From Chiral <i>ortho</i>-Benzoquinone Monoketals to Nonracemic Indolinocodeines through Diels–Alder and Cope Reactions

The S-dienol (−)-4 containing 10 carbons and one oxygen of the final product was prepared in 98.6% ee and 39% yield from cyclohexan-1,3-dione. It was attached to the aromatic ring as a monoether of catechol S-(−)-6 and subsequently subjected to oxidative ketalization in methanol. The allylated phenanthrofuran obtained was selectively oxidized at the terminal double bond. The fifth ring was completed by a “one-pot” amidation–cyclization process promoted by palladium acetate. The final homochiral indolinocodeine (−)-31 was obtained in 16 steps and 3.6% overall yield from cyclohexan-1,3-dione.