The focus of the proposed studies centers on development of a more direct and simpler route to synthesis of organosilanes and organosilanols. Such molecules are increasingly in demand for use in a wide variety of applications, in particular in pharmaceutical and other medical related activities. Unfortunately, current approaches to prepare these molecules utilize multi step-wise strategies, which require substantial time and effort. The goal of the proposed research program is the design and application of single-pot, transition metal- catalyzed reductive C-H and C-C silylations for a synthesis of a new class of organosilanes. This proposal describes novel, highly selective bond functionalization strategies through a relay of two transition metal catalyses, and the use of disposable silyl acetal directing groups, to achieve formation of a carbon-silicon bond and concomitant functionalization of a silicon group in a single vessel. The proposed studies are heavily predicated on successful recent preliminary studies from our laboratory.
Specific Aims I and II will generate the following positive outcomes: We will exploit catalytic reductive C-H bond silylations of phenols and nitrogen-containing heterocycles to provide bioactive organosilicon-containing phenols and nitrogen heterocycles. The benefit of our approach derives from the traceless O,O- and N,O-silyl acetal directing groups, which obviate the need for directing group interconversion, as well as the direct, rather than stepwise, introduction of the diversely functionalized silane group.
In Specific Aim III, we will exploit selective catalytic reductive C-C bond silylation of activated cyclopropanes over proximal Csp2-H or Csp3-H silylation with a silyl acetal-directing group for the synthesis of densely functionalized dioxasilepines and dioxsilolanes. We will also demonstrate the unprecedented application of the acetal directing groups as reaction partners for acid- mediated vinyl acetal rearrangement to access biologically active molecules.
The goal of the proposed research program is to develop novel catalytic reductive C-H and C-C bond silylations for synthesis of a new class of organosilanes from readily accessible, simple chemical building blocks. The synthetic methods developed in this research will provide broadly applicable, time- and cost- saving, synthetic routes to provide rapid access to such compounds for subsequent use in drug discovery and development, thus contributing to the promotion of human health.
| Asgari, Parham; Dakarapu, Udaya Sree; Nguyen, Hiep H et al. (2017) Aryne cycloaddition reactions of benzodioxasilines as aryne precursors generated by catalytic reductive ortho-C-H silylation of phenols with traceless acetal directing groups. Tetrahedron 73:4052-4061 |
| Hua, Yuanda; Asgari, Parham; Avullala, Thirupataiah et al. (2016) Catalytic Reductive ortho-C-H Silylation of Phenols with Traceless, Versatile Acetal Directing Groups and Synthetic Applications of Dioxasilines. J Am Chem Soc 138:7982-91 |
