Transition metal catalyzed element–element′ additions to alkynes

The efficient and stereoselective synthesis of, or precursors to, multi-substituted alkenes has attracted substantial interest due to their existence in various industrially and biologically important compounds. One of the most atom economical routes to such alkenes is the transition metal catalyzed hetero element–element′ π-insertion into alkynes. This article provides a thorough up-to-date review on this area of chemistry, including discussions on the mechanism, range of Esingle bondE′ bonds accessible and the stoichiometric/catalytic transition metal mediators employed

Haloboration of Internal Alkynes with Boronium and Borenium Cations as a Route to Tetrasubstituted Alkenes

Hail boration! 2-Dimethylaminopyridine-ligated dihaloborocations [X 2B(2-DMAP)]+ with a strained four-membered boracycle were used for the haloboration of terminal and dialkyl internal alkynes (see scheme). Esterification then provided vinyl boronate esters as useful precursors to tetrasubstituted alkenes. Following mechanistic studies, the scope of the haloboration was expanded simply by variation of the amine. Pin=2,3-dimethyl-2, 3-butanedioxy. © 2013 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of Creative Commons the Attribution Non-Commercial NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made

Chiral (Cyclopentadienone)iron Complexes for the Catalytic Asymmetric Hydrogenation of Ketones

Three chiral (cyclopentadienone)iron complexes derived from (R)-BINOL (CK1-3) were synthesized and their structures unambiguously confirmed by X-ray analysis (CK3). Under suitable conditions for the in situ conversion into the corresponding (hydroxycyclopentadienyl)iron hydrides (Me3NO, H2), the new chiral complexes were tested in the catalytic asymmetric hydrogenation of ketones, showing moderate to good enantioselectivity. In particular, the complex bearing methoxy substituents at the 3,3-positions of the binaphthyl moiety (CK2) proved remarkably more enantioselective than the unsubstituted one (CK1) and reached the highest level of enantioselectivity (up to 77% ee) ever obtained with chiral (cyclopentadienone)iron complexes. Reducto! Chiral (cyclopentadienone)iron complexes were synthesized and tested, after in situ activation, in the catalytic asymmetric hydrogenation of ketones leading to the highest enantiomeric excesses ever obtained with this type of catalyst

Discovery of novel antitumor dibenzocyclooctatetraene derivatives and related biphenyls as potent inhibitors of NF-κB signaling pathway

Several dibenzocyclooctatetraene derivatives (5-7) and related biphenyls (8-11) were designed, synthesized, and evaluated for inhibition of cancer cell growth and the NF-κB signaling pathway. Compound 5a, a dibenzocyclooctatetraene succinimide, was discovered as a potent inhibitor of the NF-κB signaling pathway with significant antitumor activity against several human tumor cell lines (GI(50) 1.38–1.45 μM) and was more potent than paclitaxel against the drug-resistant KBvin cell line. Compound 5a also inhibited LPS-induced NF-κB activation in RAW264.7 cells with an IC(50) value of 0.52 μM, prevented IκB-α degradation and p65 nuclear translocation, and suppressed LPS-induced NO production in a dose-dependent manner. The antitumor data in cellular assays indicated that relative positions and types of substituents on the dibenzocyclooctatetraene or acyclic biphenyl as well as torsional angles between the two phenyls are of primary importance to antitumor activity