Selective Anti-Markovnikov Cyclization and Hydrofluorination Reaction in Superacid HF/SbF₅: A Tool in the Design of Nitrogen-Containing (Fluorinated) Polycyclic Systems

Abstract

The selective synthesis of tetrahydroquinolines and fluorinated arylamines was performed in superacid HF/SbF5 through a superelectrophilic ammonium-carbenium activation process. This anti-Markovnikov oriented reaction was applied to the straightforward synthesis of highly valued (fluorinated) nitrogen-containing heterocyclic compounds.

Regioselective Functionalization of 9,9-Dimethyl-9-silafluorenes by Borylation, Bromination, and Nitration

“…1 H NMR for 5j′ (400 MHz, CDCl 3 ): δ 2.03 (quint, J = 6.4 Hz, 2H), 2.26 (s, 3H), 2.86 (t, J = 6.4 Hz, 2H), 3.81 (t, J = 6.4 Hz, 2H), 7.19 (t, J = 8.0 Hz, 1H), 7.34 (d, J = 7.6 Hz, 1H), 7.71 (d, J = 7.6 Hz, 1H). The analytical data matched those reported in the literature …”

Superelectrophiles: Recent Advances

“…For example, reaction of the allyl amine ( 50 ) with HF-SbF 5 provides the heterocyclic product 51 in excellent yield ( Scheme 13 ). A similar conversion was observed for p -nitroaniline derivatives, including double cyclizations to provide julolidine derivatives [ 51 ]. A mechanism was proposed for these transformations involving the unusual superelectrophile 52 , which contains the non-classical carbocation (3-center-2-electron bonding).…”

Enantioselective Synthesis of 3‐Fluorochromanes via Iodine(I)/Iodine(III) Catalysis

“…It is pertinent to note that the effect of deactivating groups under HF/SbF 5 super-acid conditions has been shown to influences the relative stabilities of the Wheland intermediates. [28] These data indicate that synthetically useful levels of efficiency will only be reached for the most electron-withdrawing systems (e.g. CN,N O 2 ,C HO) under increased Brønsted acidic conditions.I tl ogically follows that this will negatively impact on enantioselectivity.T oe nable the generation of diversely functionalized chromanes,two fluorocyclization protocols were established:M ethod Aw ith an amine:HF ratio of 1:5, and Method Bw ith a1 :7.5 ratio.…”