Abstract:
The work described herein details the synthesis and application of
biphenyls that probe the effects of hydrogen, Cl / Br, and methyl substituents
on the aryl ring of the terminal acetylenic carbon. From this work, we
successfully developed the rapid synthesis of phenyl acetylenes in 3-4 steps
from inexpensive commercially available materials. Using these mild
conditions, a wide host of functionalized acetylenes has been easily achieved,
avoiding complex and or difficult synthetic transformations
With the functionalized acetylenes in had, we demonstrated that the
subtle change from hydrogen to either methyl or halogen imparts diverse
results when subjected to [4+2] or [3+2] cycloadditions. This knowledge has
helped to explain other unexplained observations from previous work within
this project. These biphenyls were then further investigated by performing
various synthetically useful functional group transformations and comparing
the differences the substituents have on the corresponding reaction.
Noteworthy is the total synthesis of siamenol, a carbazole isolated from the
bark of Murriaya siamensis, where the key carbazole forming step is effected
by the substituents about the molecule in the synthesis of siamenol
derivatives.
