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A one-pot procedure for the synthesis of 5-benzoyl-8H-phthalazino[1,2-b]quinazolin-8-ones is achieved by an iodine-catalyzed reaction of 2-aminobenzohydrazides and 2-alkynylbenzaldehydes in good yields. The salient feature of this strategy is a domino type process including a condensation, addition, hydroamination, and a noteworthy benzyl automatic oxidation by oxygen under metal-catalyst-free conditions.

At 60 °C in DMSO, the iodine-catalyzed reaction of 3-aminopyrazine-2-carbohydrazide and 2-(arylethynyl)benzaldehydes led hydrazones. Increasing the reaction temperature to 100 °C, the amino and amido still indicated inactive, only the imine took part in the addition of acetylene bond to give 2-arylisoquinolines in high yields with the cleavage of N-N bond unexpectedly under metal-free conditions.

The Sonogashira reaction first, and then intra-molecular hydroamination of alkyne catalyzed by CuI/o-phen was proved to be an efficient method for the synthesis of imidazo[2,1-a]isoquinoline, phenanthro[9′,10′:4,5]imidazo[2,1-a]isoquinoline and acenaphtho[1′,2′:4,5]imidazo [2,1-a]isoquinoline derivatives in the presence of Cs2CO3.

An efficient base-free palladium-catalyzed intramolecular cross dehydrogenative coupling of 2-aryloxy substituted 4-chromenones to access coumaronochromones has been achieved. A range of diversely substituted coumaronochromones can be facilely synthesized in good to excellent yields (up to 90%).

2,3-Bisaryldiimidazo [1,2-a:1′,2′-c]quinazolines were obtained via a copper-catalyzed reaction between 2-(2-bromophenyl)-4,5-diphenyl-1H-imidazole and 2-bromo-1H- imidazole in good yields. This double Ullmann cross-coupling built two new Csp2-N bonds and fused tetracyclic heterocycle bearing four nitrogen atoms in one-pot procedure.

The benzyl position was found to be automatically oxidized by oxygen in the reaction of 2-(2-bromophenyl)-1H-imidazole and 1,3-dicarbonyl compounds catalyzed CuI. This domino procedure involved the subsequent α-arylation, deacylation, nucleophilic addition and benzyl automatic oxidation, and provided an efficient method for the synthesis of (benzo)imidazo[2,1-a]isoquinolinone derivatives in good yields.

The Ullmann cross-coupling reaction between 2-(2-bromophenyl)-4,5-diphenyl-1H-imidazole and 2-bromobenzenethiol occurred to give 2,3-diaryldibenzo[b,f]imidazo[1,2-d] [1,4]thiazepines in good yields. Two new bonds of Csp2-N and Csp2-S were built under the same catalytic system of CuI/o-phen in the presence of K2CO3.

Five new analogs 4-8 of rubiyunnanin B (1), mainly modified on the tetrapeptide subunit, were synthesized. These agents 4-8 were substituted D-Ala-L-Ala-L-Tyr(OMe)-L-Ala, D-Ala-L-Ala-L-Phe-L-Ala, D-Ala-L-Ala-L-Tyr-L-Ala, D-Ala-L-Ala-L-Pro-L-Ala, and D-Ala-L-Ala-L-Ala for the D-Ala-L-Ala-c-N-Me-Tyr(OMe)-L-Ala tetrapeptide subunit. Unlike the natural product, the synthetic agents 4-8 adopt only a single solution conformation, and the central peptide bond in the cyclodityrosine subunit of compounds 4-8 adopt trans stereochemistry. Cytotoxic activities of analogs 4-8 against three human cancer cell lines including A549, BGC-823, and HeLa were evaluated and all the five synthesized peptides exhibited no effects against the test cell lines. These compounds were also evaluated for their antiinsulin resistance and insulin sensitizing activities and none of them showed activity in these assays. (C) 2014 Elsevier Ltd. All rights reserved.

Isothiocyanate 6, obtained from vinyliminophosphorane 4 with CS2, reacted with various aliphatic primary amines to afford directly the 1,4,5-trisubstituted imidazolidine-2-thiones 5. However, the reaction of isothiocyanate 6 with aliphatic secondary amines provided 2,4,5-trisubstituted thiazoles 10 in good yields.

The marine natural product cyclodidemniserinol trisulfate displayed moderate HIV-1 integrase inhibitory activity. Its novel structure triggered our interest to synthesize it. In our total synthesis effort, the natural product was dissected into four fragments based on the rational retrosynthetic analysis. All four fragments were successfully prepared with orthogonal protection. And the assembly of fragment A and B furnished the C5–C30 key subunit by employing the I2-mediated deprotection and intramolecular ketal formation tandem reaction in the presence of NaHCO3 in MeCN. Our work provided flexible and practical approaches to synthesize and derive the 3,5,7-trisubstituted 6,8-dioxabicyclo [3.2.1] octane based analogs to search for new structure HIV-1 integrase inhibitors.

A general strategy for synthesizing the crinine-type Amaryllidaceae alkaloids was developed. And total syntheses of four representative crinine-type Amaryllidaceae alkaloids: (±)-haemanthidine, (±)-pretazettine, (±)-tazettine, and (±)-crinamine, were accomplished via a common intermediate 17. This crucial precursor was achieved on the basis of the NBS-promoted semipinacol rearrangement recently developed by our group and an intramolecular Michael addition, which efficiently constructed the sterically congested quaternary carbon center and the hydroindole skeleton of the crinine-type alkaloids, respectively.