6335-83-7Relevant academic research and scientific papers
Enantiospecific sp2–sp3 Coupling of ortho- and para-Phenols with Secondary and Tertiary Boronic Esters
Wilson, Claire M.,Ganesh, Venkataraman,Noble, Adam,Aggarwal, Varinder K.
, p. 16318 - 16322 (2017/12/04)
The coupling of ortho- and para-phenols with secondary and tertiary boronic esters has been explored. In the case of para-substituted phenols, after reaction of a dilithio phenolate species with a boronic ester, treatment with Ph3BiF2 or Martin's sulfurane gave the coupled product with complete enantiospecificity. The methodology was applied to the synthesis of the broad spectrum antibacterial natural product (?)-4-(1,5-dimethylhex-4-enyl)-2-methyl phenol. For ortho-substituted phenols, initial incorporation of a benzotriazole on the phenol oxygen atom was required. Subsequent ortho-lithiation and borylation gave the coupled product, again with complete stereospecificity.
MOLECULARLY IMPRINTED POLYMERS
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, (2012/03/12)
The present invention provides methods of designing molecularly imprinted polymers (MIPs) which have applications in extracting bioactive compounds from a range of bioprocessing feedstocks and wastes. The present invention is further directed to MIPs designed by the methods of the present invention.
Nickel-mediated inter- and intramolecular reductive cross-coupling of unactivated alkyl bromides and aryl iodides at room temperature
Yan, Chang-Song,Peng, Yu,Xu, Xiao-Bo,Wang, Ya-Wen
supporting information; experimental part, p. 6039 - 6048 (2012/06/18)
A nickel-mediated intermolecular reductive cross-coupling reaction of unactivated alkyl bromides and aryl iodides at room temperature has been developed and successfully extended to less explored intramolecular versions and tandem cyclization-intermolecular cross-coupling. Highly stereoselective (or stereospecific) synthesis of linear-fused perhydrofuro[2,3-b]furan (pyran) and spiroketal skeletons allows rapid access to these useful building blocks, which would be potentially valuable in the synthesis of relevant natural products. A rational explanation for the formation of contiguous stereogenic centers is given. Copyright
Efficient heterogeneously palladium-catalysed synthesis of stilbenes and bibenzyls
Cusati, Giuseppe,Wedig, Anja,Djakovitch, Laurent
scheme or table, p. 77 - 81 (2010/04/23)
An alternative heterogeneously palladium catalysed procedure for the synthesis of functional stilbenes and bibenzyls is reported. Starting from aryl bromides and using simple commercially available Pd/C catalyst at a low catalytic rate (1 mol%), stilbenes are obtained with 30-100% GC-yields and bibenzyls are produced in a one-pot fashion with 27-100% GC-yields. The procedure showed, however, some limitations when applied to strongly deactivated aryl bromides that could be in some extent overcome by using corresponding iodo derivatives.
Flash vacuum pyrolysis of methoxy-substituted lignin model compounds
Britt, Phillip F.,Buchanan III,Cooney, Mark J.,Martineau, Dan R.
, p. 1376 - 1389 (2007/10/03)
The flash vacuum pyrolysis (FVP) of methoxy-substituted fi-O-4 lignin model compounds has been studied at 500 °C to provide mechanistic insight into the primary reaction pathways that occur under conditions of fast pyrolysis. FVP of PhCH2CH2OPh (PPE), a model of the dominant β-O-4 linkage in lignin, proceeds by C-O and C-C cleavage, in a 37:1 ratio, to produce styrene plus phenol as the dominant products and minor amounts of toluene, bibenzyl, and benzaldehyde. From the deuterium isotope effect in the FVP of PhCD2CH2OPh, it was shown that C-O cleavage occurs by homolysis and by 1,2- elimination in a ratio of 1.4:1, respectively. Methoxy substituents enhance the homolysis of the β-O-4 linkage, relative to PPE, in o-CH3O- C6H4OCH2CH2Ph (o-CH3O-PPE) and (o-CH3O)2-C6H3OCH2CH2Ph ((o- CH3O)2-PPE) by a factor of 7.4 and 21, respectively. The methoxy- substituted phenoxy radicals undergo a complex series of reactions, which are dominated by 1,5-, 1,6-, and 1,4-intramolecular hydrogen abstraction, rearrangement, and α-scission reactions. In the FVP of o-CH3O-PPE, the dominant product, salicylaldehyde, forms from the methoxyphenoxy radical by a 1,5-hydrogen shift to form 2-hydroxyphenoxymethyl radical, 1,2-phenyl shift, and β-scission of a hydrogen atom. The 2-hydroxyphenoxymethyl radical can also cleave to form formaldehyde and phenol in which the ratio of 1,2-phenyl shift to β-scission is ca. 4:1. In the FVP of o-CH3O-PPE and (o-CH3O)2- PPE, products (ca. 20 mol %) are also formed by C-O homolysis of the methoxy group. The resulting phenoxy radicals undergo 1,5- and 1,6-hydrogen shifts in a ratio of ca. 2:1 to the aliphatic or benzylic carbon, respectively, of the phenethyl chain. In the FVP of (o-CH3O)2-PPE, o-cresol was the dominant product. It was formed by decomposition of 2-hydroxy-3- hydroxymethylbenzaldehyde and 2-hydroxybenzyl alcohol, which are formed from a complex series of reactions from the 2,6-dimethoxyphenoxy radical. The key step in this reaction sequence was the rapid 1,5-hydrogen shift from 2- hydroxy-3-methoxybenzyloxy radical to 2-hydroxymethyl-6-methoxyphenoxy radical before β-scission of a hydrogen atom to give the substituted benzaldehyde. The 2-hydroxybenzyl alcohols rapidly decompose under the reaction conditions to o-benzoquinone methide and pick up hydrogen from the reactor walls to form o-cresol.
Syntheses and Platelet Aggregation Inhibitory and Antithrombotic Properties of ethyl>benzenes
Kikumoto, Ryoji,Hara, Hiroto,Ninomiya, Kunihiro,Osakabe, Masanori,Sugano, Mamoru,et al.
, p. 1818 - 1823 (2007/10/02)
A series of ethyl>benzene derivatives were synthesized and evaluated for their ability to inhibit collagen-induced platelet aggregation in vitro and to protect experimantal thrombosis in mice.The results showed that the compounds were in vitro inhibitors of collagen-induced platelet aggregation.Most of them were also effective in the mouse antithrombotic assay.The compounds were found to be potent antagonists to S2 serotonergic receptor, and good correlation (r = 0.85) between their S2 serotonergic receptor antagonism and their potency as platelet antiaggregatory drugs was observed.Among the compounds studied, monophenoxy>methyl>ethyl>succinate hydrochloride (12b, MCI-9042) was selected for further pharmacological and toxicological evaluation.
Catalyst composition and method for selective dehydrogenation
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, (2008/06/13)
A method for selective dehydrogenation of a compound, comprising contacting a compound of the formula STR1 wherein each R1, R2, R3 and R4 is independently selected from the group consisting of H, (C1 -C20) alkyl, (C3 -C20) cycloalkyl, (C6 -C20) aryl, (C7 -C20) alkylaryl, (C7 -C20) aralkyl groups, as well as substituted (C1 -C20) alkyl, (C3 -C20) cycloalkyl, (C6 -C20) aryl, (C7 -C20) aralkyl and (C7 -C20) arylalkyl moieties, optionally further substituted with --OR, wherein R is R1, R2, R3 or R4 ; and wherein R1 and R2 or R3 and R4 may be joined as part of a ring structure, at a dehydrogenation temperature in the presence of a catalyst comprising about 0.01 wt %-19.9 wt % Pd and about 0.01 wt %-19.9 wt % Cu on a carbon support, wherein the total amount of (Pd+Cu) on the support is about 0.02 wt % to 20 wt %, the weight ratio of Pd:Cu is about 1:1 to 10:1, and the carbon support has a surface area of at least about 100 m2 /g and is essentially free of reactive sulfur. A selective dehydrogenation catalyst having the composition described supra is disclosed as is a method of preparing the same. This catalyst is highly selective for dehydrogenating a variety of substrates while minimizing the formation of unwanted hydrogenolysis by-products.
Carbon-Hydrogen vs. Carbon-Carbon Bond Cleavage of 1,2-Diarylethane Radical Cations in Acetonitrile-Water
Camaioni, Donald M.,Franz, James A.
, p. 1607 - 1613 (2007/10/02)
Radical cations of 1,2-diarylethanes and 1-phenyl-2-arylethanes (Ar = phenyl, p-tolyl, p-anisyl) were generated in acidic 70percent acetonitrile-water by Cu2+-catalyzed peroxydisulfate oxidation.The radical cations fragment mainly by loss of benzylic protons (C-H cleavage) rather than by alkyl C-C bond cleavage.The radical cation of 2,3-dimethyl-2,3-diphenylbutane fragments efficiently by C-C cleavage, forming cumyl radical and cumyl cation.Oxidations of bibenzyl-bicumyl mixtures show selective oxidation of bicumyl dependent on total substrate concentration, providing evidence of equilibrating radical cations and showing that bicumyl fragments faster than bibenzyl loses protons.The effects of reaction conditions and substrate structure on reactivity are discussed.
Dihydrostilbenes of Cannabis. Synthesis of Canniprene
Crombie, Leslie,Jamieson, Sally V.
, p. 1467 - 1476 (2007/10/02)
Canniprene (10) is synthesised via reaction of a phenolate-anion ylide with a benzyl-protected aldehyde.Benzoylation, followed by hydrogenation and hydrogenolysis of the resulting stilbene, leads to a half-benzoylated bibenzyl which is converted into its O-dimethylprop-2-ynyl derivative.Semi-hydrogenation, Claisen rearrangement, and debenzoylation gives canniprene.In a second synthesis the prenylated (3-methylbut-2-enylated) and benzyl-protected ring-B section is made first and converted by Wittig reaction into a dibenzyl-protected stilbene.The stilbene is reduced and the benzyl groups removed in one step, without affecting the prenyl group, by sodium in butanol: magnesium in methanol is capable of stilbene reduction without debenzylation.This practical synthesis proceeds in 19 percent overall yield from the dimethylprop-2-ynyl ether of isovanillin (14) and is applicable to isotopelabelling.The use of p-bromophenacyl (PBP) ether and methoxyethoxymethyl (MEM) ether protection as the basis for canniprene synthesis is also considered.Other bibenzyls relevant to the natural products of Cannabis are made and the methylated chroman (37) derived from canniprene is also synthesised.
