A significant substituent effect on the regioselectivity in addition of alkynes to 3-substituted pyridines
作者:Shinji Yamada、Aya Toshimitsu、Yasuko Takahashi
DOI:10.1016/j.tet.2009.01.022
日期:2009.3
A substituent at the 3-position on a pyridine ring significantly affects the regioselectivity during the addition of alkynes to pyridinium salts. When the substituent is an electron-withdrawing group, 1,6-adducts are predominantly produced, whereas, 1,2-adducts become the major products when the substituent is an electron-donating group. The changes in the regioselectivity depending on the substituent
An efficient Sonogashira coupling of a heterocyclic phosphonium salt with a terminalalkyne via C–P bond cleavage was developed. The reactions proceeded smoothly in the presence of palladium catalyst, copper(I) iodide, and N,N-diisopropylethylamine (DIPEA) in N-methyl-2-pyrrolidone (NMP) at 100 °C for 12 h, producing the corresponding alkynyl-substituted pyridine, quinoline, pyrazine, and quinoxaline