Dearomatization of Heteroarenium Salts with ArBpin Reagents. Application to the Total Synthesis of a Nuphar Alkaloid

Abstract

Rhodium-catalyzed enantioselective addition of aryl and heteroaryl boron pinacol esters to pyridinium and quinolinium salts is developed for the synthesis of enantioenrichred dihydroheteroarenes. The methodology has enabled the synthesis of 2-heteroaryl-substituted dihydropyridines in high yield and ee, which provided efficient synthetic access to a nuphar alkaloid.

Acyclic and Heterocyclic Azadiene Diels–Alder Reactions Promoted by Perfluoroalcohol Solvent Hydrogen Bonding: Comprehensive Examination of Scope

“…1 H NMR (600 MHz, CDCl 3 ): δ 9.28 (dd, J = 2.2, 0.9 Hz, 1H), 8.35 (dd, J = 8.3, 2.2 Hz, 1H), 8.09–8.03 (m, 2H), 7.82 (dd, J = 8.3, 0.9 Hz, 1H), 7.53–7.49 (m, 2H), 7.49–7.45 (m, 1H), 3.98 (s, 3H). The 1 H NMR spectrum exactly matches with that of material previously reported …”

“…The 1 H NMR spectrum exactly matches with that of material previously reported. 67 Cycloadditions of 1,3,5-Triazine (9m). General Method.…”

Catalyst-Controlled Enantioselective and Regiodivergent Addition of Aryl Boron Nucleophiles to N-Alkyl Nicotinate Salts

“…In this context, pyridinium salts are multident electrophiles that, in the presence of nucleophiles, can undergo (1,2), (1,4), or (1,6) addition to afford the corresponding dihydropyridines (DHPs). − These scaffolds are useful intermediates for the preparation of nonaromatic nitrogen heterocycles (Figure A) . Directing a nucleophile to a specific site on the ring has proven to be a nontrivial task.…”

Vicinal stereocenters via asymmetric allylic alkylation and Cope rearrangement: a straightforward route to functionally and stereochemically rich heterocycles

“…Therefore, this work yields complementary access to functionally-and structurally-complex piperidines, cyclohexanes, and related saturated heterocycles. 24 Recent state of the art approaches to complex piperidines include C-H functionalization, [25][26][27][28] from pyridine derivatives by hydrogenation or nucleophilic dearomatization, [29][30][31][32][33][34][35][36] and other methods. [37][38][39][40] A standout route to related cyclohexanes was described by Baran whereby Diels-Alder cycloaddition, desymmetrization, and decarboxylative coupling chemistry are impactfully harnessed.…”