2.4- Dimethoxybenzyl group

Amide nitrogens can be protected by 4-methoxy or 2,4-dimethoxyphenyl groups. The protecting group can be removed by oxidation with ceric ammonium nitrate.243 2,4-Dimethoxybenzyl groups can be removed using anhydrous trifluoroacetic acid.244... 

Dimethoxybenzyl groups can be removed using anhydrous trifluoroacetic acid.80... 

Protection of glutamine and aspan ine. The 2,4-dimethoxybenzyl group (Dmb) has been recommended for protection of the amide groups of asparagine and glutamine residues in peptide synthesis. The derivatives are nicely crystalline, and the Dmb group can be removed by trifluoroacetic acid or anhydrous hydrogen fluoride. 

Dimethoxybenzyl groups can be removed with the use of anhydrous tri-fluoroacetic acid. ... 

At Smith Kline French a general approach to cephalosporin and penicillin nuclear analogs was developed that utilizes a monocyclic /3-lactam (59) with the correct cis stereochemistry as a key intermediate. This is prepared by reaction of the mixed anhydride of azidoacetic acid and trifluoroacetic acid with imine (58) followed by oxidative removal of the dimethoxybenzyl group. This product could be further elaborated to intermediate (60) which, on reaction with a -bromoketones, provides isocephalosporins (61). These nuclear analogs displayed antibacterial properties similar to cephalosporins (b-79MI51000). 

The related 3,4-dimethoxybenzyl group has been cleaved from an amide with Na/NH3, 82% yield. ... 

The dimethoxybenzyl group was used for backbone protection of the pseudopeptides of the form Xaai/r(CH2N)Gly (Xaa = amino acid). It is introduced by reductive alkylation with the aldehyde and NaCNBH3. Acidolysis with TFMSA in TFA/thioanisole is used to remove it from the amine, but the efficiency is dependent upon the peptide sequence. ... 

DDQ, CHCI3, H207 The 3,4-dimethoxybenzyl group could be cleaved from a sulfonamide with DDQ (8-50% yield). ... 

The assignments of the 13C chemical shifts of laudanosine were first made by Wenkert et al. (6) and confirmed later (15). It is now apparent that compounds 2 and 3 (14) and 3,4-dimethoxyphenethylamine (6, 15) serve as satisfactory models of the isoquinoline and benzyl moieties, respectively. The substitution of a 3,4-dimethoxybenzyl group at C-l of 3, as in laudanosine (28), caused changes to occur in the chemical shifts of the aliphatic carbon atoms of the tetrahydroisoquinoline moiety analogous to those of the compounds with substituents at C-l listed in Table II (C-l, +7.9 C-3, —6.2 C-4, —3.5 NCH3, —3.6). The chemical shift changes between 27 and 28... 

Tetramethoxy-5,6,ll,12-tetrahydrodibenzo[ ,i ]cycloocten-5-one 302 was reacted with hydroxylamine-O-sulfonic acid and underwent a one-pot Beckmann (formic acid, reflux) or Schmidt (DMF, reflux) rearrangement to afford the 6-oxodibenzo[, /]-azonine 304 (Equation 42). Regioselectivity of the process was assigned based on H NMR data and on model reactions to prove preferential migration of the 3,4-dimethoxyphenyl over the 3,4-dimethoxybenzyl group <1996T8063>. 

There have been several reports of using the a,a-dimethyl-3,5-dimethoxybenzyloxycarbonyl [2-(3,5-dimethoxyphenyl)prop-2-yloxycarbonyl, Ddz] group 1 for N-protection of peptides (Scheme l).ti i7] group was evolved from the parent 3,5-dimethoxybenzyl group... 

SC3221, 1995EUP640606). A procedure proposed for the synthesis of 4-al-kylthienopyrimidinediones 178 involves protection of the nitrogen atom at position 2 with the dimethoxybenzyl group (1992SC3221). 

The dimethoxybenzyl group is cleaved from a hydroxamic acid with TFA, CH2CI2, rt, 2h.2... 

Fig. 6.15 Specific inhibition by trimethoprim and some structurally related compounds of the reaction of IgE antibodies from a trimethoprim-allergic patient with the drug. The IgE antibodies showed specificity for the 3,4-dimethoxybenzyl group of trimethoprim. Key to symbols open circle) trimethoprim (filled circle) 6-hydroxytrimethoprim (open square) 6-chlorotrimethoprim (filled square) diaveridine (filled triangle) 3,4-dimethoxyphenylethylamine (vertical open diamond) 3-(3, 4, 5 -trimethoxyphenyl)-propionic acid (filled diamond) 3,4-dimethoxybenzoic acid (inverted triangle) 4-methoxyphenylethylamine (horizontal open diamond) 3,4,5-trimethoxycinnamic acid. See also Table 6.3 and Fig. 6.16 (reproduced with permission from Smal MA et al. Allergy 1988 43 184)...

---