Dimethoxybenzoin group

The dimethoxybenzoin group has an advantage over the c-nitrobenzyl group because it produces a nonreactive benzofuran upon photolysis, whereas the... 

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

Fig. i Matrix isolation method of surface immobilization of probe oligonucleotide/poly-electrolyte mixed film for enhanced selectivity. Phase 1 Photolabile dimethoxybenzoin (DMB) protecting groups are selectively exposed to electromagnetic radiation of appropriate wavelength to provide reactive sites in which polyelectrolyte spacers can be immobilized. Phase 2 The remaining DMB-protected sites are photo-deprotected to expose sites for probe oligonucleotide immobilization onto the solid surface... 

Pirrung, M.C. and Shuey, S.W. (1994) Photoremovable protecting groups for phosphorylation of chiral alcohols. Asymmetric synthesis of phosphotriesters of (—)-3, 5 -dimethoxybenzoin. Journal of Organic Chemistry, 59, 3890-3897. 

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). ... 

In 1995, Pirrung and Bradley " reported the use of dimethoxybenzoin (DMB) carbonate to protect various alcohols, including the 5 -hydroxyl group of nucleosides. The DMB carbonate was synthesized in three steps, starting with methylation of carbonyldiimidazole with methyl triflate followed by addition of 2-(3,5-dimethoxyphenyl)-2-hydroxy-l-phenylethanone to form a relatively stable activated acylating agent. Treatment with an alcohol under basic conditions in nitromethane furnished the protected alcohol 72 in yields that ranged from 42 to 95%. 

Pirrung and Bradley also applied DMB (3, 5 -dimethoxybenzoin) to protect the phenolic group, demonstrating that 4-methoxyphenol was released upon irradiation at 350 nm in 90% yield (Eq. (69.43)). 

Pirrung, M. C. and Bradley, J.-C., Dimethoxybenzoin carbonates photochemically removable alcohol protecting groups suitable for phosphoramidite-based DNA synthesis, /. Org. Chem., 60, 1116-1117, 1995. 

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