Use of the vinyl group as an efficient protecting group for azole N- atoms: Synthesis of polyfunctionalized imidazoles and thieno[2,3-d] ⇌ [3,2-d]imidazole

Electrochemical C(sp2)-H/N-H "formal" cross-dehydrogenative coupling of olefins with benzotriazoles for synthesis of N-vinyl benzotriazoles

The paper details an electrochemical method that couples olefins with benzotriazoles to form C(sp2)-N bonds, enabling the synthesis of N-vinyl benzotriazoles in moderate to good yields. nBu4NI functions as both an electrolyte and an iodine mediator, and the method does not require oxidants or metals. It is a highly atom-economical and clean reaction, with hydrogen as the sole byproduct.

Metal-free aerobic oxidative direct C–H amination of electron-deficient alkenes via photoredox catalysis

The first example of photocatalytic dehydrogenative cross-coupling of electron-poor alkenes with azoles has been reported.

Discovery of Thienoimidazole-Based HCV NS5A Genotype 1a and 1b Inhibitors

The discovery of potent thienoimidazole-based HCV NS5A inhibitors is herein reported. A novel method to access the thienoimidazole [5,5]-bicyclic system is disclosed. This method gave access to a common key intermediate (6) that was engaged in Suzuki or Sonogashira reactions with coupling partners bearing different linkers. A detailed study of the structure-activity relationship (SAR) of the linkers revealed that aromatic linkers with linear topologies are required to achieve high potency for both 1a and 1b HCV genotypes. Compound 20, with a para-phenyl linker, was identified as a potential lead displaying potencies of 17 and 8 pM against genotype 1a and 1b replicons, respectively.

Mild Copper-Catalyzed Vinylation Reactions of Azoles and Phenols with Vinyl Bromides

An efficient and straightforward copper-catalyzed method allowing vinylation of N- or O-nucleophiles with di- or trisubstituted vinyl bromides is reported. The procedure is applicable to a broad range of substrates since N-vinylation of mono-, di-, and triazoles as well as O-vinylation of phenol derivatives can be performed with catalytic amounts of copper iodide and inexpensive nitrogen ligands 3 or 8. In the case of more hindered vinyl bromides, the use of the original bidentate chelator 8 was shown to be more efficient to promote the coupling reactions than our key tetradentate ligand 3. The corresponding N-(1-alkenyl)azoles and alkenyl aryl ethers are obtained in high yields and selectivities under very mild temperature conditions (35-110 degrees C for N-vinylation reactions and 50-80 degrees C for O-vinylation reactions). Moreover, to our knowledge, this method is the first example of a copper-catalyzed vinylation of various azoles. Finally, this protocol, practical on a laboratory scale and easily adaptable to an industrial scale, is very competitive compared to the existing methods that allow the synthesis of such compounds.

Synthesis and antitumor activity of thieno-separated tricyclic purines

The purine ring system is undoubtedly one of the most ubiquitous heterocyclic ring systems in nature as it has the distinction of being the parent ring in countless derivatives of biological relevance. It is not surprising then that modified purines possess the potential to impact several areas, including a better understanding of the biological effects of DNA damaging agents, enzyme/substrate interactions, and in the development of more potent medicinal agents. One focus for our research at Georgia Tech has centered around the design and synthesis of a series of extended purine analogues containing a heterocyclic spacer ring, with sites set on investigations into their use as (i) potential anticancer and antiviral agents, (ii) dimensional probes for enzyme and coenzyme binding sites, and (iii) structural probes of the minor groove of DNA. The synthesis and preliminary antitumor activity of two thieno-separated purine analogues are described herein. Tricyclic 1 was synthesized in 12 steps from tribromoimidazole and with an overall yield of 7%. Tricyclic 2 was synthesized in 9 steps with an overall yield of 13%. Both 1 and 2 exhibited growth inhibitory effects on HCT116 colorectal cancer cells in vitro.