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Preparation of Enantiopure Chiral Amino‐[D 1 ]methyllithium Compounds and Determination of Their Micro‐ and Macroscopic Configurational Stabilities
Author(s) -
Kapeller Dagmar C.,
Hammerschmidt Friedrich
Publication year - 2009
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200802668
Subject(s) - enantiopure drug , chemistry , methyllithium , benzaldehyde , crystallography , stereochemistry , computational chemistry , organic chemistry , enantioselective synthesis , catalysis
The smaller the better : Enantiopure aminomethyllithiums, such as depicted, the smallest of their kind, have been prepared and tested for their micro‐ and macroscopic configurational stabilities, which are delicately influenced by R 1 and R 2 . The species with R 1 =R 2 =Bn is macroscopically configurationally stable below −95 °C.Chiral amino‐[D 1 ]methyllithiums have been tested with regard to their microscopic and macroscopic configurational stabilities. The N ‐Boc‐ N ‐diethoxyphosphinyl‐substituted analogue immediately rearranged, showing complete retention of configuration at up to 0 °C. The N ‐Boc‐ N ‐PMB‐protected analogue enantiomerized at −78 °C, but displayed an ee value of 65 % at −95 °C under macroscopic conditions when quenched with benzaldehyde seconds after its generation. Isocyanomethyllithium proved to be configurationally labile at this temperature and racemized completely, even on the microscopic timescale. Only the non‐stabilized N , N ‐dibenzylaminomethyllithium was found to be virtually macroscopically configurationally stable below −95 °C.