Cyclopropanation of N-Substituted 2-Oxochromene- and 6-Bromo-2-oxochromene-3-carboxamides with Zinc Enolates Derived from 1-Aryl-2,2-dibromoalkanones
作者:V. V. Shchepin、P. S. Silaichev、R. V. Shchepin、M. A. Ezhikova、M. I. Kodess
DOI:10.1007/s11178-005-0199-6
日期:2005.4
Zinc enolates derived from 1-aryl-2,2-dibromoalkanones react with N-cyclohexyl-2-oxochromene-3-carboxamides to give N-cyclohexyl-1-alkyl-1-aroyl-2-oxo-1a,7b-dihydrocyclopropa[c]chromene-1a-carboxamides mainly as cis isomers with respect to the substituents in positions 1 and 1a. Reactions of the same zinc enolates with N-benzyl-2-oxochromene-3-carboxamide and N-benzyl-6-bromo-2-oxochromene-3-carboxamide lead to formation of 1-aryl-2-benzyl- and 1-aryl-2-benzyl-6-bromo-1-hydroxy-9c-alkyl-1,2,9b,9c-tetrahydro-5-oxa-2-azacyclopenta[2,3]cyclopropa[1,2-a]naphthalene-3,4-diones. The reaction of zinc enolates with N-aryl-2-oxochromene-3-carboxamides in a weakly polar solvent (diethyl ether or ethyl acetate) affords mixtures of cis-N-aryl-1-aroyl-1-alkyl-2-oxo-1a,7b-dihydrocyclopropa[c]chromene-1a-carboxamides and their cyclic isomers, 9c-alkyl-1,2-diaryl-1-hydroxy-1,2,9b,9c-tetrahydro-5-oxa-2-azacyclopenta[2,3]cyclopropa[1,2-a]naphthalene-3,4-diones, the latter prevailing. N-Substituted 1-alkyl-1-aroyl-2-oxo-1a,7b-dihydrocyclopropa[c]chromene-1a-carboxamides in which the aroyl group on C1 and the carboxamide group on C1a are arranged trans are formed by reactions of zinc enolates with the corresponding 2-oxochromene-3-carboxamides in the presence of hexamethylphosphoric triamide.
源自1-芳基-2,2-二溴代烷基酮的锌烯醇盐与N-环己基-2-氧代色烯-3-羧酰胺反应,主要生成顺式异构体,相对于位置1和1a的取代基,形式为N-环己基-1-烷基-1-芳酰基-2-氧代-1a,7b-二氢环丙[c]色烯-1a-羧酰胺。同样的锌烯醇盐与N-苄基-2-氧代色烯-3-羧酰胺和N-苄基-6-溴-2-氧代色烯-3-羧酰胺反应,生成1-芳基-2-苄基和1-芳基-2-苄基-6-溴-1-羟基-9c-烷基-1,2,9b,9c-四氢-5-氧-2-氮杂环戊[2,3]环丙[1,2-a]萘-3,4-二酮。锌烯醇盐与N-芳基-2-氧代色烯-3-羧酰胺在弱极性溶剂(乙醚或乙酸乙酯)中反应,得到顺式N-芳基-1-芳酰基-1-烷基-2-氧代-1a,7b-二氢环丙[c]色烯-1a-羧酰胺及其环状异构体,即9c-烷基-1,2-二芳基-1-羟基-1,2,9b,9c-四氢-5-氧-2-氮杂环戊[2,3]环丙[1,2-a]萘-3,4-二酮,后者占优势。在六甲基磷酸三胺存在下,锌烯醇盐与相应的2-氧代色烯-3-羧酰胺反应,生成N-取代的1-烷基-1-芳酰基-2-氧代-1a,7b-二氢环丙[c]色烯-1a-羧酰胺,其中C1上的芳酰基和C1a上的羧酰胺基团以反式排列。