For 5a and 5i," Met" was MgBr, and for 5d and 5e" Met" was A~(~-BU)~ CH~.'~ Lactonization of the derived hydroxy acids gave the required substrates, 5. In route (b), an unsaturated aldehyde of the type 10 reacts with Grignard reagent ll. 13-" Acidic hydrolysis affords hemiacetal type 12, which on oxidationI6 provides 5. Route (c) involves the selenolactonizationlS of olefinic acids of the type 13, to afford acids of the type 14, which ...
