Premium
Nucleophilic Additions to Alkylidene Bis(sulfoxides)—Stereoelectronic Effects in Vinyl Sulfoxides
Author(s) -
Wedel Tobias,
Gehring Timo,
Podlech Joachim,
Kordel Elena,
Bihlmeier Angela,
Klopper Wim
Publication year - 2008
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200701847
Subject(s) - chemistry , carbanion , nucleophile , medicinal chemistry , reactivity (psychology) , sulfoxide , steric effects , alkane stereochemistry , carbocation , organic chemistry , catalysis , molecule , medicine , alternative medicine , pathology
Conjugate additions of nucleophiles (e.g. enolates, amines and malonate anions) to bis( p ‐tolylsulfinyl)alkenes, alkylidene‐1,3‐dithiane‐1,3‐dioxides and alkylidene‐1,3‐dithiolane‐1,3‐dioxides have recently been published. Reasons for different selectivities and reaction rates will be discussed by consideration of steric and electronic effects. The preferred mode of attack can be explained by stereoelectronic effects (hyperconjugation) in the primarily carbanion, which is stabilized by n→S‐O‐σ* interaction with an antiperiplanar SO group. Calculation of the transition states [BP86/aug‐TZVP] for the addition of acetone enolate to the dithiane‐derived alkylidene bis(sulfoxide) revealed that 6.6–7.3 kJ mol −1 more energy is needed for an attack leading to a less‐stabilized carbanion. Two axial SO groups in dithiolane‐derived alkylidene bis(sulfoxides) lead to a higher reactivity towards nucleophiles.