4855-02-1Relevant articles and documents
New utility of electrophilic trifluoromethylthiolation reagents for the synthesis of a variety of triflones
Huang, Zhongyan,Jia, Shichong,Wang, Chen,Tokunaga, Etsuko,Sumii, Yuji,Shibata, Norio
, p. 61 - 66 (2017)
The synthesis of various triflones has been achieved using electrophilic trifluoromethylthiolation reagents as building blocks, and not as reagents. Trifluoromethanesulfonyl hypervalent iodonium ylide 1a and its diazo-analogue 1b are well-known reagents for electrophilic trifluoromethylthiolation of nucleophiles under copper catalysis. In this paper, we disclose another facet of these reagents as synthetic building blocks of triflones via intramolecular rearrangements. The diazo-compound 1b was converted into amide-, ester- and enol-triflones via the Wolff rearrangement followed by a nucleophilic reaction with aryl- and alkylamines, amino acids, alcohols, and silyl enol ether in heated conditions. On the other hand, the ylide reagent 1a was converted into vinyl triflone via an intramolecular I-O-rearrangement under heat. More interestingly, both 1a and 1b reacted with acetonitrile to give an oxazole-triflone under copper catalysis.
A convenient one-pot synthesis of per-(or poly-)fluoroalkanesulfonyl substituted cyclopropanes
Zhu, Shizheng,Chu, Qianli,Xu, Guolin,Qin, Chaoyue,Xu, Yong
, p. 195 - 198 (1998)
Per-(or poly-)fluoroalkanesulfonyl substituted cyclopropanes are prepared by a facile one-pot reaction of methyl per-(or poly-) fluoroalkanesulfones with 1,2-dibromoethane under basic reaction conditions. Similarly treatment of benzyl per-(or poly-) fluor
Synthesis of ArCF2X and [18F]Ar-CF3via Cleavage of the Trifluoromethylsulfonyl Group
Yang, Ren-Yin,Gao, Xinyan,Gong, Kehao,Wang, Juan,Zeng, Xiaojun,Wang, Mingwei,Han, Junbin,Xu, Bo
supporting information, p. 164 - 168 (2021/12/17)
A versatile synthesis of ArCF2X and [18F]Ar-CF3 type compounds from readily available ArCF2SO2CF3 has been developed. Diverse nucleophiles, including weak nucleophiles such as halides (18F-, Cl-, Br-, and I-), RSH, and ROH, could react with ArCF2SO2CF3 efficiently to give the corresponding difluoromethylene products. The control experiments and the Hammett plot indicated that the reaction might proceed through a difluorocarbocation intermediate generated from the steric hindrance-assisted cleavage of the trifluoromethylsulfonyl group.
Base promotedgem-difluoroolefination of alkyl triflones
Yang, Ren-Yin,Wang, Hui,Xu, Bo
supporting information, p. 4831 - 4834 (2021/05/25)
A new synthesis ofgem-difluoroalkenes from readily available alkyl triflones and difluorocarbene precursors such as TMSCF2Br has been reported. The reaction, regardless of electronic effect, givesgem-difluoroalkenes in good to excellent yields. The mechanism may involve deprotonation of triflones, nucleophilic addition, and the elimination of SO2CF3
Chemo-, regio- And stereoselective synthesis of monofluoroalkenes via a tandem fluorination-desulfonation sequence
Xu, Bo,Yang, Ren-Yin
supporting information, p. 7802 - 7805 (2021/08/13)
A widely applicable approach for the synthesis of Z-monofluoroalkenes from readily available alkyl triflones and NFSI has been reported. The reaction proceeded under mild conditions, affording mono-fluorinated alkenes in good to excellent yields with exce
One-Pot Substitution of Aliphatic Alcohols Mediated by Sulfuryl Fluoride
Dubois, Rudy,Epifanov, Maxim,Hodgson, Jack W.,Mo, Jia Yi,Sammis, Glenn M.
supporting information, p. 4958 - 4962 (2020/04/22)
The Mitsunobu reaction is a powerful transformation for the one-pot activation and substitution of aliphatic alcohols. Significant efforts have focused on modifying the classic conditions to overcome problems associated with purification from phosphine-based byproducts. Herein, we report a phosphine free method for alcohol activation and substitution that is mediated by sulfuryl fluoride. This new method is effective for a wide range of primary alcohols using phthalimide, di-tert-butyl-iminodicarboxylate, and aromatic thiol nucleophiles in 74 % average yield. Activated carbon nucleophiles and a deactivated phenol were also effective for this reaction in good yields. Secondary alcohols were also successful substrates using aryl thiols, affording the corresponding sulfides in 56 % average yield with enantiomeric ratios up to 99:1. This new protocol has a distinct synthetic advantage over many existing phosphine-based methods as the byproducts are readily separable. This feature was exploited in several examples that did not require chromatography for purification. Furthermore, the mild reaction conditions enabled further in situ derivatization for the one-pot conversion of alcohols to amines or sulfones. This method also provides a boarder nucleophile scope compared to existing phosphine-free methods.
Practical and efficient synthesis of aryl trifluoromethyl sulfones from arylsulfonyl chlorides with Umemoto's reagent II
Zhou, Xiaocong,Hu, Dufen,He, Xinyi,Li, Yuanqiang,Chu, Youqun,She, Yuanbin
supporting information, (2019/12/24)
A practical and efficient method for the synthesis of aryl trifluoromethyl sulfones has been developed by a tandem reaction of arylsulfonyl chlorides with Umemoto's reagent II. The advantageous features of this method are simple operation, mild reaction conditions, wide scope of substrates, high yield of products, and easy scalability.
Catalyst-Free and Redox-Neutral Innate Trifluoromethylation and Alkylation of Aromatics Enabled by Light
Liu, Peng,Liu, Wenbo,Li, Chao-Jun
supporting information, p. 14315 - 14321 (2017/10/17)
The Minisci alkylation is useful to functionalize aromatics via alkyl radical addition. Current approaches to prepare alkyl radicals follow either oxidative or reductive pathways from various functional groups. Developing new strategy beyond these traditional methods remains elusive yet highly significant. In this article, we present a redox-neutral and catalyst-free protocol to engender alkyl radicals in the context of trifluoromethylation and general alkylation of arenes. This protocol, via the Norrish type I concept to produce alkyl radicals, accommodates various functional groups and delivers the product in good yields. This method identified a series of compounds as the trifluoromethylation and alkylation reagents assisted by light. It is expected that these compounds can find potential applications in other radical-involved reactions.
Chiral fluorinated α-sulfonyl carbanions: Enantioselective synthesis and electrophilic capture, racemization dynamics, and structure
Hellmann, Gunther,Hack, Achim,Thiemermann, Eric,Luche, Olaf,Raabe, Gerhard,Gais, Hans-Joachim
supporting information, p. 3869 - 3897 (2013/04/10)
Enantiomerically pure triflones R1CH(R2)SO 2CF3 have been synthesized starting from the corresponding chiral alcohols via thiols and trifluoromethylsulfanes. Key steps of the syntheses of the sulfanes are the photochemical trifluoromethylation of the thiols with CF3Hal (Hal=halide) or substitution of alkoxyphosphinediamines with CF3SSCF3. The deprotonation of RCH(Me)SO2CF3 (R=CH2Ph, iHex) with nBuLi with the formation of salts [RC(Me)-SO2CF3]Li and their electrophilic capture both occurred with high enantioselectivities. Displacement of the SO2CF3 group of (S)-MeOCH2C(Me)(CH 2Ph)SO2CF3 (95 % ee) by an ethyl group through the reaction with AlEt3 gave alkane MeOCH2C(Me)(CH 2Ph)Et of 96 % ee. Racemization of salts [R1C(R 2)SO2CF3]Li follows first-order kinetics and is mainly an enthalpic process with small negative activation entropy as revealed by polarimetry and dynamic NMR (DNMR) spectroscopy. This is in accordance with a Cα-S bond rotation as the rate-determining step. Lithium α-(S)-trifluoromethyl- and α-(S)-nonafluorobutylsulfonyl carbanion salts have a much higher racemization barrier than the corresponding α-(S)-tert-butylsulfonyl carbanion salts. Whereas [PhCH 2C(Me)SO2tBu]Li/DMPU (DMPU = dimethylpropylurea) has a half-life of racemization at -105 °C of 2.4 h, that of [PhCH 2C(Me)SO2CF3]Li at -78 °C is 30 d. DNMR spectroscopy of amides (PhCH2)2NSO2CF 3 and (PhCH2)N(Ph)SO2CF3 gave N-S rotational barriers that seem to be distinctly higher than those of nonfluorinated sulfonamides. NMR spectroscopy of [PhCH2C(Ph)SO 2R]M (M=Li, K, NBu4; R=CF3, tBu) shows for both salts a confinement of the negative charge mainly to the Cα atom and a significant benzylic stabilization that is weaker in the trifluoromethylsulfonyl carbanion. According to crystal structure analyses, the carbanions of salts {[PhCH2C(Ph)SO2CF3] Li×L}2 (L=2 THF, tetramethylethylenediamine (TMEDA)) and [PhCH2C(Ph)SO2CF3]NBu4 have the typical chiral Cα-S conformation of α-sulfonyl carbanions, planar Cα atoms, and short Cα-S bonds. Ab initio calculations of [MeC(Ph)SO2tBu]- and [MeC(Ph)SO2CF3]- showed for the fluorinated carbanion stronger nC→σ* S-CF 3 and n O→σ* S-CF 3 interactions and a weaker benzylic stabilization. According to natural bond orbital (NBO) calculations of [R 1C(R2)SO2R]- (R=tBu, CF3) the nC→σS-R interaction is much stronger for R=CF3. Ab initio calculations gave for [MeC(Ph)SO2tBu] Li×2 Me2O an O,Li,Cα contact ion pair (CIP) and for [MeC(Ph)SO2CF3]Li×2 Me2O an O,Li,O CIP. According to cryoscopy, [PhCH2C(Ph)SO2CF 3]Li, [iHexC(Me)SO2CF3]Li, and [PhCH 2C(Ph)SO2CF3]NBu4 predominantly form monomers in tetrahydrofuran (THF) at -108 °C. The NMR spectroscopic data of salts [R1(R2)SO2R3]Li (R 3=tBu, CF3) indicate that the dominating monomeric CIPs are devoid of Cα-Li bonds. Worth their salt: Chiral Li α-(S)-trifluoromethylsulfonyl carbanion salts with ≥98 % enantiomeric excess (ee) and high configurational stability are accessible through the reaction of chiral triflones (≥98 % ee) with RLi (see figure). Their electrophilic capture occurs with high enantioselectivity. Studies of the structure and dynamics of chiral Li α-(S)-trifluoromethylsulfonyl carbanion salts revealed monomeric contact ion pairs. Copyright
Gas-phase acidities of α- and α,α-SO2CF 3-substituted toluenes. Varying Resonance demand in the electron-rich system
Zhang, Min,Badal, Md. Mizanur Rahman,Koppel, Ilmar A.,Mishima, Masaaki
, p. 813 - 820 (2013/08/15)
The gas-phase acidities (GA) of aryl(trifluoromethylsulfonyl)methanes (ArCH2SO2CF3; 1) and arylbis(trifluoromethylsulfonyl) methanes (ArCH(SO2CF 3)2; 2) were determined by measuring proton-
