Using Density Functional (M06 functional), the geometries and energies of the reactant, transition state, and product in the tantalum catalyzed hydroamination of an aminoallene were calculated. We explored the two basis sets, 6-311g(2dp) and 6-31g(dp), and found that the 6-31g(dp) set gave results comparable to those in the larger basis. All possible geometric approaches were modeled for the stereogenic [2+2] cycloaddition reaction. The geometry we term “oxygen side attack" was found to be almost always more energetically favorable than the "nitrogen side attack.” Attaching bulkier substituent groups to the nitrogen led to a greater range of transition state energies. Additionally, moving the chiral carbon closer to the oxygen changed the ordering of nitrogen side attack isomers. Adding a gem-dimethyl substituent on the allene tether had little effect.

Theoretical modeling of the asymmetric hydroamination-cyclization of aminoallenes by tantalum amide alkoxide complexes

251st National Meeting (2016)

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