Organocatalytic Enantioselective Oxidative CH Alkenylation and Arylation of N‐Carbamoyl Tetrahydropyridines and Tetrahydro‐β‐carbolines

Abstract

The first organocatalytic enantioselective CH alkenylation and arylation reactions of N‐carbamoyl tetrahydropyridines and tetrahydro‐β‐carbolines (THCs) are described. The metal‐free processes represent an efficient and straightforward approach to a variety of structurally and electronically diverse α‐substituted tetrahydropyridines and THCs in good yields with excellent regio‐ and enantioselectivities. Preliminary control experiments provide important insights into the reaction mechanism.

Nitrogen Heterocycle Synthesis through Hydride Abstraction of Acyclic Carbamates and Related Species: Scope, Mechanism, Stereoselectivity, and Product Conformation Studies

“…Our prior attempts at developing this process with tertiary allylic amides through the use of DDQ as a hydride‐abstracting agent were unsuccessful, though successful acyliminium formation was seen in the oxidation of enamides (Scheme 2). [7] The low reactivity of acyclic allylic amides contrasts that of cyclic allylic amides, which Liu and co‐workers showed to be suitable substrates for DDQ oxidations [8] . DDQ is a relatively weak hydride‐abstracting agent, leading to questions about whether hydride abstraction from acyclic amides and related species could be viable with a stronger oxidant.…”

“…[7] The low reactivity of acyclic allylic amides contrasts that of cyclic allylic amides, which Liu and co-workers showed to be suitable substrates for DDQ oxidations. [8] DDQ is a relatively weak hydride-abstracting agent, leading to questions about whether hydride abstraction from acyclic amides and related species could be viable with a stronger oxidant. Our investigation of the relative reactivities of common hydride-abstracting agents [9] revealed a single example of acyclic acyliminium ion formation through the use of Bobbitt's salt.…”

Organocatalytic Redox Deracemization of Cyclic Benzylic Ethers Enabled by An Acetal Pool Strategy

“…[10] Herein, we report the first redox deracemization of awide array of cyclic benzylic ethers on the basis of this "acetal pool" strategy. [11] 6H-Benzo [c]chromene architectures with diverse a substituents are present in an umber of bioactive molecules possessing antidiabetic,a nti-inflammatory,a nalgesic, and anticancer activities. [12] However,c atalytic enantioselective methods to access the optically pure compounds remain elusive.…”