6- Benzyloxy-2-nitro-1 -

Benzyloxy-6-bromo-4-nitro-JV-(2-propeny])aniline (5.82 g, 16 mmol), tetra-ii-butylammonium bromide (5.16 g, 16 mmol) and titjN (4.05 g, 40 mmol) were dissolved in DMF (15 ml). Palladium acetate (72 mg, 2 mol%) was added and the reaction mixture was stirred for 24 h. The reaction mixture was diluted with EtOAc, filtered through Cclite, washed with water, 5"/o HCl and brine, dried and evaporated in vacuo. The residue was dissolved in CHjClj and filtered through silica to remove colloidal palladium. Evaporation of the eluate gave the product (4.32 g) in 96% yield. 

Pyrimidine, 5-benzyl-4,6-dimethyl-2-phenyl-synthesis, 3, 118 Pyrimidine, 2-benzyl-5-nitro-synthesis, 3, 130 Pyrimidine, benzyloxy-pyrimidinone synthesis from, 3, 133 Pyrimidine, 4,5-bis(alkylamino)-synthesis, 3, 121 Pyrimidine, 2-bromo-aminolysis, 3, 100 H NMR, 3, 62 reactions... 

Electrochemically generated nickel is very selective for the reduction of ai compounds into anilines, in which alkenyl, alkyhyl, halo, cytino, formyl, ind benzyloxy groups are not affected. Sodium snlfide has been used for the selective reduction of at group in the presence of aliphatic nitro groups (Tq. 6.44. ... 

A reagent of nickel boride/hydrazine hydrate reduces both aromatic and aliphatic nitro compounds. For example, it has been used for synthesis of 4-(benzyloxy)indole and -alky ltryp-... 

Asymmetric reduction of 2-bromo-(3-nitro-4-benzyloxy) acetophenone. . 157... 

ASYMMETRIC REDUCTION OF 2-BROMO-(3-NITRO-4-BENZYLOXY)ACETOPHENONE[161... 

Cleavage of a benzyloxy bond was also accomplished by treatment with sodium in liquid ammonia [640] or by refluxing with sodium and butyl alcohol [641]. On the other hand, aluminum amalgams reduced a nitro group but did not cleave benzyl ether bond in dibenzylether of 2-nitrohydroquinone [642]. 

The reaction has been carried out on large- and small-scale batches (Note 10). This modification,8 as exemplified by 3,4,5-trimethoxybenzaldehyde, has been applied by the submitters to the preparation of other aldehydes9 such as 3,4-dimethyl-benzaldehyde10 (90% yield), 3-benzyloxy-4,5-dimethoxybenz-aldehyde11 (88% yield, with retention of the benzyl group), and 3-methoxy-4-nitrobenzaldehyde12 (62% yield, with retention of the nitro group). 

The radiosynthesis starts with the nucleophilic F-fluorination of 2-benzyloxy-4-formyl-A/,A/,A/-trimethylanilinium trifluoromethanesulfonate or 5-benzyloxy-2-nitrobenzaldehyde. Subsequent condensation with nitroethane yielded the corresponding 2-nitro-1-propanol derivatives. Reduction of the nitro moiety and deprotection provided the four stereoisomers of " F-labeled 2-amino-1-(4-fluoro-3-hydroxyphenyl)-1-propanol and 2-amino-1-(2-fluoro-5-hydroxyphe-nyl)-1-propanol, respectively. 4-p F]FMR was isolated from the 2-amino-1-(4-fluoro-3-hydroxyphenyl)-1-propanol stereoisomer mixture via semipreparative HPLC and additional chiral HPLC for enantiomeric resolution. In a similar manner enantiomeric pure 6-p F]FMR was obtained. From a synthetic point of view, 4-p F]FMR appeared to be the more promising candidate for PET investigations due to higher radiochemical yields. The main advantage of the nucleophilic approach over the electrophilic methods is the obtained high specific radioactivity (56-106 GBq/pmol) that is desired for safe use in humans with tracer doses far beyond the pharmacological level [173]. 

Benzyloxy-phenyl)-1-nitro-ethen mit Lithium-N,N-dimethyl-acetamid 3-(2-Benzyl-oxy-phenyl)-4-nitro-butansaure-dimethylamid (99%) ... 

HsCg CH3 w / H NO2 H5C6-CH2-ONa l-Benzyloxy-2-nitro-1-phenyl-propan 70 67/33 1... 

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