摘要：

Three methods are described by which diastereomerically enriched nitroaldols and their O -silylated derivatives can be prepared. threo -Nitroaldols prevail up to 10:1 over the erythro -isomers if doubly deprotonated nitroaldols 28 are quenched with acetic acid (THF/HMPT or DMPU, 100°) (see Scheme 5 and Table 2). O -Trimethyl- or O -( t -butyl)dimethylsilylated (TBDMSi) erythro -nitroaldols can be obtained by protonation of the corresponding lithium nitronates ( 35, 39 ) in THF at low temperature (see Schemes 6 and 7 ). The erythro - O -TBDMSi-nitroaldol derivatives are also formed in the fluoride catalyzed addition of TBDMSi-nitronates ( 40–45 ) to aldehydes (see Schemes 8 and 9 ), In the latter reaction no 1,2-asymmetric induction is observed if a -branched silylnitronates or aldehydes are employed (see 48/49 and 50/51 ) – The stereochemical course of the reactions leading to erythro - O -TBDMSi-nitroaldols follows topological rules of broad applicability (see Scheme 10 ); possible mechnisms are discussed. - The configuration of diasteromerically 13 C-NMR. Spectroscopy. – Some examples of the preparation of diastereimerically enriched 1,2-aminolcohols by reduction of the correspondence nitro compounds without loss of configurational purity are described (see Schemes 11 and 12 ).

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