5-Vinylpyrimidines. Synthesis via organopalladium intermediates

Reactions of 1,3-dimethyl-5-iodouracil or 2,4-dimethoxy-5-iodopyrimidine with vinyl acetate in the presence of a catalytic amount of diacetato-bis (triphenylphosphine) palladium (II) resulted in good yields of the corresponding 5-vinylpyrimidines. The reactions are viewed as resulting from regioselective addition of an initially formed 5-pyrimidinyl palladium species to the double bond of vinyl acetate followed by elimination of a palladium acetate with regeneration of the double bond and formation of the 5-vinylpyrimidine product.     

Synthesis of locked meso-beta-substituted chlorins via 1,3-dipolar cycloaddition

A novel approach toward "locked" chlorins with increased stability has been studied in detail. The chlorin skeleton is assembled in a convergent fashion from two fragments via a porphyrin forming reaction, followed by 1,3-dipolar cycloaddition of azomethine ylides, which are formed in situ. Central to the success of the process is the presence of two electron-withdrawing groups in vicinal positions at the perimeter of the porphyrin. As a result, the 1,3-dipolar cycloaddition took place regioselectively, on the bond activated by two electron-withdrawing groups. Moreover, the chlorins formed are locked and hence more stable because of the presence of two quaternary carbon atoms. Overall, in just six steps locked chlorins were constructed from easily available materials. The large array of functionalities tolerated in this approach validates it for a broad use in more advanced studies. The correlation between the results of the 1,3-dipolar cycloaddition and dipolarophile (porphyrin) LUMO energy was extensively studied. There was a definite correlation between the reaction time and the LUMO energy level, and a partial correlation between the reaction yield and the distribution of the LUMO. Additionally, various approaches toward crucial building blocks, namely 3,4-disubstituted-2,5-diformylpyrroles, were investigated.     

经钛环中间体合成三芳基乙烯

通过连续反应,合并操作等途径对Masai-Rausch反应进行了改进,提高了烯烃收率,并扩大了合成的适用范围,使其成为某些专一几何构型三芳基乙烯的合成方法之一。用改进方法合成了一些立体专一性的三芳基乙烯,收率一般为50～70%,产物除经常规分析外,还通过钛环中间体的分离与分析、比较烯烃异构化前后的波谱变化、烯烃氧化产物的制备以及反应历程分析,确定了它们的结构。     

Synthesis of new surface-active meso-substituted porphyrins

The reaction of p-dodecyloxybenzaldehyde and 3-pyridinaldehyde with pyrrole in propionic acid at reflux with subsequent column chromatography of the reaction mixture gives the statistically predicted isomeric porphyrins. The compounds obtained were characterized by PMR, IR, and electronic spectroscopy.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 79–82, January, 1989.     

Synthesis of alkylated methylene bisphosphonates via organothallium intermediates

Thallium(I) derivatives of esterified methylene bisphosphonates can be readily obtained by treating the latter with thallium(I) ethoxide under anhydrous conditions. Alkylation of the thallium(I) derivatives by a range of primary alkyl iodides takes place smoothly, and significantly higher yields are obtained than for the corresponding reactions with lithio or sodio derivatives.     

Synthesis of alpha- and beta-glycosyl isothiocyanates via oxazoline intermediates

A practical synthesis of acylated glycosyl isothiocyanates from sugar oxazolines, by reaction with thiophosgene, is reported. In the absence of any additive, the reaction is governed by the reverse anomeric effect, leading to the equatorially oriented isothiocyanate. However, in the presence of copper(II) chloride, the reaction proceeds preferentially with retention of the configuration at the anomeric center, providing the axial anomer as the major product. Noteworthy, this strategy allows accessing per-O-acetylated glycopyranosyl isothiocyanates with 1,2-cis relative configuration (e.g., the alpha-anomer in the D-gluco and D-galacto series), a problem that was outside the scope of previous methodologies.     

Synthesis of chlorins with a distal vinyl group

A series of chlorins containing a vinyl group on the periphery of the chlorin ring that was attached by linkers of various length, potential monomers for synthesis of polymers containing chlorin via copolymerization, was synthesized from methylpheophorbide a. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 163–166, March–April, 2007.     

Synthesis of conjugates of isobornylphenols and natural chlorins

A series of terpenophenol—chlorin conjugates containing terpenophenol and porphyrin fragments of various structure was synthesized. The terpenophenol fragment was added to the chlorin macrocycle using reactions of the exocyclic ester and the propionate substituent in the 17-position of methylpheophorbide a analogs. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 484–487, September-October, 2008.     

Synthesis of 2-selenoxoperhydro-1,3-selenazin-4-ones via diselenocarbamate intermediates

The reactions of the diselenocarbamates, generated from isoselenocyanates and sodium hydroselenide, with acryloyl chlorides afforded 2-selenoxoperhydro-1,3-selenazin-4-ones. The structure of the product was confirmed by X-ray diffraction analysis.     

Porphyrins. 37. Synthesis of heterodimers of porphyrins and chlorins containing pyrrolyl-methyl bridges

We have obtained various adducts, including homodimers and heterodimers of ethanebisporphyrins and ethanebischlorins containing pyrrole and dipyrrylmethane insertions, by reaction of mesodimethylaminomethylporphyrins and chlorins with -unsubstituted pyrrole derivatives in the presence of methyl iodide.For Communication 36, see [1].Dedicated to Professor M. A. Yurovskaya on her Jubilee.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 336–341, March, 2000.     

Sparsely substituted chlorins as core constructs in chlorophyll analogue chemistry. I. Synthesis

Five routes to stable chlorins bearing 0 or 1 meso substituents have been investigated, among which reaction of a 9-bromo-1-formyldipyrromethane and 2,3,4,5-tetrahydro-1,3,3-trimethyldipyrrin proved most effective. Application of this route afforded metallochlorins [Cu(II), Zn(II), and Pd(II)] including the chlorin lacking any β-pyrrole and meso substituents.     

Synthesis of copper and iron complexes of meso-substituted etioporphyrin derivatives

The synthesis of the copper complex of meso-cyanoetioporphyrin I has been effected from the corresponding meso-formyl derivative and meso-formyletiohemin. An intermediate compound of the copper complex of etioporphyrin I with the Vilsmeier complex (DMFA-POCl₃) has been isolated, and it has been reduced to the copper complex of dimethylamino-methyletioporphyrin I.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1172–1175, September, 1973.     

Synthesis and spectral properties of meso-substituted Ni2+ octaalkylporphyrinates

Nickel(II) 3,7,13,17-tetramethyl-2,8,12,18-tetrabutylporphyrinate and its 5,15-diaza, -diphenyl, and -di(4-bromophenyl) derivatives have been synthesized by the reaction of nickel(II) chloride with corresponding tetrapyrrole ligands in dimethylformamide.     

Photophysical properties of unsymmetric meso-substituted porphyrins synthesized via the Suzuki coupling reaction

A new family of porphyrins containing different groups in meso positions was synthesized by Suzuki coupling reaction of meso mono- and dibromo-diarylporphyrins with several boronate esters, catalyzed by palladium organometallic complexes. These procedures gave high yields of unsymmetric porphyrins bearing carboxylate anchoring groups, with enhanced absorptions in the red and showing no tendency for aggregation in toluene or THF solutions. Such properties are of interest for application in dye-sensitized solar cells.