Intramolecular Cobalt/Visible Light Cocatalyzed Reductive Coupling of Unactivated Arenes with Unactivated Alkenes

A protocol for the intramolecular reductive coupling of unactivated arenes with unactivated alkenes has been developed with the aid of a cooperative visible light/cobalt catalytic system. This coupling is achieved via radical cascade cyclization using amines as terminal reducing reagents and water as the main hydrogen source. In their form, readily available N-allyl benzamides are converted to the corresponding spiro cyclohexadiene-lactam or β-phenethylamine analogues in moderate to excellent yields.

Design and synthesis of novel tacrine-indole hybrids as potential multitarget-directed ligands for the treatment of Alzheimer's disease

The authors report on the synthesis and biological evaluation of new compounds whose structure combines tacrine and indole moieties. Tacrine-indole heterodimers were designed to inhibit cholinesterases and β-amyloid formation, and to cross the blood-brain barrier. The most potent new acetylcholinesterase inhibitors were compounds 3c and 4d (IC₅₀ = 25 and 39 nM, respectively). Compound 3c displayed considerably higher selectivity for acetylcholinesterase relative to human plasma butyrylcholinesterase in comparison to compound 4d (selectivity index: IC₅₀ [butyrylcholinesterase]/IC₅₀ [acetylcholinesterase] = 3 and 0.6, respectively). Furthermore, compound 3c inhibited β-amyloid-dependent amyloid nucleation in the yeast-based prion nucleation assay and displayed no dsDNA destabilizing interactions with DNA. Compounds 3c and 4d displayed a high probability of crossing the blood-brain barrier. The results support the potential of 3c for future development as a dual-acting therapeutic agent in the prevention and/or treatment of Alzheimer's disease.

A Desymmetrization-Based Total Synthesis of Reserpine

Reported herein is a desymmetrization-based synthetic approach to the fused polycyclic indole alkaloid reserpine. The centerpiece of the developed strategy features an internal desymmetrization process that enabled the use of a readily accessible and nonstereogenic reserpine E-ring precursor, in contrast to the synthesis-intensive and stereodefined E-ring intermediates employed in all past reserpine syntheses. Utilization of inexpensive reagents through an orchestrated sequence of carefully selected chemical transformations further highlight the overall effectiveness of the developed pathway.

Rhodium(iii)-catalyzed intramolecular annulation through C–H activation: concise synthesis of rosettacin and oxypalmatime

A flexible and efficient rhodium(iii)-catalyzed intramolecular annulation of benzamides bearing tethered alkynes for the synthesis of indolizinones and quinolizinones is reported.

Enantioselective total synthesis of (+)-reserpine

A catalytic, enantioselective synthesis of (+)-reserpine is reported. The route features a highly diastereoselective, chiral catalyst-controlled formal aza-Diels-Alder reaction between a 6-methoxytryptamine-derived dihydro-β-carboline and an enantioenriched α-substituted enone to form a key tetracyclic intermediate. This approach addresses the challenge of setting the C3 stereogenic center by using catalyst control. Elaboration of the tetracycle to (+)-reserpine includes an intramolecular aldol cyclization and a highly diastereoselective hydrogenation of a sterically hindered enoate.