Migration Of Benzoyl Group Research Articles

Azidation of Partially Protected Carbohydrate Derivatives: Efficient Suppression of Acyl Migration

Although azidation by nucleophilic substitution is widely used in organic chemistry, it has a limitation for partially protected carbohydrate derivatives under typical reaction conditions used for azidation (heating with NaN3, phase-transfer catalyst (optional), DMF or DMSO) as it can cause substantial migration (70%) of O-acyl protective groups. Several approaches, including the use of a temporary protective group for the unprotected hydroxyl group, to avoid acyl migration have been compared. Addition of excess of ethyl trifluroacetate effectively suppressed benzoyl migration but inhibited substitution of the chlorine atom with the azido group. The most robust procedure involved addition of excess n-butyl formate to the reaction mixture. When this protocol was followed, migration of benzoyl groups in lactose derivatives with free hydroxy group at C-3′ or C-4′ was reduced to 4%, with the yield of the target, partially protected derivatives with an azido group in the aglycone approaching 92%.

Correlation of the solid-state reactivities of racemic 2,4(6)-di-O-benzoyl-myo-inositol 1,3,5-orthoformate and its 4,4'-bipyridine cocrystal with their crystal structures.

Racemic 2,4(6)-di-O-benzoyl-myo-inositol 1,3,5-orthoformate, C21H18O8, (1), shows a very efficient intermolecular benzoyl-group migration reaction in its crystals. However, the presence of 4,4'-bipyridine molecules in its cocrystal, C21H18O8·C10H8N2, (1)·BP, inhibits the intermolecular benzoyl-group transfer reaction. In (1), molecules are assembled around the crystallographic twofold screw axis (b axis) to form a helical self-assembly through conventional O-H···O hydrogen-bonding interactions. This helical association places the reactive C6-O-benzoyl group (electrophile, El) and the C4-hydroxy group (nucleophile, Nu) in proximity, with a preorganized El···Nu geometry favourable for the acyl transfer reaction. In the cocrystal (1)·BP, the dibenzoate and bipyridine molecules are arranged alternately through O-H···N interactions. The presence of the bipyridine molecules perturbs the regular helical assembly of the dibenzoate molecules and thus restricts the solid-state reactivity. Hence, unlike the parent dibenzoate crystals, the cocrystals do not exhibit benzoyl-transfer reactions. This approach is useful for increasing the stability of small molecules in the crystalline state and could find application in the design of functional solids.

Direct regioselective benzoylation of a single C-2 hydroxyl group of β-cyclodextrin and its hydrolysis via benzoyl group migration

A simple and efficient method for the direct regioselective benzoylation of a single C-2 hydroxyl group of β-cyclodextrin was developed by using a combination of N,N′-carbonyldiimidazole and carbonate buffer in 1,4-dioxane, which does not require highly reactive reagents such as acyl chloride, or toxic solvents such as acetonitrile. Moreover, hydrolysis of the product was determined to occur via benzoyl group migration.

Evaluation of paclitaxel rearrangement involving opening of the oxetane ring and migration of acetyl and benzoyl groups

The stability of drug is a critical factor in quality control, drug efficacy, safety, storage, and production conditions. The rearrangement of paclitaxel, which involves opening of the oxetane ring and migration of acetyl group occurred on heating a powder of purified paclitaxel. Subsequently, the unusual migration of benzoyl groups progressed rapidly in organic solvents. These rearrangement derivatives were isolated carefully. The structures of the intermediate derivative A and the product derivative B were confirmed using 1H NMR, high performance liquid chromatography (HPLC), and mass spectrometry. We proposed the rearrangement pathway here for the first time. Neither derivative exhibited bioactivity in SKOV3 (ovarian cancer) or MDA-MB-435 (breast cancer) cell culture assays.

Synthesis of Carba Analogues of Deoxy-4-C-(hydroxymethyl)pentofuranoses, Intermediates in the Synthesis of Carbocyclic Nucleosides

Racemic dimethyl 4-methoxy- (11 and 12), diallyl 4-allyloxy- (13 and 14) and dimethyl 4-(ethylsulfanyl)-2-hydroxycyclopentane-1,1-dicarboxylates (15 and 16) were prepared by base-catalyzed addition of methanol, allyl alcohol and ethylsulfane, respectively, to dimethyl (4-oxobut-2-en-1-yl)malonate (6). Deallylation of 13 and 14 afforded 4-hydroxycyclopentanes 27 and 28. Reduction of 11-16 with lithium aluminium hydride gave the corresponding 4-substituted 2,2-bis(hydroxymethyl)cyclopentanols. Dimethyl (2S,3S,4R)-, (2R,3S,4R)-3-benzyloxy-4-formyloxy-2-hydroxycyclopentane-1,1-dicarboxylates (35, 36) and dimethyl (2S,3S,4R)-, (2R,3S,4R)-3-benzyloxy-2-benzoyloxy-4-methoxycyclopentane-1,1-dicarboxylates (39, 40) were synthesized starting from D-glucose. Reduction of dimethyl cyclopentane-1,1-dicarboxylates 39 and 40 with lithium aluminium hydride, benzoylation of the formed hydroxy derivatives, hydrogenolysis of benzyl groups, conversion of the liberated hydroxy groups into dithiocarbonates and their reduction with tributylstannane afforded, after removal of the protecting groups, (2R,4R)-1,1-bis(hydroxymethyl)-4-methoxycyclopentan-2-ol ((2R,4R)-17) and (3R,4R)-1,1-bis(hydroxymethyl)-4-methoxycyclopentan-3-ol (51). Reduction of a mixture of esters 35 and 36 gave (2R,3R)-2-benzyloxy-5-(hydroxymethyl)hexane-1,3,6-triol (52) as the major product and (2R,3S,4R)-3-benzyloxy-1,1-bis(hydroxymethyl)cyclopentane-2,4-diol (53) as the minor product. The latter was converted into (3R,4R)-1,1-bis(hydroxymethyl)cyclopentane-3,4-diol (58). 3-Deoxycarba analogues 51 and 58 arose by migration of benzoyl group in the preparation of the dithiocarbonates.

A Novel Benzoyl Group Migration: Synthesis and Biological Evaluation of 1-Benzoyl-2-des(benzoyloxy)paclitaxel

A Novel Benzoyl Group Migration: Synthesis and Biological Evaluation of 1-Benzoyl-2-des(benzoyloxy)paclitaxel

Elektrochemische untersuchungen von 3-imidazolin-5-thionen

The electrochemical behaviour of some methyl-, tert. butyl- and phenyl-substituted derivatives of 3-imidazoline-5-thiones has been examined by polarography and voltammetry in acetonitrile. Based on these data and on preparative electrolysis a mechanism for both the reduction and oxidation and the N → S benzoyl group migration is presented.

Aminosaccharides : Part V. Koenigs-knorr reaction of the acetobromo derivatives of 2-deoxy-2-(2,4-dinitroanilino)- d-glucopyranose and its monomethyl ethers

Syntheses of 4,6-di- O-acetyl-2-deoxy-2-(2,4-dinitroanilino)-3- O-methyl-α- d-glucopyranosyl bromide ( 3) and the isomeric 3,6-di- O-acetyl-4- O-methyl ( 4) and 3,4-di- O-acetyl-6- O-methyl ( 2) derivatives are described. 2-Deoxy-2-(2,4-dinitroanilino)-6- O-methyl- d-glucose ( 7) was synthesised via ethyl 3,4-di- O-benzoyl-2-deoxy-2-(2,4-dinitroanilino)-6- O-trityl-α- d-glucopyranoside ( 14) and its de- O-tritylated derivative ( 15). When 15 and its β-anomer 26 were methylated, little migration of benzoyl groups from C-4 to C-6 occurred. Compounds 3, 4, and 2 reacted with ethanol, in nitromethane solution with silver carbonate present, to form mainli β- d-glycopyranosides. In chloroform solution with pyridine as catalyst, 3 and 4 reacted rapidly with ethanol to give α- d-glycopyranosides as the major products, but 2 reacted slowly to give low yields of both glycosides. A possible mechanism for the pyridine-catalysed ethanolysis of 3, 4, and the unmethylated halide 1, involving participation of AcO-6, is discussed.

Novel Photocyclization of a Highly Phenylated β,γ-Unsaturated Ketone to a Cyclopropyl Ketone, Involving Benzoyl Group Migration

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNovel Photocyclization of a Highly Phenylated β,γ-Unsaturated Ketone to a Cyclopropyl Ketone, Involving Benzoyl Group MigrationLinwood P. Tenney, David W. Boykin Jr., and Robert E. LutzCite this: J. Am. Chem. Soc. 1966, 88, 8, 1835–1836Publication Date (Print):April 1, 1966Publication History Published online1 May 2002Published inissue 1 April 1966https://doi.org/10.1021/ja00960a059RIGHTS & PERMISSIONSArticle Views121Altmetric-Citations24LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (303 KB) Get e-Alerts Get e-Alerts

Reaction of Ammonia with Some Acetylated and Benzoylated Monosaccharides. IX. The Migration of Benzoyl Groups in the Ammonolysis of 1,2,3,4,6-Penta-O-benzoyl-D-galactoses1

Reaction of Ammonia with Some Acetylated and Benzoylated Monosaccharides. IX. The Migration of Benzoyl Groups in the Ammonolysis of 1,2,3,4,6-Penta-O-benzoyl-D-galactoses¹