An Alternative Route for Synthesis of Chiral 4‐Substituted 1‐Arenesulfonyl‐2‐imidazolidinones: Unusual Utility of (4S,5S)‐ and (4R,5R)‐4,5‐Dimethoxy‐2‐imidazolidinones and X‐Ray Crystallography

An unusual synthesis of (S)-1-arenesulfonyl-4-(1-adamantyl)-2-imidazolidinones 15a–d and (R)-1-arenesulfonyl-4-tert-butyl-2-imidazolidinones 19a–d has been developed from trans-1-apocamphanecarbonyl-4,5-dimethoxy-2-imidazolidinones 6 and 7 as chiral synthons. Diastereomerically pure trans-1-apocamphanecarbonyl-4,5-dimethoxy-2-imidazolidinones 6 and 7 were successfully subjected to regioselective reduction using bulky organocuprates that afforded 1-apocamphanecarbonyl-5-methoxy-2-imidazolidinones 10 and 11. This new finding was used for synthesis of chiral 4-substituted 2-imidazolidinones 15a–d and 19a–d through the corresponding intermediates 13 and 17 by treatment with steric bulky tert-butylcuprate or 1-adamantylcuprate