Diastereoselective ring-closing metathesis in the synthesis of dihydropyrans
An investigation into the factors influencing the diastereochemical outcome of the ring-closing metathesis based synthesis of dihydropyrans is presented in this paper. Divinyl carbinols derived from alpha-hydroxy carboxylic acid esters are elaborated to trienes with two diastereotopic vinyl moieties. Depending on the steric demand of the oxo substituent of the divinyl carbinol moiety (either unprotected OH, TBDMS, or benzyl ether) different diastereomers are preferrably formed upon ring-closing metathesis. An extension to diastereoselective double ring-closing metathesis in the formation of spirocycles has also been investigated.
Schmidt
B
Universitat Dortmund, Fachbereich Chemie, Organische Chemie, Otto-Hahn-Strasse 6, D-44227 Dortmund, Germany.
Wildemann
H