We have recently reported that treatment of an acyclic iodo-ester with n- or t-butyllithium effected intramolecular cyclization to give the hemiacetal, which was reduced with Et 3 SiH in the presence of BF 3 ·Et 2 O to give 2,6-syn-tetrahydropyran. 7 As an application of this method to the synthesis of natural products, we focused our attention on the synthesis of (−)-centrolobine (1). Retrosynthetic analysis revealed two possible synthetic routes, A and B, using iodo-esters 2 and 3, ...