Synthesis of trifluoromethyl allenes
Phenyl bromodifluoroacetate as bench-stable trifluoromethylation reagent converts readily available alcohols to trifluoromethanes in a Cu-catalyzed deoxytrifluoromethylation reaction. This reaction should be useful for a variety of medicinal, agricultural, and materials chemists.
F. de Azambuja, S. M. Lovrien, P. Ross, B. R. Amber, R. A. Altman, J. Org. Chem., 2019, 84, 2061-2071.
The ability of bipyridyl-derived ligands to control the regioselectivity of Cu-catalyzed nucleophilic trifluoromethylation reactions of propargyl electrophiles provides various di-, tri-, and tetrasubstituted (trifluoromethyl)allenes, which can be further modified to generate complex fluorinated substructures.
B. R. Ambler, S. Peddi, R. A. Altman, Org. Lett., 2015, 17, 2506-2509.
Cu(CH3CN)4BF4 catalyzes a radical bis(trifluoromethylation) of alkynes and 1,3-enynes with Togni reagent II and (bpy)Zn(CF3)2 at room temperature to afford the corresponding 1,2-bis(trifluoromethylated) alkenes and 1,4-bis(trifluoromethylated) allenes in good yields. This protocol exhibits broad substrate scope and excellent functional group compatibility.
H. Shen, H. Xiao, L. Zhu, C. Li, Synlett, 2020, 31, 41-44.
A Pd-catalyzed reaction of vinyl bromides and trifluoromethylated diazoalkanes provides trifluoromethylated, tetrasubstituted allenes in very good yield under mild reaction conditions. This reaction proceeds via oxidative addition of Pd(0) to the vinyl bromide followed by base-promoted reductive elimination. An acid catalyzed cyclization of the allenes gives trifluoromethylated indenes.
C. Pei, Z. Yang, R. M. Koenigs, Org. Lett., 2020, 22, 7300-7304.