Synfacts 2011(9): 1011-1011  
DOI: 10.1055/s-0030-1260924
Organo- and Biocatalysis
© Georg Thieme Verlag Stuttgart ˙ New York

Controlling the Reaction Mechanism to Construct Dihydrocoumarins

Contributor(s): Benjamin List, Olga Lifchits
D. Enders*, X. Yang, C. Wang, G. Raabe, J. Runsik
RWTH Aachen University, Germany
Further Information

Publication History

Publication Date:
19 August 2011 (online)


Enders and colleagues report the synthesis of chromans 4 and dihydrocoumarins 5 by a dienamine-catalyzed Michael reaction- hemiacetalization cascade. Despite using the same substrates 1 and 2 and the same catalyst 3 - used previously to construct isomeric chromans 9 - the authors were able to enforce a different catalytic regime. Thus, through a judicial choice of acidic additives, the formation of dienamine 7 (pathway A) could be favored over iminium activation (pathway B), which leads to an undesired oxa-Michael reaction. The reported reaction offers entry to a different type of chroman scaffolds 4 as well as ­dihydrocoumarin derivatives 5.