First enantioselective total synthesis of altersolanol A.

The first enantioselective total synthesis of altersolanol A, a secondary metabolite from the endophytic fungi Stemphylium globuliferum and Alternaria solani, is described. The key step towards the tetrahydroanthraquinone core was an asymmetric Diels-Alder (D-A) cycloaddition promoted by (R)-3,3'-diphenyl-BINOL/boron Lewis acid with good to excellent yields and excellent diastereo- and enantioselectivity (>95 : 5 dr and 98 : 2 er).