Chemical transformation of (+)-dehydroabietic acid leading to a formal synthesis of (+)-coleon A

Article abstract of DOI:10.1248/cpb.39.3041

(R)-6-Hydroxy-7-isopropyl-3-(3-methoxypropyl)-3,4-dimethylnaphtho[2,3-b ]furan-2(3H)-one (3), prepared from (+)-dehydroabietic acid (2), was converted into (R)-9-acetoxy-6-benzoyloxy-7-isopropyl-3-(3-methoxypropyl)-3,4-dimethyl naphtho[2,3-b]furan-2,5,8(3H)-trione (10) and its 9-acetyl compound (11) by a series of reactions: sodium borohydride reduction, acetylation, alkaline hydrolysis, benzoyl peroxide oxidation, Jones oxidation, and m-chloroperbenzoic acid oxidation. The trione 10 was further transformed into (R)-5,6,8,9-tetraacetoxy-7-isopropyl-3(3-methoxypropyl)-3,4-dimethylnap htho[2,3-b]furan-2(3H)-one (15) by alkaline hydrolysis and reductive acetylation. Since the conversion of 15 into coleon A (1) has already been reported, the present work can be regarded as a new formal synthesis of coleon A.