The impact of the steric and electronic factors in both the para-substituted benzaldimine and 2,2-diarylglycine components on the regioselectivity and enantioselectivity of the palladium-catalyzed decarboxylative allylation of allyl 2,2-diarylglycinate aryl imines was explored. These studies revealed that using 2,2-di(2-methoxyphenyl)glycine as the amino acid linchpin allowed for the exclusive synthesis of the desired homoallylic benzophenone imine regioisomers, independent of the nature of the imine moiety, in typically high yields. The resulting enantiomeric ratios, however, are slightly decreased in comparison to the transformations involving the corresponding allyl 2,2-diphenylglycinate imines, but this is more than balanced out by the increases in yield and regioselectivity. Overall, these studies suggest a general strategy for the highly regioselective functionalization of 2-azaallyl anions.
Two
kinds of aromatic polyesters containing thioether units had
been prepared through the reaction of 4,4′-thiodibenzoyl chloride
(T-DC) (or 4,4′-bis(4-chloroformylphenylthio)benzene (BPBDC))
and 1,1-bis(4-hydroxyphenyl)-1-phenylethane (BHPPE) by the method
of interfacial polycondensation. These polyesters showed good solubility,
and could afford tough films with tensile strengths of 103.6–108.3
MPa. The glass transition temperature (T
g) of these polyesters ranged from 189.8 to 235.6 °C and initial
degradation temperatures (T
d) were 450–454
°C. The activation energies of degradation were in range of 156.6–160.3
KJ/mol. The limiting oxygen indexes (LOIs) of these polyesters ranged
from 37 to 39, and UL-94 V-0 rating could achieve via this approach.
The thermal degradation kinetics and thermal pyrolysis mechanism of
these polyesters was studied by thermogravimetric analysis and Py-GC/MS
analysis, respectively.
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