Cu(I)-Catalyzed Asymmetric α-Allenylation of Activated Ketimines with 3-Butynoates

Abstract

An asymmetric α-regioselective allenylation reaction of activated ketimines with 3-butynoates is disclosed under Cu­(I) catalysis, probably via the generation of nucleophilic γ-allenylcopper species in the presence of diisopropylethylamine. A broad range of imines, derived from diverse ketones such as isatins, pyrazolediones, isoquinoline-1,3,4-triones, and even trifluoromethyl alkynyl ketones, can be utilized, generally affording the corresponding α-allenyl amine derivatives in high yields (≤97%) with excellent enantioselectivities (≤99% ee).

Asymmetric Catalytic Ketimine Mannich Reactions and Related Transformations

“…In 2020, Du, Chen, and coworkers reported Cu(I)-catalyzed asymmetric α-allenylation of activated ketimines with 3-butynoates (Scheme 42) [128]. Screening of catalysts and reaction conditions was conducted with isatin-derived ketimines.…”

Strategies for the Catalytic Enantioselective Synthesis of α-Trifluoromethyl Amines

“…The tertiary amine of 35 provides an additional H-bonding interaction with the nucleophile. The reactions are exceptionally fast (10 min at 0 °C), and the yields and stereoselectivities are universally high …”

Pd‐Catalyzed Asymmetric Addition of Arylboronic Acids to Pyrazolinone Ketimines

“…For example, Enders group pioneered squaramide‐catalyzed enantioselective Strecker reaction of pyzazolin‐5‐one derived ketimines with trimethylsilyl cyanide toward chiral pyrazolone α‐aminonitriles [8] . Subsequently, a few organocatalytic or metal‐catalyzed versions of pyzazolin‐5‐one‐derived ketimines with various nucleophiles, such as naphthols, [9] 2,4‐dihydro‐3H‐pyrazol‐3‐one, [10] 1H‐indol‐4‐ols, [11] β‐ketoacids, [12] silyl enol ethers [13] and benzyl but‐3‐ynoates, [14] were reported. Despite these significant advances, asymmetric addition of arylboronic acids as aryl pronucleophiles to pyrazolinone ketimines remains unexplored so far, probably because of the lack of effective asymmetric catalytic system.…”