Copper-Catalyzed Radical Addition Of Alkynes

Compared with alkenes, alkynes have been rarely employed as substrates for the atom transfer radical addition reaction, mainly due to the lower reactivity and poor regio- and stereoselectivity. Given the high efficiency of forming functionalized alkenes in a single reaction, the exploration of atom transfer radical addition of alkynes is of significant importance. Toward this, this dissertation focuses on the development of Cu-catalyzed radical addition of alkynes and related compounds, which consists of the following two parts:First, a highly traws-selective Cu-catalyzed carbohalogenation including carbobromination, carboiodination, and carbochlorination of terminal alkynes with activated tertiary alkyl halides has been realized, providing quaternary-carbon containing alkenyl halides in good yields with excellent regio- and stereoselectivity. Meanwhile, an unprecedented alkyne trans-carboalkynylation process has been achieved via the tandem trans-carbohalogetnaion/Sonogashira coupling reaction, which furnishes highly functionalized 1,3-enynes in a single chemical transformation.Meanwhile, a Cu-catalyzed cascade annulation of enynals with alkenyl or alkynyl a-bromocarbonyls for the synthesis of various cyclohexenone-fused polycyclic compounds is described. Up to six new C-C bonds and four new carbocycles can be established in a single reaction, highlighting the high efficiency and step-economy of this protocol. A wide range of functional groups such as F, Cl, OMe, CF3, CO2Et, Ac, amide, thienyl, and alkyl substituents are well tolerated. This reaction offers a novel and straightforward entry to the synthesis of ketones featuring the unprecedented addition of carbon radicals to aldehydes.