The cis- and trans-isomers of a silacycloheptene were selectively synthesized by the alkylation of a silyl dianion, a novel approach to strained cycloalkenes. The trans-silacycloheptene (trans-SiCH) was significantly more strained than the cis isomer, as predicted by quantum chemical calculations and confirmed by crystallographic signatures of a twisted alkene. Each isomer exhibited distinct reactivity toward ring-opening metathesis polymerization (ROMP), where only trans-SiCH afforded high-molar-mass polymer under enthalpy-driven ROMP. Hypothesizing that the introduction of silicon might result in increased molecular compliance at large extensions, we compared poly(trans-SiCH) to organic polymers by single-molecule force spectroscopy (SMFS). Force-extension curves from SMFS showed that poly(trans-SiCH) is more easily overstretched than two carbon-based analogues, polycyclooctene and polybutadiene, with stretching constants that agree well with the results of computational simulations.

The first solid-state characterization of statistical copolymers of vinyl alcohol and styrene (poly(VA-stat-St)) by cross-polarization magic angle spinning (CP-MAS) spectroscopy is described. Poly(VA-stat-St) is not available from the traditional feedstocks styrene (St) and vinyl acetate (VAc) due to a mismatch in reactivity ratios. BN 2-vinylnaphthalene (BN2VN) is a synthetic solution to this challenge as it copolymerizes with activated monomers (e.g., styrene, methyl methacrylate), and the BN naphthalene side chain can be oxidatively converted to hydroxyl (−OH) side chains. While high levels of BN2VN incorporation are readily achieved (e.g., >75 mol % BN2VN), prior work has identified that poly(VA-stat-St) is poorly soluble in organic solvents when the molar fraction of VA exceeds 0.50, presumably due to the hydrophilic character of the hydroxyl group as well as possible interchain hydrogen bonding. Circumventing this solubility challenge, we describe quantitative solid-state 13 C CP-MAS spectra demonstrating high conversion (85−99%) of poly(BN2VN-stat-St) to poly(VA-stat-St). 11 B CP-MAS confirmed the removal of organoborane functional groups.

The electrophilic substitution of indoles with tetronic acid and N-acetyltetramic acid mediated by BF 3 •OEt 2 was investigated. This strategy allowed for the preparation of nine indole-substituted furan-2ones (indolyl-γ-lactones) and 3-pyrrolin-2-ones (indolyl-γ-lactams) and is more straightforward than previously reported synthetic methods. During the course of our investigation, we also discovered a facile synthesis of tetronates and a tetramate via a BF 3 -mediated addition of alcohols to tetronic acid and N-acetyltetramic acid, respectively.