Asymmetric Synthesis of 2,3,4-Trisubstituted Functionalised Tetrahydrofurans via an Organocatalytic Michael Addition as Key Step

The organocatalytic Michael addition of various aldehydes to (2E,4E)-ethyl 5-nitropenta-2,4dienoate has been achieved under the catalysis of diphenylprolinol trimethylsilyl ether furnishing the products in good to excellent yields (61-94%) and high stereoselectivities (dr up to >98:2, ee=97 to > 99%). Starting from these Michael adducts, 2,3,4trisubstituted functionalized tetrahydrofurans are available in two steps by reduction of the aldehyde followed by an intramolecular oxa-Michael addition in good yields (54-76%) and stereoselectivities (dr up to >95:5, ee= 97 to >99%).