Substituted 1H-1,2,3-Triazol-4-yl-1H-pyrrolo[2,3-b]pyridines by De Novo One-Pot Ring-Forming Coupling/Cyclization/Desilylation Cu Alkyne/Azide Cycloaddition (AAC) Sequence

Substituted 1H-1,2,3-triazol-4-yl-pyrrolo[2,3-b]pyridines are efficiently prepared by a one-pot coupling/cyclization/desilylation Cu alkyne/azide cycloaddition (CuAAC) sequence in the sense of a consecutive three-component fashion. The key feature of this new de novo formation of azole and triazole anellation is the sequentially Pd/Cu-catalyzed process employing tri(iso-propyl)silyl (TIPS) butadiyne as a four-carbon building block. In addition, the sequence can be expanded in a four-component fashion also employing the in situ formation of the required azides.

BippyPhos: a single ligand with unprecedented scope in the Buchwald-Hartwig amination of (hetero)aryl chlorides

Over the past two decades, considerable attention has been given to the development of new ligands for the palladium-catalyzed arylation of amines and related NH-containing substrates (i.e., Buchwald-Hartwig amination). The generation of structurally diverse ligands, by research groups in both academia and industry, has facilitated the accommodation of sterically and electronically divergent substrates including ammonia, hydrazine, amines, amides, and NH heterocycles. Despite these achievements, problems with catalyst generality persist and access to multiple ligands is necessary to accommodate all of these NH-containing substrates. In our quest to address this significant limitation we identified the BippyPhos/[Pd(cinnamyl)Cl]2 catalyst system as being capable of catalyzing the amination of a variety of functionalized (hetero)aryl chlorides, as well as bromides and tosylates, at moderate to low catalyst loadings. The successful transformations described herein include primary and secondary amines, NH heterocycles, amides, ammonia and hydrazine, thus demonstrating the largest scope in the NH-containing coupling partner reported for a single Pd/ligand catalyst system. We also established BippyPhos/[Pd(cinnamyl)Cl]2 as exhibiting the broadest demonstrated substrate scope for metal-catalyzed cross-coupling of (hetero)aryl chlorides with NH indoles. Furthermore, the remarkable ability of BippyPhos/[Pd(cinnamyl)Cl]2 to catalyze both the selective monoarylation of ammonia and the N-arylation of indoles was exploited in the development of a new one-pot, two-step synthesis of N-aryl heterocycles from ammonia, ortho-alkynylhalo(hetero)arenes and (hetero) aryl halides through tandem N-arylation/hydroamination reactions. Although the scope in the NH-containing coupling partner is broad, BippyPhos/[Pd(cinnamyl)Cl]2 also displays a marked selectivity profile that was exploited in the chemoselective monoarylation of substrates featuring two chemically distinct NH-containing moieties.

Oligodeoxynucleotides containing 3-bromo-3-deazaadenine and 7-bromo-7-deazaadenine 2'-deoxynucleosides as chemical probes to investigate DNA-protein interactions

We describe the design and proof of concept of a pair of chemical probes for investigating DNA-protein interactions-specifically, the incorporation of 7-bromo-7-deazaadenine and 3-bromo-3-deazaadenine 2'-deoxynucleosides (Br(7)C(7)dA and Br(3)C(3)dA) into oligodeoxynucleotides (ODNs)-and their utility. Whereas the bromo substituent of the Br(7)C(7)dA unit in an ODN duplex acts sterically to inhibit binding with NF-kappaB, which interacts with the duplex in its major groove, the bromo substituent of the Br(3)C(3)dA unit acts sterically to inhibit binding with RNase H, which interacts with the duplex in its minor groove. In addition, the utilization of ODNs containing 7-deazaadenine and 3-deazaadenine 2'-deoxynucleosides (C(7)dA and C(3)dA), together with the pair of chemical probes, afforded valuable information on the requirement for nitrogen atoms located in either the major or minor grooves. Accordingly, we were able to show the utility of ODNs containing Br(7)C(7)dA, Br(3)C(3)dA, C(7)dA, and C(3)dA for the investigation of DNA-protein interactions.