Fluoren-9-yl-methoxycarbonyl

Mellor, S. L. Chan, W. C. 4-[2,4-Dimethoxyphenyl(V-fluoren-9-yl-methoxycarbonyl-V-alkylaminooxy)-methyl]phenoxymethyl polystyrene ... 

Another popular protecting group is tert-butyloxycarbonyl (BOC), which is eliminated as isobutene and carbon dioxide at acidic pH or elevated temperatures. In automated solid-state synthesis, however, the Fmoc (fluoren-9-yl-methoxycarbonyl) group has become the standard, because the cleavage of the protecting group can be followed spectrophotometrically (Scheme 9.4.7). 

To a solution of the S-(+)-4-acethoxy-9-[2-(5-ethyl-l,2,3,6-tetrahydro-pyridin-3yl)-l-(lH-indol-2-yl)-l-methoxycarbonyl-ethyl]-3a-ethyl-5-hydroxy-8-methoxy-6-methyl-3a,4,5,5a,6,ll,12,12b-octahydro-lH-6,12a-diaza-indeno[7,l-ca]fluorene-5-carboxylic acid methyl ester in dioxane and glacial acetic acid was added 37% aqueous formaldehyde and the mixture stirred at 35°C for 24 h. The solution was evaporated in vacuo and the residue suspended in chloroform and washed with cold aqueous 5% K2C03 solution. The chloroform layer was dried (MgS04), filtered, and evaporated. The residue was chromatographed eluting with EtOAc/MeOH, 10% NH4OH to give the product navelbine. 

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