Synthesis of 3-SCF₂H-/3-SCF₃-chromones via Interrupted Pummerer Reaction/Intramolecular Cyclization Mediated by Difluoromethyl or Trifluoromethyl Sulfoxide and Tf₂O

Abstract

The reaction of alkynyl aryl ketones bearing an o-methoxy group with difluoromethyl sulfoxide in the presence of Tf 2 O was found to conveniently afford the corresponding 3-SCF 2 H-substituted chromones. The combining use of difluoromethyl sulfoxide/Tf 2 O could represent the first reagents system that can introduce the biologically important SCF 2 H moiety under base-free conditions via an interrupted Pummerer reaction. The same protocol could also be applied to the synthesis of 3-SCF 3 -substituted chromones by replacing difluoromethyl sulfoxide with trifluoromethyl sulfoxide and CH 3 CN with toluene.

Tf2O‐Catalyzed Tandem Cyclization/Trifluoromethylselenolation of Alkynes for Synthesis of CF3Se‐Containing Heterocycles

“…Besides, TfOH generated from the reaction between Tf 2 O and EtOH is probably the real catalytic species (Table 1, entries 14–16). Based on the above experiments and previous reports, [22,23a,b] a possible mechanism was proposed in Scheme 4. Initially, TfOH was formed with the reaction between Tf 2 O and EtOH.…”

“…The electrophilic intermediate B then combined with the triple bond of substrate 2 a to generate episelenonium C , which underwent intramolecular cyclization of the amide and deprotonation to release the final product 3 a and H + , the latter could activate 1 a to continue the reaction and realize the catalytic cycle. Alternatively, the pathway involving cyclization to obtain intermediate D and nucleophilic substitution could not be precluded yet (path b) [23b] …”

Synthesis of deuteriodifluoromethylthiolated isocoumarins-1-imines and isocoumarins enabled by multi-component reagents system (MCRS)

“…Based on the experimental results and previous literature investigations, 13–17,19 a plausible mechanism was depicted in Scheme 4b. The initial step of this MCRS-enabled process involved the in situ generation of BnSOCF 2 D from the reaction of BnSCF 2 D and m CPBA.…”

“…14 Since Procter's seminal report on the application of BnSOCF 3 in direct trifluoromethylthiolation, 15 a series of applications of related sulfoxides with valuable fluorinated moiety have emerged in organic synthesis. 13,16 Inspired by the above advancements and our preliminary works, 16 d we previously proposed the multi-component reagents system (MCRS) strategy, 17 a useful tool for the construction of di/trifluoromethylthiolated indoles, benzo[ b ]furan and benzo[ b ]thiophene (Scheme 1b). Given our continuing research on MCRS strategy, we hypothesized that the biologically interesting deuteriodifluoromethylthio group might be integrated into various heterocyclic compounds from the reaction of BnSCF 2 D, m CPBA and Tf 2 O. Herein, we report that by adopting the MCRS protocol, various biologically interesting deuteriodifluoromethylthiolated isocoumarins-1-imines/isocoumarins could be synthesized via BnSCF 2 D/ m CPBA/Tf 2 O-enabled intramolecular cyclization/deuteriodifluoromethylthiolation of 2-alkynylbenzamides and 2-alkynylbenzoates (Scheme 1c).…”