One-Pot, Four-Different-Component Annulations: Flexible and Efficient Conversion of n-Sized Cycloalkenones into n+4 Alkenolides.

Abstract Five-, six-, and seven-membered conjugated cycloalkenones undergo one-pot conjugate addition with tri- n -butyltinlithium followed by 1,4-addition to vinyl ketones and then aldol addition to aldehydes leading to cyclic hemiketals 2 . Lead tetraacetate oxidative fragmentation produces various 4-atom enlarged, vicinally disubstituted, regiospecifically and stereospecifically unsaturated macrolides 3 .