Formal amide insertion strategy for the synthesis of anatoxin-a using rhodium catalysis

A formal synthesis of anatoxin-a was accomplished by using rhodium-catalyzed formal amide insertion reaction. The key reaction was performed on a gram scale using 0.4 mol % of Rh-2((NHCOBu)-Bu-t)(4) catalyst, affording a 9-azabicyclo[4.2.1]nonane derivative in good yield. The nitrogen-bridged molecule was converted to Wiseman's intermediate through diastereoselective reduction, site-selective deoxygenation and functional group interconversions. (C) 2016 Elsevier Ltd. All rights reserved.