Short syntheses of 1-substituted dibenzothiophene derivatives.

The 1-substituted dibenzothiophene motif is an unusual substitution pattern that has previously been accessed via a multi-step synthesis. We demonstrate a simple one-pot preparation of 1-lithiodibenzothiophene from commercial materials via a cascade of two benzyne additions and conversion to several derivatives by addition of electrophiles. A chiral amine containing the 1-dibenzothiophene motif was also prepared. This work avoids the use of precious metals or tert-butyllithium and is much shorter and more convenient than existing routes to 1-substituted dibenzothiophenes.