Solvent-controlled nucleophilic trifluoromethylthiolation of Morita–Baylis–Hillman carbonates: dual roles of DABCO in activating the Zard's trifluoromethylthiolation reagent and the MBH carbonates

Abstract

A novel amine-catalyzed nucleophilic trifloromethylthiolation between Morita-Baylis-Hillman carbonates and O-octadecyl-Strifluorothiolcarbonate has been developed. The regioselectivity of this reaction can be controlled by choosing different solvent, affording primary allylic SCF3 products in THF and secondary allylic SCF3 products in CHCl3 as major products. The mechanistic investigation indicated that DABCO plays dual roles in activating the Zard's trifluoromethylthiolation reagent and the MBH carbonates.

Tertiary Amine‐Catalyzed Difluoromethylthiolation of Morita–Baylis–Hillman Carbonates of Isatins with Zard's Trifluoromethylthiolation Reagent

“…On the basis of previous literature and our own results, a plausible mechanism has been proposed as shown in Scheme ,. We supposed that DABCO played dual roles in activating Zard's trifluoromethylthiolation reagent and the MBH carbonate.…”

Unconventional Transformations of Morita–Baylis–Hillman Adducts

“…Although mechanistic studies to rationalise these results are not described in the original paper, the reaction likely unfolds according to the mechanism reported by Shi (Scheme 15A). 42 Under the optimised conditions, the present transformation enables the synthesis of diverse trifluoromethylthiolated alkenes 98 in moderate to excellent yield and excellent E-selectivity.…”

“…Recently, other reaction strategies towards regioselective -allylation have also been exploited beyond the S N 2′ and the S N 2′-S N 2 pathways. Thermodynamic control, 42,43 dipolar annulation via ammonium ylide intermediates, 44 and photoredox catalysis 45 are examples of alternative approaches enabling -allylation of MBH derivatives.…”

“…In 2015, Shi and co-workers reported a solvent-controlled regiodivergent trifluoromethylthiolation of MBH carbonates 96 with Zard's reagent 97 catalysed by DABCO (Scheme 15). 42 In particular, THF favours the -allylation 98 whereas CHCl 3 favours the -allylation 99. The authors proposed that in both solvents the reaction proceeds through -allylation.…”

Engineered mesoporous ionic‐modified γ‐Fe2O3@hydroxyapatite decorated with palladium nanoparticles and its catalytic properties in water

“…1,4‐Diazabicyclo[2.2.2]octane (DABCO) has been used as a catalyst for some organic transformations such as aza‐Michael addition, Knoevenagel condensation, allylic trifluoromethylthiolation of Morita–Baylis–Hillman carbonates, N ‐methylation of indoles and nucleophilic substitution reactions of benzyl halides. DABCO can chemically be grafted to the surface of γ‐Fe 2 O 3 @hydroxyapatite (MHA), and the dual role of ionic‐modified MHA, with organophilic and hydrophilic characteristics, can lead to reactant compounds and Pd NPs in a solid support physically coming together …”