(4R,5S)-5-ethyl-4-hydroxydihydrofuran-2(3H)-one

(Z,2S,4aS,6S,7R,11aR)-7-tert-butyldiphenylsilanyloxy-6-ethyl-2-(4-methoxyphenyl)-4a,6,7,8,11,11a-hexahydro-4H-1,3,5-trioxabenzocyclononene