Iodine-Atom-Transfer-Type Carbocyclization of 2-(2-Propynyloxy)ethyl Iodides Involving a Lithium Alkylidene Carbenoid Intermediate
作者:Toshiro Harada、Chie Kitano、Kenta Mizunashi
DOI:10.1055/s-2007-973907
日期:2007.4
In the presence of 1-hexynyllithium, 2-(2-propynyl-oxy)ethyliodides undergo carbocyclization with 1-iodo-1-hexyne to afford 3-(diiodomethylene)tetrahydrofurans in an atom-economical manner with incorporation of the two iodine atoms from the substrates and the reagent.
LDA catalyzes cycloisomerization of 2-(2-propynyloxy)ethyl iodides to give 3-(iodomethylene)tetrahydrofurans. The reaction is proposed to proceed through a mechanism involving exo-cyclization of an alkynyllithium intermediate and protonation of the resulting alkylidene carbenoid by the starting iodide. [reaction: see text]