10.1039/b412811g
The research discusses the stereochemistry involved in the formation of contiguous cyclopropanes through cascade cyclization of a skipped dienyl homoallyl triflate. The study aims to understand the role of double bond geometry in the cyclization process and to determine the absolute stereochemistry of the reaction. The experiments involve the solvolysis of asymmetric homoallylic triflates, which bear a terminal stannyl substituent, to produce disubstituted cyclopropanes and bicyclopropanes with high enantiopurity. Key reactants include homoallylic triflates with a triflate leaving group at one end and a cation-stabilizing tin group at the other. The researchers synthesized various intermediates using a series of organic reactions, such as protection and deprotection of alcohols, reduction with Red-Al, and displacement with lithio tri-n-butylstannane. They also used tri?ic anhydride for solvolysis and analyzed the products through 1H NMR, HPLC on a chiral stationary phase, and X-ray crystallographic analysis to determine the stereochemistry and enantiomeric purity of the resulting cyclopropanes and bicyclopropanes.