The enantioselective allylation of thiophene-2-carbaldehyde with allyltrichlorosilane under Lewis base catalysis has been studied. The use of catalytic amount (1mol%) of chiral bipyridine N,N-dioxides provided the corresponding 1-(thiophen-2-yl)-but-3-en-1-ol with asymmetric induction reaching 97% ee.
The prepared chiral (S)-1-(thiophen-2-yl)-but-3-en-1-ol was used as the crucial chiral building block in a formal total synthesis of duloxetine.