Amine functionality, saccharide

In 2008, Tang and co-workers reported the utilization of tertiary amine-functionalized saccharide-thiourea 211 as a bifunctional hydrogen-bonding catalyst for the enantioselective aza-Henry [224] (nitro-Mannich) addition [72] of... 

In 159 and 163-166 the tertiary amine function is coordinated to the boron atom and transmits the electronic change due to the ester formation to the chromophore. In 160-162 the boron atom is directly connected to the chromophore. After the complexation of the saccharide, the change of the charge transfer, e.g., for 159 [249-251], or the fluorescence bands, e.g., for 160-166 [252-255], can be measured and interpreted. The most selective binding of n-glucose has been achieved with host 164 that forms a 1 1 complex with a macrocyclic structure (Scheme 1). 

In carbohydrate chemistry, the most described method for the preparation of saccharidic thionocarbamates involves preliminary introduction of the amine function on a partially or non-protected saccharidic template. The condensation of amino sugars with carbon disulfide or thiophosgene leads to cyclization in 1,3-oxazolidine- or l,3-oxazine-2-thiones. This reaction involves the formation of an intermediate isothiocyanate, which reacts further with a 3- or y-located hydroxyl group. The viability and facility of this process depends on the saccharidic ring size and the inherent strain. Some major rules can be put into light from the cases studied 30... 

An interesting procedure has been proposed for the synthesis of amylose-b-PS block copolymers through the combination of anionic and enzymatic polymerization [131]. PS end-functionalized with primary amine or dimethylsilyl, -SiMe2H groups were prepared by anionic polymerization techniques, as shown in Scheme 56. The PS chains represented by the curved lines in Scheme 56 were further functionalized with maltoheptaose oligomer either through reductive amination (Scheme 57) or hydrosilyla-tion reactions (Scheme 58). In the first case sodium cyanoborohydride was used to couple the saccharide moiety with the PS primary amine group. 

Protocols of peptide chemistry and, to some extent, biooligomer synthesis (e.g., nucleotides, saccharides) are valuable sources of information on this topic with regards to solid-phase synthesis peculiarities. Here we focus on a particular functional group transformation, which takes the role of depro-tecting a masked functionality, namely the nitro-to-amine reduction. This approach provides a versatile tool for planning multistep derivatizations of heterocycles, as exemplified in Fig. 15.45... 

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