The barrier to enantiomerization of N-Boc-2-lithiopyrrolidine: the effect of chiral and achiral diamines.
(-)-Sparteine and TMEDA dramatically lower both enthalpy and entropy of activation for the barrier to enantiomerization of N-Boc-2-lithiopyrrolidine in diethyl ether, whereas N,N'-diisopropylbispidine has little effect; the entropy of activation for enantiomerization is zero in the presence of TMEDA and slightly negative in the presence of sparteine; these data suggest a subtle change in mechanism of enantiomerization in the presence of TMEDA and sparteine.
Yousaf
Taher I
TI
Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA.
Williams
Roger L
RL
Coldham
Iain
I
Gawley
Robert E
RE