Thiourea-catalyzed nucleophilic addition of TMSCN and ketene silyl acetals to nitrones and aldehydes

The effect of hydrogen bonding between nitrones and urea derivatives in the nucleophilic addition reaction was examined. Thioureas bearing an electron-withdrawing group on an aromatic ring, behave like Lewis acid to promote the addition of TMSCN and ketene silyl acatals to various nitrones and aldehydes. Presumed interaction between nitrones and thioureas was supported by NMR experiments. (C) 2003 Elsevier Science Ltd. All rights reserved.