Learn More
Electrostatic effects exert strongly stabilizing influences on cations, in many cases controlling the conformational preferences of these cations. The lowest energy conformers are ones where the positive charge is brought closest to substituents bearing partial negative charges. These conformational biases, along with stereoelectronic effects, can control(More)
The three-dimensional structures of dioxocarbenium ions related to glycosyl cations were determined by an analysis of spectroscopic, computational, and reactivity data. Hypothetical low-energy structures of the dioxocarbenium ions were correlated with both experimentally determined (1)H NMR coupling constants and diastereoselectivity results from(More)
Nucleophilic substitution reactions of monosubstituted tetrahydropyran acetals give opposite selectivities when a remote alkyl or alkoxy substituent is present at C-4. Coupled with earlier computational reports on the intermediates of glycosylation reactions, these results are consistent with the preference for the oxocarbenium ion intermediate derived from(More)
A 1,2-dioxolane (FINO2) was identified as a lead compound from a screen of organic peroxides. FINO2 does not induce apoptosis, but instead initiates ferroptosis, an iron-dependent, oxidative cell death pathway. Few compounds are known to induce primarily ferroptosis. In contrast to the perceived instability of peroxides, FINO2 was found to be thermally(More)
Mechanistic evidence suggests that the Lewis acid-promoted allylic rearrangement of alpha-silyloxy allylic silanes proceeds along an ionic reaction pathway involving a contact ion pair. The driving force for this transformation is alleviation of steric congestion at the allylic position of the alpha-silyloxy allylic silane and stabilization of pi cc by(More)
Silylene transfer to allylic sulfides results in a formal 1,2-sulfide migration. The rearrangement yields substituted silacyclobutanes, not the expected silacyclopropanes. The silacyclobutanes were elaborated by insertions of carbonyl compounds selectively into one carbon-silicon bond. A mechanism for the 1,2-sulfide migration is proposed involving an(More)
Evidence is provided that nucleophilic attack on five-membered ring oxocarbenium ions occurs from the inside face of the envelope. An eight-five fused-bicyclic system in which two substituents are constrained to pseudoequatorial positions underwent nucleophilic addition with selectivity that was comparable to an unconstrained monocyclic system. On the other(More)
[reaction: see text] The annulation reactions of alkenes with peroxycarbenium ions enable the synthesis of a variety of functionalizable 1,2-dioxolanes. Triethysilyl-protected peroxycarbenium ions proved to be optimal for the annulation reaction. Using this method, plakinic acid analogues can be synthesized in three steps from the corresponding ketone and(More)
(13)C NMR spectroscopic integration employing short relaxation delays was evaluated as a quantitative tool to obtain ratios of diastereomers, regioisomers, constitutional isomers, mixtures of unrelated compounds, peptoids, and sugars. The results were compared to established quantitative methods such as (1)H NMR spectroscopic integration, gas(More)