An efficient diastereoselective glyoxylate-ene reaction using N-glyoxyloyl camphorpyrazolidinone as an enophile

The diastereoselective glyoxylate-ene reaction of N-glyoxyloyl camphorpyrazolidinone (1) with various alkenes 2a–g in the presence of Lewis acid is described. The corresponding α-hydroxyl carbonyls were generally obtained in moderate to high chemical yields (64–87%) and with high levels of diastereoselectivities (up to 94% de). The predominance of products with the S absolute configuration at the newly formed stereogenic center was established by single crystal X-ray analysis and the importance of stereochemical induction is discussed.