1995 Volume 53 Issue 7 Pages 593-603
The comprehensive synthesis of a variety of lignans based on our conceptually new synthetic strategy is described.
Lignans were synthesized effectively by using the key intermediate 2. The compound 2 was synthesized in a stereoselective manner by the Michael addition of the O-TBS cyanohydrin to 2-butenolide, followed by the aldol reaction of the resulting enolate with an aromatic aldehyde. The key intermediate 2 was converted into : lignans of the aryltetralin series including podophyllotoxin stereoselectively; 1-arylnaphthalene and 1-aryl-4-hydroxynaphthalene lignans in a one-pot procedure by the acid-catalyzed cyclization and the aromatizationlactonization, respectively; lignans of the furofuran and bislactone-type furofuran series by the stereoselective intramolecular cyclization. Finally, we describe the asymmetric synthesis of lignans utilizing the chiral benzyl-lactones 68 and 73 as key intermediates which were synthesized via the Michael addition of the cyanohydrin 15 to chiral α, β-unsaturated esters 65 and 71.
