Abstract:
Recent studies have shown that the rhodium (II) acetate decomposition chemistry
observed for a-diazoketones tethered to thienyl, furanyl, and benzofuranyl moieties is
dependent not only on the nature of the heteroatom but also on the length of the aliphatic
tether linking the diazoketone moiety with the aromatic fragment. The present thesis
expands on these results and focuses on a-diazoketones tethered to benzothiophenes,
pyrroles and indoles by a methylene linker.
In the case of benzothiophenes, it was shown that the rhodium catalyst
decomposition of I-diazo-4-(3-benzothienyl)-2-butanone (146) and 1-diazo-4-(3benzothienyl)-
2-butanone (152) allow for the isolation of 1,2,3a,3b-tetrahydro-3Hbenzo[
b]cyclopenta[1,3]cyclopropa- [1 ,2-d]thiophen-3-one (147) and 1,2,3a,3btetrahydro-
3H-benzo[b]cyclopenta[1,3]cyclopropa[1,2-d]thiophen-3-one (153). However
treatment of 1-diazo-3-(3-Benzothienyl)-2-Propanone (165) with Rh(II) acetate results in
the formation of 2,3-Dihydro-1H-benzo[b]cyclopenta[d]thiophen-2-one (159), while 1diazo-
3-(2-Benzothienyl)-2-Propanone with the same condition gives 5,5-bis( 1benzothiophen-
2-ylmethyl)-2(5H)-furanone (166) along with the tricycle 159.
The chemistry of the pyrrolyl and the indolyl moieties linked to terminal adiazoketone
systems was also investigated. The decomposition of I-diazo-(2-pyrrolyl)-2propanone
(173) results in the formation of two products; the N-H insertion product IHpyrrolizin-
2(3H)-one (176) and the alkylation product 4,6-dihydrocyclopenta[b]pyrrol5(
1 H)-one (180). When 1-Diazo-3-(3-indoly)-3-propanone (194) is treated with catalytic
amount of Rh (II) 3,4-dihydrocyclopenta[b]indol-2(1H)-one (193) is isolated
quantitatively. The later reaction when monitored using IH NMR the intermediate 200
can be seen whose structure was confirmed by the comparison to series of model
compounds.
The mechanisms underlying these reactions as well as their synthetic utility is
discussed.
