Steric effects sulfonation

Finally, since besides the inductive effect of the sulfoxide and the sulfone functional groups, hydrogen bonding, field effects and steric effects to solvation may or may not work in the same direction, the pKx values can be useful in assigning configurations of suitable pairs of stereoisomeric sulfoxide and sulfone carboxylic acids291. 

Reaction 31 appears to be little affected by substituent electronic effects or by steric effects of either sulfonyl chloride or styrenes. Treatment of /5-chlorosulfones with triethylamine in benzene affords the corresponding a, /5-unsaturated sulfones in excellent yield. The copper-catalyzed addition of sulfonyl iodides to simple and cyclic alkenes has also been exploited76. 

When Z is SOR or SO2R (e.g., a-halo sulfoxides and sulfones), nucleophilic substitution is retarded. The SnI mechanism is slowed by the electron-withdrawing effect of the SOR or SO2R group,and the Sn2 mechanism presumably by the steric effect. 

Phenyl vinyl sulfones reacted with cyclohexanone enamines 332 to afford adducts which, upon hydrolysis, gave 2-(2-phenylsulfonyl)alkylcyclohexanone 333a . However, in the reaction with phenyl styryl sulfone, two products 333b and 334 were obtained by the nucleophilic attack at the and a-carbon atoms . Steric effects, electrostatic interactions between the nitrogen atom of the enamine and the oxygen atoms of the sulfone group, and medium effects contribute to the regioselectivity of the reaction. ... 

Heteroaromatic sulfoxides and sulfones ligand exchange and coupling in sulfuranes and //Avo-substitutions, 49, 1 Heteroaromatic systems, Claisen rearrangements in, 42, 203 Heteroaromatics, quantitative analysis of steric effects in, 43, 173 Heterocycles aromaticity of, 17, 255 chiral induction using, 45, 1 containing the sulfamide moiety,... 

Oxazoles and benzoxazoles yield salts with acids, alkyl halides, methyl toluene-p-sulfonate, triethyloxonium fluoroborate, etc. Quaternization is subject to the well-known steric effect of bulky substituents 2-phenylbenzoxazole, for instance, does not react with ethyl iodide even at 240 °C. The weakly basic nature of oxazole (see Section 4.18.2.4) is reflected in the instability of its simple salts, such as hydrochlorides and picrates, which are readily hydrolyzed, even in air. 2-Aminooxazoles and 2-aminobenzoxazoles are alkylated at the ring nitrogen atom the anilinonaphthooxazole (124), on the other hand, reacts with methyl iodide to yield a mixture of methyl derivatives (equation 1). 

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