Asymmetric spiroacetalization catalysed by confined Brønsted acids
作者:Ilija Čorić、Benjamin List
DOI:10.1038/nature10932
日期:2012.3
the design and synthesis of confined Brønstedacids based on a C2-symmetric imidodiphosphoric acid motif, enabling a catalytic enantioselective spiroacetalization reaction. These rationally constructed Brønstedacids possess an extremely sterically demanding chiral microenvironment, with a single catalytically relevant and geometrically constrained bifunctional active site. Our catalyst design is expected
S-(+)-5-(Phenylthio)-2-pentanol and S-(+)-4-(Phenylthio)-2-butanol: Readily Prepared, Useful Additions to the Chirality Pool. Highly Enantioselective Syntheses of Naturally Occurring Spiroketal Pheromones
作者:Hong Liu、Theodore Cohen
DOI:10.1021/jo00112a025
日期:1995.4
The new chirons (S)-4-(phenylthio)-2-butanol (4) and (S)-5-(phenylthio)-2-pentanol (3) have been prepared efficiently in high enantiomeric excess by enzymatic reduction of the corresponding readily available ketones. Using the latter as a chiral building block, the highly optically enriched insect pheromonal components (5S,7S)-7-methyl-1,6-dioxaspiro[4.5]decane (7), (2S,6R)-2-methyl-1,7-dioxaspiro[5.5]undecane (8), and (2S,6R)-2-methyl-1,7-dioxaspiro[5.6]dodecane (9) have been synthesized in one pot by sequential deprotonation, reductive lithiation, transmetalation with cerium(III) chloride, treatment with lactones, and acidification.
A ketal-tethered RCM strategy toward the synthesis of spiroketal related natural products
作者:Sunil K. Ghosh、Changhong Ko、Jia Liu、Jiashi Wang、Richard P. Hsung
DOI:10.1016/j.tet.2006.06.113
日期:2006.11
An unconventional approach to construct spiroketals and spiroaminals via ring-closing metathesis [RCM] of cyclic ketals and aminals, respectively, is described here. This method possesses a good generality with no loss of stereochemical integrity at the spirocenter under the standard RCM conditions. This approach has been applied to the synthesis of an insect pheromone to demonstrate its synthetic