Various substituted 1,4-benzodioxines were synthesized through an Ullmann-type intramolecular Caryl-O coupling cyclization reaction using a catalytic amount of BINOL-CuI complex. This methodology was successfully utilized as the key step in the total synthesis of isovanillyl sweetening agents 5-(2,3-dihydro-1,4-benzodioxin-2-yl)-2-methoxyphenol and 5-(2,3-dihydro-1,4-benzoxathiin-2-yl)-2-methoxyphenol in 15.8% and 14.85% overall yields in five steps from isovanillin.
在一定量的 BINOL-CuI 复合物催化下,通过乌尔曼型分子内 Caryl-O 偶联环化反应合成了各种取代的
1,4-苯并二恶烷。作为
异香兰素甜味剂 5-(2,3-二
氢-
1,4-苯并二恶烷-2-基)-2-
甲氧基苯酚和 5-(2,3-二
氢-1,4-
苯并
恶烷-2-基)-2-
甲氧基苯酚总合成的关键步骤,成功地利用了这一方法。