Stereochemistry of the reactions of lithium di-tert-butylbiphenyl with alkyl halides

Homoaromaticity in Carbene Intermediates

“…Homoaromaticity in carbocations is well established, especially in the 7-norbornenyl ( 1 ) and 8-endotricyclo[3.2.1.0 2,4 ]octyl systems ( 2 ) . The related radicals have not provided convincing evidence to support homoaromaticity …”

“…Stabilization Energies of Carbenabicyclohexane 3S, 7-Carbenanorbornene (4S), endo-8-Carbenatricyclo[3.2.1.02,4 ]octane (5S), and 7-Norbornenyl Cation (1) a The stabilization energy SE ) Ealkene(f) + Ecarbene(f) -Ecarbene(i) -Ealkane(i) in kcal/mol. For the cation, the energies for the cationic intermediates replace the analogous carbene species.…”

A Study into the Possible Homoaromatic Nature of Some Related Carbene and Cationic Intermediates with the Potential for Transannular Interaction

“…In contrast to the cationic intermediates, triplet carbene intermediates 8T , 9T , 10T , and 11T , Table , do not display the idiosyncrasies associated with cyclic electron delocalization, which is in harmony with the lack of homoaromaticity in related radical systems . The fused cyclopropane bond in these intermediates is increased by only 0.010−0.018 Å compared to that of their hydrocarbon parents.…”

Chemical Synthesis of (RP)- and (SP)-[16O,17O,18O]Phosphoenol Pyruvate

“…Next, the 1-phenyl-substituted C 2 moiety had to be coupled with acetone, which was the critical step of the sequence. For this to be achieved, chlorohydrin ( S )- 19 was transformed first with n -BuLi at −78 °C into the corresponding lithium alkoxide, whose chlorine atom was exchanged for lithium by means of lithium sand in combination with di- tert -butyl-biphenyl (DTBB). , The respective β-oxidoalkyl lithium formed as intermediate was finally added to acetone to give 1,3-diol ( R )- 7 in 57% yield. This coupling step delivered an acceptable yield, which varied significantly.…”