Furanyl spiroketals: thermodynamic control of remote asymmetry

(E,E)-2-Alkyl-8-furanyl-1,7-dioxa-spiro[5.5]undecanes (1a-i) have been prepared in good yield and with very high diastereoselectivity from lactones (2a-e) and alkynes (3a,b) using lithium acetylide coupling, hydrogenation, desilylation and acid catalysed cyclisation/equilibration.