Abstract:
This research was directed towards the investigation of
the Smiles rearrangement in hydrazidic systems and the synthesis
of related heterocyclic compounds. The work can be conveniently
divided into two main sections.
Section 1 of the thesis relates to the synthesis and examination
of the O+N migration of phenoxy- derivatives of hydrazidic
halides. In general, hydrazidic halides were found to
react with 2-nitrophenol and 4-nitrophenol to give corresponding
a-nitrophenoxy- compounds. These a-nitrophenoxy- compounds
were found to rearrange in warm base to give the corresponding
N-benzoyl compounds via a proposed five-membered transition
state.
Experiments conducted in styrene revealed no radical contribution
to the rearrangement. Cross-over product analysis indicated
the rearrangement as intramolecular and consistent with
the Smiles rearrangement.
The preparation of N-a-chlorobenzylidene-N'-2-nitrophenyl-
-N'-(2,4-dibromophenyl)hydrazine from N-benzoyl-N'-2-nitrophenyl-
N'-(2,4-dibromophenyl)hydrazine was accomplished using phosphorus
oxychloride. Examination of this hydrazidic chloride
indicated a marked decrease .in reactivity as compared to the
N-a-chlorobenzylidene-N'-phenylhydrazine case.
Section 2 concerns itself with the preparation of heterocyclic
compounds using an analogy of the five-membered transition state present in the Smiles rearrangement of a substituted
benzylidene derivatives A new preparation of 2,4-phenyl1,3,4-
oxadiazol-S-one using N-benzoyl-N'-phenylhydrazine and
ethyl thiochloroformate is reported.
Two new preparations of N-a-thiobenzoyl-N'-(2,4-dibromophenylhydrazine
are reported using sodium hydrosulfide in conjunction
with N-a-bromobenzylidene-N'-(2,4-dibromophenyl)hydrazine
in the first, and phosphorus pentasulfide with N-benzoylN'-(
2,4-dibromophenyl)hydrazine in the second. The latter is
preferred due to the formation of a sulfide co-product in the
former.
Two preparations of 2-phenyl-4-(2,4-dibromophenyl)-1,3,4-
thiadiazol-S-one are reported using N-thiobenzoyl-N'-(2,4-dibromophenyl)
hydrazine and ethyl chloroformate and ethyl thiochloroformate
Two rapid and easy preparations of 2-phenyl-4-(2,4-dibromophenyl)-
1,3,4-triazol-S-one are reported using ethyl chloroformate
and ethyl thiochloroformate. Sodium cyanate in conjunction
with a-aminobenzylidene-N'-(2,4-dibromophenyl)hydrazine
also provided 2-phenyl-4-(2,4-dibromophenyl)-1,3,4-triazol-S-one
Section 2 concludes with an examination of two possible
mechanistic routes to the prepared heterocycles.
