Stereochemical Diversity through Cyclodimerization: Synthesis of Polyketide-like Macrodiolides

[reaction: see text] An expeditious procedure for the direct formation of stereochemically well-defined macrodiolides is described. Cyclodimerizations of enantioenriched C7 and C8 hydroxy esters 6 in the presence of catalytic amounts of distannoxane transesterification catalysts afford 14- to 22-membered macrodiolides 7-9 bearing up to six stereocenters. Additional structural diversity is introduced by further stereoselective reactions on selected macrodiolides 7a, 7g, 10a, and 11.