Regioselectivity, methylation

For this reason the regioselective methylation of various 4-substituted 1-acetyl-imidazoles was studied.1[2] While reaction with l-acetyl-4-phenylimidazole furnished the isomers l-methyl-5-phenylimidazole and l-methyl-4-phenylimidazole in a ratio of 93 7, reaction with l-acetyl-4-methylimidazole produced an isomer ratio of 86 14. 

Models of the agelasimines A and B, namely 7-benzyl-A (3),AT(6)-dimethyladenine and 7-benzyl-1,2-dihydro-1,3-dimethyladenine, respectively, have been synthesized from 3-methyladenine, the key steps involved being regioselective methylation of 7-benzyl-3-methyladenine and 7-benzyl-1,2-dihydro-3-methyladenine <93H(35) 143 ). 

The example below leads to the regioselective methylation of methylcyclohexanone. Only 2% of the minor regioisomer is formed. 

No.26, 1998,p.6899-904 CELLULOSIC BLENDS WITH POLY(ACRYLONITRILE) CHARACTERIZATION OF HYDROGEN BONDS USING REGIOSELECTIVELY METHYLATED CELLULOSE DERIVATIVES Shin J-H Kondo T... 

Shin J.-H., Kondo X, Cellulosic blends with poly(acrylonitiile) Characterization of hydrogen bonds using regioselectively methylated cellulose derivatives. Polymer, 39, 1998, 6899-6904. 

The diversity of C—H functionalization methods currently available allows for rapid analog preparation of natural products. Baran s total synthesis (+)-hongoquer-cin A leveraged a ligand-accelerated regioselective methylation of functionalized... 

First, 11 was converted into the ketone 10 through deprotection of the TBS group with TBAF followed by PCC oxidation. At this stage, regioselective methylation of the enolate of 10 was highly desirable, though the selectivity of the enolate formation from 10 might well be toward the less substituted... 

The regioselective methylation of the meta-hydroxyl group of caffeic acid (47a) and 5-hydroxyfemlic acid (47b) was accomplished using an extract of poplar and 5-adenosyl... 

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