New formal syntheses of laurencione, a labile dihydrofuranone derivative from the red alga Laurencia spectabilis

Article abstract of DOI:10.1055/s-1996-4335

A straightforward formal synthesis of the marine natural product laurencione was developed, utilizing elaboration of 5-acetoxy-3-chloropentan-2-one as the starting compound. The synthetic route consisted of (i) α-sulfenylation, (ii) α-chlorination of the resulting β-oxo sulfide, (iii) Hg²⁺-catalyzed methanolysis, (iv) methanolysis of the γ-acetoxy-α,α-dimethoxy ketone with subsequent cyclization and (v) acid hydrolysis of the acetal. Alternatively, laurencione was prepared from 1,1-dichloroacetone by a sequence of reactions involving (i) imination, (ii) regiospecific β-hydroxyethylation, (iii) hydrolysis, (iv) base-induced rearrangement of the resulting functionalized tetrahydrofuran and (v) final acid hydrolysis of laurencione methyl ether.