2,4-Dimethoxybenzyl

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). [Pg.295]

The trivial name bisnorisopenicillin has been coined for the 6-acylamino-3-thia-l-a2abicyclo[3.2.0]heptane-2-carboxylic acid (85) structural class. While not extensively investigated, an example of this class has been prepared as shown in Scheme 66 (78JMC413). The following features of this sequence are noteworthy (a) the exclusively cis cycloaddition to form intermediate (86) and (b) the use of the 2,4-dimethoxybenzyl amide blocking group. [Pg.333]

The dimethoxybenzyl ether has also been used for protection of the anomeric hydroxyl in carbohydrates. ... [Pg.55]

The acetal can also be cleaved with DDQ (CH2C12, H2O, 66% yield) to afford the monobenzoate. Treatment of a 3,4-dimethoxybenzyl ether containing a free hydroxyl with DDQ (benzene, 3 A molecular sieves, rt) affords the 3,4-dimethoxy-benzylidene acetal. ... [Pg.134]

Dimethoxybenzyl esters prepared from the acid chloride and the benzyl alcohol are readily cleaved oxidatively by DDQ (CH2CI2, H2O, rt, 18 h, 90-95% yield). A 4-methoxybenzyl ester was found not to be cleaved by DDQ. The authors have also explored the oxidative cleavage (ceric ammonium nitrate, CH3CN, H2O, 0°, 4 h, 65-97% yield) of a variety of 4-hydroxy- and 4-amino-substituted phenolic esters. ... [Pg.259]

The related 3,4-dimethoxybenzyl group has been cleaved from an amide with Na/NH3, 82% yield. ... [Pg.402]

Methyl-1,2-dihydropapaverine (175, R = OMe) rearranges to the 2-methyl-3-(3,4-dimethoxybenzyl)-6,7-dimethoxy-3,4-dihydroisoquinolin-ium salt (176, R = OMe) under very mild conditions (treatment with 2% hydrochloric acid). A similar rearrangement of l-(3,4-methyl-enedioxybenzyl) - 2 - methyl - 6,7 - dimethoxyisoquinoline (175, R, R = —O—CHj—O—) affords 3-(3,4-methylenedioxybenzyl)-2-methyl-6,7-di-methoxy-3,4-dihydroisoquinolinium chloride (176, R, R = O—CHj—O—) (256). The reaction was shown to be an allylic rearrangement with internal return (275,275). [Pg.292]

The related [(3,4-dimethoxybenzyl)oxy]methyl group has been used similarly, except that, as expected, it is more easily cleaved (DDQ, CH2CI2, t-BuOH, phosphate buffer, pH 6.0, 23°, 110 min, 88% yield). ... [Pg.37]

Hg(OCOCF3)2, CF3COOH, anisole. The dimethoxybenzyl thioether is also cleaved with this reagent. ... [Pg.460]

A/-(1 -lsopropyl-4-nitro-2-oxo-3-pyrrolin-3-yl), 577 A/-2,4-Dimethoxybenzyl, 577 A/-2-Azanorbornenyl, 578 A/-2,4-Dinitrophenyl, 578 Quaternary Ammonium Salts, 578 A/-Benzyl, 579... [Pg.498]

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. ... [Pg.577]

DDQ, CHCI3, H207 The 3,4-dimethoxybenzyl group could be cleaved from a sulfonamide with DDQ (8-50% yield). ... [Pg.640]

R = 3,5-dinitrophenyl, 2-nitrobenzyl, 3,5-dimethoxybenzyl, pyrenyl-methyl, desyl, 4-methoxybenzoylmethyl... [Pg.667]

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