Lithium TADDOLate-triethylboron system as a promoter for the catalytic enantioselective Michael addition of malonates to chalcone.
The reaction mixture obtained by treating equimolar amounts of a TADDOL with lithium triethylborohydride promotes the catalytic enantioselective Michael addition of malonates to chalcone with good yields and moderate enantioselectivities. The catalyst is alternatively generated reacting the 1,4-diol with butyllithium and triethylborane. The adduct of dibenzyl malonate to chalcone is attained with 99% ee, after one recrystallization. The reaction scale-up was achieved successfully.
Irurre
J
J
Department of Organic Chemistry, Institut Químic de Sarrià, Universitat Ramón Llull, Via Augusta 390, E-08017 Barcelona, Spain. jirur@iqs.url.es
Riera
M
M
Amela-Cortés
C
C