杨玲玲, 刘乾才
(华东师范大学 化学系,上海 200062)
有机电致发光材料(OLED)在现代光电技术领域有着广阔的应用前景,近年来,已成为人们广泛关注的热点[1]。为了发展长寿命、全色平板显示器件,具有较高的热稳定性、无定型薄膜空穴传输材料被广泛应用于发光材料[2,3]。其中,多聚芴通过修饰可以改善发光性能,将其作为结构单元在OLED材料中得到了的广泛应用[4,5]。9,9′-螺二芴为结构单元的材料具有良好的热稳定性和空穴传输性能而引起了人们的注意[6,7]。
螺碳化合物通过sp3杂化的碳原子相连的两条共轭链所形成的刚性结构,能够有效地阻止激发子的形成,从而能有效地提高光纯度和光稳定性[8]。但含N=N键的螺二芴衍生物的报道很少[9]。我们曾报道了二氮杂芴取代的螺二芴及9,9-二烷基芴衍生物的合成,本文通过简便的合成方法将两个氮原子引入螺二芴结构,以期得到一类新型的有机光电材料前驱物。
Scheme1
以水合茚三酮为起始原料,分别与芳甲基酮(1a~1e)缩合后与水合肼环合制得2-芳基-3,4-二氮杂芴酮(2a~2e)。 2在H2NNH2·H2O-H2O/(CH2CH2OH)2O/EtOH体系[10]中还原成2-芳基-3,4-二氮杂芴(3a~3e)。 进一步研究发现,2a~2c与2-溴联苯的格氏试剂反应可顺利得到相应的叔醇(4a~4c); 4用HCO2Na/ HCO2H关环合成了3个2-芳基-3,4-二氮杂螺二芴(5a~5c)(Scheme 1)。其结构经1H NMR,13C NMR和元素分析表征。
X-4型显微熔点仪(温度计未校正);Bruker DR×500(氢谱500 MHz,碳谱125 MHz)型核磁共振仪(CDCl3为溶剂,TMS为内标);Vario EL元素分析仪;柱色谱分离用硅胶H,青岛海洋化工厂,100目~200目或300目~400目。
所用试剂均为市售化学纯或分析纯,溶剂使用前均按标准方法处理。
(1)2a~2e的合成[11,12](以2a为例)
在圆底烧瓶中依次加入苯乙酮(1a)1.2 g(10 mmol),水合茚三酮1.78 g(10 mmol)和AcOH 15 mL,搅拌下回流反应3 h~4 h。冷却至室温,于0 ℃~20 ℃滴加85%水合肼1 mL,反应过夜。过滤,滤饼经柱层析[洗脱剂A:V(二氯甲烷) ∶V(石油醚)=1 ∶1]纯化得2-苯基-3,4-二氮杂芴酮(2a)。用类似的方法合成2b~2e。
2a:1H NMRδ: 8.20(d,J=7.5 Hz, 1H), 8.13~8.15(m, 2H), 8.01(s, 1H), 7.87(d,J=7.5 Hz, 1H), 7.75~7.78(m, 1H), 7.54~7.59(m, 4H)。
(2) 3a~3e的合成(以3a为例)
圆底瓶中依次加入2a0.5 g(1.9 mmol),一缩聚乙二醇20 mL和乙醇2 mL,搅拌下滴加85%水合肼3 mL,滴毕,回流反应过夜(有白色晶体析出,冷却静置后有更多结晶析出)。抽滤,滤饼干燥得2-苯基-3,4-二氮杂芴(3a)。用类似的方法合成3b~3e。
3a:1H NMRδ: 8.34~8.35(dd br, 1H), 8.13(d,J=7.0 Hz, 2H), 7.95(s, 1H), 7.60(d,J=6.5 Hz, 1H), 7.46~7.54(m, 5H), 4.00(s, 2H, CH2);13C NMRδ: 161.75, 156.66, 142.88, 141.29, 138.02, 137.26, 130.17, 129.56, 128.89, 127.94, 127.17, 125.32, 122.01, 120.01, 34.67(CH2)。
(3)4a~4c的合成(以4a为例)
N2保护,在三颈瓶中加入镁粉0.1 g(4.2 mmol),几粒碘和THF 10 mL,搅拌下滴加2-溴联苯0.98 g(4.2 mmol)的THF(30 mL)溶液, 滴毕,回流反应1 h~2 h。滴加2a0.36 g(1.4 mmol)的THF(15 mL)溶液,回流反应过夜。冷却至室温,倒入饱和氯化铵溶液中,抽滤,滤饼用CH2Cl2重结晶得2-苯基-9-联苯-9-芴醇(4a)。用类似的方法合成4b和4c。
4a:1H NMR(DMSO-d6)δ: 8.46(d,J=8.0 Hz, 1H), 8.06(d,J=6.5 Hz, 2H), 7.74(s, 1H), 7.64~7.66(m, 1H), 7.58(t,J=8.0 Hz, 1H), 7.42~7.52(m, 5H), 7.35(t,J=7.5 Hz, 1H), 7.22~7.24(dd br, 1H), 6.83~6.86(m, 2H), 6.64(s, 1H), 6.57(d,J=5.0 Hz, 2H), 6.17(d,J=6.0 Hz, 1H), 5.73(d,J=6.5 Hz, 1H);13C NMRδ: 159.57, 156.89, 151.56, 149.03, 140.09, 139.83, 138.90, 136.65, 136.47, 131.00, 130.91, 129.72, 129.22, 128.96, 128.16, 127.44, 127.40, 126.88, 126.80, 126.52, 126.26, 126.06, 124.93, 120.99, 119.25, 79.72(C-OH)。
(4) 5a~5c的合成(以5a为例)
将4a1.3 g(3.16 mmol)溶于甲酸中,搅拌下加入甲酸钠9 g,回流反应52 h。倾入冰水中,有淡黄色固体生成,过滤,滤饼经柱层析(洗脱剂A)纯化得2-苯基-3,4-二氮杂螺二芴(5a)。用类似的方法合成5b和5c。
5a:1H NMRδ: 8.42(d,J=7.5 Hz, 1H), 7.88~7.95(m, 4H), 7.53(t,J=7.5 Hz, 1H), 7.38~7.44(m, 5H), 7.31(t,J=7.4 Hz, 1H), 7.19(s, 1H), 7.15(t,J=7.4 Hz, 2H), 6.80(d,J=7.5 Hz, 1H), 6.76(d,J=7.4 Hz, 2H);13C NMRδ: 161.82, 157.67, 148.96, 148.43, 146.53, 141.86, 137.90, 136.68, 131.30, 129.72, 128.87, 128.76, 128.61, 128.32, 127.13, 124.27, 124.09, 122.12, 120.42, 118.86, 63.86(Spiro sp3C); EI-MSm/z(%): 394(M+, 100), 365(53), 289(30), 181(22), 69(29), 55(17); Anal.calcd for C29H18N2: C 88.30, H 4.60, N 7.10; found C 88.28, H 4.66, N 6.77。
2~5的实验结果见表1,其余表征数据[14]与Scheme 1吻合。
参考文献[11,12]方法合成了2a~2e,但邻位卤代苯乙酮(2-碘代苯乙酮、2-溴代苯乙酮)与水合茚三酮、水合肼在相同条件下均未能得到相应的2-卤代苯基-3,4-二氮杂芴酮衍生物,其原因可能是邻位卤代基团空间位阻导致二氮杂环无法形成。
表1 2~5的实验结果
在2还原成3的反应中发现,按常规黄鸣龙还原条件无法获得满意的结果,可能是KOH的加入破坏了产物。实验参照文献[12]方法将2和水合肼在适当溶剂中回流后冷却结晶即可获得预期还原产物3,其结果通过1H NMR和13C NMR验证:研究发现-CH2-的1H NMR化学位移在4.0左右,而其13C NMR化学位移在35.0左右,2在190附近的C=O特征峰消失。
对于5的合成,利用2-溴联苯的格氏试剂和2反应得到4。 4在二氯甲烷洗中溶解性较差,直接利用二氯甲烷洗涤可得到较纯的产物;利用常规Gomberg条件(AcOH/HCl)[13]无法将4环合成5,通过对不同反应条件的尝试,发现利用多聚磷酸(PPA)可实现关环[9],但产率较低且需要高温和较长反应时间(20 h左右);利用HCO2Na/ HCO2H体系回流下可以以较高收率(50%~79%)获得5。 5的结构通过核磁碳谱氢谱,元素分析及质谱验证。螺二芴sp3螺碳的13C NMR化学位移在63.8左右,而叔醇C3COH的化学位移在79.0~89.0。
合成了一系列2-芳基-3,4-二氮杂芴酮,2-芳基-3,4-二氮杂芴及2-芳基-3,4-二氮杂螺二芴衍生物,并对合成条件进行了探讨。研究发现:(1)芳甲基酮和水合茚三酮、水合肼缩合环化过程中芳基邻位取代基特别是卤素的位阻会阻碍产物的形成;(2)无法采用典型黄鸣龙方法还原2-芳基-3,4-二氮杂芴酮,可直接利用水合肼在适当溶剂中还原芴羰基为亚甲基;(3)利用一般的螺二芴环合体系无法获得满意的结果,探索发现利用HCO2Na/HCO2H体系可顺利完成关环,为环合合成氮杂螺二芴衍生物提供了一种新的合成方法;(4)3a~3c和5b, 5c上的芳基卤代基团也可以进一步通过偶联反应使其共轭体系通过芳环或不饱和官能团如烯键或炔键得以延伸,为构建结构新颖的多环芳烃共轭体系提供了可能。
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[14]2b:1H NMRδ: 8.21(d,J=7.6 Hz, 1H), 7.98(s, 1H), 7.87~7.92(m, 5H), 7.75~7.78(m, 1H), 7.58~7.61(d br, 1H);13C NMRδ: 190.17(C=O), 160.93, 159.34, 142.19, 138.40, 136.55, 135.35, 134.87, 132.15, 131.08, 128.59, 125.29, 122.43, 117.08, 97.57(C-I).2c:1H NMRδ: 8.52(s, 1H), 8.21(d,J=7.6 Hz, 1H), 8.09(d,J=7.9 Hz, 1H), 7.96(s, 1H), 7.87(dd,J=4.0 Hz, 4.2 Hz, 2H), 7.77(t,J=7.3 Hz, 1H), 7.59(t,J=7.5 Hz, 1H), 7.27~7.31(dd,J=7.9 Hz, 5.7 Hz, 1H);13C NMRδ: 189.95(C=O), 161.10, 158.83, 142.34, 139.55, 138.11, 136.45, 136.21, 135.11, 132.13, 131.12, 130.70, 126.26, 125.26, 122.50, 117.20, 94.89(C-I).2d: (氢谱证实产物为2d和1d的1 ∶1的混合物);1H NMRδ: 8.52(s, 1H), 8.20(d,J=7.5 Hz, 1H), 8.00~8.05(m, 5H), 7.58(d,J=7.5 Hz, 1H), 7.52(t,J=8.0 Hz, 1H), 7.03(d,J=8.7 Hz, 2H), 6.98(d,J=8.7 Hz, 2H), 3.91(s, 3H, OCH3), 3.87(s, 3H, OCH3), 2.53(s, 3H, CH3CO).2e:1H NMRδ: 8.22(dd,J=8.5 Hz, 7.5 Hz, 3H), 8.05(s, 1H), 7.88(d,J=7.5 Hz, 1H), 7.75~7.80(m, 3H), 7.68(d,J=7.5 Hz, 2H), 7.58(t,J=7.5 Hz, 1H), 7.49(t,J=7.5 Hz, 2H), 7.40(t,J=7.5 Hz, 1H)(因溶解问题未获得较好的碳谱). 3b:1H NMRδ: 8.34~8.36(dd br, 1H), 7.95(s, 1H), 7.86~7.90(m, 4H), 7.62(d,J=7.8 Hz, 1H), 7.52~7.54(m, 2H), 4.02(s, 2H, CH2);13C NMRδ: 161.98, 155.63, 142.91, 141.42, 138.13, 137.79, 136.64, 130.37, 128.70, 128.01, 125.36, 122.05, 119.64, 96.09(C-I), 34.68(CH2). 3c:1H NMRδ: 8.50(s, 1H), 8.36~8.37(dd br, 1H), 8.12(d,J=7.8 Hz, 1H), 7.96(s, 1H), 7.82(d,J=7.9 Hz, 1H), 7.62~7.64(m, 1H), 7.53~7.55(m, 2H), 7.26~7.29(m, 1H), 4.03(s, 2H, CH2);13C NMRδ: 161.36, 154.33, 143.68, 141.84, 137.99, 136.87, 135.13, 130.84, 130.16, 127.53, 126.03, 125.74, 120.89, 120.68, 95.04(C-I), 34.22(CH2). 3d:1H NMRδ: 8.30(d,J=7.1 Hz, 1H), 8.07(d,J=8.7 Hz, 2H), 7.85(s, 1H), 7.56(d,J=7.1 Hz, 1H), 7.45~7.51(m, 2H), 7.01(d,J=8.7 Hz, 2H), 3.94(s, 2H, CH2), 3.86(s, 3H, OCH3). 3e:1H NMRδ: 8.37~8.39(dd br, 1H), 8.24(d,J=8.4 Hz, 2H), 8.04(s, 1H), 7.78(d,J=8.4 Hz, 2H), 7.69(d,J=7.2 Hz, 2H), 7.63(d,J=6.7 Hz, 2H), 7.47~7.55(m, 4H), 7.40(t,J=7.4 Hz, 1H), 4.05(s, 2H, CH2)(因溶解度不好,未获取13C NMR谱).4b:1H NMRδ: 8.44(d,J=8.0 Hz, 1H), 7.86(t,J=9.5 Hz, 4H), 7.76(s, 1H), 7.64~7.65(m, 1H), 7.57(t,J=7.5 Hz, 1H), 7.41~7.45(m, 2H), 7.34(t,J=7.5 Hz, 1H), 7.22~7.23(m, 1H), 6.83(d,J=6.0 Hz, 2H), 6.64(s, 1H), 6.56(s, 2H), 6.17~6.18(d,J=4.5 Hz, 1H), 5.70~5.72(m, 1H, OH);13C NMRδ: 169.25, 165.57, 161.08, 158.53, 149.54, 149.31, 148.29, 147.25, 145.83, 145.60, 140.58, 140.36, 138.72, 138.35, 137.59, 136.91, 136.89, 136.30, 136.00, 135.72, 135.55, 134.42, 130.52, 128.61, 106.42, 89.20(C-OH).4c:1H NMRδ: 8.48(d,J=4.0 Hz, 2H), 8.13(d,J=7.8 Hz, 1H), 7.87(d,J=5.6 Hz, 2H), 7.67~7.68(m, 1H), 7.61(t,J=8.0 Hz, 1H), 7.44~7.48(m, 2H), 7.32~7.39(m, 2H), 7.25(dd,J=2.0 Hz, 3.3 Hz, 1H), 6.85~6.89(m, 2H), 6.65(s, 1H), 6.60(s, 2H), 6.22(s, 1H), 5.75(br, 1H, OH);13C NMRδ: 159.66, 155.27, 151.43, 148.86, 139.66, 138.65, 138.60, 137.99, 136.12, 134.90, 130.80, 130.75, 130.64, 128.92, 127.11, 126.59, 126.02, 125.77, 124.66, 120.80, 119.19, 94.93(C-I), 79.59(C-OH).5b:1H NMRδ: 8.42(d,J=7.5 Hz, 1H), 7.90(d,J=8.0 Hz, 2H), 7.71(dd,J=8.5 Hz, 9.0 Hz, 4H), 7.54(t,J=7.5 Hz, 1H), 7.44(t,J=7.5 Hz, 2H), 7.33(t,J=7.5 Hz, 2H), 7.16(t,J=8.5 Hz, 3H), 6.81(d,J=8.0 Hz, 1H), 6.76(d,J=7.5 Hz, 2H);13C NMRδ: 162.09, 156.71, 149.00, 148.59, 146.32, 141.86, 137.95, 137.66, 136.09, 131.52, 128.96, 128.73, 128.37, 124.32, 124.10, 122.18, 120.50, 118.53, 96.41(C-I), 63.81(Spiro sp3C); EI-MSm/z(%): 520(M+, 3), 394(98), 365(56), 289(34), 214(20), 181(19), 143(26), 69(37), 55(25); Anal.calcd for C29H17N2I: C 66.94, H 3.29, N 5.38; found C 67.08, H 3.44, N 5.28.5c:1H NMRδ: 8.42(d,J=8.0 Hz, 1H), 8.27(s, 1H), 7.95(d,J=8.0 Hz, 1H), 7.91(d,J=7.5 Hz, 2H), 7.73(d,J=8.0 Hz, 1H), 7.55(t,J=7.5 Hz, 1H), 7.45(t,J=7.5 Hz, 2H), 7.34(t,J=7.5 Hz, 1H), 7.13~7.19(m, 4H), 6.83(d,J=8.0 Hz, 1H), 6.76(d,J=8.0 Hz, 2H);13C NMRδ: 162.14, 156.06, 148.99, 148.58, 146.19,141.82, 138.56, 137.53, 135.81, 131.53, 130.39, 128.91, 128.69, 128.33, 126.32, 124.28, 124.03, 122.18, 120.50, 118.81, 94.59(C-I), 63.74(Spiro sp3C); EI-MSm/z(%): 520(M+, 47), 394(95), 365(53), 289(32), 181(30), 97(48), 71(74), 57(100); Anal.calcd for C29H17N2I: C 66.94, H 3.29, N 5.38; found C 66.94, H 3.58, N 5.10.