Related Experiment Video
Updated: Aug 25, 2026

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones
Published on: February 7, 2019
Addition of lithiated 5-hydroxymethyl-1,3-dithiane to benzaldehyde: HMPA-controlled trans stereoselectivity
Zaiguo Li1, Alexei N Kurchan, Andrei G Kutateladze
1Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208-2436, USA.
Abstract:
Addition of 5-substituted dithianyl anions to carbonyl compounds normally produces trans adducts. The presence of a nucleophilic hydroxymethyl group in position 5 dramatically decreases the trans stereoselectivity of the reaction in THF. The trans/cis ratio shows a bell curve dependence on HMPA, fitted to a quantitative model involving a series of equilibrated ion pairs, of which an intermediate contact ion pair possessing three (effective) HMPA molecules yields the trans adduct with much higher stereoselectivity. [structure: see text]
More Related Videos
Related Concept Videos
Regioselectivity and Stereochemistry of Hydroboration
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
Radical Anti-Markovnikov Addition to Alkenes: Overview
Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
Electrophilic Addition of HX to 1,3-Butadiene: Thermodynamic vs Kinetic Control
Regioselectivity of Electrophilic Additions-Peroxide Effect

