✍ Scribed by Wilken, Jörg ;Martens, Jürgen
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New, chiral β‐sec‐amino alcohols 3a–d, 4a–e, and 5a–h have been synthesized from the enantiomerically pure amine (all‐R)‐2a. For the diastereo‐ and regioselective α‐hydroxyalkylation of the chiral (all‐R)‐N‐nitroso‐2‐azabicyclo[3.3.0]octane (all‐R)‐2d, Seebach's “one pot” method was chosen. The versatile nucleophilic intermediate reacts regio‐and stereoselectively with a variety of electrophiles to afford 3‐substituted pyrrolidine derivatives, e.g. (erythro)‐(α__R__,β__S__)‐amino alcohol frameworks with four sterically crowded stereogenic centers, and (β__S__)‐configured tricyclic structures with a cycloalkynol building block (see formulae 3a–d, 4a–e, and 5a–h). Alkylation products are obtained in fair yields with a high degree of stereoselectivity (diastereomeric ratios dr up to 93:7). A mechanistic interpretation of the stereochemical course of this reaction is presented. – This is a further example of the synthesis of interesting new chiral ligands from the industrial waste material (all‐R)‐2‐azabicyclo[3.3.0]octane‐3‐carboxylic acid benzyl ester (all‐R)‐1a. The catalytic ability of selected (erythro)‐ and new, related stereoisomeric amino alcohol structures were tested in the enantioselective borane reduction using the prochiral acetophenone as model substrate (enantiomeric excesses ee up to 86%).
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## Abstract New, chiral bicyclic 3‐hydroxypiperidines (4__S__)‐2a–e are synthesized from the β‐amino alcohols (3__R__)‐1a–e. In an one‐step reaction (4__S__)‐2a–e are obtained by a high diastereoselective ring expansion (__dr__ ⩾ 95:5). As well, the amino alcohol (3__S__)‐1a leads to the correspond
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