3 ,5 -Dimethoxybenzoin carbamate

This group is stable to 50% TFA/CH2CI2, NaOH, and 20% piperidine/DMF. 11. 3, 5 -Dimethoxybenzoin Carbamate (DMBOCONR2)... 

Dimethoxybenzoin Carbamate (DMBOCONR2). The DMB carbamate can also be introduced through the 4-nitrophenyl carbonate. It has been prepared from an isocyanate and 3, 5 -dimethoxybenzoin. The synthesis of a number of other substituted benzoins as possible protective groups has been described. ... 

Scheme 13 Photocyclization of Dimethoxybenzoin Carbamate Derivatives and Structure of the Inert Cyclic Carbamate...

Importantly, TV-carbamoyl derivatives of primary amines obtained from photolabile benzoins exist in varying proportions as cyclic hydroxyoxazolidinone tautomers. Therefore, the preparation of TV-carbamoyl derivatives of benzoins is applicable only for secondary amines and TV-alkylated amino acids. 244 At basic pH unsymmetrical benzoins, such as 3,5-dimethoxybenzoin, their mixed carbonate and carbamate derivatives, tend to equilibrate to the isomeric forms. Nevertheless, in TFA and aqueous solutions at pH 8 the structural integrity is fully maintained. 244 Preparation of 3,5-dimethoxybenzoin-derived carbamates of secondary amines and amino acids can be mediated by either CDI/methyl triflate in ni-tromethane 246 or 4-nitrophenyl chloroformate/DMAP in dry THF. 244 ... 

Pirrung, M.C. and Huang, F C.-Y.D (1995) Photochemical deprotection of 3, 5 -dimethoxybenzoin (DMB) carbamates derived from secondary amines. Tetrahedron Letters, 36, 5883—5884. 

Dimethoxybenzoin (DMB) carbonates (39) were found to be photochemically removable alcohol protecting groups. DMB carbonates can be installedby the carbamate product (38) of DMB-OH (37) and iV,iV -carbonyldiimidazole activated by methylation (eqs 32 and 33). ... 

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