Synthesis, molecular structure and fluxional behavior of (R)-7-p-tolyldinaphtho[2,1-b;1 ',2 '-d]stibole: the first isolated example of optically active group 15 dinaphthoheteroles
S. Yasuike et al., Synthesis, molecular structure and fluxional behavior of (R)-7-p-tolyldinaphtho[2,1-b;1 ',2 '-d]stibole: the first isolated example of optically active group 15 dinaphthoheteroles, TETRAHEDR L, 42(3), 2001, pp. 441-444
The condensation of dibromo-p-tolylstibane with 2,2'-dilithio-1,1'-binaphth
yl 3, generated in situ from optically active a,2'-dibromo-1,1'-binaphthyl
(8)-(+)-2 by treatment with tert-butyllithium, afforded optically active (R
)-(-)-7-p-tolyldinaphtho[2,1-b;1',2'-d]stibole 1c, which is fluxional in th
e NMR time scale at elevated temperatures. The energy barrier (DeltaG(doubl
e dagger)) resulting from the flipping of the two naphthalene rings was est
imated to be 85 +/- 1 kJ mol(-1) and its half life (t(1/2)) for racemizatio
n was determined to be 5.2 h in benzene at 20 degreesC. (C) 2001 Elsevier S
cience Ltd. All rights reserved.