Synthesis of 3′H-spiro[cyclohexane-1,1′-isobenzofuran]-2,5-dien-4-one and Skeleton construction of a type D spirobisnaphthalene structure via dearomatization by a high-valence iodine reagent and Diels–Alder reaction

Abstract

The core skeleton syntheses of 3′H-spiro[cyclohexane-1,1′-isobenzofuran]-2,5-dien-4-one, and their derivatives (3a–3w) of spirobisnaphthalene urnucratins, plecmillins, and lignan kadsulignan, were explored using Suzuki–Miyaura coupling product biphenols as the precursors and intramolecular oxidative dearomatization with high-valence iodine reagent PIFA as the key step in 46–91% yields. A wide range of functional groups were tolerated. Then, using this strategy in combination with the Diels–Alder reaction, two skeleton molecules (5ah and 6d) of the natural products urnucratins and plecmillins were successfully constructed in 78% and 39% overall yields, which provides a potential methodology for the total synthesis of Type D spirobisnaphthalene urnucratins and other natural products with similar structures.