Asymmetric syntheses of lignans utilizing novel diastereoselective Michael addition of cyanohydrin: Syntheses of (+)-fargesin and (-)- picropodophyllone

Article abstract of DOI:10.1016/S0040-4020(97)00643-1

The Michael addition reaction of lithium salt of cyanohydrin to (S)- and (R)-3-(2,2-dimethyl-1,3-dioxolan-4-yl)-cis-2-propenoate (2 and 3) proceeded in 93% de in the presence of two equivalents of HMPA at -100 °C. This diastereoselectivity could be elucidated by the stereocontrol based on the 1,3-allylic strain. Utilizing this reaction, stereocontrolled syntheses of (+)-fargesin (6) and (-)-picropodophyllone (7) were achieved.