Recent Progress in Arylmetalative Cyclization/Annulation of Functionalized Alkynes with Organoboranes

Abstract

Achieving complex molecular assemblies in modular modes is always one of the top priorities of the organic chemist. Cyclization/annulation of functionalized alkynes through carbo metalation has an impactful swath in synthetic organic chemistry. There have recently been considerable contributions in this arena uncovering several new chemical spaces towards new solutions for various fields of biology. On the other hand, organoboronic reagents are fascinating reactive chemprobs, are partake in a broad range of chemical transformations. Particularly utility of these reagents in the carbo‐metalation of alkynes is the subject of high perusal in organic chemistry. To this degree, tuning various transition‐metal catalysts with organoboranes and functionalized alkynes is an intriguing subject for the synthesis of various classes of acyclic and cyclic adducts. Mechanistically, these arylative cyclizations proceed through initial aryl‐metalation on alkynes which provides alkenyl metal species, that concomitantly react with the pendent electrophile. The stereo‐ and regioselective reactivity of this C‐metal is steered by chelation with the coordinating group and/or electrophile on alkyne. In this review, we focused on the critical achievements of the field with the emphasis on the stereoselective capture of the vinyl metal complex with a pendent electrophile. In this field, compilation of the detailed mechanistic pathways in this realm would be helpful to find the gaps and hence to discover novel transformations.

Pd(0)-Catalyzed Asymmetric Cyclization/Coupling Cascade of Alkyne-Tethered Unsaturated Carbonyls: Development and Mechanism Elucidation

“…Alkynes are readily available reagents and have been utilized as a versatile type of functional groups in organic synthesis . In general, transition metals exhibit high coordinating ability toward alkynes, thus significantly facilitating their fruitful transformations . Among them, palladium represents one of the most powerful metal catalysts in this field and receives particular interest from synthetic community .…”

Rhodium(I)/Chiral Diene Complexes Catalyzed Asymmetric Desymmetrization of Alkynyl-Tethered 2,5-Cyclohexadienones Through an Arylative Cyclization Cascade

“…The catalytic asymmetric desymmetrization of meso or prochiral molecules results in the formation of chiral molecules with multiple stereogenic centers by breaking molecular symmetry. This approach has garnered considerable interest for its potential in crafting complex molecules . Specifically, substituted 2,5-cyclohexadienones derived from 4-substituted phenols a have emerged as a promising class of substrates due to their compatibility with various catalytic transformations.…”