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Temperature and Solvent Effect on the Nucleophilic Addition of n ‐Butyllithium to the N ‐(Trimethylsilyl)imine of (2 S )‐Lactal
Author(s) -
Cainelli Gianfranco,
Giacomini Daria,
Walzl Martin
Publication year - 1995
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.199521501
Subject(s) - solvent , chemistry , imine , butyllithium , nucleophile , nucleophilic addition , trimethylsilyl , medicinal chemistry , organic chemistry , catalysis
Are the Felkin–Ahn and Cram chelate models reliable? These models predict asymmetric induction without consideration of solvent and temperature. However, the addition of n ‐butyllithium to the N ‐(trimethylsily)imine of (2 S )‐lactal leads to syn/anti ratios between 98:2 and 28:72 when performed in different solvents and at different temperatures. The reaction appears to be the first example of nucleophilic addition that follows the isoinversion principle (isoinversion temperature T i = −21 °C). This indicates a stepwise process with at least two diastereoselective steps that are affected differently by temperature and solvent.