Enantioselective Synthesis of a Tetrasubstituted Oxocane via a Double Diastereoselective Hetero Diels-Alder Reaction
31. Dezember 2001 (online)
A procedure for the enantioselective preparation of tetra-substituted medium sized cyclic ethers is presented. An oxocane is prepared by a sequence which involves a double diastereoselective hetero Diels-Alder reaction between a chiral aldehyde and a diene bearing an allylic chiral centre. The cycloadduct is transformed into a linear ether which is then converted to the cyclic ether by a highly regioselective intramolecular alkylation of a lithiosulfone with an epoxide. The sense of induction of the chiral centre on the diene is discussed.
hetero Diels-Alder reaction - double diastereoselectivity - intramolecular alkylation - cyclic ethers