- Difluorocarbene Addition to Alkenes and Alkynes in Continuous Flow
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The first in-flow difluorocarbene generation and addition to alkenes and alkynes is reported. The application of continuous flow technology allowed for the controlled generation of difluorocarbene from TMSCF3 and a catalytic quantity of NaI. Th
- Rullière, Pauline,Cyr, Patrick,Charette, André B.
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supporting information
p. 1988 - 1991
(2016/06/01)
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- Evaluating the thermal vinylcyclopropane rearrangement (VCPR) as a practical method for the synthesis of difluorinated cyclopentenes: Experimental and computational studies of rearrangement stereospecificity
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Vinyl cyclopropane rearrangement (VCPR) has been utilised to synthesise a difluorinated cyclopentene stereospecifically and under mild thermal conditions. Difluorocyclopropanation chemistry afforded ethyl 3-(1'(2'2'-difluoro-3'-phenyl)cyclopropyl) propenoate as all four stereoisomers (18a, 18b, 22a, 22b) (all racemic). The trans-E isomer (18a), prepared in 70% yield over three steps, underwent near quantitative VCPR to difluorocyclopentene 23 (99 %). Rearrangements were monitored by 19F NMR (100-180 °C). While cis/trans cyclopropane stereoisomerisation was facile, favouring trans-isomers by a modest margin, no E/Z alkene isomerisation was observed even at higher temperatures. Neither cis nor trans Z-alkenoates underwent VCPR, even up to much higher temperatures (180 °C). The cis-cyclopropanes underwent [3,3]-rearrangement to afford benzocycloheptadiene species. The reaction stereospecificity was explored by using electronic structure calculations, and UB3LYP/6-31G methodology allowed the energy barriers for cyclopropane stereoisomerisation, diastereoisomeric VCPR and [3,3]-rearrangement to be ranked in agreement with experiment.
- Orr, David,Percy, Jonathan M.,Tuttle, Tell,Kennedy, Alan R.,Harrison, Zo A.
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p. 14305 - 14316
(2015/02/05)
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- Studies on Organic Fluorine Compounds. 38. Ring-Opening Reactions of gem-Difluorocyclopropyl Ketones with Nucleophiles
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Syntheses of gem-difluorocyclopropyl ketones (3a-d) and their reactions with nucleophiles are described.Ring-opening reaction of 3a,c,d having a hydrogen substituent at C1 adjacent to the carbonyl group with a methanolate anion gave carboxylic acid derivatives derived from C1-C2 bond scission (between the carbon atom with an acyl group and the carbon atom with fluorine substituents).On the other hand, reaction of 3a-c with a thiolate anion resulted in the C1-C3 bond cleavage (carbon-carbon bond opposite to the difluoromethylene group).
- Kobayashi, Yoshiro,Taguchi, Takeo,Morikawa, Tsutomu,Takase, Toyohiko,Takanashi, Hiroshi
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p. 3232 - 3236
(2007/10/02)
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- A STEREOSPECIFIC SYNTHESIS OF CONJUGATED FLUORODIENES BY A RING-OPENING REACTION OF gem-DIFLUOROCYCLOPROPANE DERIVATIVES
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Ring-opening reactions of trans- and cis -gem-difluorocyclopropane derivatives (1) with appropriate bases proceeded stereospecifically to give (E,E)- and (E,Z)-fluorodiene derivatives (2), respectively.
- Kobayashi, Yoshiro,Morikawa, Tsutomo,Yoshizawa, Atsuko,Taguchi, Takeo
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p. 5297 - 5300
(2007/10/02)
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