4-Methoxybenzyl group

M CF3SO3H, PhSCH3 or Tl(OCOCF3)3. The 5-adamantyl group is less prone to sulfoxide formation than is the 5-4-methoxybenzyl group. It is also more stable to CF3COOH. 

HF, anisole, 0°, 30 min or TfOH, TFA, anisole, 30 min. This group is stable to refluxing TFA, whereas the more frequently used 4-methoxybenzyl group is not. ... 

When the Ac group is removed (20% piperidine/DMF or 5% hydrazine/DMF), it becomes the Hmb group that is used to improve solubility and prevent aspar-tamide formation and is readily cleaved with TFA. The related 2-Fmoc-4-methoxybenzyl group has also been prepared and used in peptide synthesis. ... 

For the solid-phase experiments [115], the commercially available Wang and HMPB-AM resins were chosen due their stability under the applied reaction conditions and an easy cleavage with TFA/DCM mixtures. Moreover, a novel, tailor-made and readily available linker, derived from inexpensive syringaldehyde was designed and proven to be superior to both standard Wang and HMPB-AM resins. For an initial study, as a proof of concept , the Wang linker was mimicked with a 4-methoxybenzyl group at N-1 position of a pyrazinone, and the sequence was evaluated in solution (Scheme 41). 

The 4-methoxybenzyl group is removed with 1 M TMSBr or 1M TMSOTf in TFA containing thioanisole and m-cresol as scavengers, that is, it is performed under identical conditions to those reported for the related cysteine derivative. 7 The Mob group is removed more efficiently by the DMSO/TFA method, which leads to formation of the diselenide as discussed in Section 6.2.3.I.2. 

The 4-methoxybenzyl group of 2-(4-methoxybenzyl)-l,2/3-triazole 1-oxides 445 is labile under strong acidic conditions and migrates to the 3-position as shown in Scheme 127. 

With malonic esters and amides substituted at the central carbon atom, triazole formation is accompanied by decarboxylation and 4-alkyl- or 4-aryl-5-hydroxytriazoles are isolated (69ACS(B)i09i). The 4-methoxybenzyl group has recently been found to be a versatile W-protecting group for the synthesis of AT-substituted 1,2,3-triazoles (82jcs(pi)627). 

In 2004, Kim and coworker developed their own cinchona PTCs containing a specific bulky aryl moiety, 3,5-di-tert-butyl-4-methoxybenzyl group, such as 75, and applied them to the asymmetric a-alkylation of the cyclic [i-kctocstcrs, for example, 2-(ethoxycarbonyl)-l-indanone73 (n — 0) or 2-(cthoxycarbonyl)-1 -tctralonc 73 (n— 1) as shown in Scheme 6.22 [47]. The enantioselectivities showed a considerable variation (44—99% ee) depending on the nature of electrophile. 

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