Synthesis of More Highly Oxidized Alkyl Citrates via Direct Regio- and Stereoselective Oxidation

An approach to more highly oxidized alkyl citrates by direct regio- and stereoselective oxidations is reported. The total synthesis and structural assignment of alkyl citrate L-731-128 are described, and the synthesis of its C4 oxidized congener L-731,127 utilized a regio- and stereoselective enolate oxidation with oxygen gas. A highly stereoselective Rubottom oxidation of a cyclic silylketene acetal then enabled oxidation at C2 to afford the cinatrins C-1 and C-3.

Automated summary

This study reports an approach to achieve higher oxidation of alkyl citrates through direct regio- and stereoselective oxidations. The synthesis and structural assignment of alkyl citrate L-731-128 were described. The C4 oxidized congener L-731,127 was synthesized using regio- and stereoselective enolate oxidation and oxygen gas oxidation. Furthermore, a highly stereoselective Rubottom oxidation was utilized to achieve oxidation at C2, yielding cinatrins C-1 and C-3.