DABCO-catalyzed ring opening of activated cyclopropanes and recyclization leading to γ-lactams with an all-carbon quaternary center
作者:Shaoxia Lin、Ling Li、Fushun Liang、Qun Liu
DOI:10.1039/c4cc03392b
日期:——
A novel and efficient method for the construction of gamma-lactams with an all-carbon quaternary center is developed via a DABCO-catalyzed reaction of EWG-activated cyclopropanecarboxamides and electron-deficient alkenes. The process involves sequential ring-opening of activatedcyclopropanes, intermolecular Michael addition and intramolecular aza-cyclization.
We report here that a series of bridged O,O-ketal fusedspiro piperidone-cyclopropane derivatives 3 can be constructed with excellent yields and good diastereoselectivity by the one-pot reaction of 1-acylcyclopropanecarboxamides 1 with electron-deficient alkene 2a (EWG = CHO) via the domino process involving [4 + 2] annulation/intermolecular electrophilic addition/intramolecular cyclization. Furthermore
A convenient and efficient synthesis of substituted dihydrofurans is developed via ring-enlargement of 1-dimethylaminopropenoyl-1-carbamoyl/benzoyl cyclopropanes catalyzed by ammonium acetate in acetic acid with high regio- and stereoselectivity. Some of the newly synthesized substituted dihydrofurans are subjected to further synthetic transformation in the presence of NaOH (aq) in ethanol to afford
Efficient and divergent one-pot synthesis of cyclopropyl amides and esters from readily available 1-acetylcyclopropanes via iodoform reaction based on the selection of reaction conditions is reported. A series of substituted cyclopropyl amides were synthesized from 1-acetylcyclopropanes, iodine, and ammonia in water in the presence of K2CO3 in good yields, whereas substituted cyclopropyl esters were
据报道,基于反应条件的选择,通过碘仿反应从易得的1-乙酰基环丙烷通过一锅法高效,多样地合成了环丙基酰胺和酯。在K 2 CO 3存在下,由1-乙酰基环丙烷,碘和氨在水中以高收率合成了一系列取代的环丙基酰胺,而由1-乙酰基环丙烷与碘和醇在乙醇中的反应制得了取代的环丙基酯。 DBU的存在。 环丙烷-碘仿反应-碘-酰胺-水