1,3-Dipolar cycloadditions of azomethine ylides to alkenylboronic esters. Access to substituted boron analogues of β-proline and 3-hydroxypyrrolidines

3-Boronic esters-substituted pyrrolidines were prepared via 1,3-dipolar cycloadditions of azomethine ylides to alkenyl boronates. Hydrolysis gave boron analogues of substituted β-prolines, while treatment with trimethylamine oxide afforded the corresponding pyrrolidin-3-ols.