Dithiasuccinoyl group

Another cyclic imide that has been used as a protective group for primary amines is the dithiasuccinoyl group (Dts) [230,303,304]. This group is stable towards acids (e.g. during deprotection of Boc-protected amines), but can be cleaved with thiols under basic conditions (2-mercaptoethanol (0.2 mol/L), NEt3 (0.5 mol/L), DCM, 25 °C, 5 min [303]). 

However, in attempted prepeirations of 1,2-trans-linked O-glycosides of N-acetyl-D-glucosamine (8 and 9, Figure 1), the presence of the Af-acetylamino group at C-2 results in the predominant formation of a 1,2-oxazoline, a problem which can be avoided if the amino group is protected with either a trichloroethoxycarbonyl, an ailyloxycarbonyl, or a dithiasuccinoyl group (Figure 3b). 

In the case of GlcNAc, it is desirable to replace the iV-acetyl with an electron-withdrawing group like A-allyloxycarbonyl (Aloe), A-trichloroethoxycarbonyl (Troc), or A-dithiasuccinoyl (Dts) in order to decrease side product (oxazoline) formation. 

While the Al -phthaloyl (Phth)P 9 and Al -dithiasuccinoyl (Dts)t derivatives of amino acids are used as reversible protecting groups, the aliphatic N-maleoyl groupt is mainly exploited as a reactive handle for postsynthetic modifications of peptides with thiol-functionalized labels and probes, e.g. carbohydrates, lipids, and chromophores. These N -diacyl derivatives are highly stable to even strong acids, but are cleaved under basic conditions. 

Replacement of the A -acetyl group of GlcNAc with an electron-withdrawing A-aUyloxy-carbonyl (Aloe) [103], A -trichloroethoxycarbonyl (Troc) [87,104-106] or A-dithiasuccinoyl (Dts)... 

Barany G, Merrifield RB (1977) New amino protecting group removable by reduction -chemistry of dithiasuccinoyl (dts) function. J Am Chem Soc 99 7363-7365... 

The dithiasuccinoyl (Dts, 13) [76] is remarkably stable to acid, including 6 N HCl at 110°C, and is selectively removed by base-catalyzed reduction such as with 0.2 M mercaptoethanol in DCM. However, the cumbersome preparation of Dts-amino acids and the unavailability of a complete range of adequately side-chain protected derivatives have limited its use in SPS. The TFA acid-labile 2-nitropyridinyl (Nps, 7) group is also cleaved by thio-lysis [13]. 

E. Meinjohanns, M. Meldal, H. Paulsen, and K. Bock, Dithiasuccinoyl (Dts) amino-protecting group used in syntheses of 1,2-trans-ammo sugar glycosides, J. Chem. Soc., Perkin Trans., 1 (1995) 405-415. 

In early studies into the use of the dithiasuccinoyl (Dts) primary amine protecting group, the desired (V-alkylated derivatives (6) were prepared from the reaction between O-ethyl-AAalkyl (or aryl) thiocarbamates (9) and cblorocarbonylsulfenyl chloride (5) (eq9). ... 

The results of a detailed study of the removal of N -dithiasuccinoyl (Dts) protecting groups by thiols have been reported in full. ... 

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