Synthesis of 5-hydroxy-2,3,4,5-tetrahydro-[1H]-2-benzazepin-4-ones: selective antagonists of muscarinic (M3) receptors
作者:Benjamin Bradshaw、Paul Evans、Jane Fletcher、Alan T. L. Lee、Paul G. Mwashimba、Daniel Oehlrich、Eric J. Thomas、Robin H. Davies、Benjamin C. P. Allen、Kenneth J. Broadley、Amar Hamrouni、Christine Escargueil
DOI:10.1039/b801206g
日期:——
Two approaches to tetrahydro-[1H]-2-benzazepin-4-ones of interest as potentially selective, muscarinic (M3) receptor antagonists have been developed. Base promoted addition of 2-(tert-butoxycarbonylamino)methyl-1,3-dithiane 5 with 2-(tert-butyldimethylsiloxymethyl)benzyl chloride 14 gave the corresponding 2,2-dialkylated 1,3-dithiane 15 which was taken through to the dithiane derivative 19 of the parent 2,3,4,5-tetrahydro-[1H]-2-benzazepin-4-one by desilylation, oxidation and cyclisation via a reductive amination. After conversion into the N-tert-butyloxycarbonyl, N-toluene p-sulfonyl and N-benzyl derivatives 20–22, hydrolysis of the dithiane gave the N-protected tetrahydro-[1H]-2-benzazepin-4-ones 23–25. However, preliminary attempts to convert these into 5-cycloalkyl-5-hydroxy derivatives were not successful. In the second approach, ring-closing metathesis was used to prepare 2,3-dihydro-[1H]-2-benzazepines which were hydroxylated and oxidized to give the required 5-hydroxy-2,3,4,5-tetrahydro-[1H]-2-benzazepin-4-ones. Following preliminary studies, ring-closing metathesis of the dienyl N-(2-nitrophenyl)sulfonamide 48 gave the dihydrobenzazepine 50 which was converted into the 2-butyl-5-cyclobutyl-5-hydroxytetrahydrobenzazepin-4-one 55 by hydroxylation and N-deprotection followed by N-alkylation via reductive amination, and oxidation. This chemistry was then used to prepare the 2-[(N-arylmethyl)aminoalkyl analogues 69, 72, 76 and 78. N-Acylation followed by amide reduction using the borane–tetrahydrofuran complex was also used to achieve N-alkylation of dihydrobenzazepines and this approach was used to prepare the 5-cyclopentyl-5-hydroxy-2,3,4,5-tetrahydro-[1H]-2-benzazepin-4-one 103 and the 5-cyclobutyl-8-fluoro-5-hydroxy-2,3,4,5-tetrahydro-[1H]-2-benzazepin-4-one 126. The structures of 2-tert-butyloxycarbonyl-4,4-propylenedithio-2,3,4,5-tetrahydro-[1H]-2-benzazepine 20 and (4RS,5SR)-2-butyl-5-cyclobutyl-4,5-dihydroxy-2,3,4,5-tetrahydro-[1H]-2-benzazepine 53 were confirmed by X-ray diffraction. The racemic 5-cycloalkyl-5-hydroxy-2,3,4,5-tetrahydro-[1H]-2-benzazepin-4-ones were screened for muscarinic receptor antagonism. For M3 receptors from guinea pig ileum, these compounds had log10KB values of up to 7.2 with selectivities over M2 receptors from guinea pig left atria of approximately 40.
针对四氢-[1H]-2-苯并氮杂环-4-酮作为潜在选择性毒蕈碱(M3)受体拮抗剂,已开发出两种合成途径。通过碱促反应,将2-(叔丁氧羰基氨基)甲基-1,3-二硫杂环烷-5与2-(叔丁基二甲基硅氧基甲基)苯甲基氯化物-14反应,得到了相应的2,2-二烷基化的1,3-二硫杂环烷-15,然后通过去硅化、氧化和还原胺化反应合成了母体2,3,4,5-四氢-[1H]-2-苯并氮杂环-4-酮的二硫杂环烷衍生物-19。在转化为N-叔丁氧羰基、N-甲苯p-磺酰基和N-苄基衍生物-20至-22后,二硫杂环烷的水解得到了N保护的四氢-[1H]-2-苯并氮杂环-4-酮-23至-25。然而,初步尝试将这些化合物转化为5-环烷基-5-羟基衍生物未成功。在第二种方法中,采用环闭合钠发生反应制备了2,3-二氢-[1H]-2-苯并氮杂环,并对其进行羟基化和氧化,得到所需的5-羟基-2,3,4,5-四氢-[1H]-2-苯并氮杂环-4-酮。经过初步研究,dienyl N-(2-硝基苯基)磺酰胺-48的环闭合钠发生反应生成了二氢苯并氮杂环-50,随后通过羟基化和去保护N基,再通过还原胺化进行N-烷基化和氧化,得到了2-丁基-5-环丁基-5-羟基四氢苯并氮杂环-4-酮-55。该化学反应进一步用于合成2-[(N-芳基甲基)氨基烷基]类似物-69、72、76和78。采用N-酰化,然后使用硼烷–四氢呋喃络合物进行酰胺还原,也用于实现二氢苯并氮杂环的N-烷基化,此方法可合成5-环戟基-5-羟基-2,3,4,5-四氢-[1H]-2-苯并氮杂环-4-酮-103和5-环丁基-8-氟-5-羟基-2,3,4,5-四氢-[1H]-2-苯并氮杂环-4-酮-126。2-叔丁氧羰基-4,4-丙烯二硫-2,3,4,5-四氢-[1H]-2-苯并氮杂环-20和(4RS,5SR)-2-丁基-5-环丁基-4,5-二羟基-2,3,4,5-四氢-[1H]-2-苯并氮杂环-53的结构通过X射线衍射得到确认。对外消旋的5-环烷基-5-羟基-2,3,4,5-四氢-[1H]-2-苯并氮杂环-4-酮进行了毒蕈碱受体拮抗活性筛选。在来自豚鼠回肠的M3受体实验中,这些化合物的log10KB值最高可达7.2,对来自豚鼠左心房的M2受体的选择性约为40。