The C-1-C-11 subunit of tedanolide was constructed using a boron-mediated syn aldol reaction as the key step to control the C-6 and C-7 stereocenters. Other features of this work include the asymmetric Sharpless dihydroxylation to incorporate the C-2, C-3 hydroxyl groups, selective protection of the hydroxyl group at C-2 as well as the usage of a tert-butyl ester to tolerate the attack of Grignard and enolate reagents. (C) 2001 Elsevier Science Ltd. All rights reserved.