A Highly Strained Planar‐Chiral Platinacycle for Catalytic Activation of Internal Olefins in the Friedel–Crafts Alkylation of Indoles

Allylic alcohols: Valuable synthetic equivalents of non-activated alkenes in gold-catalyzed enantioselective alkylation of indoles

“…In particular, the vinyl group of the compound 10b (ee ¼ 80%) was reduced under heterogeneously Pd-catalyzed hydrogenation reaction to the corresponding d-ethyl-THC 10f (yield ¼ 85%, ee ¼ 74%), and the optical rotation value compared with that of the known compound [22]. In such a way, the absolute configuration of 10b was determined to be S, and the configurations of 10a,cee assigned by analogy (Scheme 5).…”

Chiral Cationic Platinum Complexes: New Catalysts for The Activation of Carbon-Carbon Multiple Bonds Towards Nucleophilic Enantioselective Attack

“…A highly strained planar-chiral platinacycle 39 was recently described and was chosen as the catalytic precursor for the intramolecular hydroarylation of unactivated olefins (Scheme 12) [30]. The access to such complex constituted the first example of diastereoselective direct cycloplatination of a chiral ferrocene derivative.…”

Asymmetric Construction of Polycyclic Indoles through Olefin Cross‐Metathesis/Intramolecular Friedel–Crafts Alkylation under Sequential Catalysis

“…When the protecting group on the N atom of the indole ring was changed from methyl to benzyl, the reaction proceeded relatively slowly, but the yield and enantioselectivity were satisfactory (97 % yield, 95 % ee; Table 2, entry 7). In general, electron-rich indolyl enones ( Table 2, entries 2 and 3) were more reactive than electron-deficient substrates ( Table 2, entries [4][5][6]. Excellent yields and enantioselectivities were observed for aryl indolyl enones with a variety of aryl groups (97-99 % yield, 96-98 % ee; Table 2, entries [8][9][10][11].…”

“…[2] Chiral Brønsted acids have been shown to be efficient catalysts for asymmetric Friedel-Crafts reactions. [3,4] In particular, intramolecular Friedel-Crafts-type reactions provide a direct route to polycyclic indoles, such as tetrahydropyrano [3,4-b]indoles (THPIs) and tetrahydro-b-carbolines (THBCs), [5,6] which are frequently encountered in biologically active natural products and pharmaceuticals. [7] Despite considerable efforts devoted to asymmetric intramolecular Friedel-Crafts-type Michael addition reactions, there are few successful examples.…”