4-position of coumarins as trimethylsilyl ethers. From 3-methylcoumarin, 3,4-cis-adducts were formed stereoselectively. The de-trimethylsilylation of the adducts with 1 M HCl aq or TBAF in THF at 25 °C produced 4-(2-hydroxyphenyl)-5,5-diaryl-γ-butyrolactones. The γ-butyrolactones were further transformed to 2-(2,2-diaryl-2,3-dihydrobenzofuran-3-yl)acetic acids by treatment with 1 M HCl aq at reflux temperature
在TMSC1的存在下,
香豆素与
二苯甲酮的电还原偶联使加合物在
香豆素的4位反应为三甲基甲
硅烷基醚。由3-甲基
香豆素立体选择性地形成3,4-顺式加合物。在25°C下用1 M HCl
水溶液或TBAF在THF中对加合物进行脱三甲基甲
硅烷基化反应,生成4-(2-羟苯基)-5,5-二芳基-
γ-丁内酯。通过在回流温度下用1M HCl
水溶液处理,将
γ-丁内酯进一步转化为2-(2,2-二芳基-
2,3-二氢苯并呋喃-3-基)
乙酸。用1M HCl的MeOH溶液使加合物进行脱三甲基甲
硅烷基化反应,得到2-(2,2-二芳基-
2,3-二氢苯并呋喃-3-基)
乙酸甲酯。加合物的脱三甲基甲
硅烷氧基化或
γ-丁内酯的脱
水产生了4-(二芳基甲基)
香豆素。