重氮盐与肟的反应 Ⅱ.某些芳香醛、酮、腈的合成

芳香族重氮盐可与肟反应,得到芳香醛和芳香酮^[1-4]。本文报道利用重氮盐与肟的反应合成对-乙酰基苯甲醛(1a)、对-乙酰氨基苯甲醛(1b)、对-溴苯乙酮(1c)、对-硝基苯乙酮(1d)、邻-氯苯甲腈(2a)以及2,4-二硝基苯甲腈(2b)的实验结果。这些化合物均为有机合成原料及重要中间体。     

(AG)(DNP)的合成和结构表征

通过氨基胍(AG)重碳酸盐与2,4-二硝基苯酚(DNP)反应,制备了新型离子型化合物2,4-二硝基苯酚氨基胍(AG)-(DNP).通过X射线单晶衍射、元素分析、红外光谱和热分析对其进行了表征.测试结果表明:该晶体属于单斜晶系,空间群P21/n,a=0.4922(1)nm,b=2.3307(3)nm,c=0.9404(6)nm,β=91.621(2)°,Z=2,Dc=1.590g/cm3,F(000)=144.该化合物分子由氨基胍阳离子和2,4-二硝基苯酚阴离子以静电引力结合,分子间存在氢键.该化合物是一种具有潜在应用前景的气体发生剂.     

5-苯甲酰基-2,4-二羟基苯甲醛的合成、晶体结构及紫外吸收性能研究

以2,4-二羟基二苯甲酮为原料,经过醚化、Vilsmeier-Haack反应和脱甲基化三步反应制备5-苯甲酰基-2,4-二羟基苯甲醛,反应总收率达到74.1%。通过~1H NMR、~(13)C NMR、IR、MS和X-ray单晶衍射对目标产物进行结构表征,晶体结构显示两个苯环并不共平面,分子内和分子间的氢键连接分子形成三维网状结构。考查该化合物的紫外吸收性能,在293 nm和324 nm有很好的紫外吸收,兼具长波紫外线UVA和中波紫外线UVB的吸收性能。     

L-苯甘氨酸衍生物新型三齿手性氨基醇的合成

对叔丁基苯胺经二甲基化、甲酰化得到5-叔丁基-2-二甲氨基苯甲醛;L-苯甘氨酸经LiAlH4直接还原,得到的二齿手性氨基醇与上述醛经缩合、还原,得到新型三齿手性氨基醇(2S)-2-[(5-叔丁基-2-二甲氨基)苯基]甲氨基-2-苯基乙醇。用红外光谱(IR)、质谱(MS)和核磁共振氢谱(1H-NMR)等对产物进行了结构表征。     

取代基结构对聚[(3-烷基)噻吩-2,5]-取代苯甲烯衍生物三阶非线性光学性能的影响

采用3-烷基噻吩与对硝基苯甲醛和对二甲氨基苯甲醛的聚合反应得到了5种聚(3-烷基)噻吩取代苯甲烯衍生物:聚(3-丁基)噻吩对硝基苯甲烯(PBTNBQ)、聚(3-己基)噻吩对硝基苯甲烯(PHTNBQ)、聚(3-丁基)噻吩对二甲氨基苯甲烯(PBTDMABQ)、聚(3-己基)噻吩对二甲氨基苯甲烯(PHTDMABQ)和聚(3-辛基)噻吩对二甲氨基苯甲烯(POTDMABQ).计算其光学禁带宽度分别为PBTNBQ(1.82eV),PHTNBQ(1.85eV),PBTDMABQ(1.71eV),PHTDMABQ(1.78eV)和POTDMABQ(1.67eV).利用简并四波混频技术测量了5种聚合物薄膜的三阶非线性极化率,分别为1.74×10^-8,1.82×10^-8,5.62×10^-9,8.64×10^-9和1.22×10^-8esu,均具有较大的三阶非线性光学性能.针对取代基结构对聚(3-烷基)噻吩取代苯甲烯衍生物的三阶非线性光学性能的影响从分子内极化程度和主链电子的离域程度两个方面进行了讨论.     

窄能隙共轭聚合物:聚[(3-烷基)噻吩-2,5]-取代苯甲烯衍生物的合成与表征

合成了3-丁基噻吩和3-辛基噻吩,并分别与对硝基苯甲醛和对二甲氨基苯甲醛进行聚合反应得到了具有极低能隙的聚(3-丁基噻吩)对硝基苯甲烯(PBTNBQ)、聚(3-丁基噻吩)对二甲氨基苯甲烯(PBTDMABQ)和聚(3-辛基噻吩)对二甲氨基苯甲烯(POTDMABQ).采用红外光谱、核磁共振氢谱和紫外-可见吸收光谱确认了产物的结构,发现中间产物聚(3-烷基)噻吩取代苯甲烷衍生物中存在部分醌化产物.根据E_g与入射光子能量hν的关系,采用2种模型计算了3种聚合物薄膜的光学禁带宽度为PBTNBQ1.63,1.84eV;PBTDMABQ1.44,1.75eV和POTDMABQ1.32,1.69eV,属窄能隙共轭聚合物.     

三苯基咪唑共轭Schiff碱的合成及其光学性能

联苯甲酰、对硝基苯甲醛和乙酸铵在冰乙酸介质中经缩合反应制得2-(4-硝基苯基)-4,5-二苯基咪唑(1); 1经铁粉还原制得2-(4-氨基苯基)-4,5-二苯基咪唑(2); 2与4-二甲氨基苯甲醛经缩合反应合成了一种具有D-π-A结构的新型三苯基咪唑Schiff碱（3）,其结构经¹H NMR,¹³C NMR, IR和MS(ESI)表征。利用紫外-可见吸收光谱和荧光光谱研究了3在不同溶剂中的光物理行为。结果表明：3的最大吸收峰位于311~332 nm和378~380 nm,荧光发射峰位于433~436 nm和457~461 nm。由于具有D-π-A结构,3表现出明显的扭曲分子内电荷转移现象。     

一种新型的侧链型聚氨酯高分子钌聚合物的合成

通过分子设计,将带有-OH端基的钌(Ⅱ)联吡啶配合物[Ru(bpy)2L]PF6{L=希夫碱4-[(N甲-基-N羟-乙基)氨基]苯甲醛缩肼基硫代甲酸甲酯}与甲苯-2,4异-氰酸酯、丙烯酸羟乙酯发生共聚合反应,合成了新的侧链型聚氨酯高分子钌聚合物(4)。4的结构经红外光谱和差热分析表征。     

L-亮氨酸衍生物手性氨基醇的合成与应用

以N,N-二甲基苯胺为原料,经对位溴化、邻位甲酰化得到5-溴-2-(二甲氨基)苯甲醛;L-亮氨酸经酯化、格氏反应得到二齿手性氨基醇;将5-溴-2-(二甲氨基)苯甲醛与上述氨基醇经缩合、还原得到三齿手性氨基醇;产物经红外光谱(IR)、质谱(MS)及核磁共振氢谱(1H-NMR)表征,考察了二齿手性氨基醇和三齿手性氨基醇作为...     

2,6-二[4-′(N,N-二苯基氨基)芪]苯并[1-2,4-5]二噁唑的合成与发光特性

通过对二苯氨基苯甲醛与2,6-二(4-氯甲基苯基)苯并[1-2,4-5]二唑之间的Wittig-Horner反应,设计并合成了一个2,6-二[4-′(N,N-二苯基氨基)芪]苯并[1-2,4-5]二唑新化合物,目的在于均二苯乙烯分子中同时引入空穴传输和电子传输结构单元,可望提高均二苯乙烯型发光材料的发光强度和光量子效率.采用UV-VisI、R1、HNMR和元素分析等分析方法对合成产物结构进行了确认,并考察了溶剂对其光致发光特性的影响.所合成化合物的相关分析数据表明:1)其分子中的两个均二苯乙烯基均为反式“芪”结构特征;2)随溶剂极性增高,其UV-Vis光谱和荧光光谱的λmax红移;3)可用作蓝色发光材料.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.