Synthesis of Chiral Heteroaryl-Substituted Dihydropyran Derivatives via Ring Closing Enyne Metathesis Reaction

The ring closing enyne metathesis reactions have been applied to systems derived from homopropargylic alcohol backbones are described. The key intermediates 2-benzofuranyl and 2-benzothiophenyl homopropargylic alcohols were synthesized from their corresponding carboxyaldehyde derivatives and resolved to give the corresponding enantiopure acetates and the alcohols with high ee values through enzymatic resolution. Then, enantiomerically enriched enyne skeletons derived from homopropargylic alcohols were subjected to the ring closing metathesis reaction via first generation Grubbs' catalysts and corresponding chiral heteroaryl-substituted dihydropyran derivatives were obtained with good yields.