A concise synthesis of the octalactins

The total synthesis of octalactins A and B is achieved in 15 steps and 10% overall yield from commercially available materials. Key steps include the Paterson-Aldol reaction for the rapid assembly of the carbonate, methylenation of cyclic carbonate and subsequent Claisen rearrangement of the corresponding alkenyl-substituted cyclic ketene acetal to provide the core unsaturated medium-ring lactone and the use of enzyme-mediated acetate deprotection in the presence of a medium-ring lactone.