:NaN2005-2005
Publication Date(Web):2011/01/24
DOI:10.1039/C0DT01004A
A new fluorous PCP pincer ligand has been coordinated to Ni(II), Pd(II) and Pt(II). The air stable palladium complex, which promotes Heck reactions between methyl acrylate and either aryl bromides or iodides, can be recovered intact by fluorous solid-phase extraction and was reused four times in the Heck reaction between methyl acrylate and 4-bromoacetophenone without loss in catalytic activity.
Co-reporter:Michal Fornalczyk, Kuldip Singh and Alison M. Stuart
Organic & Biomolecular Chemistry 2012 - vol. 10(Issue 16) pp:NaN3342-3342
Publication Date(Web):2012/02/23
DOI:10.1039/C2OB25081K
Two approaches have been developed for the enantioselective Reformatsky reaction of ethyl iododifluoroacetate with ketones to form a quaternary carbon centre using (1R,2S)-1-phenyl-2-(1-pyrrolidinyl)-1-propanol as the chiral ligand. Good yields and high enantioselectivities (80–91% ee) were achieved with a range of alkyl aryl ketones in a convenient one-pot protocol using ethyl iododifluoroacetate and diethylzinc to form the difluorinated Reformatsky reagent homogeneously. In the traditional two-step Reformatsky reaction using the preformed Reformatsky reagent generated from ethyl iododifluoroacetate and zinc dust, good yields and good enantioselectivities (75–84% ee) were also obtained.
Co-reporter:Michal Fornalczyk, Kuldip Singh and Alison M. Stuart
Chemical Communications 2012 - vol. 48(Issue 29) pp:NaN3502-3502
Publication Date(Web):2012/02/02
DOI:10.1039/C2CC17985G
The first enantioselective Reformatsky-type reaction of ethyl iodofluoroacetate has been accomplished with alkyl aryl ketones. High diastereoselectivities and excellent enantioselectivities for the major diastereomer (93–95% ee) were achieved with large alkyl groups. For smaller alkyl groups the diastereoselectivities were moderate, but excellent enantioselectivities were obtained for both diastereomers (79–94% ee).
Co-reporter:Gemma C. Geary, Eric G. Hope, Kuldip Singh and Alison M. Stuart
Chemical Communications 2013 - vol. 49(Issue 81) pp:NaN9265-9265
Publication Date(Web):2013/08/16
DOI:10.1039/C3CC44792H
The air and moisture stable fluoroiodane 8, readily prepared on a 6 g scale by nucleophilic fluorination of the hydroxyiodane 7 with TREAT-HF, has been used as an electrophilic fluorinating reagent for the first time to monofluorinate 1,3-ketoesters and difluorinate 1,3-diketones in good isolated yields.
