Stabilized and Destabilized Carbocations in the 1,6-Methano[10]annulene Series
作者:Xavier Creary、Kevin Miller
DOI:10.1021/jo035006w
日期:2003.10.1
2-Chloromethyl and 3-chloromethyl-1,6-methano[10]annulenesystems solvolyze in methanol to give simple substitution products. Solvent effect studies and the special salt effect support the involvement of cationic intermediates stabilized by the 1,6-methano[10]annulene group. Rate data indicate that the degree of cation stabilization greatly exceeds that of naphthyl groups. B3LYP/6-31G computational
esters can be carried out with high levels of enantioselectivities utilizing commercially available isothiourea catalysts under base-free conditions. The reaction, which proceeds via the in situformation of chiral C1 ammonium enolates, is best carried out under cryogenic conditions combined with a direct trapping of the activated α-chlorinated ester derivative to prevent epimerization, thus allowing
活化芳基乙酸酯的不对称 α-氯化可以在无碱条件下使用市售的异硫脲催化剂以高水平的对映选择性进行。该反应通过原位形成手性 C1 烯醇化铵进行,最好在低温条件下进行,同时直接捕获活化的 α-氯化酯衍生物以防止差向异构化,从而实现高达 er 99 的对映选择性: 1.
MURO, TOMIO, J. PHARM. SOC. JAP., 1982, 102, N 1, 27-35