A new route to diastereoselective synthesis of (±) trans cognac lactone in five steps is described. The key intermediate methyl 3 formylbutanoate(4) was prepared from methyl crotonate(1) in high yield. Addition o...A new route to diastereoselective synthesis of (±) trans cognac lactone in five steps is described. The key intermediate methyl 3 formylbutanoate(4) was prepared from methyl crotonate(1) in high yield. Addition of n amylmagnesium bromide/cuprous iodide to the formyl of(4), through formation of seven membered ring chelate which involved both carbonyl function groups of (4) and MgX or Cu as a central metal, afforded (±) trans cognac lactone(5) in 52% yield with high diastereoselectivity: ratio of trans to cis isomers was 973 by GC. The procedure had advantages of simplicity, high stereoselectivity of products and mild reaction conditions.展开更多
文摘A new route to diastereoselective synthesis of (±) trans cognac lactone in five steps is described. The key intermediate methyl 3 formylbutanoate(4) was prepared from methyl crotonate(1) in high yield. Addition of n amylmagnesium bromide/cuprous iodide to the formyl of(4), through formation of seven membered ring chelate which involved both carbonyl function groups of (4) and MgX or Cu as a central metal, afforded (±) trans cognac lactone(5) in 52% yield with high diastereoselectivity: ratio of trans to cis isomers was 973 by GC. The procedure had advantages of simplicity, high stereoselectivity of products and mild reaction conditions.
