A Highly Efficient Access to Spiroketals, Mono-unsaturated Spiroketals, and Furans: Hg(II)-Catalyzed Cyclization of Alkyne Diols and Triols
摘要:
Hg(II) salts are identified as highly efficient catalysts for the versatile construction of spiroketals from alkyne diols in aqueous conditions. Monounsaturated spiroketals and furans were accessed with equal ease when propargylic triols (or propargylic diols) were subjected to similar conditions. Even the semiprotected alkyne diols gave the corresponding spiroketals with the same ease in a cascade manner. The reactions are Instant and high yielding at ambient temperatures. Regioselectivity issues are well addressed.
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
Highly efficient catalytic routes to spiroketal motifs
作者:Selvasothi Selvaratnam、Joanne H.H. Ho、Paul B. Huleatt、Barbara A. Messerle、Christina L.L. Chai
DOI:10.1016/j.tetlet.2008.12.075
日期:2009.3
The versatile and efficient synthesis of a variety of spiroketal motifs via the double intramolecular hydroalkoxylation of aliphatic and aromatic alkyne diols was achieved using simple and readily accessible Ir(I) and Rh(I) cyclooctadienecomplexes as catalysts.