REACTION CASCADES BASED ON SQUARATE ESTERS - 1,3-DIOXOLANE AS A CHAPERONE FUNCTIONAL GROUP FOR LITHIUM IONS

摘要

The consequences of adding enantiomerically pure 1-lithiocyclohexene-5,6-diol acetonide and 1-cyclopentenyllithium seriatim to diisopropyl squarate has been studied The first-stage addition leads to a chromatographically separable mixture of diastereomeric keto alcohols, which are formed in a ratio approximating 1:1. Separate reaction of these intermediates with the second cycloalkenyl anion initiates a cascade of chemical steps. The consequences of the second-stage stereoselectivity are profound in dictating the manner in which the polycyclic end products are formed. Copyright (C) 1996 Elsevier Science Ltd [References: 25]