Bislatumlides AF (16) represent the only biscembranoids formed by the undescribed coupling pattern of DielsAlder cycloaddition between the Δ(1(2)) double bond involving an α,βunsaturated γlactone ring as a dienophile group and a trisubstituted conjugated Δ(21(34))/Δ(35(36))butadiene moietyLactones that occur naturally are primarily saturated and unsaturated γ and δlactones, but to a lesser extent, macrocyclic lactones The γlactones and δlactones are intramolecular esters of the related hydroxy fatty acids They provide the aromaThe stereoselective synthesis of the cisγ,δdisubstituted α,βunsaturated δlactone fragment of the leustroducsins or phoslactomycins was accomplishedThe new synthetic strategy involves a catalytic asymmetric ketene–aldehyde 22 cycloaddition leading to the formation of a cisdisubstituted βlactoneRing extension by enolate condensation and
Synthetic Approaches To A B Unsaturated D Lactones And Lactols Boucard 07 European Journal Of Organic Chemistry Wiley Online Library
