First synthesis of Estrogen-Imidazolium Cyclophanes

A series estrogen-imidazolium cyclophanes have been synthesized for the first time by direct quaternization of 2,4-bis(N-imidazolylmethyl)estrogens and corresponding dibromides in highly diluted acetonitrile solution in excellent yields. All new compounds were characterized by MS, 'HNMR and elemental analysis.     

Synthesis of indolo[2,3-c]quinolines from 3-arylindole-2-ketoximes

Treatment of the 2,4-dinitrophenyl ethers of some 3-arylindole-2-ketoximes with base results in a cyclisation reaction to yield indolo[2,3-c]quinolines.     

Synthesis of DNA conjugates by solid-phase fragment condensation via aldehyde-nucleophile coupling

Oligodeoxyribonucleotides were synthesized that contain a novel nucleoside, 2′-O-(2,3-dihydroxypropyl)cytidine. Its 2′-diol group was blocked by an allyloxycarbonyl protecting group. Selective deprotection of diol group(s) of the support-immobilized blocked oligodeoxyribonucleotide by Pd(0) followed by periodate oxidation resulted in generation of the 2′-aldehyde group(s) on solid-phase. The modified oligonucleotides were used to prepare a number of conjugates with acridine, biotin and N-modified laminin peptides by oxime, hydrazone and hydrazine formation. The method may be applicable to the synthesis of oligonucleotide-peptide conjugates.     

Aluminium triflate-catalysed regioselective cycloisomerisation of non-activated unsaturated oximes

A novel cycloisomerisation of oximes bearing non-activated C-C double bonds occurs in an Al(III)-catalysed reaction. This process leads to 5-, 6- and 7-membered ring oxygen and nitrogen-containing heterocycles in good yields.     

Synthesis of N-hydroxyenamide, a potential precursor of chartelline

In our synthetic plan for chartelline A-C, a compound including N-hydroxyenamide moiety was designed as an important intermediate. Synthesis of the required N-hydroxyenamide by N-acylation of a suitable oxime derivative has been developed using model compounds.     

o-Phthalic Anhydride/Zn(OTf)2 co-catalyzed Beckmann rearrangement under mild conditions

o-Phthalic anhydride/Zn(OTf)₂ co-catalyzed Beckmann rearrangement was developed, producing the corresponding amide in up to 99% yield with acid-sensitive functionalities tolerated well, and the scale of the reaction could be enlarged to 77 mmol and the excellent yield was maintained. A successive procedure was developed. Moreover, the reaction was carried out at rt under nearly neutral conditions, and the workup was concise. These features illustrated the potential of the protocol in amide synthesis.     

Construction of 1H-indazoles from ortho-aminobenzoximes by the Mitsunobu reaction

Recently, there has been an upsurge in the occurrence of the indazole motif in drug discovery. Accordingly, newer, milder and more efficient routes towards their synthesis have emerged in the literature. We recently reported the Mitsunobu-triggered cyclodehydration of salicylaldoximes to transient 1,2-benzisoxazoles, and salicylhydroxamic acids to their corresponding 3-hydroxybenzisoxazoles. We hypothesized subjecting ortho-aminobenzoximes to Mitsunobu conditions will likewise induce a cyclodehydration to deliver the corresponding 1H-indazoles. Indeed, secondary anilines afforded the predicted N¹-substituted 1H-indazoles, and primary anilines, after activation with a Boc group, furnished the N¹-Boc 1H-indazoles in good to excellent yields. This work further expands the chemical repertoire of the Mitsunobu reaction, representing its unprecedented use in the construction of the 1H-indazole nucleus.     

A Practical Synthesis of 3-Oximido-substituted-1,5-diazacycloheptane Dihydrochloride

From 3-hydroxyl-1, 5-diazacycloheptane dihydrobromide, we have synthesized a series of new compounds, 3-oximido-substituted-l, 5-diazacycloheptane dihydrochloride, in high yields. The experimental operations are convenient and mild.     

N-取代-5-磺酰基吡唑肟醚衍生物的合成及生物活性研究

以吡唑酮、盐酸羟胺、硫酚、2-氯-5-氯甲基吡啶等化合物为原料,设计合成了5个未见文献报道的磺酰基吡唑肟醚新化合物,其结构经元素分析、1HNMR、IR和MS验证。初步生物活性测试表明,部分化合物具有一定的杀菌活性。