The cyclization of (4-methoxy-5-hexenyl)lithium (1), which was prepared by lithium-iodine exchange between 3-methoxy-6-iodo-1-hexene (2) and 1.75 molar equiv of t-BuLi in diethyl ether-n-pentane solution at -78 degrees C, has been investigated in a variety of solvent systems. The isomeric composition of the cis- and trans-1-methoxy-2-methylcyclopentane produced upon cyclization of 1 followed by quench with MeOH has been found to be dramatically dependent on the solvent system in which the isomerization is conducted.
Stereochemistry of the cyclization of alkoxy-substituted 5-hexenyllithiums: effect of solvent and lithium iodide on diastereoselectivity
作者:William F. Bailey、Xinglong Jiang
DOI:10.1016/j.tet.2005.01.042
日期:2005.3
The stereochemistry of the cyclization of 4-methoxy-5-hexenyllithium, 4-(methoxymethoxy)-5-hexenyllithium, 4-tert-butoxy-5-hexenyllithium, and 3-methoxy-5-hexenyllithium, each of which was generated from the corresponding iodide by low-temperature lithium–iodine exchange, has been studied in a variety of solvent systems. The results of these studies demonstrate that the stereochemical outcome of the