The novel alkylation of the sodium enolate of propioveratrone (4) with or- bromopropioveratrone (5) in liquid ammonia gave the racemic diketone 9. A mechanism for the stereoselectivity of this alkylation is proposed and the structural requirements of the reaction are discussed. Cyclodehydration of 9 to the furan 8 followed by hydrogenation via the all-cis tetrahydrofuran 25 afforded nordihydroguaiaretic acid (NDGA) tetramethyl ether ...
