Levulinyl group

Arabinofuranosyl donor 418 glycosylated acceptor 419, to yield after levulinyl-deprotection and repetitive glycosylation with 419, the linear trisaccharide 420 (O Scheme 67d). Coupling of latent BCB donor 422, with active CB donor 421, led after deprotection of the levulinyl groups to diol 423 (O Scheme 67b). The crucial double 8-arabinofuranosylation of diol 423... 

Protection of alcohols.1 Alcohols can be converted into the 2-phenylsulfonyl-ethylcarbonyl derivatives by reaction with 1 in pyridine at 20° (75-100% yield). The protecting group can be removed by treatment with N(C2H5)3 in pyridine at 20°, conditions that do not affect benzyl, levulinyl, and several base-labile protecting groups. The PSEC group is stable to 110% HOAc at 20°. 

FIGURE 10.1 Some monosaccharide building blocks used in the assembly of (a) HA, (b) CS, and (c) heparin/HS showing the array of protecting groups. All, allyl Bn, benzyl Bz, benzoyl Fmoc, 9-fluorenylmethoxycarbonyl Lev, levulinyl NAP, 2-naphthylmethyl PBB, p-bromobenzyl Phth, phthaloyl PMB, / -methoxybenzyl PMP, p-methoxyphenyl TBDPS, ferf-butyldiphenylsilyl TBS, ferf-butyldimethylsilyl TCA, trichloroacetyl TDS, dimethylthexylsilyl Tol, 4-tolyl. 

UDP-A-MurNAc-depsipentapeptide) derivatives including fluorescent-labeled derivatives. Shin-ichiro Nishimura et al. reported the synthesis of UDP-MurNAc-pentapeptide derivatives possessing a levulinyl (Lev) group on the side chain of the Lys residue [82, 83] for subsequent introduction of fluorescent label or oligosaccharide moieties by oxime formation after their incorporation through cell-wall biosynthesis. The 4-fluorinated UDP-MurNAc-pentapeptide was also synthesized as a stable biosynthesis inhibitor [84],... 

The levulinoyl esters are prepared from the free hydroxyl group by treatment of levulinic acid with DCC [255,256] or l-[3-(dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride (EDAC) [257] in the presence of DMAP (O Scheme 38). Additionally, 3 - and 5 -0-levulinyl protected derivatives of 2 -deoxy nucleosides have been prepared by regioselective enzymatic acylation using a variety of lipases and acetonoxime levulinate as acylating agent [258]. In contrast to other ester substituents, the 0-levulinoyl group is far less prone to migration [259]. 

The authors applied this acceptor-dependent 8-arabinofuranosylation method to the synthesis of octaarabinofuranoside 417. Their retros)mthesis of compound 417 led to three components, a hnear methyl trisaccharide 416, a branched BCB trisaccharide 415, and to CB furanosyl donor 409. Levulinyl protective groups were chosen in fragments 415 and 416 for selective deprotection prior to furanosyl coupling (O Scheme 66). Three arabinose building blocks were used in the assembly. 

Figure 1.8 Aminoo>y end-group functionalized PNIPAM synthesized by copper-catalyzed ATRP reacted with (JV-levulinyl)-modified BSA (PDB 3V03), establishing a novel approach to design well defined protein-polymer conjugates. ...

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