82045-06-5Relevant academic research and scientific papers
Evaluating the thermal vinylcyclopropane rearrangement (VCPR) as a practical method for the synthesis of difluorinated cyclopentenes: Experimental and computational studies of rearrangement stereospecificity
Orr, David,Percy, Jonathan M.,Tuttle, Tell,Kennedy, Alan R.,Harrison, Zo A.
, p. 14305 - 14316 (2015/02/05)
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.
METHOD FOR PRODUCING DIFLUOROCYCLOPROPANE COMPOUND
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Page/Page column 7, (2012/11/08)
Provided is a method for producing a difluorocyclopropane compound under milder reaction conditions and with high selectivity and high yield. The method for producing a difluorocyclopropane compound of the present invention is characterized by using sodium bromodifluoroacetate as a difluorocyclopropanation agent. With the disclosed method, a difluorocyclopropane compound can be produced under milder reaction conditions and with a higher conversion rate and a higher yield compared to conventional art. Further, by-products can be reduced significantly, thus allowing waste to be greatly reduced. Accordingly, the production method of the present invention is easy to implement industrially (can be employed on an industrial scale) and is thus extremely practical and useful.
Sodium bromodifluoroacetate: A difluorocarbene source for the synthesis of gem -difluorocyclopropanes
Oshiro, Kojun,Morimoto, Yoshimichi,Amii, Hideki
experimental part, p. 2080 - 2084 (2010/08/13)
As a new difluorocarbene source, sodium bromodifluoroacetate (BrCF 2CO2Na) was found to be effective for high-yielding synthesis of gem-difluorocyclopropanes and gem-difluorocyclopropenes under mild conditions. Georg Thieme Verlag Stuttgart.
Studies on Organic Fluorine Compounds. 38. Ring-Opening Reactions of gem-Difluorocyclopropyl Ketones with Nucleophiles
Kobayashi, Yoshiro,Taguchi, Takeo,Morikawa, Tsutomu,Takase, Toyohiko,Takanashi, Hiroshi
, p. 3232 - 3236 (2007/10/02)
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).
A STEREOSPECIFIC SYNTHESIS OF CONJUGATED FLUORODIENES BY A RING-OPENING REACTION OF gem-DIFLUOROCYCLOPROPANE DERIVATIVES
Kobayashi, Yoshiro,Morikawa, Tsutomo,Yoshizawa, Atsuko,Taguchi, Takeo
, p. 5297 - 5300 (2007/10/02)
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.
