Benzyl group cleavage

Alkyl methacrylates, hydrolysis of polymeric ester functionality, 259 Aluminum-hydrogen bond, nucleophilic substitution, 264 Amines alkylation, 28 benzyl-group cleavage, 25 Aminomethylation chloromethylated polymers, 19 Deltfpine reaction, 19 Anionic polymerization advantages, 85... 

The linker moiety was then removed. We previously reported that p-acylaminobenzyl ethers were selectively cleaved by DDQ oxidation in a rate con arable to the cleavage of an MPM group (10). DDQ oxidation of 25, however, gave complex mixture of undesired debenzylated products formed by over-oxidation of many benzyl groups. Cleavage of the BA tag moiety in 25 was thus carried out in 20% TFA in CHCI3 to give the desired 26 in 15% yield. The... 

FeCl3, AC2O, 55-75% yield.The relative rates of cleavage for the 6-, 3-, and 2-O-benzyl groups of a glucose derivative are 125 24 1. Sulfuric acid has also been used as a catalyst. ... 

Treatment of a tertiary benzylamine also affords the Troc derivative with cleavage of the benzyl group (CI3CCH2OCOCI, CH3CN, 93% yield). ... 

The Teoc derivative can be prepared by cleavage of an N-Bn bond with Teoc-Cl in THE. This is a general method for removal of benzyl groups from nitrogen. Methyl and ethyl groups are also cleaved, but more slowly (24 h vs. 4 h) and in lower yield ... 

Some of the methods used to cleave the benzyl group should also be effective for cleavage of the MPM group. ... 

Pd-C, 4.4% HCOOH, CH3OH, 25°, 10 h, 80-90% yield. The cleavage of benzylamines with H2/Pd-C is often very slow. Note in example 1 above that one of the benzyl groups can be selectively removed from a dibenzyl derivative. 

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 completion of the synthesis of gilvocarcin V (2) only requires a few functional group manipulations. Hydrogenolysis of the four benzyl groups, followed by acetylation of the liberated hydroxyl groups, provides 30 in 68 % overall yield. After cleavage of the MOM ether in 30 with bromotrimethylsilane, application... 

The benzyl group can serve as a hydroxy-protecting group if acidic conditions for ether cleavage cannot be tolerated. The benzyl C—O bond is cleaved by catalytic hydrogenolysis,176 or by electron-transfer reduction using sodium in liquid ammonia or... 

Desulfoxidation was achieved using Ra-Ni in ether. This was followed by selective hydrogenolysis of the benzyl group on W2 Ra-Ni under a hydrogen atmosphere in EtOH.420-422 Desulfoxidation had to be performed in ether use of ethanol as the solvent in desulfoxidation led to cleavage of a C-7-C-8 bond (Scheme 4.123). 

The same general method has been applied using A -benzylpiperidone 32 as the ketonic component (note the cleavage of the benzyl group) <06TL5463>. 

---