74195-12-3Relevant academic research and scientific papers
Acidities of Sulfoximines and Related Oxosulfonium Cations. Cyclopropyl Effects and Structures of α-Sulfonyl-Type Carbanions
Bordwell, Frederick G.,Branca, John C.,Johnson, Carl R.,Vanier, Noel R.
, p. 3884 - 3889 (2007/10/02)
(Dimethylamino)methylphenyloxosulfonium cation, PhS(O)(NMe2)CH3+, was found to be more acidic than the parent sulfoximine, PhS(O)(NMe)CH3, by about 19 pKa units.The latter is about equal in acidity to PhS(O)CH3 and about 5 pKa units less acidic than PhSO2CH3.The cyclopropyl compounds, c-PrG, with G equal to Ph(NMe2)SO+, p-MeC6H4(NMe2)SO+, F3CSO2, and Ph(PhSO2N)SO, were found to be about 4-7 pKa units less acidic than their acyclic methyl analogues, CH3G.This is interpreted as evidence for a demand on the part of sulfone-type functions for p character in cyclopropyl carbanions.Evidence is presented to show that carbanions of the type GCH2-, where G is an electron-withdrawing function such as RSO2, RS(O)(NR), RSO, Ph2PO, (RO)2PO, and the like, are planar or nearly planar.Acidity data indicate that the preferential generation of chiral, rather than achiral, planar α-sulfonyl carbanions is a consequence of a preferred kinetic pathway rather than an inherent greater thermodynamic stability.Factors controlling the stereoselective generation and reactions of carbanions are reviewed.
