Synthesis of highly substituted 2,6-anti-configured tetrahydropyrans. First steps towards an efficient access to amphidinol 3 ring system

Highly functionalised and polysubstituted tetrahydropyrans, akin to the middle core of the amphidinols, can be efficiently synthesised, with full stereocontrol and in good yields, using as key steps an anti-allylation reaction coupled with an intramolecular Sakurai cyclisation. Three approaches were devised in order to reach a broad range of substitution patterns.