- A photoprecursor for difluorocarbene
-
4,4-Difluoropyrazolidine-3,5-dione was synthesized as a precursor for the corresponding pyrazolinedione, envisioned as a photochemical source of difluorocarbene. However, this azo compound proved to be far too unstable. In contrast, 10,10-difluorobicyclo[4.3.1]deca-1,3,5-triene, readily synthesized from indane, was found to be a practical source of difluorocarbene for photochemical as well as thermal cyclopropanation reactions.
- He, Yigang,Lemal, David M.
-
-
Read Online
- Palladium-catalyzed allylic alkylation dearomatization of β-naphthols and indoles withgem-difluorinated cyclopropanes
-
A palladium-catalyzed allylic alkylation dearomatization of β-naphthols and indoles withgem-difluorinated cyclopropanes has been developed. This reaction provided an efficient route to access 2-fluoroallylic β-naphthalenones and indolenines bearing quaternary carbon centers in good yields with highZ-selectivityviaC-C bond activation, C-F bond cleavage and the dearomatization process, benefiting from the wide substrate scope and good functional group tolerance. Moreover, 2-fluoroallylic furanoindoline and pyrroloindolines were achieved in good efficiencyviacascade allylic alkylation, dearomatization and cyclization processes in the presence of Et3B.
- Fu, Zhiyuan,Zhu, Jianping,Guo, Songjin,Lin, Aijun
-
supporting information
p. 1262 - 1265
(2021/02/09)
-
- Ring-Opening Functionalization of Simple gem-Difluorocyclopropanes by Single-Electron Oxidants
-
It was reported for the first time that single-electron oxidants such as CAN or K2S2O8 affected facile ring opening of simple gem-difluorocyclopropanes to afford 1,3-dibromo-2,2-difluoropropanes in good yields by the action of KBr, and the appropriate choice of conditions allowed to incorporate not only second halogen atoms but also hydroxy or acetamido groups at the C1 position in the difluoropropane structures in a regiospecific fashion after initiation of the reaction by the introduction of the first bromine atom at the C3 position. ?
- Goto, Toshihito,Kawasaki-Takasuka, Tomoko,Yamazaki, Takashi
-
p. 9509 - 9518
(2019/08/26)
-
- Synthesis, properties and application of electronically-tuned tetraarylarsonium salts as phase transfer catalysts (PTC) for the synthesis of gem-difluorocyclopropanes
-
Preparation of gem-difluorocyclopropane from α-methylstyrene and chlorodifluoromethane was investigated under basic two-phase conditions. Although simple tetraalkylammonium salts appeared uneffective as phase-transfer catalysts (PTC) for this purpose, tetraphenylarsonium chloride displayed moderate activity, and inspired studies of the phenomena. To improve its efficiency we synthesized set of electronically-tuned tetraarylarsonium analogues. Their preparation revealed interesting exchange process of aryl substituents on the arsonium center, whereas activity studies demonstrated a correlation of catalytic efficiency with electronic effects of the substituents. Two of the tetraarylarsonium catalysts were characterized by X-ray studies.
- Grudzień, Krzysztof,Basak, Tymoteusz,Barbasiewicz, Micha?,Wojciechowski, Tomasz M.,Fedoryński, Micha?
-
supporting information
p. 106 - 110
(2017/04/11)
-
- Difluorocarbene Addition to Alkenes and Alkynes in Continuous Flow
-
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.
-
supporting information
p. 1988 - 1991
(2016/06/01)
-
- Development of (Trifluoromethyl)zinc Reagent as Trifluoromethyl Anion and Difluorocarbene Sources
-
The trifluoromethylation of carbonyl compounds is accomplished by the stable (trifluoromethyl)zinc reagent generated and then isolated from CF3I and ZnEt2, which can be utilized as a trifluoromethyl anion source (CF3-). The reaction proceeds smoothly with diamine as a ligand and ammonium salt as an initiator, providing the corresponding trifluoromethylated alcohol products. Moreover, the (trifluoromethyl)zinc reagent can also be employed as a difluorocarbene source (:CF2) not only for gem-difluoroolefination of carbonyl compounds with phosphine but also for gem-difluorocyclization of alkenes or alkynes via the thermal decomposition, respectively.
- Aikawa, Kohsuke,Toya, Wataru,Nakamura, Yuzo,Mikami, Koichi
-
supporting information
p. 4996 - 4999
(2015/11/03)
-
- METHOD OF PRODUCING DIFLUOROCYCLOPROPANE COMPOUNDS
-
PROBLEM TO BE SOLVED: To provide a method of producing difluorocyclopropane compounds efficiently. SOLUTION: According to a method of this invention, a bis (trifluoromethyl) zinc DMPU complex that is represented by (CF3)2 Zn (DMPU)2 (1) (where DMPU shows N,N'-dimethyl propylene urea) and is stable at room temperature and useful as a reaction reagent, and olefins or acetylenes are reacted with each other, to obtain difluorocyclopropane compounds. COPYRIGHT: (C)2015,JPOandINPIT
- -
-
Paragraph 0035; 0036
(2016/12/26)
-
- An improved method for difluorocyclopropanation of alkenes
-
Difluorocyclopropanation of alkenes using fluorinated acetate salts using convential heating is often a slow, inefficient, and energy-intensive process. We report here a modified protocol which enables the rapid (5 min) preparation of 1,1-difluorocyclopropanes, using microwave irradiation. The new procedure is not only considerably faster than previously reported methods, but it also employs easily removed, low boiling-point solvents and avoids the use of highly toxic or ozone-depleting substances. Georg Thieme Verlag Stuttgart. New York.
- Gill, Duncan M.,McLay, Neil,Waring, Michael J.,Wilkinson, Christopher T.,Sweeney, Joseph B.
-
p. 1756 - 1758
(2014/08/05)
-
- Synthesis of gem-difluorocyclopropa(e)nes and O-, S-, N-, and P-difluoromethylated compounds with TMSCF2Br
-
Two-in-one: Me3SiCF2Br is an efficient difluorocarbene source and is compatible with both neutral and aqueous basic conditions. Bromide-ion-initiated [2+1] cycloaddition with alkenes/alkynes and hydroxide ion promoted α-addition with (thio)phenols, (thio)alcohols, sulfinates, heterocyclic amines, and H-phosphine oxides give the corresponding gem-difluorinated compounds with broad functional-group tolerance. Copyright
- Li, Lingchun,Wang, Fei,Ni, Chuanfa,Hu, Jinbo
-
supporting information
p. 12390 - 12394
(2013/12/04)
-
- Conversion between difluorocarbene and difluoromethylene ylide
-
The interconversion between difluoromethylene ylide and difluorocarbene is described. The difluoromethylene ylide precursor, Ph3P +CF2CO2-, could be turned into an efficient difluorocarbene reagent, w
- Zheng, Jian,Lin, Jin-Hong,Cai, Ji,Xiao, Ji-Chang
-
supporting information
p. 15261 - 15266
(2013/11/06)
-
- Methyl 2,2-difluoro-2-(fluorosulfonyl)acetate, a difluorocarbene reagent with reactivity comparable to that of trimethylsilyl 2,2-difluoro-2- (fluorosulfonyl)acetate (TFDA)
-
Under specific high concentration, high temperature conditions, methyl 2,2-difluoro-2-(fluorosulfonyl)acetate (MDFA) has been found to act as a very efficient source of difluorocarbene, exhibiting carbene reactivity characteristics comparable to those exhibited by trimethylsilyl 2,2-difluoro-2-(fluorosulfonyl)acetate (TFDA). For example, in reaction with highly unreactive n-butyl acrylate and using only 2 equiv of MDFA, a yield of 76% of difluorocyclopropane product was obtained after 2 days.
- Eusterwiemann, Steffen,Martinez, Henry,Dolbier, William R.
-
experimental part
p. 5461 - 5464
(2012/08/07)
-
- Synthesis of gem-difluorinated cyclopropanes and cyclopropenes: Trifluoromethyltrimethylsilane as a difluorocarbene source
-
Highly versatile: The Ruppert-Prakash reagent (Me3SiCF 3) can be an efficient source of difluorocarbene. By varying the nonmetallic initiator that is used (F- at lower temperatures and I- at higher temperatures), a range of structurally diverse alkenes and alkynes can be converted into the corresponding gem-difluorinated cyclopropanes and cyclopropenes in good yields (see scheme). Copyright
- Wang, Fei,Luo, Tao,Hu, Jinbo,Wang, Ying,Krishnan, Hema S.,Jog, Parag V.,Ganesh, Somesh K.,Prakash, G. K. Surya,Olah, George A.
-
supporting information; experimental part
p. 7153 - 7157
(2011/09/12)
-
- Chloride ion-catalyzed generation of difluorocarbene for efficient preparation of gem-difluorinated cyclopropenes and cyclopropanes
-
A chloride ion-catalyzed generation of difluorocarbene from a relatively non-toxic and inexpensive precursor, Me3SiCF2Cl (1), under mild and neutral conditions leads to an efficient preparation of gem-difluorocyclopropenes and difluorocyclopropanes through [2 + 1] cycloaddition reactions with alkynes and alkenes, respectively.
- Wang, Fei,Zhang, Wei,Zhu, Jieming,Li, Huaifeng,Huang, Kuo-Wei,Hu, Jinbo
-
supporting information; experimental part
p. 2411 - 2413
(2011/04/15)
-
- Sodium trifluoroacetate: An efficient difluorocarbene precursor for alkenes
-
A novel and efficient difluorocarbene precursor was achieved. In a convenient procedure, a variety of alkenes could be gem-difluorocyclopropanated with sodium trifluoroacetate to give the corresponding products in moderate to high yields, using azobisisob
- Chang, Ying,Cai, Chun
-
p. 1440 - 1441
(2007/10/03)
-
- Trimethylsilyl fluorosulfonyldifluoroacetate (TFDA): A new, highly efficient difluorocarbene reagent
-
TFDA is readily prepared from the reaction of fluorosulfonyldifluoroacetic acid with trimethylsilyl chloride, and it is a very effective and efficient source of difluorocarbene for use in addition reactions to alkenes of a broad scope of reactivities. Acid-sensitive substrates may require an additional purification step involving treatment of the distilled TFDA with sufficient Et3N to remove the acid impurity. Other trialkylsilyl fluorosulfonyldifluoroacetates can also be prepared, and they have been found to have reactivities similar to TFDA. The triethyl derivative, TEFDA is more convenient to prepare in a pure state and has similar reactivity to TFDA. Thus, it may prove to be a superior reagent.
- Dolbier Jr., William R.,Tian, Feng,Duan, Jian-Xin,Li, An-Rong,Ait-Mohand, Samia,Bautista, Olivia,Buathong, Saiwan,Baker, J. Marshall,Crawford, Jen,Anselme, Pauline,Cai, Xiao Hong,Modzelewska, Aneta,Koroniak, Henryk,Battiste, Merle A.,Chen, Qing-Yun
-
p. 459 - 469
(2007/10/03)
-
- Synthesis of gem-Difluorocyclopropanes in a Phase-transfer Catalysed System
-
Reaction of CH2Br2 with CBr2F2 and alkenes 1a-e in the presence of 60percent aqueous KOH and tetrabutylammonium hydrogensulphate as a catalyst affords gem-difluorocyclopropanes 2a-e.
- Balcerzak, Pawel,Fedorynski, Michal,Jonczyk, Andrzej
-
p. 826 - 827
(2007/10/02)
-
- Chlorofluorocarbene from Reaction of Fluorotrichloromethane with Reduced Titanium. Synthesis of 1-Chloro-1-fluorocyclopropanes
-
Generation of chlorofluorocarbene by reaction of CFCl3 with reduced titanium at O deg C, in the presence of various alkenes, produces 1-chloro-1-fluorocyclopropanes in good yield.Evidence from the syn/anti product ratios, including generation of chloroflu
- Dolbier, William R.,Burkholder, Conrad R.
-
p. 589 - 594
(2007/10/02)
-
- Substituted furazans and insecticidal and acaricidal use
-
Insecticidal and acaricidal novel substituted furazans of the formula STR1 n which R1 and R2 are identical or different and represent hydrogen, halogen, alkyl, alkoxy, alkylthio, halogenoalkyl, halogenoalkoxy, halogenoalkylthio or op
- -
-
-
- The Reduction of CBr2F2 by Lead - a Novel Pathway to Difluorocarbene
-
CBr2F2 (1) is reduced by lead metal even at room temperature with intermediate formation of :CF2.At 40 to 60 deg C this reaction is rapid and nearly quantitative.Electron-rich olefins allow the trapping of difluorocarbene in the form of the corresponding 1,1-difluorocyclopropanes in up to 90percent yield.In dichloromethane, dichloroethane or acetonitrile the reduction proceeds only in the presence of molar amounts of complexing anions like bromide or chloride.Tetrabutylammonium salts proved to be advantageous.The reduction does not proceed via carbanions, since the corresp onding protonated products are not observed, even in the presence of good proton donors.Electrochemical investigations of the reduction of 1 at Ni-, Pt-, Sn- and Pb-electrodes support the suggested mechanism. - Key words: Reduction of CBr2F2, Difluorocarbene
- Fritz, Heinz P.,Kornrumpf, Wolfgang
-
p. 1375 - 1380
(2007/10/02)
-