Antipolar mechanism of thermal allylic rearrangements

Abstract

The Antipolar Mechanism of Thermal Allylic Rearrangements Sir:A striking example of 1,3-sigmatropic rearrangement1 where a p orbital is binding the migrating group to the carbon skeleton2 appears to have been established3(1) See for full discussion, R.

Direct Access to S-Heterocycles by Scandium(III) Triflate Catalyzed Cyclization of Aromatic Thiols and Diols

“…As the product ratio of 3af and 3′af and yield were affected by the concentration of 7a (Schemes 5e and 5f), both an intramolecular and an intermolecular allylic rearrangement might occur. 19 A catalytic amount of the triflate might operate as a promoter for intramolecular allylic cyclization through a -allyl cationic species. 20 In conclusion, a Sc(OTf) 3 -catalyzed cyclization of aromatic thiols with diols through the formation of S-C and C-C bonds has been developed.…”

“…Although the exact reaction mechanism is still unclear, a possible reaction pathway is proposed on the basis of the above information and precedents reported in the literature [18][19][20] (Scheme 6). First, the diol 2f is dehydrated in the presence of the Sc(OTf) 3 catalyst to form 3-methylbut-2-en- Letter Synlett 1-ol (6a) and 2-methylbut-3-en-2-ol (6b).…”

[1,3]‐Sigmatropic Shift of an Allylic Chloride

“…6 Configurations were assigned based on the configuration of 5. 7 Other sigmatropic rearrangements, for example Kwart's shift of allylic phenylthioethers [29] showed a strong dependence of the reaction outcome on concentration and was explained through bimolecular mechanisms for rearrangement. 8 For a recent example of an epimerization on a similar time scale as [1,3]-sigmatropic rearrangement, see [30].…”

The Problem Of Tautomerism

“…Examples of intermolecular triad anionotropic tautomerism are also known, such as following equilibria: R X ......... CH=CH-CH;x = Hal[72], SPh[123] Examples of intermolecular triad anionotropic tautomerism are also known, such as following equilibria: R X ......... CH=CH-CH;x = Hal[72], SPh[123] …”