| Abstract
| - Addition of highly stabilized ester nucleophiles to 1,2-dioxines affords good to high yields of γ-lactoneswith high diastereoselectivity. Heterolytic or homolytic cleavage of the 1,2-dioxines underappropriate conditions generates the key reactive cis γ-hydroxy enones, which ultimately affordthe observed γ-lactones. Diastereoselectivity is installed as a result of anti 1,4-addition by the esterenolate to the cis enones followed by intramolecular cyclization. The reaction is tolerant of a rangeof substitution patterns on the 1,2-dioxine while a broad range of esters are also accommodated.In addition to the synthesis of racemic γ-lactones, highly enantioenriched γ-lactones can also besynthesized when chiral cobalt(II) catalysts are employed for the initial homolytic ring-opening ofthe 1,2-dioxine.
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