Enantioselektive Verseifung der Diacetate von 2‐Nitro‐1,3‐diolen mit Schweineleber‐Esterase und Herstellung enantiomerenreiner Derivate von 2‐Nitro‐allylalkoholen (chirale Verknüpfungsreagenzien)

Abstract

Enantioselective Saponification of Diacetates of 2‐Nitro‐1,3‐propanediols by Pig‐Liver Esterase and Preparation of Enantiomerically Pure Derivatives of 2‐Nitro‐allylic Alcohols (Chiral Multiple‐Coupling Reagents)The reproducible enantioselective saponification of open‐chain and cyclic diacetates of meso‐2‐nitro‐1,3‐propanediols (see 4b–13b) with pig‐liver esterase (PLE) gives monoacetates (see 4c–l3c) of > 95% enantiomeric excess. The Re enantiotopic acetate group appears to be saponified preferentially, as proved by the X‐ray crystal structure analysis of three camphanoates 4d, 6d, and 7d. Elimination of H₂O or AcOH from the hydroxy acetates thus available gives derivatives of nitro‐allylic alcohols (see 20–24, 27, and 29) which are subjected to diastereoselective Michael additions or S_N2′ substitutions.