ChemInform Abstract: Cation-Stabilizing Auxiliaries: A New Concept in Biomimetic Polyene Cyclization.

ChemInform Abstract

A concept is presented which allows the enhancement of highly stereoselective polyene cyclizations by a cation-stabilizing auxiliary appropriately positioned on the substrate. Thus, the polyene precursor (X), which is modified by substitution with an isobutenyl auxiliary at the pro-C-8 atom, leads to a 77% combined yield of the cyclization products (XIa), (XIb), and (XII) as compared with 30% fora previously reported example without auxiliary. - The substrate (X) is accessible by the reaction sequence shown in the scheme starting from the aldehyde (I).