Functionalized alicyclic molecules are inherently more advantageous than their planar, aromatic analogues because they contain greater saturation and the possibility of chiral carbon centers, both attributes that have been shown to increase potential success of pharmaceuticals during clinical trials. Arenes represent a wealth of opportunities as synthons for functionalized alicyclic molecules because of their abundance in nature, their stability, and the diversity of substituents present. However, due to the innate aromatic stability of these molecules, arenes are difficult to modify through addition reactions. This stability can be overcome through the use of the π-basic metal fragment, {TpMo(NO)(DMAP)} (where Tp = trispyrazolyl(borate) and DMAP = N,N-dimethylaminopyridine), which donates electron density from the metal into the arene, disrupting aromaticity, and making the arene more reactive. Using this methodology, the synthesis of a variety of novel small compounds has been shown through the tandem electrophilic, nucleophilic additions and subsequent removal of the metal complex through oxidation. This work demonstrates novel arene reactivity using the TpMo(NO)(DMAP)(η2-naphthalene) metal complex. The metal complex activates the coordinated naphthalene toward Michael additions α,β-unsaturated ketones in the presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf). The products of these one-pot reactions are hexahydrophenanthrenes, which are the result of a sequential, Michael-Michael ring-closing (MIMIRC) reaction. The double addition ([A+A] MIMIRCs) reactions using either either ethyl vinyl ketone (EVK) or methyl vinyl ketone (MVK) have been accomplished with high stereoselectivity of the addition to the naphthalene ring. To further demonstrate the synthetic potential of these reactions, [A+B] MIMIRCs, wherein the second Michael acceptor is different from the first, have been accomplished. Thus, from a fully aromatic core (naphthalene), organic products with no less than four new stereocenters and three new carbon-carbon bonds have been isolated.

Michael-Michael ring closing reactions promoted by TpMo(NO)(DMAP)(η2-naphthalene)

254th National Meeting (2017)

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