Wieczorek A, Hammerschmidt F. On the preparation and determination of configurational stability of chiral thio- and bromo[D1]methyllithiums.
J Org Chem 2012;
77:10021-34. [PMID:
23106613 PMCID:
PMC3557930 DOI:
10.1021/jo301441g]
[Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Thio- and bromo[D1]methyllithiums (ee 99%)
were generated
from the respective stannanes by tin–lithium exchange at temperatures
ranging from 0 to −95 °C. Thio[D1]methyllithiums 6 were found to be microscopically configurationally labile
on the time scale of the thiophosphate-α-mercaptophosphonate
rearrangement even at −95 °C. Thio[D1]methyllithiums 13a and 13b underwent a thia-[2,3]-Wittig rearrangement
down to −95 °C and 13b only down to −50
°C. The former were microscopically configurationally stable
below −95 °C, and the latter racemized completely at −50
°C. Chiral bromo[D1]methyllithiums are chemically
unstable at −78 °C but microscopically configurationally
stable at the time scale of their addition to benzaldehyde and acetophenone.
Collapse