the 
 first asymmetric insertion reactions of donor  donor 
 carbenoids , i.e. , those with no pendant electron - withdrawing groups , 
 are reported . 
 this process enables the synthesis of densely substituted 
 benzodihydrofurans with high levels of enantio- and diastereoselectivity . 
 preliminary results show similar efficiency in the preparation of 
 indanes . 
 this new method is used in the first enantioselective synthesis 
 of an oligoresveratrol natural product ( e--viniferin ) .