Title
Metal-Free and syn-Selective Hydrohalogenation of Alkynes through a Pseudo-Intramolecular Process
Author
Haruyasu Ashara, Yusuke Mukaijo, Kengo Muragishi, Kento Iwai, Akitaka Ito, Nagatoshi Nishiwaki
Year
2021
Journal
European Journal of Organic Chemistry
Abstract
A new metal-free hydrohalogenation method for alkynes has been developed, which proceeds through a pseudo-intramolecular process. In this reaction, ethynylaniline serves as a substrate to quantitatively form an anilinium salt upon treatment with hydrochloric acid. The spatial proximity facilitates the efficient electrophilic addition of HCl to the ethynyl group in syn-mode, affording the corresponding chloroalkene without overaddition. This protocol was applied to HBr and HI, and the corresponding bromo- and iodoalkenes were obtained, respectively. The obtained chloroalkene was converted to tri-substituted alkenes possessing different aryl/alkynyl groups through Pd-catalyzed cross-coupling reactions.
Instrument
FT/IR-4200
Keywords
hydrohalogenation, cross-soupling reactions