An asymmetric approach to coumarin anticoagulants via hetero-Diels-Alder cycloaddition

We have developed a general, two-step protocol for the synthesis of chiral non-racemic coumarin anticoagulants (e.g. warfarin. coumachlor and acenocoumarol). This approach features a one-pot three-component tandem Knoevenagel-hetero-Diels-Alder reaction between in situ generated 3-arylidene-2,4-chromanediones and iso-propenyl ether derived from (-)-menthol. (C) 2001 Elsevier Science Ltd. All rights reserved.