The synthesis of simple alkyl substituted spiroacetals by α,α′-alkylation of metalated acetone dimethylhydrazone with appropriate electrophiles and subsequent acid catalyzed cleavage and ring closure of the products is described.
Ammonium-Salt-Tagged IMesAuCl Complexes and Their Application in Gold-Catalyzed Cycloisomerization Reactions in Water
作者:Katrin Belger、Norbert Krause
DOI:10.1002/ejoc.201403153
日期:2015.1
The total synthesis and characterization of ammonium-salt-taggedIMesAuClcomplexes is described. Moreover, we have demonstrated their catalytic activity and recyclability in cycloisomerizationreactions of allenic and acetylenic alcohols in water. The water-soluble gold catalysts can be stabilized by the addition of LiCl.
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
An efficient synthesis of 5,5-spiroketals (i.e., 1,6-dioxaspiro[4.4]nonane derivatives) is described from 2-(sulfonimidoylmethylene)tetrahydrofurans involving a consecutive epoxide opening/oxa-Michael spiroketalization sequence. This methodology was applied to the very direct synthesis of chalcogran, a beetle pheromone. sulfoximine - 5,5-spiroketals - consecutive reaction - chalcogran