FRINK Linked Data Fragments server

Matches in SemOpenAlex for { <https://semopenalex.org/work/W82364162> ?p ?o ?g. }

• W82364162 abstract "Catalytic Deprotection of Acetals In Strongly Basic Solution Using a Self- Assembled Supramolecular “Nanozyme” Michael D. Pluth, Robert G. Bergman,* and Kenneth N. Raymond* Acetals are among the most commonly used protecting groups for aldehydes and ketones in organic synthesis due to their ease of installation and resistance to cleavage in neutral or basic solution. [1] The common methods for hydrolyzing acetals almost always involve the use of either Bronsted acid or Lewis acid catalysts. [2] Usually aqueous acids or organic solutions acidified with organic or inorganic acids have been used for reconversion of the acetal functionality to the corresponding carbonyl group; however, recently a number of reports have documented a variety of strategies for acetal cleavage under mild conditions. These include the use of Lewis acids such as bismuth(III) [3] or cerium(IV), [4, 5] functionalized silica gel, such as silica sulfuric acid [6] or silica-supported pyridinium p-toluenesulfonate, [7] or the use of silicon-based reagents such as TESOTf- 2,6-Lutidine. [8] Despite these mild reagents, all of the above conditions require either added acid or overall acidic media. Marko and co-workers recently reported the first example of acetal deprotection under mildly basic conditions using catalytic cerium ammonium nitrate at pH 8 in a water-acetonitrile solution. [5] Also recently, Rao and co-workers described a purely aqueous system at neutral pH for the deprotection of acetals using β-cyclodextrin as the catalyst. [9] Herein, we report the hydrolysis of acetals in strongly basic aqueous solution using a self-assembled supramolecular host as the catalyst. During the last decade, we have used metal-ligand interactions for the formation of well-defined supramolecular assemblies with the stoichiometry M 4 L 6 (M = Ga III (1 refers to K 12 [Ga 4 L 6 ]), Al III , In III , Fe III , Ti IV , or Ge IV , L = N,N′-bis(2,3- dihydroxybenzoyl)-1,5-diaminonaphthalene) (Figure 1). [10] The metal ions occupy the vertices of the tetrahedron and the bis- bidentate catecholamide ligands span the edges. The strong mechanical coupling of the ligands transfers the chirality from one metal center to the other, thereby requiring the ΔΔΔΔ or ΛΛΛΛ configurations of the assembly. While the 12- overall charge imparts water solubility, the naphthalene walls of the assembly provide a hydrophobic environment which is isolated from the bulk aqueous solution. This hydrophobic cavity has been utilized to kinetically stabilize a variety of water-sensitive guests such as tropylium, [11] iminium ions, [12] diazonium ions, [13] and reactive phosphonium species. [14] Furthermore, 1 has been used to encapsulate catalysts [15] for organic transformations as well as act as a catalyst for the 3-aza-Cope rearrangement of enammonium substrates [16] and the hydrolysis of acid-labile orthoformates. [17] Figure 1 Left: A schematic representation of the host M 4 L 6 assembly. Only one ligand is shown for clarity. Right: A model of the empty assembly; hydrogen atoms are omitted for clarity. Our recent work using 1 as a catalyst for orthoformate hydrolysis prompted our investigation of the ability of 1 to catalyze the deprotection of acetals (Scheme 1). With the ability of 1 to favor encapsulation of monocationic guests, we anticipated that the rates of acetal hydrolysis could be accelerated by stabilization of any of the cationic protonated intermediates along the mechanistic pathway upon encapsulation in 1. In contrast to the stability of 2,2-dimethoxypropane in H 2 O at pH 10, addition of the acetal to a solution of 1 at this pH quickly yielded the products of hydrolysis (acetone and methanol). Addition of a strongly binding inhibitor for the interior cavity of 1, such as NEt 4+ (log (K a ) = 4.55), inhibited the overall reaction, confirming that 1 is active in the catalysis. Scheme 1. Catalytic deprotection of acetals under basic conditions using 1 as a catalyst . The hydrolysis reactions were screened by mild heating (50 °C) of 5 mol % of 1 with respect to the acetal substrate at pH 10 in H 2 O in a sealed NMR tube. Dimethylsulfoxide was used as an internal integration standard. To examine the reaction scope, a variety of alkyl acetals and ketals were screened (Table 1). Smaller substrates, which are able to fit into the cavity of 1, are readily hydrolyzed. However, larger substrates, such as 2,2-dimethoxyundecane (entry 6) or 1,1-dimethoxynonane (entry 7), remain unchanged, suggesting that they are too large to enter the interior cavity of 1. The basic solution caused" @default.
• W82364162 created "2016-06-24" @default.
• W82364162 creator A5047518475 @default.
• W82364162 creator A5073204417 @default.
• W82364162 creator A5085114228 @default.
• W82364162 date "2008-06-09" @default.
• W82364162 modified "2023-09-28" @default.
• W82364162 title "Catalytic Deprotection of Acetals In Strongly Basic Solution Using a Self-Assembled Supramolecular Nanozyme" @default.
• W82364162 cites W1566080486 @default.
• W82364162 hasPublicationYear "2008" @default.
• W82364162 type Work @default.
• W82364162 sameAs 82364162 @default.
• W82364162 citedByCount "0" @default.
• W82364162 crossrefType "journal-article" @default.
• W82364162 hasAuthorship W82364162A5047518475 @default.
• W82364162 hasAuthorship W82364162A5073204417 @default.
• W82364162 hasAuthorship W82364162A5085114228 @default.
• W82364162 hasConcept C161790260 @default.
• W82364162 hasConcept C163638829 @default.
• W82364162 hasConcept C178790620 @default.
• W82364162 hasConcept C184651966 @default.
• W82364162 hasConcept C185592680 @default.
• W82364162 hasConcept C21951064 @default.
• W82364162 hasConcept C2777380813 @default.
• W82364162 hasConcept C2777731525 @default.
• W82364162 hasConcept C32909587 @default.
• W82364162 hasConcept C40875361 @default.
• W82364162 hasConcept C93275456 @default.
• W82364162 hasConceptScore W82364162C161790260 @default.
• W82364162 hasConceptScore W82364162C163638829 @default.
• W82364162 hasConceptScore W82364162C178790620 @default.
• W82364162 hasConceptScore W82364162C184651966 @default.
• W82364162 hasConceptScore W82364162C185592680 @default.
• W82364162 hasConceptScore W82364162C21951064 @default.
• W82364162 hasConceptScore W82364162C2777380813 @default.
• W82364162 hasConceptScore W82364162C2777731525 @default.
• W82364162 hasConceptScore W82364162C32909587 @default.
• W82364162 hasConceptScore W82364162C40875361 @default.
• W82364162 hasConceptScore W82364162C93275456 @default.
• W82364162 hasLocation W823641621 @default.
• W82364162 hasOpenAccess W82364162 @default.
• W82364162 hasPrimaryLocation W823641621 @default.
• W82364162 hasRelatedWork W1976647446 @default.
• W82364162 hasRelatedWork W2077372672 @default.
• W82364162 hasRelatedWork W2157348216 @default.
• W82364162 hasRelatedWork W2340633478 @default.
• W82364162 hasRelatedWork W2514311959 @default.
• W82364162 hasRelatedWork W2889500535 @default.
• W82364162 hasRelatedWork W2951209298 @default.
• W82364162 hasRelatedWork W2951685031 @default.
• W82364162 hasRelatedWork W2952077507 @default.
• W82364162 hasRelatedWork W2952226347 @default.
• W82364162 hasRelatedWork W2952574959 @default.
• W82364162 hasRelatedWork W2953030547 @default.
• W82364162 hasRelatedWork W2967145957 @default.
• W82364162 hasRelatedWork W2974362749 @default.
• W82364162 hasRelatedWork W2999194351 @default.
• W82364162 hasRelatedWork W3088299518 @default.
• W82364162 hasRelatedWork W3122519997 @default.
• W82364162 hasRelatedWork W3208365903 @default.
• W82364162 hasRelatedWork W2867698963 @default.
• W82364162 hasRelatedWork W2880764714 @default.
• W82364162 isParatext "false" @default.
• W82364162 isRetracted "false" @default.
• W82364162 magId "82364162" @default.
• W82364162 workType "article" @default.