Direct transformations of ketones to gamma-unsaturated thiols via [2,3]-sigmatropic rearrangement of allyl sulfinyl carbanions: A combined experimental and computational study
Aa. Fokin et al., Direct transformations of ketones to gamma-unsaturated thiols via [2,3]-sigmatropic rearrangement of allyl sulfinyl carbanions: A combined experimental and computational study, J ORG CHEM, 65(10), 2000, pp. 2984-2995
The reaction of a series of ketones with dimsylsodium in dimethyl sulfoxide
resulting in the formation of gamma-unsaturated thiols was studied experim
entally. [2,3]-Sigmatropic rearrangements of beta-unsaturated sulfinyl carb
anions are involved at the key step of those transformations. DFT computati
ons at the B3LYP/6-31+G* level indicated that such rearrangements, as well
as some typical [2,3]-sigmatropic rearrangements, e.g., thermal rearrangeme
nts of allyl sulfoxides and Wittig rearrangements of sulfur ylides and lith
iated allyloxy methyl anions, are concerted and moderately synchronous proc
esses. Negative (diatropic) nucleus-independent chemical shifts (NICS) and
high diamagnetic susceptibility exaltations indicate that the transition st
ructures of these [2,3]-sigmatropic migrations are aromatic.