Calcium(II)‐Catalyzed Alkenylation of N‐Acyliminiums and Related Ions with Vinylboronic Acids

Abstract

Efficient C−C bond‐forming reactions between N,O‐acetals and vinylboronic acids were achieved via a calcium(II)‐catalyzed formation of a N‐acyliminium intermediate or a related ion. This strategy can give a rapid access to a wide variety of alkenyl‐functionalized nitrogen‐containing compounds in good to excellent yields under simple reaction conditions.magnified image

Synthesis of Functionalized Isoindolinones via Calcium Catalyzed Generation and Trapping of N-Acyliminium Ions

“…Our group has a growing interest in developing methodology to catalytically generate reactive intermediates and in particular using calcium complexes to mediate these processes. , Calcium represents a relatively underexplored metal in catalysis; however, over the past decade, there has been an increase in interest in exploring the reactivity of calcium, which has resulted in a wealth of innovative uses for this abundant element. − We, and others, have recently reported the use of Ca­(NTf 2 ) 2 as an excellent catalyst to produce N -acyliminium ions from readily available 3-hydroxyisoindolinones. Due to the importance of these scaffolds in both total synthesis − and medicinal chemistry, we wanted to explore this reaction further.…”

Triflamides and Triflimides: Synthesis and Applications

“…For example, in the reactions of furylcarbinol with amines under the action of Ca(NTf 2 ) 2 , the Aza-Piancatelli rearrangement occurs, and after the addition of Et 3 N to the reaction mixture, an intramolecular Michael addition proceeds with the formation of the corresponding tetrahydrobenzo[b]azepines in 33-93% yields [111]. The reactions of N,O-acetals with vinylboronic acids in the presence of Ca(NTf 2 ) 2 lead to the formation of isoindolinones in good to quantitative yields [112].…”

Ultrasonic-assisted-synthesis of isoindolin-1-one derivatives

“…A variety of 3-hydroxyisoindolin-1-ones 1 were synthesized through selective addition of organometallic reagents (for example RMgX, RLi or R 2 Zn) 5–8 as well as reduction 9,10 of phthalimides. The secondary benzamides and aldehydes have been exploited as the starting materials to generate the hydroxyisoindolin-1-ones through tandem oxidative C–H activation and annulation reactions in the presence of palladium or rhodium catalysts.…”