Steroid intermediates. Synthesis and transformations of 7-aryl-4,7-dioxoheptanoic acids
The 7-aryl-3-methyl-4,7-dioxoheptanoic acids [(5)–(7)] have been synthesized in an attempt to provide steroid precursors with a built-in angular C(13)-methyl group. The acids undergo various transformations with basic and acidic reagents, but fail to undergo the next cyclization step in the Robinson sequence. A convenient method for preparing 3-methyl-2-furaldehyde, one of the key reactants, is described. Further, the 1,2-dihydrocyclopenta-[a]naphthalen-3-ones [(21)–(24)], carrying oxygen-functions at the 5-, 7-, and 9-positions, have been synthesized as part of a projected route to ring-B-oxygenated steroids.