[mim=N-methylimidazol-2-yl, mBnzim=N-methylbenzimidazol-2-yl] are catalysts for the cyclisation of alkynoic acids to lactones. The unsaturated acids, 4-pentynoic acid, 4-hexynoic acid and 5-hexynoic acid were cyclised to γ-methylene-γ-butyrolactone, E-5-ethylidenetetrahydro-2-furanone and 6-methylidenetetrahydo-2-pyrone, respectively. Cyclisation of 4-hexynoic acid proceeds stereoselectively with exclusive formation
方形平面阳离子
铑(I)二羰基配合物[Rh((mim)2 CH 2)(CO)2 } + BPh 4 - ](1)和[Rh((mbnzim)2 CH 2)(CO)2 } + BPh 4 - ](2)[mim =
N-甲基咪唑-2-基,mBnzim =N-甲基
苯并咪唑-2-基]是用于将炔酸环化成内酯的催化剂。将不饱和酸
4-戊酸,4-
己酸和5-
己酸环化为γ-亚甲基-
γ-丁内酯E.-5-亚乙基四氢-2-
呋喃酮和6-亚甲基四氢-2-
吡喃酮。4-
己酸的环化立体选择性地进行,唯一形成了5-亚乙基四氢-2-
呋喃酮的E-异构体。配合物1和2还催化炔属醇环化成含氧杂环。