n  n - linked 
 dimeric indole alkaloids represent an unexplored 
 class of natural products for which chemical synthesis has no practical 
 solution . to meet this challenge , an electrochemical oxidative dimerization 
 method 
 was developed , which was applied as the pivotal step of the 
 first total synthesis of dixiamycin b. this method is also general 
 for n 
 n dimerization of substituted carbazoles and -carbolines , 
 providing entry into seldom explored chemical space .