Tellurium/lithium exchange reactions in the synthesis of spiroketals and 1,6-dioxygenated systems
作者:Alcindo A. Dos Santos、Jefferson L. Princival、João V. Comasseto、Simone M.G. de Barros、José E. Brainer Neto
DOI:10.1016/j.tet.2007.03.178
日期:2007.6
O-dianions have been generated through concomitant acid/base and tellurium/lithium exchange reactions. The di-lithium salts were transmetallated with cerium chloride to the corresponding di-cerium salts and subsequently reacted with lactones and carboxylic acid anhydrides to yield the respective spiroketals. The di-lithium entities were also converted into the corresponding cyanocuprates that add in
Ready Access to Benzannulated [5,5]-Oxaspirolactones Using Au(III)-Catalyzed Cascade Cyclizations
作者:Yash Mankad、Sagar S. Thorat、Pronay Das、Gamidi Rama Krishna、Ravindar Kontham、D. Srinivasa Reddy
DOI:10.1021/acs.joc.1c02843
日期:2022.3.4
showcases an unprecedented Au(III)-catalyzed cascade cyclization of 2-(4-hydroxyalkynyl)benzoates to access benzannulated [5,5]-oxaspirolactones related to biologically active natural products. This reaction proceeds through an initial 5-endo-dig mode of hydroalkoxylation of the alkynol segment to give the oxocarbenium species (via cyclic enol-ether) followed by the addition of carboxylate onto the oxocarbenium