Facile synthesis of polysubstituted furans and dihydrofurans via cyclization of bromonitromethane with oxodienes
作者:Rongshun Chen、Xia Fan、Zhaozhong Xu、Zhengjie He
DOI:10.1016/j.tetlet.2017.08.027
日期:2017.9
A series of polysubstituted furans and dihydrofurans have been prepared from readily available oxodienes and bromonitromethane in modest to excellent yields. This facile synthetic method is developed on the basis of proprietary properties of nitro group such as strong electron-withdrawing ability and cleavability. The conversion of nitro-substituted dihydrofurans to furans is presumably realized by
Though numerous cyanation reactions have been developed for the synthesis of benzonitriles, the construction of valuable fully substituted benzonitriles is still a challenging task. Herein, we reported a tertiary amine-catalyzed [3 + 3]-benzannulation for the green synthesis of CF3-functionalized fully substituted benzonitriles. This strategy features exclusive chemoselectivity, high atom-economy,
Substituent‐Controlled Divergent Cascade Cycloaddition Reactions of Chalcones and Arylalkynols: Access to Spiroketals and
<i>Oxa</i>
‐Bridged Fused Heterocycles
作者:Tianlong Zeng、Jingyang Kong、Hongkai Wang、Lingyan Liu、Weixing Chang、Jing Li
DOI:10.1002/adsc.202100523
日期:2021.8.13
Herein, we report substituent-controlled divergentcascadecycloadditionreactions of chalcones and arylalkynols in the presence of PtI2. Depending on the substituent on the chalcone, either spiroketals or oxa-bridged fusedheterocycles could be obtained in the ranges of 86–97% and 87–95% yields under identical reaction conditions. Control experiments were carried out to elucidate the origin of the
Organocatalytic Asymmetric [4+2] Cycloaddition of 1-Acetylcyclopentene and 1-Acetylcyclohexene for the Synthesis of Fused Carbocycles
作者:Utpal Nath、Subhas Chandra Pan
DOI:10.1002/ejoc.201701238
日期:2017.11.24
The first organocatalytic asymmetric [4+2] cycloaddition reaction employing 1-acetylcyclopentene and 1-acetylcyclohexene is described. Enones having cyano group are used as the dienophile partner in this method. The reaction provides a useful practical route for the synthesis of bicyclic fused carbocycles having four contiguous stereocentres.
Novel transformation of methylenecyclopropanes (MCPs) with acyl cyanoalkenes has been achieved to give oxaspiro[2.5]octenes. This annulation is successfully catalyzed by magnesium halides under mild reaction conditions, and shows a broad functional group tolerance. The reaction includes a rare reaction course, which involves an intramolecular oxa-Michael addition of Mg enolate after the ring opening