Chemie freier, cyclischer vicinaler Tricarbonyl-Verbindungen (`1,2,3-Trione'), Teil 1, Reaktionsweise von Diazomethan und seinen Derivaten mit 5,5-Dimethylcyclohexan-1,2,3-trion (=`Oxo-dimedon') und verwandten Cyclohexan-1,2,3-trionen
摘要:
Interactions of diazomethane and of its derivatives as typical nucleophiles with cyclic 1,2,3-triones as efficient electrophiles lead to different results: a) formation of oxiranes (C,O insertion under loss of N-2), b) nucleophilic addition yielding diazoaldols, c) formation of ring-enlargement products (C,C insertion under loss of N-2), and d) formation of dioxoles via redox reactions (under loss of N-2). Our results and those of other groups allow us to recognize that the unexpected outcome of the reaction of oxodimedone and several related species is due to a closed-shell diazoaldol formation followed by an open-shell redox reaction leading to dioxoles.
Cyclic Ether Synthesis via Palladium-Catalyzed Directed Dehydrogenative Annulation at Unactivated Terminal Positions
作者:Samuel J. Thompson、Danny Q. Thach、Guangbin Dong
DOI:10.1021/jacs.5b07384
日期:2015.9.16
Here, a palladium-catalyzed functionalization of unactivated sp(3) C-H bonds with internal alcohol nucleophiles is described. Directed by an oxime-masked alcohol, annulation chemoselectively occurs at the β position, leading to a range of aliphatic cyclic ethers with four- to seven-membered rings. Tethered primary, secondary, and tertiary free hydroxyl groups can all react to give the corresponding