通过重氮前体的光解在甲醇中生成具有不饱和邻位取代基(乙烯基氧基、1-丙烯氧基、烯丙基、2-丁烯基、2,4-戊二烯基)的芳基卡宾。发现分子间 OH 插入与双键的分子内加成竞争。与类似的分子间反应相比,三线态敏化强烈影响产物分布。根据 k S /k ST 和 k T /k TS 速率比对分子内过程的单线态和三线态成分进行剖析和评估。单线态芳基卡宾的分子内环加成反应效率很低,可能是由于需要围绕外环 C-CH: 键旋转。相比之下,相对于分子间类似物,三重芳基卡宾的非集中分子内加成强烈加速。最有可能的,
通过重氮前体的光解在甲醇中生成具有不饱和邻位取代基(乙烯基氧基、1-丙烯氧基、烯丙基、2-丁烯基、2,4-戊二烯基)的芳基卡宾。发现分子间 OH 插入与双键的分子内加成竞争。与类似的分子间反应相比,三线态敏化强烈影响产物分布。根据 k S /k ST 和 k T /k TS 速率比对分子内过程的单线态和三线态成分进行剖析和评估。单线态芳基卡宾的分子内环加成反应效率很低,可能是由于需要围绕外环 C-CH: 键旋转。相比之下,相对于分子间类似物,三重芳基卡宾的非集中分子内加成强烈加速。最有可能的,
o-Allyloxyanisoles are selectively and easily deallylated by treatment with sec- or tert-butyllithium at low temperature. The reaction is proposed to proceed through a tandem intermolecular carbolithiation-β-elimination process, which can also be considered an SN2′ attack of the organolithium on the allyl ether.
Intramolecular reactivity of functionalized arylcarbenes: 2-allyloxyphenylcarbenes
作者:Frank Gotzhein、Wolfgang Kirmse
DOI:10.1016/s0040-4039(97)00090-7
日期:1997.2
2-Allyloxyphenylcarbenes (8) undergo intramolecular addition (→ 9) and (formal) CH insertion (→ 11) competitively. Stereochemical labels indicate that 11 and major amounts of 9 arise from triplet 8. The intermolecular OH insertion of singlet 8 with methanol (neat) is ca. 50 times faster than intramolecular addition. Under these conditions, intramolecular reactions and intersystem crossing of triplet