Palladium(0)‐Catalyzed Directed syn‐1,2‐Carboboration and ‐Silylation: Alkene Scope, Applications in Dearomatization, and Stereocontrol by a Chiral Auxiliary

Abstract

We report the development of palladium(0)‐catalyzed syn‐selective 1,2‐carboboration and ‐silylation reactions of alkenes containing cleavable directing groups. With B2pin2 or PhMe2Si‐Bpin as nucleophiles and aryl/alkenyl triflates as electrophiles, a broad range of mono‐, di‐, tri‐ and tetrasubstituted alkenes are compatible in these transformations. We further describe a directed dearomative 1,2‐carboboration of electron‐rich heteroarenes by employing this approach. Through use of a removable chiral directing group, we demonstrate the viability of achieving stereoinduction in Heck‐type alkene 1,2‐difunctionalization. This work introduces new avenues to access highly functionalized boronates and silanes with precise regio‐ and stereocontrol.

Salt‐Stabilized Silylzinc Pivalates for Nickel‐Catalyzed Carbosilylation of Alkenes

“…However, the silylative difunctionalization of alkenes using Si−M reagents is rare. Sporadic examples of direct arylsilylation of unactived alkenes by palladium‐ [9] and nickel/copper catalysis [10] were only recently reported, which largely relied on the use of difficultly accessible Si−B as the pronucleophiles (Scheme 1a; top right) [11] . The type of R 3 Si−ZnCl reagent, which was prepared by a facile transmetalation from Si−Li with ZnCl 2 , has also proven to be an alternative choice in the nickel‐catalyzed silylacylation of vinylarenes, as reported by Brown and co‐workers (Scheme 1a; bottom right) [12] .…”

Picolinamides and Iodoalkynes Enable Palladium‐Catalyzed syn‐Aminoalkynylation of Di‐ and Trisubstituted Alkenes to Give Pyrrolidines

“…[9] Following the pioneering research of Engle's group on the use of bidentate directing groups in the hydroamination of unactivated alkenes, [10] a multitude of related olefin functionalizations have been reported. [11] Bishomoallylic picolinamides were demonstrated to be suitable substrates for alkene CÀ H activation, [6,12] directed Heck reactions, [6] 1,2difunctionalization, [13] and hydrofunctionalization reactions (Scheme 1D). [14] However, to the best of our knowledge no systematic study utilizing the picolinamide as both an auxiliary and a coupling partner for alkene 1,2-difunctionalization has been reported to date (Wu's group reports a single example using the picolinamide group during reaction-optimization of an aminocarbonylation reaction, affording the target compound in 26 % yield [11h] ).…”