Commercially available o-phenylenediamine (1) was treated with methyl a-bromo-a-aryl acetate to obtain 3-aryl-3,4-dihydro-1H-quinoxalin-2-one (2). The latter was reacted with benzyl bromide to obtain 4-benzyl-3-aryl-3,4-dihydro-1H-quinoxalin-2-one (3). Treatment of 3 with ethyl 3-bromopropionate resulted in the formation of 3-(4-benzyl-3-aryl-2-oxo-3,4-dihydro-2H-quinoxalin-1-yl)propionic acid ethyl ester (4), which on reaction with LiAlH4 gave 9-benzyl-10-phenyl-3,4,10,10a-tetrahydro-2H,9H-1-oxa-4a,9-diazaphenanthrene (5) via a reductive cyclization. In another sequence of reactions, 2 was treated with benzyl chloroformate to obtain 3-oxo-2-aryl-3,4-dihydro-2H-quinoxalin-1-carboxylic acid benzyl esters (6). The latter on treatment with ethyl 3-bromopropionate gave 4-(2-ethoxycarbonylethyl)-3-oxo-2-phenyl- 3,4-dihydro-2H-quinoxaline-1-carboxylic acid benzyl esters (7). Then 7 was reductively cyclized with LiAlH4 to obtain 10-phenyl-3,4,10,10a-tetrahydro-2H-1-oxa-4a,9-diazaphenanthrene-9-carboxylic acid benzyl esters (8). In an yet another sequence of reactions, 2 was treated with catalytic amount of p-toluene sulphonic acid in toluene under refluxing conditions to obtain 3-phenyl-1H-quinoxaline-2-one (9). The latter, on treatment with ethyl 3-bromopropionate gave 3-[3-phenyl-2-oxo-2H-quinoxalin-1-yl]propionic acid ethyl esters (10), followed by reductive cyclization with LiAlH4 to afford 10-phenyl-3,4-dihydro-2H,10aH-1-oxa-4a,9-diazaphenanthrene (11). All the new products obtained in the above three sequences of reactions have been adequately characterized by spectral data.
将市售的
邻苯二胺(1)与 a-
溴-a-芳基
乙酸甲酯处理,得到 3-芳基-3,4-二氢-1H-
喹喔啉-2-酮(2)。后者与
溴化苄反应,得到 4-苄基-3-芳基-3,4-二氢-1H-
喹喔啉-2-酮(3)。用
3-溴丙酸乙酯处理 3,可生成 3-(4-苄基-3-芳基-2-氧代-3,4-二氢-2H-
喹喔啉-1-基)
丙酸乙酯 (4),该
乙酯与 LiAlH4 反应,通过还原环化生成 9-苄基-10-苯基-3,4,10,10a-四氢-2H,9H-1-氧杂-4a,9-二氮
菲 (5)。在另一序列反应中,2 与
氯甲酸苄酯进行处理,得到 3-氧代-2-芳基-3,4-二氢-2H-
喹喔啉-1-
羧酸苄酯 (6)。后者经
3-溴丙酸乙酯处理后得到 4-(2-乙氧羰基乙基)-3-氧代-2-苯基-3,4-二氢-2H-
喹喔啉-1-
羧酸苄酯(7)。然后用 LiAlH4 对 7 进行还原环化反应,得到 10-苯基-3,4,10,10a-四氢-2H-1-氧杂-4a,9-二氮
菲-9-
羧酸苄酯 (8)。在另一系列反应中,在回流条件下,2 与
对甲苯磺酸在
甲苯中进行催化处理,得到 3-苯基-1H-
喹喔啉-2-酮(9)。后者经
3-溴丙酸乙酯处理后,得到 3-[3-苯基-2-氧代-2H-
喹喔啉-1-基]
丙酸乙酯(10),然后用 LiAlH4 还原环化,得到 10-苯基-3,4-二氢-2H,10aH-1-氧杂-4a,9-二氮
菲(11)。上述三个反应序列中得到的所有新产品都已通过光谱数据进行了充分表征。