ABSTRACT
Conjugated dienes (1,3-dienes) are versatile and valuable chemical feedstocks that can be used as two-carbon or four-carbon synthons with vast applications across the chemical industry. However, the main challenge for their productive incorporation in synthetic routes is their chemo-, regio-, and stereoselective functionalization. Herein, we introduce a unified strategy for the 1,2-hydroarylation and 1,4-trifluoromethylarylation of 1,3-dienes using anilines in hexafluoroisopropanol. DFT calculations point toward a kinetically controlled process in both transformations, particularly in the trifluoromethylarylation, to explain the regiodivergent outcome. In addition, we perform an extensive program of functionalization and diversification of the products obtained, including hydrogenation, oxidation, cyclizations, or cross-coupling reactions, that allows access to a library of high-value species in a straightforward manner.
ABSTRACT
Nitrogen containing compounds, such as anilines, are some of the most widespread and useful chemical species, although their high and unselective reactivity has prevented their incorporation into many interesting transformations, such as the functionalization of alkenes. Herein we report a method that allows the trifluoromethylarylation of alkenes using anilines, for the first time, with no need for additives, transition metals, photocatalysts or an excess of reagents. An in-depth mechanistic study reveals the key role of hexafluoroisopropanol (HFIP) as a unique solvent, establishing a hydrogen bonding network with aniline and trifluoromethyl reagent, that is responsible for the altered reactivity and exquisite selectivity. This work uncovers a new mode of reactivity that involves the use of abundant anilines as a non-prefunctionalized aromatic source and the simultaneous activation of trifluoromethyl hypervalent iodine reagent.
