81693-79-0Relevant academic research and scientific papers
Microwave accelerated, Ni/C-catalyzed cross-couplings of in situ-derived zirconocenes
Lipshutz, Bruce H.,Frieman, Bryan
, p. 1309 - 1316 (2004)
Both vinyl and alkyl zirconocenes undergo rapid couplings with aryl halides under heterogeneous conditions in a microwave reactor using Ni/C as catalyst. Ligand variations both in type and stoichiometry play major roles in the extent of conversion.
ortho-Directing Chromium Arene Complexes as Efficient Mediators for Enantiospecific C(sp2)–C(sp3) Cross-Coupling Reactions
Bigler, Raphael,Aggarwal, Varinder K.
supporting information, p. 1082 - 1086 (2018/01/10)
A new strategy for the coupling of a broad scope of electronically diverse aromatics to boronic esters is reported. The coupling sequence, which relies on the directed ortho-lithiation of chromium arene complexes followed by boronate formation and oxidation, occurs with complete ortho-selectivity and enantiospecificity to give the coupling products in excellent yields and with high functional group tolerance. An intermediate chromium arene boronate complex was characterized by X-ray, NMR, and IR experiments to elucidate the reaction mechanism.
Iron-catalyzed alkylations of aryl sulfamates and carbamates
Silberstein, Amanda L.,Ramgren, Stephen D.,Garg, Neil K.
supporting information; experimental part, p. 3796 - 3799 (2012/08/28)
The alkylation of aryl sulfamates and carbamates using iron catalysis is reported. The method constructs sp2-sp3 carbon-carbon bonds and provides synthetically useful yields across a range of substrates (>35 examples). The directing group ability of sulfamates and carbamates, accompanied by their low reactivity toward conventional cross-couplings, renders these substrates useful for the synthesis of polyfunctionalized arenes.
First Kumada reaction of alkyl chlorides using N-heterocyclic carbene/palladium catalyst systems
Frisch, Anja C.,Rataboul, Franck,Zapf, Alexander,Beller, Matthias
, p. 403 - 409 (2007/10/03)
For the first time it is shown that N-heterocyclic carbenes are suitable ligands for the palladium-catalyzed coupling of alkyl chlorides with aryl Grignard reagents. A variety of simple as well as functionalized primary alkyl chlorides provide the corresponding alkyl benzenes in general in good to very good yield. By comparing the 1,3-dimesitylimidazol-2-ylidene (IMes) palladium(0) naphthoquinone complex with the previously known palladium phosphine catalyst for the model coupling reaction of 1-chlorohexane with phenylmagnesium bromide it is demonstrated that the new catalyst system is superior.
Design of liquid crystalline block molecules with nonconventional mesophase morphologies: Calamitic bolaamphiphiles with lateral alkyl chains
Koelbel,Beyersdorff,Xiao Hong Cheng,Tschierske,Kain,Diele
, p. 6809 - 6818 (2007/10/03)
Novel bolaamphiphiles, consisting of a biphenyl rigid core, polar 2,3-dihydroxypropoxy groups at each terminal end, and an additional long alkyl chain in a lateral position have been synthesized. The structures of these ternary block molecules were systematically changed by variation of the length and position of the alkyl chain, by introduction of additional spacer units between one of the 2,3-dihydroxypropyl groups and the rigid core, and by replacement of one of the 2,3-dihydroxypropoxy groups by a single hydroxy group. The influence of these structural variations on the liquid crystalline properties of these new materials was investigated by polarized-light microscopy, differential scanning calorimetry, and X-ray diffraction. These investigation have shown that, by elongation of the lateral chain, a transition from a smectic monolayer structure (SmA1) via a strongly distorted layer structure (SmA+), a centered rectangular columnar phase (Colr/c2mm) and a noncentered rectangular columnar phase (Colr/p2gg) to a hexagonal columnar phase (Colh/p6mm) takes place. Elongation of the bolaamphiphilic core leads to the loss of the columnar phases, which are replaced by smectic phases, whereas reduction of its length favors the hexagonal columnar phase. This phase sequence is explained as a result of the microsegregation of the lateral alkyl chains from the rigid aromatic cores. The segregated alkyl chains are organized in columns that interrupt the smectic layers. The hydrogen bonding keep the bolaamphiphilic cores fixed end to end, so that they form networks of cylinders around the lipophilic columns. The space required by the alkyl chains with respect to the length of the bolaamphiphilic cores is restricted and largely determines the geometry of the cylinders, which leads to the observed phase sequence. The obtained mesophase morphologies, built up by three distinct sets of subspaces, are related to morphologies of some ternary block copolymers. Furthermore, the investigated compounds represent a novel class of materials, capable of forming supramolecular columnar mesophases.
Organolithium addition to styrene and styrene derivatives: Scope and limitations
Wei, Xudong,Johnson, Paul,Taylor, Richard J.K.
, p. 1109 - 1116 (2007/10/03)
Styrene and a range of aryl-substituted styrene derivatives are shown to undergo efficient carbolithiation-trapping reactions in diethyl ether at -78 to -25 °C. The reactivities of different types of organolithium reagents were found to be: tertiary, secondary > primary; ? alkenyl, methyl, phenyl. Electron donating groups (e.g. methoxy and dialkylamino) at the ortho- or para- positions of the benzene ring deactivate the double bond towards organolithium addition, but their reactions with butyllithium can be facilitated by using TMEDA as co-solvent. 2-Benzyloxystyrene and 2-allyloxystyrene undergo efficient carbolithiation at -78 °C, but at room temperature alkyl transfer occurs, generating the corresponding alkylated phenol. 2-Vinylnaphthalene also undergoes carbolithiation-carboxylation in reasonable yield.
Thyroid Hormone Analogues. Synthesis of 3'-Substituted 3,5-Diiodo-L-thyronines and Quantitative Structure-Activity Studies of in Vivo Thyromimetic Activities in Rat Liver and Heart
Leeson, Paul D.,Ellis, David,Emmett, John C.,Shah, Virendra P.,Showell, Graham A.,Underwood, Anthony H.
, p. 37 - 54 (2007/10/02)
Twenty-nine 3'-substituted derivatives of the thyroid hormone 3,3',5-triiodo-L-thyronine (T3) have been synthesized by using established methods and by new route involving manipulation of a 3'-formyl intermediate.In vitro hormone receptor binding (to intact nuclei) and in vivo thyromimetic activity (induction of mitochondrial 3-phosphoglycerate oxidoreductase, GPDH) were measured in rat liver and heart for these new analogues and for the 18 previously reported 3'-substituted 3,5-diiodo-L-thyronines.Analysis of the binding data using theoretical conformational and quantitative structure-affinity methods implies that the 3'-substituent recognition site on the thyroid hormone receptor is hydrophobic and limited in depth to the length of the natural iodo substituent, but has sufficient width to accomodate a phenyl or cyclohexyl group.Receptor binding is reduced by approximately 10-fold in 3'-acyl derivatives which form strong intramolecular acceptor hydrogen bonds with the ajacent 4'-hydroxyl.The compounds studied showed no differences in their relative affinities for heart and liver nuclei, suggesting that receptors in these tissues are similar.However, the relationships between thyromimetic activity (induction of GPDH) and nuclear binding showed some tissue differences.A high correlation between activity and binding is observed for full agonists in the heart, but an equally significant correlation for the liver data is only seen when 3'-substituent bulk (molar reactivity) is included in the analysis.These results suggest the possibility that differential tissue penetration or access to receptors may occur in vivo.
