13319-71-6Relevant articles and documents
Aryne 1,2,3,5-Tetrasubstitution Enabled by 3-Silylaryne and Allyl Sulfoxide via an Aromatic 1,3-Silyl Migration
Shi, Jiarong,Li, Lianggui,Shan, Chunhui,Wang, Junli,Chen, Zhonghong,Gu, Rongrong,He, Jia,Tan, Min,Lan, Yu,Li, Yang
supporting information, p. 2178 - 2184 (2021/02/16)
Although benzyne has been well-known to serve as a synthon that can conveniently prepare various 1,2-difunctionalized benzenes, the sites other than its formal triple bond remain silent in typical benzyne transformations. An unprecedented aryne 1,2,3,5-tetrasubstitution was realized from 3-silylbenzyne and aryl allyl sulfoxide, the mechanistic pathway of which includes a regioselective aryne insertion into the SO bond, a [3,6]-sigmatropic rearrangement, and a thermal aromatic 1,3-silyl migration cascade.
Improved Synthesis of MediPhos Ligands and Their Use in the Pd-Catalyzed Enantioselective N-Allylation of Glycine Esters
Albat, Dominik,Neud?rfl, J?rg-Martin,Reiher, Martin,Schmalz, Hans-Günther
supporting information, p. 4237 - 4242 (2021/08/24)
A new class of chiral C2-symmetric diphosphines (MediPhos) was recently shown to give superior results in the Pd-catalyzed asymmetric N-allylation of amino acid esters. We here describe a new, improved protocol for the preparation of such ligands through bidirectional SN2-coupling of a tartrate-derived ditosylate with 6-alkyl-2-bromophenols followed by double lithiation/phosphanylation. This method gave access to a series of nine ligands with branched alkyl substituents, which were benchmarked in the enantioselective Pd-catalyzed N-allylation of tert-butyl glycinate with racemic (E)-2,8-dimethylnona-5-en-4-yl methyl carbonate (up to 95 % ee). In addition, the analogous transformation of tert-butyl glycinate with methyl (E)-nona-5-en-4-yl carbonate was optimized. The obtained allylic amines were then used in the stereoselective synthesis of the conformationally restricted proline-derived dipeptide analogs ProM-17 and ProM-21.
Chiral Phosphine–Phosphite Ligands in Asymmetric Gold Catalysis: Highly Enantioselective Synthesis of Furo[3,4-d]-Tetrahydropyridazine Derivatives through [3+3]-Cycloaddition
Du, Qingwei,Neud?rfl, J?rg-Martin,Schmalz, Hans-Günther
supporting information, p. 2379 - 2383 (2018/01/27)
The AuI-catalyzed reaction of 2-(1-alkynyl)-2-alken-1-ones with azomethine imines regio- and diastereoselectively affords furo[3,4-d]tetrahydropyridazines in a tandem cyclization/intermolecular [3+3]-cycloaddition process under mild conditions.
Examination of Selectivity in the Oxidation of ortho- and meta-Disubstituted Benzenes by CYP102A1 (P450 Bm3) Variants
Munday, Samuel D.,Dezvarei, Shaghayegh,Lau, Ian C.-K.,Bell, Stephen G.
, p. 2512 - 2522 (2017/07/12)
Cytochrome P450 CYP102A1 (P450 Bm3) variants were used to investigate the products arising from the P450 catalysed oxidation of a range of disubstituted benzenes. The variants used all generated increased levels of metabolites compared to the wild-type enzyme. With ortho-halotoluenes up to six different metabolites could be identified whereas the oxidation of 2-methoxytoluene generated only two aromatic oxidation products. Addition of an ethyl group markedly shifted the selectivity for oxidation to the more reactive benzylic position. Epoxidation of an alkene was also preferred to aromatic oxidation in 2-methylstyrene. Significant minor products arising from the migration of one substituent to a different position on the benzene ring were formed during certain P450-catalysed substrate turnovers. For example, 2-bromo-6-methylphenol was formed from the turnover of 2-bromotoluene and the dearomatisation product 6-ethyl-6-methylcyclohex-2,4-dienone was generated from the oxidation of 2-ethyltoluene. The RLYF/A330P variant altered the product distribution enabling the generation of certain metabolites in higher quantities. Using this variant produced 4-methyl-2-ethylphenol from 3-ethyltoluene with ≥90 % selectivity and with a biocatalytic activity suitable for scale-up of the reaction.
Regioselective monobromination of aromatics via a halogen bond acceptor-donor interaction of catalytic thioamide and N-bromosuccinimide
Bovonsombat, Pakorn,Teecomegaet, Pattaradra,Kulvaranon, Panisanun,Pandey, Aditi,Chobtumskul, Kittithorn,Tungsirisurp, Sireethorn,Sophanpanichkul, Punyanuch,Losuwanakul, Satreerat,Soimaneewan, Dechathon,Kanjanwongpaisan, Patcharida,Siricharoensang, Pornpawit,Choosakoonkriang, Sirirat
, p. 6564 - 6572 (2017/10/17)
Regioselective monobromination of various aromatics was achieved at room temperature using N-bromosuccinimide and 5 mol% of thioamides in acetonitrile. With thiourea as catalyst, activated aromatics, such as anisole, acetanilide, benzamide and phenol analogues containing electron donating or withdrawing groups, were brominated with high regioselectivity. Room temperature brominations of weakly activated aromatics and deactivated 9-fluorenone were accomplished by 5 mol% thioacetamide, higher substrates concentrations and longer reaction times. A backbonding of the bromine lone pairs with the π*of C[dbnd]S group and a halogen bond between the halogen bond donor bromine and the halogen bond acceptor sulfur of the thioamide are thought to be the principal interactions and cause of N-bromosuccinimide activation.
The Catalyst-Controlled Regiodivergent Chlorination of Phenols
Maddox, Sean M.,Dinh, Andrew N.,Armenta, Felipe,Um, Joann,Gustafson, Jeffrey L.
supporting information, p. 5476 - 5479 (2016/11/17)
Different catalysts are demonstrated to overcome or augment a substrate's innate regioselectivity. Nagasawa's bis-thiourea catalyst was found to overcome the innate para-selectivity of electrophilic phenol chlorination, yielding ortho-chlorinated phenols that are not readily obtainable via canonical electrophilic chlorinations. Conversely, a phosphine sulfide derived from 2,2′-Bis(diphenylphosphino)-1,1′-binaphthyl (BINAP) was found to enhance the innate para-preference of phenol chlorination.
Vanadium bromoperoxidase (VBrPO) mimics: Synthesis, structure and a comparative account of the catalytic activity of newly synthesized oxidovanadium and oxido-peroxidovanadium complexes
Palmajumder, Eshita,Patra, Swarup,Drew, Michael G. B.,Mukherjea, Kalyan K.
, p. 8696 - 8703 (2016/10/13)
The bioinspired catalytic activities of two newly synthesised vanadium(iv)dioxido (complex 1) and vanadium(v) oxido-peroxido (complex 2) complexes with the neutral tridentate benzimidazole ligand, 2,6-di-(1H-benzo[d]imidazol-2-yl)pyridine (Byim) have been established. The bromoperoxidase activities of these complexes have been established through the activation of C-H bonds of substrates like phenol, o-cresol and p-cresol. The products, characterized by GC analysis shows that good conversions have been achieved. Considering the catalytic efficiency of the complexes, complex 2, with one in-built peroxido group is found to be more potent than complex 1. The catalytic cycles of both the complexes have been established from experimental results.
Synthesis of C2-symmetric bisphosphine ligands from tartaric acid, and their performance in the Pd-Catalyzed asymmetric o-allylation of a phenol
Dindaroglu, Mehmet,Akyol Dincer, Sema,Schmalz, Hans-Guenther
supporting information, p. 4315 - 4326 (2014/07/21)
Starting from tartaric acid derived chiral diols or dicarboxylic acid dichlorides with either a 2,2-dimethyl-1,3-dioxolane (Taddol) or a 2,3-dimethoxy-2,3-dimethyl-1,4-dioxane (Tatrol) core structure, and BH 3-protected ortho-phosphanyl phenols, a set of fourteen new C 2-symmetric diphosphine ligands was synthesized. In addition, three related ligands were obtained from ortho-diphenylphosphino-anilines. The fully characterized ligands were then tested in the Pd-catalyzed enantioselective O-allylation of 4-methoxyphenol using crotyl methyl carbonate as a reagent. In addition, a pseudo-intramolecular variant of the reaction, using crotyl 4-methoxyphenyl carbonate as a substrate, was studied. The so-called Trost ligand was used as a reference. Although the Trost ligand (3 mol-%) gave up to 84% ee, one of the new ligands showed higher activity (50% ee with 0.075 mol-%). Copyright
Preparation of carbazole and dibenzofuran derivatives by selective bromination on aromatic rings or benzylic groups with N-bromosuccinimide
Fang, Lei,Zhang, Haun,Fang, Xubin,Gou, Shaohua,Cheng, Lin
, p. 635 - 641 (2014/06/23)
N-Bromosuccinimide (NBS), a bromine source, has been used to study the bromination of toluidine and cresols systematically to clarify the underlying mechanism and the orientation effect. It has been found that bromination of toluidine and cresols which possess electron-donating NH2/OH with NBS gives electrophilic aromatic substitution products quickly instead of the desired benzylic bromination products. In contrast, when the electronic effect of the substituted groups is reversed, only the benzylic bromination products are gained. Based on this methodology, several potential AChE inhibitors, such as 2-methoxy-5-(benzylamino)methyl-dibenzofuran, 3-bromo-2-methoxy-5-methyl-9H- carbazole, 3,6-dibromo-2-methoxy-5-methyl-9H-carbazole, and 5-(bromomethyl)-2- methoxy-9H-(phenylsulfonyl)-carbazole have been synthesized.
SUBSTITUTED PHENOLS HAVING ANTICONVULSANT PROPERTIES
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Page/Page column 36, (2014/01/08)
Substituted phenol compounds and methods of using the compounds, e.g., for anesthetizing a subject, are disclosed.
