Stereocomplementary Synthesis of cis‐ and trans‐2‐(p‐Bromophenyl)‐5‐methylthiazolidin‐4‐ones: Useful Umpolung‐type Suzuki–Miyaura Cross‐coupling Partner and Donor

Novel cis- and trans-2-(p-bromophenyl)-5-methylthiazolidin-4-ones, S,N-containing heterocyclic compounds, were provided in a cis-stereocomplementary and trans-stereocomplementary synthetic manner. cis-Selective cyclo-condensation proceeded between 2-sulfanylpropanoic acid (thiolactic acid) and an imine derived from 4-bromobenzaldehyde and methylamine, whereas Ti(OiPr)4 and Ti(OiBu)4-promoted trans-selective cyclo-condensation proceeded between benzyl 2-sulfanylpropanoate and the imine. The obtained cis- and trans-2-(p-bromophenyl)-5-methylthiazolidin-4-ones were successfully converted to 2-(3-furyl)phenyl derivatives and bis(pinacolato)diborane derivatives utilizing Suzuki–Miyaura and Miyaura–Ishiyama cross-coupling reactions, respectively, in an umpolung manner.