Intermediate of Fluvastatin;t-Butyl-(±)-(E)-7-[3`-(4``-fluoro-phenyl)-1`-(1``-methylethyl)indol-2`-yl]-3,5-dihydroxy-6-heptenoate;Fluvastatin intermediate F4;(Tert-Butylester)tert-butyl-(E)-3,5-dihydroxy-7-[3'-(4"-fluorophenyl)-1'-methylethyl-indol-2'-yl