Sugars branched-chain amino, preparation

Primary amine formation is equally well promoted in alkaline medium, e.g., aqueous ethanolic NaOH solution, that selectively poisons the catalyst for hydrogenolysis reactions. However, saturated NH3/alcohol solutions best afford almost quantitative yields of primary amines from catalytic reduction of nitriles. Ammonia adds to imine 1 to give a 1,1-diamine, which is hydrogenolyzed to the primary amine. In the presence of NHj, finely divided Ni can be used, platinized finely divided Ni for the hydrogenation of hindered nitriles, and rhodium-on-alumina for sensitive compounds. Mild reduction of 3-indoleacetonitrile to tryptamine [equation (c)] is effected at RT over 5% rhodium-on-alumina in 10% ethanolic NH3 with little side reaction , and branched chain amino sugars are conveniently prepared using this selective hydrogenation [equation (d)] . 

The branched-chain amino-sugar derivative (32) has been prepared from the unsaturated branched-chain sugar (33) by the sequence shown in Scheme 9 these were then used to prepare analogues of the nucleoside moiety of the polyoxins which are referred to in Chapter 19. 

Brimacombe s group have used the addition of mercuric azide to the 3-C-methylene derivative (262) to prepared branched-chain amino-sugars [e.g. (263)] as outlined in Scheme 100. - The conversion of the branched-chain azide... 

A Wittig reaction was used to prepare the methoxymethylene branched-chain amino-sugar (38), which was then modified conventionally to the diacid derivative (39) and hence converted to thienamycin (described in Chapter 23).Another synthesis of thienamycin from the same 3-azido-2,3,6-trideoxy-D-arabino-hexoside precursor used for preparing (38) adopted a double inversion technique to make the 4-C-cyano sugar (40), displacing triflate esters first by acetate and then by cyanide (18Ji overall yield). 

H. H. Baer and Z. S. Hanna, The preparation of amino sugars and branched-chain sugars by palladium-catalysed allylic substitution of alkyl hex-2-enopyranosides, Can. J. Chem. 59 889 (1981). 

During the past nine years the subject of total synthesis of sugars and cyclitols has been vividly developed. The discovery of a large number of unusual sugars in nature—deoxy, amino, branched chain sugars (many of them components of antibiotics)—made their synthesis attractive. On the other hand, improvements in organic reagents and synthetic methods allowed a return to older preparations which could be now better performed. Finally, some synthetic ideas already described in this series, in the first chapter of the volume on the total synthesis of carbohydrates, are further expanded. 

Oxirans - The use of pyranose epoxides in the preparation of sugar amino acids and peptides, aminodeoxy, halodeoxy, branched-chain, cyclopropanated and aziridino sugars has been reviewed. ... 

Anhydromaltose has been converted to the pseudo-disaccharides (25) containing 3-amino-3-deoxy-epz-inositol or 1-amino-l-deoxy-l-L-myo-inositol via the 6-deoxy-6-nitromaltose derivative (26). The branched-chain unsaturated 6-nitro-sugar (27), prepared conventionally from D-glucose, yielded isomeric dithianyl adducts which were similarly cyclized to give the nitro-cyclitols (28) and (29), of interest as potential intermediates for the synthesis of tetrodo-... 

It has been established that the kinetically favoured product formed on the addition of cyanide ion to l,2 5,6-di-0-isopropylidene-a-D-r/6o-hexofuranos-3-ulose has the D-a//o-configuration, whereas the thermodynamically favoured product has the D- / co-configuration. Conversion of the D-a/to-isomer into the lactone derivative (248) was used to establish its stereochemistry. Other branched-chain derivatives, including the amino-sugar (249), were also prepared. 

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