Synthesis 2007, 1566-1570
In the course of our work on the synthesis of analogues of the specific antimycobacterial 3,3-dimethyl-3H-benzofuro[3,2- f]chromene, we prepared the previously unreported 5-bromo-2,2- dimethyl-2H-chromen-6-ol. We wish to report here an original syn- thetic scheme using this compound. The preparation of various 5- bromo-2,2-dimethyl-6-(aryloxy)-2H-chromenes was first investigated. This was followed by a palladium-catalysed cyclisation reaction, which takes place only in the presence of air, and leads to 3,3-dimethyl-3H-benzofuro[3,2-f]chromenes or 3,3-dimethyl-3H-4,7- dioxa-10-aza-benzo[c]fluorene. The antimycobacterial properties of these analogues have been investigated