FIGR ID=jo0625249n00001> journals/joceah/72/i09/figures/jo0625249n00001.gif" ALIGN="left" HSPACE=5> |
The reaction mechanism o
f the Co(CO)
4--catalyzed carbonylative rin
g expansion o
f N-benzoyl-2-methylaziridine to a
fford
N-benzoyl-4-methyl-2-azetidinone and
N-benzoyl-3-methyl-2-azetidinone wasinvesti
gated by usin
g the B3LYP density
functional theory methodolo
gy in con
junction with the conductorpolarizable continuum model/united atom Kohm-Sham method to take into account solvent e
ffects.Computations predict that the most
favorable reaction mechanism di
ffers
from the experimental proposalsexcept
for the nucleophilic rin
g-openin
g step, which is the rate-determinin
g one. The re
gioselectivityand stereospeci
ficity experimentally observed is explained in terms o
f the located reaction mechanism.The substitution o
f the methyl
group at the carbon
ges/
gi
fchars/alpha.
gi
f" BORDER=0> o
f aziridine by the phenyl one
gives rise to theobtainin
g o
f an only product that corresponds to the CO insertion into the C(substituted)-N bond inaccordance with experimental
findin
gs. When the ethyl
group replaces the methyl one the CO insertionoccurs into the two C-N bonds, but the re
gioselectivity o
f the process is hi
gher than that o
f the methylsubstituent.
