Debenzylation benzyl ether

N-Debenzylation. Benzyl ethers are unaffected when A-benzylamines undergo C—N bond scission with the title reagent. 

Debenzylation. Benzyl ethers, cleaved by catalysis of Sc(CTf i, Friedel-Crafts acylation. - Scan tipurpose catalyst. Besides prontotu Diels-Alder reaction and Meerweii -... 

Debenzylation. Benzyl ethers, Ai-benzylamides, and benzyl ester(s) are efficiently... 

Debenzylation. Benzyl ether and benzylidene derivatives of carbohydrates are cleaved with NaBr0j-Na2S204 in a biphasic reaction system. Esters are stable under such conditions. 

Debenzylation. Benzyl ethers of complex oligosaccharides are selectively cleaved on exposure to FeClj in CH Clj at 0° without affecting acetates, benzoates, phthalimides, acyl amides, and sensitive glycosidic linkages. 

Debenzylation of benzylamines and benzyl ethers is carried out with ammonium formate[l 13,l 14]. Hydrosilanes are also used for debenzylation[l I5. ... 

Figure 3 Debenzylation of a pharmaceutical intermediate containing benzyl ether and aromatic chlorine.

Other examples of debenzylation of benzyl ethers on the frequently used Pd/C catalysts are summarized in Table 4.2. 

In some cases the hydrogenation of the double bond in an unsaturated benzyl ether is necessary without debenzylation. To hydrogenate the carbon-carbon double bond 5% Pd/C in AcOEt was used for 1.5 hours (Scheme 4.40).136 The benzyl ether-protecting group was removed over Pd(OH)2 in AcOEt for 1 hour. 

Benzyl esters of carboxylic acids are frequently used in organic synthesis for the protection of carboxyl groups. The C-O bond in benzyl esters can be cleaved more easily than the corresponding benzyl ether bond. The hydrogenolysis of an ester leads to carboxylic acid and toluene. Examples of debenzylation of benzyl esters of carboxylic acids on Pd/C catalysts are summarized in Table 4.4. 

Hydroxythiadiazole and neat trimethyl orthoacetate showed a 20 80 ratio of N- versus O-alkylation products by H NMR <2002EJ01763>. The acidic hydroxyl group of thiadiazole 130 can be selectively protected as the benzyl ether 113 (Equation 22) <2004TL5441>. Nonhydrogenative debenzylation of the bisbenzyl thiadiazole 116 was achieved with boron tribromide to afford the bis-l,2,5-thiadiazole 131 (Equation 23) <2004TL5441>. 

With the nitrogen atom well protected as the cyclic carbamate 105, all attempts to open the 1,6-anhydro ring under acidic conditions failed owing to the lability of the two allylic benzyl ethers present in the molecule. However, it was possible to debenzylate 105 with lithium in ammonia to form the new cyclic carbamate 108 and acetylation then gave 109. 

Most of the early syntheses of psilocin and psilocybin employ the O-benzyl ether as a protecting group. This provides more stability to the chemical intermediates, but also requires the additional step of reductive debenzylation. The flow chart of this process is conversion of 4-hydroxyindole to 4-benzyloxyindole via the sodium salt, with benzyl chloride the conversion of this with oxalyl chloride to 4-benzyloxyindole-3-glyoxylchloride the conversion of this to 4-benzyloxy-3-(N,N-dimethyl-glyoxamide with anhydrous dimethylamine the conversion of this to... 

Cyclization of the bis-epoxides 123 (mixtures of diastereomers) with benzylamine afforded the azepanes 124 in a preferential 1-endo-tet methodology (Equation 17) <1995JOC5958> however, with the corresponding 3,4-benzyl ethers of the bis-epoxides rather than the // / -acetonide protecting group, no cyclization to six-membered ting species was observed. The azepanes 124 were then converted in two steps to the amino sugar hydrochloride salts 126 via the N-debenzylated intermediates 125 (Scheme 16). 

Hydroxy-8,9-methylenedioxyphenanthridine, [10]. The method developed by Kessar et al. [11] for phenanthridines and related compounds was applied to the synthesis [10] of 3-hydroxy-8,9-methylenedioxyphenanthridine (22) (Scheme 5). Thus, the benzylidene aniline 23, prepared from 6-chloropiperonal and 3-benzyloxyaniline, was reduced to the secondary amine 24. Treatment of 24 with excess lithium diisopropylamide furnished, on work-up, the benzyl ethers 25 (22%) and 26 (6%) respectively. Catalytic debenzylation of the former generated 22. 

Regioselective debenzylation can be achieved by treatment with Lewis acids such as ferric chloride and S11CI4 or under acetolysis conditions with acetic anhydride and sulfuric acid, and several examples are depicted in Scheme 2.3.9 Acetolysis results in cleavage of the most acid-sensitive benzyl group. In general, primary benzyl ethers can be selectively acetolysed in the presence of secondary benzyl ethers. The regioselectivity of the reaction can be explained as follows sulfuric acid protonates acetic anhydride followed by the formation of an acetyl ion and acetic acid. The acetyl ion reacts with the sterically most accessible oxygen which is at... 

After debenzylation (Pd-C, cyclohexene) of the hypercores (e.g., 25) by transfer hydrogenation, they were treated with aryl branched, benzyl ether dendrons (Scheme 5.6) that were prepared by similar iterative transformations,1271 i.e., benzylic bromination and phenolic O-alkylation (See Section 5.4.2). Thus, hexaphenol core 27 was reacted with six equivalents of the benzylic bromide building block 28 to give the benzyloxy terminated dendrimer 29. Key features of these dendrimers include cores with flexible alkyl spacers and a three-directional, quaternary carbon branching center. 

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