A stereoselective synthesis of a pyranonaphthoquinone derivative found in aromatic
polyketide-derived aphid pigments is reported herein. This approach features the anionic
[4+2]-annulation of phthalides with a carbohydrate-derived optically active enone.
Additional synthetic steps provide access to the monomer fragment of uroleuconaphins
and viridaphins. The optimization for a facile preparation of phthalides bearing sulfonyl
or cyano groups are also studied.
Key words
aphid pigment - polyketide - dimeric pyranonaphthoquinone - total synthesis - natural
product - anionic annulation - Hauser–Kraus annulation