Reactions of Neopentyl 2,2,2-Trifluoroethanesul-fonate (Tresylate) with Nuclcophiles: A Model Study for the Coupling of Nucleophiles with Tresyl Agarose

摘要

Recently, Demiroelou et al. presented evidence for the need to revise the previously held picture of the reactions of 2,2,2-tri-fluoroethancsulfonyl (trcsyl) agarose with nuclcophiles such as hydroxide, ihioiatc anions. and primary amines. Though tlies showed clearly that the reaction does not go by a simple S_N2 displacement at carbon, the revised structures that they proposed for the coupled products, an alkslsulfuric acid, a dialkyl thiosulfate. and a dialkyi sulfamate. reapcctisels, appeared to us to be incorrect, justifiable neither by precedent nor by the well-established principles of reaction mechanisms. It seemed much more likely thai the attachment ol nucieophiles would occur by way of some form of the beta-elimination Michael-type addition sequence shown by Stirling for compounds of the general structure -SO_2-CH-C-Lg-Lg — leaving group). Related conversions, for example, ol tress 1 fluoride into sulfoaeeuc acid and related products. and a tress late ester into a mess late ester have been reported. We now describe experiments with neopentyl tresylate (1). a model system chosen to 1) asoid the problems of determining the structures of polymers. 2) be un-fikely to show S_N2 reactions at the primary carbon, and hence 3) be well set up toshow the coupling leactions of tresyl agarose with amines and thiols.