Diastereoselective Chain Elongation Reactions Using Microreactors for Application in Complex Molecule Assembly

Diastereoselective chain-elongation reactions are important transformations for the assembly of complex molecular structures, such as those present in polyketide natural products. Here we report new methods for performing crotylation reactions and homopropargylation reactions by using newly developed low-temperature flow-chemistry technology. In-line purification protocols are described, as well as the application of the crotylation protocol in an automated multi-step sequence. Polyketides in flow: By using new low-temperature reactors, the scope of reactions conveniently performed in a flow process has been extended to encompass diastereoselective chain elongations. Various aldehydes undergo Roush crotylations and Marshall homopropargylation reactions smoothly in flow (see scheme), with incorporated in-line work-ups that drastically reduce the amount of time required for these transformations.