1H-1,3-Diazepines, 5H-1,3-diazepines, 1,3-diazepinones, and 2,4-diazabicyclo[3.2.0]heptenes,
作者:Ales Reisinger、Rainer Koch、Paul V. Bernhardt、Curt Wentrup
DOI:10.1039/b317099c
日期:——
Tetrazolo[1,5-a]pyridines/2-azidopyridines 1 undergo photochemical nitrogen elimination and ring expansion to 1,3-diazacyclohepta-1,2,4,6-tetraenes 3, which react with alcohols to afford 2-alkoxy-1H-1,3-diazepines 4
(5), with secondary amines to 2-dialkylamino-5H-1,3-diazepines 16, sometimes via isolable 2-dialkylamino-1H-1,3-diazepines 15, and with water to 1,3-diazepin-2-ones 19. The latter are also obtained by elimination of isobutene or propene from 2-tert-butoxy- or 2-isopropoxy-1H-1,3-diazepines 4 or 5. 1,3-Diazepin-2-one 22B and 1,3-diazepin-4-one 24 were obtained from hydrolysis of the corresponding 4-chlorodiazepines. Diazepinones 19 undergo photochemical ring closure to diazabicycloheptenones 25 in high yields. The 2-alkoxy-1H-1,3-diazepines 4 and 5 interconvert by rapid proton exchange between positions N1 and N3. The free energies of activation for the proton exchange were measured by the Forsén–Hoffman method as ΔG‡298
= 16.2 ± 0.6 kcal mol−1 as an average for 4a–c in CD2Cl2, acetone-d6, and methanol-d4, and 14.1 ± 0.6 kcal mol−1 for 4c in acetone/D2O. The structures of 2-methoxy-5,6-bis(trifluoromethyl)-1H-1,3-diazepine 4k, 1,2-dihydro-4-diethylamino-5H-1,3-diazepin-2-one 22bB, and diazabicycloheptanone 26 were determined by X-ray crystallography. The former represents the first reported X-ray crystal structure of any monocyclic N-unsubstituted 1H-azepine.
Tetrazolo[1,5-a]吡啶/2-叠氮吡啶 1 经过光化学氮消除和环扩展,生成 1,3-二氮杂环庚-1,2,4,6-四烯 3,这些化合物与醇反应生成 2-烷氧基-1H-1,3-二氮唑 4 (5),与二级胺反应生成 2-二烷基氨基-5H-1,3-二氮唑 16,有时通过可分离的 2-二烷基氨基-1H-1,3-二氮唑 15 进行反应,并与水反应生成 1,3-二氮唑-2-酮 19。后者也可通过从 2-叔丁氧基或 2-异丙氧基-1H-1,3-二氮唑 4 或 5 中消除异丁烯或丙烯来获得。1,3-二氮唑-2-酮 22B 和 1,3-二氮唑-4-酮 24 是通过水解相应的 4-氯二氮唑获得的。二氮唑酮 19 经过光化学环闭合生成高产率的二氮杂双环庚酮 25。2-烷氧基-1H-1,3-二氮唑 4 和 5 通过 N1 和 N3 位之间的快速质子交换互变。通过 Forsén–Hoffman 方法测定质子交换的活化自由能为 ΔG‡298 = 16.2 ± 0.6 kcal mol−1,作为 4a–c 在 CD2Cl2、氢代丙酮-d6 和氢代甲醇-d4 中的平均值,4c 在丙酮/D2O 中的值为 14.1 ± 0.6 kcal mol−1。2-甲氧基-5,6-双(三氟甲基)-1H-1,3-二氮唑 4k、1,2-二氢-4-二乙氨基-5H-1,3-二氮唑-2-酮 22bB 和二氮杂双环庚酮 26 的结构通过X射线晶体学确定。前者代表了第一个报道的任何单环 N-未取代 1H-氮唑的 X 射线晶体结构。