5150-42-5Relevant academic research and scientific papers
Oxygen-Free Regioselective Biocatalytic Demethylation of Methyl-phenyl Ethers via Methyltransfer Employing Veratrol- O-demethylase
Grimm, Christopher,Lazzarotto, Mattia,Pompei, Simona,Schichler, Johanna,Richter, Nina,Farnberger, Judith E.,Fuchs, Michael,Kroutil, Wolfgang
, p. 10375 - 10380 (2020/10/02)
The cleavage of aryl methyl ethers is a common reaction in chemistry requiring rather harsh conditions; consequently, it is prone to undesired reactions and lacks regioselectivity. Nevertheless, O-demethylation of aryl methyl ethers is a tool to valorize natural and pharmaceutical compounds by deprotecting reactive hydroxyl moieties. Various oxidative enzymes are known to catalyze this reaction at the expense of molecular oxygen, which may lead in the case of phenols/catechols to undesired side reactions (e.g., oxidation, polymerization). Here an oxygen-independent demethylation via methyl transfer is presented employing a cobalamin-dependent veratrol-O-demethylase (vdmB). The biocatalytic demethylation transforms a variety of aryl methyl ethers with two functional methoxy moieties either in 1,2-position or in 1,3-position. Biocatalytic reactions enabled, for instance, the regioselective monodemethylation of substituted 3,4-dimethoxy phenol as well as the monodemethylation of 1,3,5-trimethoxybenzene. The methyltransferase vdmB was also successfully applied for the regioselective demethylation of natural compounds such as papaverine and rac-yatein. The approach presented here represents an alternative to chemical and enzymatic demethylation concepts and allows performing regioselective demethylation in the absence of oxygen under mild conditions, representing a valuable extension of the synthetic repertoire to modify pharmaceuticals and diversify natural products.
A detour route for meta functionalization of phenols
Chittimalla, Santhosh Kumar,Kuppusamy, Rajesh,Bandi, Chennakesavulu
, p. 1991 - 1996 (2014/11/08)
Cyclohexadienones participate in a two-step procedure, a Michael addition followed by aromatization, providing hitherto difficult-to-synthesize meta-functionalized phenol derivatives in good yield. Application of the developed approach is exemplified by synthesizing C-aryl acetophenones, C-aryl glycines, and elemicin - an allylphenol natural product. Georg Thieme Verlag Stuttgart · New York.
Reductive cleavage of aryl O-carbamates to phenols by the Schwartz reagent. Expedient link to the directed ortho metalation strategy?
Morin, Justin,Zhao, Yigang,Snieckus, Victor
supporting information, p. 4102 - 4105 (2013/09/12)
A general, mild, and efficient method for the reductive cleavage of aryl O-carbamates to phenols, 1 → 2 using the Schwartz reagent is reported. The method is selective, tolerating a large number of functional groups; may be carried out by direct or by an economical in situ procedure; and, notably, establishes a synthetic connection to the directed ortho metalation strategy (Figure 1) allowing new entries into difficult to prepare contiguously substituted aromatics and heteroaromatics.
Schwartz Reagents: Methods of In Situ Generation and Use
-
Page/Page column 7; 15, (2010/06/19)
Embodiments of the invention provide a method of using Schwartz Reagent, Cp2Zr(H)Cl, without accumulating or isolating it. Methods provide mixtures of Cp2ZrCl2, reductants that selectively reduce Cp2ZrCl2, and substrates. After reaction of Cp2ZrCl2 and the reductant, an intermediate reduction product is formed, apparently Schwartz Reagent. The in situ Schwartz Reagent then selectively reduces certain functional groups on the substrate. Substrates include tertiary amides, tertiary benzamides, aryl O-carbamates, and heteroaryl N-carbamates, which are reduced to aldehydes, benzaldehydes, aromatic alcohols, and heteroaromatics, respectively. Compared to prior methods, reagents are inexpensive and stable, reaction times are short, and reaction temperature in certain cases is conveniently room temperature. It has been estimated that using the in situ method described herein instead of synthesized or commercially obtained Schwartz Reagent provides a 50% reduction in cost.
Facile and regioselective dealkylation of alkyl aryl ethers using niobium(V) pentachloride
Sudo, Yukinori,Arai, Shigeru,Nishida, Atsushi
, p. 752 - 758 (2007/10/03)
A simple and facile method for the cleavage of carbon-oxygen bonds promoted by niobium pentachloride(V) is described. Excellent yields and regioselectivities were observed with various alkyl aryl ethers to give the phenols. NMR studies revealed the formation of monoaryloxy niobium salt(V), and a neighboring-group effect may play a significant role in the regioselectivity. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
Synthesis of the CD-ring of the anticancer agent streptonigrin: studies of aryl-aryl coupling methodologies
McElroy, William T.,DeShong, Philip
, p. 6945 - 6954 (2007/10/03)
A series of functionalized 4-bromopyridines, representing the C-ring of the anticancer agent streptonigrin have been prepared and their abilities to undergo Pd-catalyzed cross-coupling with streptonigrin D-ring siloxanes were evaluated. The coupling reaction was generally tolerant to the preparation of hindered CD biaryls; however, the electronic effects of both partners play a pivotal role in the success of the coupling process. Analogs of the CD biaryl were prepared by coupling of aryl siloxane derivatives (D-ring component) with highly functionalized 4-bromopyridines (C-ring); however, the CD biaryl of the natural product could not be prepared in high yield by siloxane coupling due to the facile formation of reduced pyridine under the coupling conditions. Alternatively, the fully functionalized CD biaryl of streptonigrin was prepared using a Suzuki coupling of appropriately functionalized C-ring bromide and D-ring aryl boronic acid. The described approach is highly convergent and readily amenable to the synthesis of analogs.
Cross coupling strategies towards the synthesis of the streptonigrin CD moiety
Crous, Renier,Dwyer, Catherine,Holzapfel, Cedric W.
, p. 721 - 726 (2007/10/03)
An efficient route to an appropriate model of the streptonigrin 4- phenylpyridine CD moiety is reported. 4-Chloro-3-nitropyridine was found to be the key precursor and its reactivity in cross coupling reactions was further investigated.
Hydrogen peroxide/boric acid: An efficient system for oxidation of aromatic aldehydes and ketones to phenols
Roy, Amrita,Reddy,Mohanta, Pramod K.,Ila,Junjappa
, p. 3781 - 3791 (2007/10/03)
Hydrogen peroxide activated by boric acid in the presence of sulfuric acid has been shown to be an efficient oxidizing system for direct conversion of aromatic aldehydes and ketones to phenols.
Method for the production of alkoxy- and aryloxy-phenols
-
, (2008/06/13)
Alkoxybenzaldehydes and aryloxybenzaldehydes are converted to the corresponding phenols by reacting the benzaldehydes in an organic solvent phase with formic acid and hydrogen peroxide in an aqueous solvent phase to produce the corresponding formate ester. The formate ester is then saponified to produce the corresponding phenol.
Baeyer-Villiger oxidation of β-aryl substituted unsaturated carbonyl compounds with hydrogen peroxide and catalytic selenium dioxide
Guzman,Mendoza,Garcia,Garibay,Oliveras,Maldonado
, p. 2121 - 2133 (2007/10/02)
A simple and cheap oxidative procedure using 30% H2O2 and catalytic SeO2 allows to transform 2-aralkylidenecycloalkanones and hydroxy- or alkoxybenzaldehydes to give, in high yields, enollactones and arylformates, respectively.
