Stereoselective reduction and reductive dephosphonylation of β-iminophosphonates

Article abstract of DOI:10.1016/S0040-4039(02)00521-X

Proline-like 2,4-dialkyl-5-phosphonylpyrrolidines 2 were obtained stereoselectively by reduction of the corresponding β-iminophosphonates 1 with NaBH₄. The detailed characterization of compounds 2 was accomplished by ¹H and ¹³C NMR as well as by crystal structure analysis. When 1 was reduced with LiAlH₄ the reaction gave dephosphonylated pyrrolidines 3. The latter method is suitable for providing substituted pyrrolidines regioselectively. A possible mechanism for the dephosphonylation is proposed.