Room-temperature B(OAc)3-promoted Diels-Alder reaction of juglone with styrenes: total syntheses of tetrangulol and anhydrolandomycinone.

The Diels-Alder reaction of juglone with various styrenes in the presence of 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) was promoted by B(OAc)(3) at room temperature. The reaction proceeded smoothly and gave the products in a good yield and with excellent regioselectivity. This strategy was applied to the total syntheses of tetrangulol and anhydrolandomycinone.