Esters Schiemann reaction

Methyl (5)-2-(Acetylamino)-3-(2-fluoroimidazol-5-yl)propanoate (a-A -Acetyl-2-fluoro-L-histidinc Methyl Ester, 21) Typical Procedure for the Photochemical, One-Pot Balz-Schiemann Reaction ... 

Difunctional compounds, including certain halogenated ethers, aldehydes, ketones, phenols, amines, and nitro compounds, have been prepared by the Sandmeyer reaction. However, fluorophenols and fluoro acids are best obtained from the corresponding ethers and esters, respectively, which have been fluorinated by the Schiemann reaction. ... 

C. Wiese and co-workers have synthesized 5-fluoro-D/L-dopa and the corresponding [ F]5-Fluoro-L-dopa starting from 5-nitrovanillin via malonic ester synthesis, the Balz-Schiemann reaction, and the separation of the racemic mixture [ F]5-fluoro-D/L-dopa utilizing a chiral FIPLC system. The inactive 5-fluoro-D/L-dopa was obtained in an eight-step synthesis with an overall yield of 10%. 

THF is useful in the malonic ester synthesis since it dissolves many sodio derivatives. Use of aqueous THF facilitates diazotization of salts of aminopolyphenyls which are sparingly soluble in water and is recommended also for the Schiemann reaction. It is superior to ether as solvent for coupling of an acetylenic Grignard reagent with a propargylic halide. Cremlyn and Chisholm found THF superior to dioxane or Cellosolve as solvent for the hydrogenation of cholesterol at ordinary temperature and pressure with perchloric acid as catalyst. 

Saligenin, 719 Sandmeyer reaction, 1098 Santonin, 19, 608 (—)-j8-Santonin, 995 Sarcosine methyl ester, 1160 Sarett reagent, 145-146 Schiff bases, 139, 273, 318, 428, 430, 746, 788, 885 reduction, 1230 Schiemann reaction, 394,1140 Scopoletin, 790 ScylUtol, 1209 Sebacamide, 1265 Sebadc acid, 584, 1265 Sebadl, 159... 

Sandmeyer reaction, synthesis, of bromo compound, 36, 39, 45, 48, 52, 75, 217 of chloro compound, 48, 110, 113 of cyano compound, 90, 91, 216 of iodo compound, 182, 183, 184, 185 use of mercuric nitrate in, 52 Saponification of an ester, 113, 152 Schiemann reaction, 165, 167 Schotten-Baumann reaction, 145 Skraup reaction, 28, 85, 193, 204, 235 Sommelet reaction, 281 Sulfenyl chloride, formation from chlorine and disulfide, 214... 

The Balz-Schiemann reaction has been used for the preparation of the 4-iluoro-derivatives of pyridine and 2,5-, 2,6-, and 3,5-lutidine it has also been used to obtain 5-fluoronicotinic acid, required for conversion into the corresponding pyridylmethanol via LiAlH reduction of the ethyl ester. The introduction of F into fluoroaromatic compounds has been achieved via isotopic exchange in diazonium tetrafluoroborates. U.v. irradiation of aqueous solutions of the appropriate diazonium tetrafluoroborates has been used to procure the first ring-fluorinated imidazoks, e.g. photolysis of the diazonium solution obtained by adding sodium nitrite to 2-amino-imidazole in aqueous fluoroboric acid provides 2-fluoroimidazole contaminated with only a small amount of 2-azidoimidazole, the sole product of thermal decomposition of imidazole-2-diazonium tetrafluoroborate. 

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