Ceric ammonium nitrate, cleavage

Amines can also be protected by this reagent cleavage must be carried c acidic media to avoid amine oxidation. The byproduct naphthoquinone can 1 moved by extraction with basic hydrosulfite. Ceric ammonium nitrate also s as an oxidant for deprotection, but the yields are much lower. 

Dimethoxybenzyl esters prepared from the acid chloride and the benzyl alcohol are readily cleaved oxidatively by DDQ (CH2CI2, H2O, rt, 18 h, 90-95% yield). A 4-methoxybenzyl ester was found not to be cleaved by DDQ. The authors have also explored the oxidative cleavage (ceric ammonium nitrate, CH3CN, H2O, 0°, 4 h, 65-97% yield) of a variety of 4-hydroxy- and 4-amino-substituted phenolic esters. ... 

Ceric ammonium nitrate, CH3CN, H2O, 0°, 95% yield. In the presence of chloride ion, cleavage fails." ... 

Ceric ammonium nitrate (CAN), CH3CN, H2O, it, 12 h, 96% yield. Benzylamides are not cleaved under these conditions. Some of the methods used to cleave the benzyl group should also be effective for cleavage of the PMB group. Ceric ammonium nitrate is also used to cleave the PMB group from a sulfonamide nitrogen. ... 

Recently a new linker of this category has been described. A novel benzyloxyani-line linker 1 that uses ceric ammonium nitrate (CAN) as a cleavage reagent, was described by Balasubramanian and Gordon (Scheme 3.1) [37]. 

Removal of the 0-substituted Fp group can be achieved by conversion into the cationic alkene-Fp complex using Ph3CPF6 and subsequent treatment with iodide, bromide or acetonitrile. Oxidative cleavage with ceric ammonium nitrate in methanol provides the methyl esters via carbon monoxide insertion followed by demetallation. The [3 + 2]-cydoaddition has been successfully applied to the synthesis of hydroazulenes (Scheme 1.11) [34]. This remarkable reaction takes advantage of the specific nucleophilic and electrophilic properties of V-allyl-, cationic t 5-dienyl-, cationic ri2-alkene- and ti4-diene-iron complexes, respectively. 

O-tethered P-keto esters, through the intermediacy of aiylidene keto esters, have been efficiently utilized for the construction of immobilized dihydropyridines. Ceric ammonium nitrate (CAN) oxidation to pyridines followed by acidolytic cleavage provides a facile entry into nicotinic acid derivatives 57 [42], A three-component Biginelli cyclization of ureas on resin with a solution mixture of aldehydes and P-keto esters provides dihydropyrimidines 58 in high yield and purity [43], Heterocycles such as dihydropyridines and pyrimidines have historically proven to be a rich source of antimicrobial, antitumor, antiviral, and cardiovascular agents. 

Oxidation of 1-(4-methoxyphenyl)-2-( -substituted phenyl) et hands, 6, by Cerium(IV). Dehydration prevented the oxidative-cleavage study of l-(4-hydroxyphenyl)-2-(4,-substituted phenyl)ethanols, 4, (8). As an alternative study, the oxidation of these phenolic compounds using the homolytic oxidant ceric ammonium nitrate (CAN) in an acidic environment was initiated. However, preliminary oxidations of these compounds were unsuccessful due to the apparent formation of complexes of cerium(IV) with the phenolic hydroxyl groups. 

Two oxidants essentially dominate these oxidations lead tetraacetate in organic solvents and periodic acid in aqueous media. On occasion, other oxidation reagents cause the cleavage of vicinal diols ceric ammonium nitrate [424], sodium bismuthate [482, 483], chromium trioxide [482, 555], potassium dichromate with perchloric acid [949], manganese dioxide [817], and trivalent [779, 789] or pentavalent [798] iodine compounds. 

Dicobaltoctacarbonyl (Co2(CO)8) is a reagent used in synthetic organic chemistry to protect carbon-carbon triple bonds because it reacts with them to form stable complexes. These complexes are easily transformed back to the parent alkyne by oxidative cleavage employing agents such as ferric nitrate, ceric ammonium nitrate (CAN), DMSO, or amine A-oxides. 

Eor Boc protected amino acids Ceric ammonium nitrate, MeOH, rt, 38-83% yield. When the reaction is conducted at reflux Boc cleavage is accompanied by esterification. ... 

The synthetic utility of this enantioselective alkylation of an arylimine rehes on a practical method for the dearylation of the resulting chiral amine. A two-step procedure was illustrated for amine 3a (R =Me), which begins with a protection step (n-BuLi/ClC02CH2Ph) followed by oxidative cleavage of the aryl moiety (ceric ammonium nitrate CAN). The N-protected amine 4a was isolated in only 58% overall yield without significant loss of enantiomeric purity (Scheme 3). 

Three different pyridine syntheses starting from polymer-bound enones have been reported. The first synthesis starts from 2-alkylidene- or 2-arylidene-B-ketoesters immobilized on Wang or Sasrin resin (Fig. 6.21). These substrates reacted with enaminones in a Hantzsch reaction to 1,4-dihydropyridines which could be oxidized to the corresponding pyridines with ceric ammonium nitrate (CAN). Cleavage was performed with TFA/DCM. Sixteen compounds were synthesized, with HPLC purities of between 70% and 99%. 

Oxidative cleavage of bicyclic alcohols. Oxidation of either exo- or endo-norbornanol (1) with 2 equiv. of ceric ammonium nitrate in 50% aqueous acetonitrile at 50° gives three products of oxidative cleavage, 3- and 4-cyclopentene-acetaldehydes (2) and (3) and 3-nitratocyclopentaneacetaldehyde (4).3 Oxidation... 

Oxidative cleavage of 7-oxo-6,7-dihydroisoxazolo[3,4-i/]- and diphenylfuro[3,4-with ceric ammonium nitrate gives 5-acyl-4-nitro-3(2//)-pyridazinones and 4,5-dibenzoylpyridazines (Scheme 117), some of which can be difficult to synthesize in other ways <8381018,89S213). 

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