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On the Configurational Stability of Chiral, Nonracemic Fluoro‐ and Iodo‐[D 1 ]Methyllithiums
Author(s) -
Kail Dagmar C.,
Malova Krizkova Petra,
Wieczorek Anna,
Hammerschmidt Friedrich
Publication year - 2014
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.201304766
Subject(s) - transmetalation , methyllithium , carbene , acetophenone , chemistry , benzaldehyde , medicinal chemistry , organic chemistry , stereochemistry , catalysis
Enantiomerically pure fluoro‐[D 1 ]methyllithium and iodo‐[D 1 ]methyllithiums of up to 92 % ee were generated by transmetalation of the corresponding stannanes with MeLi in THF at various temperatures. The intermediate halo‐[D 1 ]methyllithiums were trapped with benzaldehyde or acetophenone already present in excess in the reaction mixture to either give halohydrins or to disintegrate to carbene. The fluoro‐[D 1 ]methyllithiums were found to be microscopically configurationally stable within the tested range of −95 to 0 °C, but chemically only stable at temperatures below −95 °C due to a rapidly increasing portion disintegrating to carbene. The iodo‐[D 1 ]methyllithiums were configurationally labile relative to the rate of addition to PhCHO at all temperatures tested (−95 to −30 °C). Disintegration to carbene interfered as well.