Ceric ammonium nitrate CAN

Ceric ammonium nitrate (CAN), CH3CN, H2O, rt, 12 h, 96% yield. - Benzylamides are not cleaved under these conditions. 

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. ... 

The immediate outcome of the Hantzsch synthesis is the dihydropyridine which requires a subsequent oxidation step to generate the pyridine core. Classically, this has been accomplished with nitric acid. Alternative reagents include oxygen, sodium nitrite, ferric nitrate/cupric nitrate, bromine/sodium acetate, chromium trioxide, sulfur, potassium permanganate, chloranil, DDQ, Pd/C and DBU. More recently, ceric ammonium nitrate (CAN) has been found to be an efficient reagent to carry out this transformation. When 100 was treated with 2 equivalents of CAN in aqueous acetone, the reaction to 101 was complete in 10 minutes at room temperature and in excellent yield. 

When ceric ammonium nitrate (CAN) was used as a source of ceric ion, the presence of nitric acid was found to play a significant role. Ceric ion in water is believed to react in the following manner ... 

Samal et al. [25] reported that Ce(IV) ion coupled with an amide, such as thioacetamide, succinamide, acetamide, and formamide, could initiate acrylonitrile (AN) polymerization in aqueous solution. Feng et al. [3] for the first time thoroughly investigated the structural effect of amide on AAM polymerization using Ce(IV) ion, ceric ammonium nitrate (CAN) as an initiator. They found that only acetanilide (AA) and formanilide (FA) promote the polymerization and remarkably enhance Rp. The others such as formamide, N,N-dimethylformamide (DMF), N-butylacetamide, and N-cyclohexylacetamide only slightly affect the rate of polymerization. This can be shown by the relative rate (/ r), i.e., the rate of AAM polymerization initiated with ceric ion-amide divided by the rate of polymerization initiated with ceric ion alone. Rr for CAN-anilide system is approximately 2.5, and the others range from 1.04-1.11. 

Finally, epoxides can be converted into other functional groups under certain well-defined conditions. For example, ceric ammonium nitrate (CAN) catalyzes the efficient conversion of epoxides to thiiranes (i.e., 124 125) at room temperature in te/t-butanol <96SYN821>. 

Initially, 50 was converted into the benzoxazinone 51 by reaction with phosgene in the presence of triethylamine and 51 was isolated in 95% yield upon crystallization from methanol. Deprotection of the pMB group from 51 was accomplished with ceric ammonium nitrate (CAN) in aqueous acetonitrile. Efavirenz was isolated in 76% yield after crystallization from EtOAc-heptane (5 95), as shown in Scheme 1.19. There were two issues identified in this route. First, lequiv of ani-saldehyde was generated in this reaction, which could not be cleanly rejected from product 1 by simple crystallization to an acceptable level under the ICH guideline. Anisaldehyde was removed from the organic extract as a bisulfite adduct by washing with aqueous Na2S205 twice, prior to the crystallization of 1. Secondly,... 

The reaction of aliphatic, aromatic, heterocyclic, conjugated, and polyhydroxy aldehydes with NBS and ammonia gave the corresponding nitriles in high yields at 0°C in water (Eq. 9.18).39 Ceric ammonium nitrate (CAN)40 and iodine41 are also effective as the oxidizing reagents. 

Feldman and Skoumbourdis have utilized an oxidative hydrolysis of the thioimidate with ceric ammonium nitrate (CAN) to generate dibromophakellstatin 78 as the final step in their synthetic sequence (Equation 14) <20050L929>. 

The ceric ammonium nitrate (CAN) promoted oxidation of oxazoles with various substitution patterns was investigated and yielded the corresponding imides 108 in good yields, tolerating a wide variety of functional groups and substituents on the oxazole moiety <06OL5669>. 

The diester 110 (E = CC Et) reacts with a mixture of trimethyltin chloride and sodium cyanoborohydride under AIBN catalysis to give the cyclopentane 111 as a 4 1 mixture of cis- and fraws-isomers. The products are destannylated to the acetals 112 by treatment with methanolic ceric ammonium nitrate (CAN). The 1,7-octadienyl derivative 113 was similarly converted into the cyclohexanes 114 (cis/trans = 1 1) (equation 60)67. 

Only a few examples exist for the intermolecular trapping of allyl radicals with alkenes68,69. The reaction of a-carbonyl allyl radical 28 with silyl enol ether 29 occurs exclusively at the less substituted allylic terminus to form, after oxidation with ceric ammonium nitrate (CAN) and desilylation of the adduct radical, product 30 (equation 14). Formation of terminal addition products with /ram-con figuration has been observed for reaction of 28 with other enol ethers as well. 

An oxidative Mannich cyclization methodology allowed the synthesis of indolizidine skeletons. The oxidation of the a-silylamide 140 with ceric ammonium nitrate (CAN) formed in situ an iV-acylaminium cation, which cyclized to afford the bicyclic compound 141 (Scheme 35) <1998JOC841>. 

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]. 

Unlike benzylic groups, they cannot be made directly from the alcohol. Instead, the phenoxy group must be introduced by a nucleophilic substitution.30 Mitsunobu conditions are frequently used.31 The PMP group can be cleaved by oxidation with ceric ammonium nitrate (CAN). 

Dihydropyrimidines are normally readily oxidized to the corresponding pyrimidines by dehydrogenation, hydrogen transfer, or disproportionation reactions <1994HC(52)1, 1996CHEC-II(6)93>. For example, the oxidation of a series of trifluoromethyl ketones 522 with DDQ occurred readily at room temperature <1997H(44)349>. Facile room temperature oxidation with ceric ammonium nitrate (CAN) has also been achieved <2003ARK(xv)22>. 

Meldrum s acid, like other 1,3-dicarboxyl compounds, was amenable to radical reactions at C-5. The radical reaction between Meldrum s acid benzyl alkyl ethers mediated by InCl3/Cu(OTf)2 has been reported to proceed regioselectively at the benzylic position of the ether moiety (Scheme 35) <2006AGE1949>. Radical reaction of Meldrum s acid and alkenes was carried out with 2equiv of ceric ammonium nitrate (CAN) to give the a-carboxy-lactones which were subsequently subjected to decarboxylative methylenation affording the a-methylene lactones in 35-50% yield (Scheme 35) <2006SL1523>. 

Solid-phase synthesis of pyrido[2,3 pytirtiidines 514 was achieved by Hantzsch condensation of Wang resin-supported Knoevenagel derivative 513 with 6-aminouracil derivatives 512 as an a-oxo enamine component in the presence of ceric ammonium nitrate (CAN) in DMA followed by hydrolysis with TFA in CH2GI2. Compound 513 was prepared by treatment of a hydroxylated polymer, such as Wang or Sasrin resin, with diketene, followed by condensation with benzaldehyde (Equation 41) <1996TL4643>. 

In 2000, Tanino and his co-workers developed the novel [5- -2]-cycloaddition reaction of a propargyiic cation equivalent bearing allylic silane 17 with enol silane 18 to give the corresponding cycloheptyne complexes 19 in good yields with an excellent diastereoselectivity (Scheme 3). While ceric ammonium nitrate (CAN) is generally used to... 

Yoshimura has introduced the p-methoxybenzyl group for N-protection in piperazine-2,5-diones (83CL1001 85BCJ1413). The N-alkylation is carried out with sodium hydride and p-methoxybenzyl bromide in DMF at room temperature. Deprotection is achieved by ceric ammonium nitrate (CAN) in acetonitrile-water. 

Allylic carboxylation. Diethyl oxomalonate (1) undergoes a thermal ene reaction with mono-, di-, and trisubstituted alkenes at 145 180°. The reaction is also subject to catalysis with Lewis acids, which can lead to a different ene product. The products are a-hydroxymalonic esters. The corresponding malonic acids are converted to carboxylic acids by bisdecarboxylation with NaI04 and a trace of pyridine- or with ceric ammonium nitrate (CAN). Diethyl oxomalonate then functions as an cnophilic equivalent of C02. 

Protection2 and activation1 of carboxylic acids. Carboxylic acids react with 1 in the presence of a 2-chloropyridinium salt, proton sponge, and DMAP to form amides (2). These amides are stable to acids and bases but deprotection is possible with oxidative hydrolysis with ceric ammonium nitrate (CAN). If the oxidation is carried out in the presence of an amine, an amide is obtained in 70-95% yield. For this purpose, the combination of copper(II) oxide and ceric pyridinium chloride is far superior to CAN.4 No racemization was observed in the benzoylation of an a-amino ester. 

Oxidation of 3,4-dihydropyrimidin-2(l //)-oncs (DHPMs) with ceric ammonium nitrate (CAN) in acetic acid resulted in ethyl 2,4-dioxo-6-phenyltetrahydropyrimidin-5-carboxylates as the major product. However, DHPMs undergo a regioselective oxidation with CAN in the presence of sodium hydrogencarbonate in neutral aqueous acetone solution to yield ethyl 6-meihyl-4-aryl(alkyl)pyrimidin-2(l //)-one-5-carboxylates. A mechanism involving a nitrolic acid intermediate has been suggested.72... 

PVA (Merck) with molecular weight of 72,000 and degree of saponification of 98.5-99.2%, was used as supplied, AN (Merck) was purified by reduced pressure distillation. Ceric ammonium nitrate (CAN) (Merck) was used after vacuum drying. Acetic acid (Merck), dimethylformamide (DMF) and dimethylsulfoxide (DMSO) (Merck) were used without further purification. Other reagents used in the study were also all Merck products. 

The bicyclic iron complex 362 on oxidative decomplexation with ceric ammonium nitrate (CAN) affords the refused cyclopenteno-/3-lactam (Equation 43) <1997HCA121>. 

A ceric ammonium nitrate (CAN) mediated stereoselective cyclization of epoxypropyl cinnamyl ethers 352 provides a facile route to 3,4,5-trisubstituted tetrahydropyran derivatives 353 (Equation 149) <2004TL2413>. 

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