How is 1,10-Dimethoxy-6-methyl-5,6,6a,7-tetrahydro-4H-dibenzo[de,g]quinoline-2,9-diol (CAS: 476-70-0) typically synthesized?

1,10-Dimethoxy-6-methyl-5,6,6a,7-tetrahydro-4H-dibenzo[de,g]quinoline-2,9-diol is typically synthesized through a multi-step process involving the condensation of suitable starting materials followed by ring closure. Commonly, the synthesis involves the use of a catalytic amount of p-toluenesulfonic acid (PTSA) and heating. The yield is around 80%, and the reaction is highly selective for the desired product.