Fig. 1: Significances and strategies for Sonogashira coupling of nonactivated alkyl electrophiles.

a Representative alkynyl-containing drugs (ethynylestradiol, hormone drug for estrogen medication; efavirenz, an antiretroviral drug for HIV/AIDS; dynemicin A, an antitumor drug for cancer treatments; alfaprostol, a veterinary drug for breeding control). b Important applications of alkynes in bioconjugation and molecular imaging. c Challenges in Sonogashira coupling of nonactivated alkyl electrophiles. d State-of-the-art catalytic systems for Sonogashira coupling of nonactivated alkyl electrophiles. e This work: deaminative Sonogashira coupling of alkyl amines catalyzed by nickel and amide-type pincer ligand (L4).