Toward the synthesis of spirastrellolide a: construction of a tetracyclic C26-C40 subunit containing the DEF-bis-spiroacetal.

[reaction: see text] A stereo-controlled synthesis of the fully elaborated C26-C40 tricyclic [5,6,6]-bis-spiroacetal of spirastrellolide A containing the C28 chlorine substituent is reported, exploiting asymmetric Sharpless dihydroxylation and boron-mediated allylation methodology

Toward the synthesis of spirastrellolide A: construction of two C1-C25 diastereomers containing the BC-spiroacetal.

[reaction: see text] Stereo-controlled syntheses of two possible C1-C25 diastereomers of spirastrellolide A containing the cis-disubstituted tetrahydropyran and [6,6]-spiroacetal are reported, exploiting boron-mediated asymmetric aldol and allylation methodology