Photochemical Rearrangements and Fragmentations of Benzene Derivatives and Annelated Arenes

In this article the numerous intramolecular reactions of electronically excited benezene derivatives, which in many instances are only mentioned in original papers, are systematically analyzed and arranged according to reaction types. All known reaction types can be classified, and subdivided into reactions of the benzene ring (ionization, ring opening, ring alteration), reactions with participation of side chains (α-, β-, γ-cleavage, homolysis, heterolysis), reactions of substituents with side chains (cyclization, dealkylation, cleavage of protective groups), and reactions of side chains with the aromatic ring (substitution, addition, dearomatization, cyclization). The selectivity of the energetically feasible competing reactions is primarily determined by geometric factors. Applications of the empirical effects are numerous and varied in preparative organic chemistry. Many of the reactions under discussion are already utilized industrially (e.g. in photochromism, UV stabilization, photography, information storage, printing, coating and polymer technology, and pharmacy).     

A Convenient Synthesis of New Annelated Pyrimidines and Their Biological Importance

Several bicyclic/tricyclic‐fused pyrimidines were synthesized from the reactions of amino esters and bifunctional nucleophiles such as 2‐methylthio‐thiazoline and 2‐methylthio‐imidazoline. The synthesized compounds were tested for their in vitro antimicrobial activities that revealed mild to moderate growth inhibitory potentials.     

Synthesis of p-Alkylcalixarenes by Friedel-Crafts Alkylation

Calix[n]arenes 1 - 3 (n = 4, 6 and 8) were alkylated with alkyl chlorides in the presence of anhydrous aluminium chloride in chloroform by Friedel-Crafts reaction to give p-alkylcalix[n]arenes 5 - 7 (n = 4, 6 and 8) in good to excellent yields.     

三氟乙酸酐催化的Friedel-Crafts酰化反应——4-乙基-2,5-二甲氧基苯基烷基酮的合成

本文报道了在三氟乙酸酐催化下的Friedel-Crafts酰化反应,即用8种不同取代基的脂肪酸与2-乙基-1,4-二甲氧基苯的酰化反应合成了相应的4-乙基-2,5-二甲氧基苯基烷基酮,并用IR、UV、NMR及MS进行了结构鉴定,同时讨论了该反应的规律.     

介孔硅铝酸盐的合成及其在傅克反应中的催化性能

采用溶胶凝胶法合成了一系列有序性好且酸性较强的介孔硅铝酸盐材料。利用X射线粉末衍射(XRD)、透射电镜(TEM)、²⁷Al核磁共振(²⁷Al NMR)、氨气程序升温脱附(HN₃-TPD)及吡啶吸附红外光谱(Py-FT-IR)对制备的介孔硅铝酸盐材料的结构和性能进行表征,并考察了材料在苯甲醚和苯甲醇的傅克烷基化反应中的催化活性。实验结果表明：合成过程中,表面活性剂的用量、硅铝物质的量的比会影响材料结构的有序性,醋酸用量对材料结构有序性影响很小;进一步研究结果表明,n_Si / n_Al比会影响材料的酸催化活性,当n_Si / n_Al=10时材料的酸催化活性最高。氨气程序升温脱附和吡啶吸附红外光谱表明n_Si / n_Al=10的材料含有最多的B酸酸量。     

介孔硅铝酸盐的合成及其在傅克反应中的催化性能

采用溶胶凝胶法合成了一系列有序性好且酸性较强的介孔硅铝酸盐材料。利用X射线粉末衍射(XRD)、透射电镜(TEM)、27Al核磁共振(27Al NMR)、氨气程序升温脱附(HN3-TPD)及吡啶吸附红外光谱(Py-FT-IR)对制备的介孔硅铝酸盐材料的结构和性能进行表征,并考察了材料在苯甲醚和苯甲醇的傅克烷基化反应中的催化活性。实验结果表明:合成过程中,表面活性剂的用量、硅铝物质的量之比会影响材料结构的有序性,醋酸用量对材料结构有序性影响很小;进一步研究结果表明,nSi/nAl比会影响材料的酸催化活性,当nSi/nAl=10时材料的酸催化活性最高。氨气程序升温脱附和吡啶吸附红外光谱表明nSi/nAl=10的材料含有最多的B酸酸量。     

九钨三锰硅酸钾异构体的合成及其转移氧原子的性质

Hill~[1],Finke~[2]和Neumann~[3]曾分别报道[Pw_(11)O_(39)M]~(n-)、[P_2W_(17)O_(61)M]~(n-)和[SiW_(11)O_(39)Ru]~(5-)具有催化烯烃环氧化反应的性质,三取代的Keggin杂多阴离子有相似的性质.本文首次报道α-和β-K_6H_4[SiW_9O_(37)Mn_3(H_2O)_3]·xH_2O的合成及其转移氧原子的性质,为研究杂多酸盐的催化提供了一个新的含锰杂多阴离子.     

Synthesis and Pharmacological Activity of Annelated Pyrimidine Derivatives

A series of 1-glycosyl-2-glycosylthiopyrimidine (4), annelated pyrimidine derivatives, pyrazolo[3,4-d]-pyrimidine (8), ditetrazolo[1,5-a;1‘,5‘-c]pyrimidine (9), 2,9a,10-triazaanthracene (12), thieno[2,3-d]pyrimidine (14),9-thia-1,3,5,7-tetraazafluorene-8-one (15), 7-oxa-9-thia-1,3,5-triazafluorene-8-one (16), 5-oxa-9-thia-1,3-diaza-fluorene (21a and 21b) derivatives have been synthesized via a sequence of heterocyclization reactions of suitably functionalized 6-[5-(4-bromophenyl)oxazol-4-yl]-1，2，3，4-tetrahydro-2-thioxo-4-oxopyrimidine-5-carbonitrile (2) with different electrophiles and nucleophiles. The new compounds were prepared with the objective to study their pharmacological properties.     

Synthesis and Antimicrobial Activity of Some Annelated Quinazoline Derivatives

A highly efficient and versatile synthetic approach to the synthesis of annelated quinazoline derivatives viz 1,2,4‐triazino[4,3‐c]quinazoline 5–7 , 11 , thiazolidinylquinazoline 9 , quinazolino[4,3‐b]quin‐azolin‐8‐one 12 and imidazoquinazolines 14a,b,15 is presented. Also, a variety of pyrazolylquinazolines 19–21 and pyrimidinylquinazolines 22a,b were obtained via a sequence of heterocyclization reactions of 4‐methyl‐N‐[4‐(4‐oxo‐3,4‐dihydroquinazolin‐2‐yl)phenyl]benzene‐sulfonamide ( 2 ) with different reagents. The new compounds were synthesized with the objective of studying their antimicrobial activity.     

Synthesis and Pharmacological Activity of Annelated Pyrimidine Derivatives

A series of 2,3-diglycosylpyrimidine 4, annelated pyrimidine derivatives, pyrazolo-[3,4-d]pyrimidine 8, ditetrazolo[1,5-a; 1′5′]pyrimidine 9, 2,9a,10-triazaanthracene 12, thieno- [2,3-d]pyrimidine 14, 9-thia-1,3,5,7-tetraazafluorene-8-one 15, 7-oxa-9-thia-1,3,5-triazafluorene-8-one 16, and 5-oxa-9-thia-1,3-diazafluorene 21a , b derivatives have been synthesized via a sequence of heterocyclization reactions of suitably functionalized 6-[5-(4-bromophenyl)oxazol-4-yl]-1,2,3,4-tetrahydro-2-thioxo-4-oxopyrimidine-5-carbonitrile (2) with different electrophiles and nucleophiles. The new compounds were prepared with the objective to study their pharmacological properties.     

Synthesis of N-Squaramidoacids and Their Application in Asymmetric Borane Reduction of Prochiral Ketones

A series of novel N-squaramidoacid ligands were prepared conveniently. Without converting to corresponding amino alcohols, these ligands could be used in asymmetric borane reduction of prochiral aromatic ketones to give secondary alcohols in good to excellent enantiomeric excesses. The results showed that N-squaramidoacids are more efficient ligands than N-sulfonyl amino acids. N-Squaryl proline was proved to be an excellent ligand in this catalytic asymmetric process.     

Tetramethylheptalenes and Their Tricarbonylchromium Complexes: Synthesis,Structures, and Thermal Rearrangements

The thermal 4 : 1 equilibrium mixture of 1,3,5,6- and 1,3,5,10-tetramethylheptalene ( 13a and 13b , resp.) has been prepared, starting from the thermal equilibrium mixture of dimethyl 6,8,10-trimethylheptalene-1,2- and -4,5-dicarboxylate ( 6a and 6b , resp.; cf. Scheme 5). These heptalenes undergo double-bond shifts (DBS) even at ambient temperature. Treatment of the mixture 13a / 13b 4 : 1 with [Cr(CO)₃(NH₃)₃] in boiling 1,2-dimethoxyethane resulted in the formation of all four possible mononuclear Cr(CO)₃ complexes 19a – 19d of 13a and 13b , as well as two binuclear Cr(CO)₃ complexes 20a and 20b , respectively, in a total yield of 87% (cf. Scheme 7). The mixture of complexes was separated by column chromatography, followed by preparative HPLC (cf. Fig. 2). The structures of all complexes were established by X-ray crystal-structure analyses (complex 19b and 20b ; cf. Figs. 6 – 8) and extensive ¹H-NMR measurements (cf. Table 3). In 20b , the two Cr(CO)₃ groups are linked in a `syn'-mode to the highly twisted heptalene π-skeleton. The correspondence of the <sup>1</sup>H-NMR data of 20a with that of 20b indicates that the two Cr(CO)<sub>3</sub> groups in 20a also have a `syn'-arrangement. The thermal behavior of the mononuclear complexes 19a – 19d has been studied at 85° in hexafluorobenzene (HFB). At this temperature, all four complexes undergo rearrangement to the same thermal equilibrium mixture (cf. Table 8). The rates for the thermal equilibration of each complex have been determined by ¹H-NMR measurements (cf. Figs. 9 – 12) and analyzed by seven different kinetic schemes (Chapt. 2). The equilibration rates are in agreement with two different haptotropic rearrangements that take place, namely intra- and inter-ring shifts of the Cr(CO)₃ group, whereby both rearrangements are accompanied by DBS of the heptalene π-skeleton (cf. Scheme 9). All individual kinetic steps possess similar ΔG^≠ values in the range of 29 – 31 kcal⋅mol⁻¹ (cf. Table 8). The occurrence of inter-ring haptotropic migrations of Cr(CO)₃ groups has already been established for anellated aromatic systems (cf. Scheme 10); however, it is the first time that these rearrangements have been unequivocally demonstrated for Cr(CO)₃ complexes of non-planar bicyclic [4n]annulenes, such as heptalenes. The mechanism of migration may be similar to that proposed for aromatic systems (cf. Schemes 10 and 11).     

The Synthesis of 4-Arylcarbonyl-3-methoxycarbonyl-2-phenylfurans by Friedel-Crafts Acylation Reactions

Keto esters 8, 4-arylcarbonyl-3-methoxycarbonyl-2-phenylfurans, potential precursors of the synthesis of furofuran lignans, were obtained from dimethyl 2-phenylfuran-3,4-dicarboxylate 2.Diester 2 was selectively hydrolyzed to monoacid 6 followed by converting to its acid chloride 7.Friedel-Crafts acylation reactions of 7 with aromatic compounds afforded keto esters 8.The geometric structures of 8 and its precursors were elucidated and verified by NMR spectra.     

Synthesis by Friedel-Crafts reaction of partially saturated analogs of amitriptyline

It is postulated that one aromatic ring and the amine group in the side chain could be sufficient for the specific fixation of the molecule of a tricyclic antidepressant and for warranting its activity. Some partially saturated derivatives of amitriptyline were prepared, in order to check if pharmacologic activity is retained.     

溴代稠环芳烃的氧化溴化法合成

以HBr/H2O2为溴化体系,采用氧化溴化法合成了6种稠环芳烃的溴化物。 合成反应无需催化剂,通过控制反应温度和溴化试剂用量,可以在稠环芳烃化合物的活性位选择性地单溴化或双溴化,产率可达51.1%～94.2%。 产品经熔点和1H NMR法确认,合成操作简单安全,环境污染少,有工业应用前景。     

The Synthesis of Substituted 2-Aminophenyl Heterocyclic Ketones

The synthesis of substituted 2-aminophenyl heterocyclic ketones, key intermediates to the preparation of 1,4-benzodiazepines has been achieved in one step and in good, yield from the corresponding anthranilic acid, by treatment with heterocyclic lithium reagents and chlorotrimethylsilane.