CHEMISTRY LETTERS

C-H functionalization of camphor through emerging approaches
Sennari G, Yamagishi H and Sarpong R
Camphor and related monoterpenoid natural products have served as versatile "chiral pool" materials in organic chemistry for over half a century. Historically, many researchers have used a variety of transformations involving orchestrated rearrangements of the bornane skeleton to functionalize the camphor framework, expanding the utility of this chiral building block. Recent developments in C-H functionalization methodologies provide myriad opportunities to derivatize the camphor framework in a selective and predictable fashion. In this review, a short summary of the methods for functionalization of the camphor scaffold using rearrangement chemistry is provided followed by a discussion of emerging methods for directed C-H functionalizations that provide diverse new ways to derivatize the camphor framework.
Insights into Protein Allostery in the CsoR/RcnR Family of Transcriptional Repressors
Higgins KA and Giedroc D
CsoR/RcnR transcriptional repressors adopt a disc-shaped, all α-helical dimer of dimers tetrameric architecture, with a four-helix bundle the key structural feature of the dimer. Individual members of this large family of repressors coordinate Cu(I) or Ni(II)/Co(II) or perform cysteine sulfur chemistry in mitigating the effects of metal or metabolite toxicity, respectively. Here we highlight recent insights into the functional diversity of this fascinating family of repressors.
Two-Step Synthesis of Furans by Mn(III)-Promoted Annulation of Enol Ethers
Corey EJ and Ghosh AK
Enol ethers, β-dicarbonyl compounds and the Mn(III) reagent MnO(OAc) react under mild conditions to form 1-alkoxy-1.2-dihydrofurans in good (70-98%) yields. The latter are readily converted to furans by acid-catalyzed elimination of ROH.
Formation of C-C Bonds via Ruthenium Catalyzed Transfer Hydrogenation: Carbonyl Addition from the Alcohol or Aldehyde Oxidation Level
Shibahara F and Krische MJ
Under the conditions of ruthenium catalyzed transfer hydrogenation employing isopropanol as terminal reductant, π-unsaturated compounds (1,3-dienes, allenes, 1,3-enynes and alkynes) reductively couple to aldehydes to furnish products of carbonyl addition. In the absence of isopropanol, π-unsaturated compounds couple directly from the alcohol oxidation level to form identical products of carbonyl addition. Such "alcohol-unsaturate C-C couplings" enable carbonyl allylation, propargylation and vinylation from the alcohol oxidation level in the absence of stoichiometric organometallic reagents or metallic reductants. Thus, direct catalytic C-H functionalization of alcohols at the carbinol carbon is achieved.
Pd(II)-Catalyzed Cross-Coupling of C( )-H Bonds and Alkyl-, Aryl- and Vinyl-Boron Reagents Pd(II)/Pd(0) Catalysis
Wasa M, Chan KS and Yu JQ
Pd(II)-catalyzed cross-coupling of -C-H bonds in benzoic acid and phenylacetic acid amides with alkyl-, aryl- and vinyl-boron reagents have been achieved Pd(II)/Pd(0) catalysis, demonstrating the unprecedented versatility of C-H activation reactions.
Palladium-Catalyzed Highly Regioselective C-3 Arylation of Imidazo[1,5-]pyridine
Huang C, Giokaris A and Gevorgyan V
A direct palladium-catalyzed highly regioselective C-3 arylation of imidazo[1,5-]pyridine with aryl bromides has been developed. This reaction is quite general with respect to the aryl or hetaryl bromide.
Recent evidence for multifactorial biofilm regulation by heme sensor proteins NosP and H-NOX
Fu J, Hall S and Boon EM
Heme is involved in signal transduction by either acting as a cofactor of heme-based gas/redox sensors or binding reversely to heme-responsive proteins. Bacteria respond to low concentrations of nitric oxide (NO) to modulate group behaviors such as biofilms through the well-characterized H-NOX family and the newly discovered heme sensor protein NosP. NosP shares functional similarities with H-NOX as a heme-based NO sensor; both regulate two-component systems and/or cyclic-di-GMP metabolizing enzymes, playing roles in processes such as quorum sensing and biofilm regulation. Interestingly, aside from its role in NO signaling, recent studies suggest that NosP may also sense labile heme. In this , we briefly summarize H-NOX-dependent NO signaling in bacteria, then focus on recent advances in NosP-mediated NO signaling and labile heme sensing.