Lead tetraacetate vinyl esters

LAURIC ACID, VINYL ESTER, 30, 106 Laurone, 31, 68 Lauroyl chloride, 31,68 Laurylmethylamine, 36, 48 Lead acetate trihydrate, 31, 19 Lead sulfide, 31, 19 Lead tetraacetate, 35, 18 Lithium aluminum hydride, 32, 46 33, 33, 82 36, 49... 

The Diels-Alder reaction of 3-methoxyfuran with octyl vinyl ketone took place at room temperature in quantitative yield to afford exclusively the endo cycloadduct (27) (81CC221). Reduction of the carbonyl group with lithium tri-r-butoxyaluminum hydride produced a single alcohol (28). Ozonolysis of the double bond followed by Jones oxidation yielded the lactone ester (29). Hydrolysis of the ester and lead tetraacetate oxidation gave the lactone acetate. This was converted by further hydrolysis and Jones oxidation to the bis-lactone (30), a known intermediate in the synthesis of ( )-isoavenaciolide (Scheme 6). 

Independently, the groups of Evans [375,376,377] and J0rgensen [378] have shown that /3,y-unsaturated a-keto esters react with ethyl vinyl ether in the presence of enantiomerically pure bisoxazoline copper(II) complexes as catalysts leading to enantiomerically enriched dihydropyrans. For instance 212 and 213 in ether at 20 °C and in the presence of complex 214 add to give the endo adduct 215 in 60% yield and with 96.5% ee. The latter is then converted into ethyl -D-ma no-p)Tanoside tetraacetate 216 (O Scheme 77) [379]. 

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