The first example of a (1R,2S,5R)-(−)-menthyl chiral auxiliary in intramolecular nitrilimine cycloadditions: synthesis of enantiopure pyrazolo[1,5-a][4,1]benzoxazepines and pyrazolo[1,5-a][4,1]benzodiazepines
摘要:
By using (1R, 2S, 5R)-(-)-menthyl as a chiral auxiliary, we have developed a synthesis of hydrazonoyl chlorides 2 and 8, treatment of which with silver carbonate promoted the in situ generation of the corresponding nitrilimines 3 and 9. The latter underwent intramolecular cycloaddition giving, respectively, enantiopure pyrazolo[1,5a] [4,1]benzoxazepines 4,5 and pyrazolo[1,5-a][4,1]benzodiazepines 10. (C) 1999 Elsevier Science Ltd. All rights reserved.
Depending upon the reaction conditions, intramolecular cycloadditions of variously substituted N-alkenoyl aryl azides 4 give the [1,2,3]triazolobenzodiazepine 5, bridgehead aziridines 6 or imines 7. The dipolarophilic activity of the CN double bond of the latter compounds is also exploited in the synthesis of [1,2,4]triazolobenzodiazepines 10 by means of nitrilimine cycloadditions.
The first example of a (1R,2S,5R)-(−)-menthyl chiral auxiliary in intramolecular nitrilimine cycloadditions: synthesis of enantiopure pyrazolo[1,5-a][4,1]benzoxazepines and pyrazolo[1,5-a][4,1]benzodiazepines
作者:Giorgio Molteni、Tullio Pilati
DOI:10.1016/s0957-4166(99)00422-x
日期:1999.10
By using (1R, 2S, 5R)-(-)-menthyl as a chiral auxiliary, we have developed a synthesis of hydrazonoyl chlorides 2 and 8, treatment of which with silver carbonate promoted the in situ generation of the corresponding nitrilimines 3 and 9. The latter underwent intramolecular cycloaddition giving, respectively, enantiopure pyrazolo[1,5a] [4,1]benzoxazepines 4,5 and pyrazolo[1,5-a][4,1]benzodiazepines 10. (C) 1999 Elsevier Science Ltd. All rights reserved.