Synthesis And Reaction Has Clau Sim Clau Discussed

The biomimic syntheses of homoclausenamide (1) and zetaclausenamide (2) were studied. From the key intermediate (9) which was prepared from phenethyl alcohol as starting material, the desired compounds (1) and (2) were obtained in overall yields of 2.1% and 2.0%, respectively:When the cyclization of (9) was carried out in CH₂Cl₂ with BF₃·Et₂O as catalyst, the compounds (1), (19), (20) and (21) were obtained in yields of 5.7%, 2.0%, 26.5% and 16.9%, respectively, and their formative mechanism was explained. Under the same cyclization condition, compound (9-1) gave the products of (2) and (1) in yields of 21.6% and 4.4%, respectively.In order to improve the yield of the desired compound (1), varried cyclization conditions of (9) were tried. When the reaction was carried in CH₂Cl₂ with TiCl₄ as catalyst, the compounds (24) and (25) were obtained, and when F₃CCOOH was used as catalyst, the compound (26) was obtained. No satisfying result was obtained, even the yield of (1) can be raised to 11.2% by...