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Enantioselective 1,3-Dipolar Cycloadditions Of Diazoacetates With Electron-Deficient Olefins, Mukund P. Sibi, Levi M. Stanley, Takahiro Soeta
Enantioselective 1,3-Dipolar Cycloadditions Of Diazoacetates With Electron-Deficient Olefins, Mukund P. Sibi, Levi M. Stanley, Takahiro Soeta
Levi M. Stanley
A general strategy for highly enantioselective 1,3-dipolar cycloaddition of diazoesters to β-substituted, α-substituted, and α,β-disubstituted α,β-unsaturated pyrazolidinone imides is described. Cycloadditions utilizing less reactive α,β-disubstituted dipolarophiles require elevated reaction temperatures, but still provide the corresponding pyrazolines with excellent enantioselectivities. Finally, an efficient synthesis of (−)-manzacidin A employing this cycloaddition methodology as a key step is illustrated.
The Role Of Achiral Pyrazolidinone Templates In Enantioselective Diels−Alder Reactions: Scope, Limitations, And Conformational Insights, Mukund P. Sibi, Levi M. Stanley, Xiaoping Nie, Lakshmanan Venkatraman, Mei Liu, Craig P. Jasperse
The Role Of Achiral Pyrazolidinone Templates In Enantioselective Diels−Alder Reactions: Scope, Limitations, And Conformational Insights, Mukund P. Sibi, Levi M. Stanley, Xiaoping Nie, Lakshmanan Venkatraman, Mei Liu, Craig P. Jasperse
Levi M. Stanley
We have evaluated the role of achiral pyrazolidinone templates in conjunction with chiral Lewis acids in room temperature, enantioselective Diels−Alder cycloadditions. The role of the fluxional N(1) substituent was examined, with the bulky 1-naphthylmethyl group providing enantioselectivities up to 99% ee, while templates with smaller fluxional groups gave lower selectivities. High selectivities were also observed in reactions of 7d with chiral Lewis acids derived from relatively small chiral ligands, suggesting the pyrazolidinone templates are capable of relaying stereochemical information from the ligand to the reaction center. Lewis acids capable of adapting square planar geometries, such as Cu(OTf)2, Cu(ClO4)2, and Pd(ClO4)2, …