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Diverse N-Heterocyclic Ring Systems via Aza-Heck Cyclizations of
N-(Pentafluorobenzoyloxy)sulfonamides
Adele Faulkner, James S. Scott, and John F. BowerAngew. Chem. Int. Ed. 2016, 55, p. xxx
Current Literature
Wipf Group
Leila Terrab
8/6/16
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Narasaka-Heck reaction
J. Am. Chem. Soc. 2015, 137, 7224−7230 2Leila Terrab @ Wipf Group Page 2 of 8 11/12/2016
Proposed Aza-Heck cyclization
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Mechanism
Limitation of this aza-Pd II intermediate:- Protodepalladation- Β-hydride elimination
Optimization of oxidative addition:- Choice of electron withdrawing nature of R
Optimization of alkene insertion:- Addition of NEt3
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Scope
80 % Yield
42 % Yield
58% Yield(>10:1 d.r.)solvent: n-BuCN:DMF
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Interesting aza-Heck applications
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Comparison to aza-Wacker cyclizationaza-Wacker cyclization of alkenyl NH-sulfonamides:
Tet Lett.. 2010, 51, 5124
- Alkenyl NH sulfonamides not prepared directly from the alcohol
- Electron-deficient alkenes not used due to possible conjugate addition
- Can not engage in cascade polycyclizationsand bridged systems
aza-Heck electron-deficient alkene
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Summary
Org. Lett.. 2012, 14, 268
- Expanded the application of aza-Heck cyclizations beyond the previously reported Narasaka-Heck reaction (limited to oximes as SM)
- Used the nitrenoid property of N-(pentafluorobenzoyloxy)sulfonamides to install alkene substituents and to undergo the Pd-catalysis cyclization
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