Prototropic organic reactions

Hydrogen and deuterium atom tunnelling has been reported to be common in prototropic organic reactions. The importance of tunnelling to fully understand chemical reactivity in organic chemical reactions has been established. ... 

Valence and prototropic tautomeric reactions are among the most important mechanisms that govern transformations of a broad variety of photochromic organic systems.1,2 Until recently, no examples of photochromic compounds have been reported whose photochromic behavior was due to a combination of these two tautomeric reactions. Such a combination, which is characteristic of ring-chain tautomerism3 has been implemented in the photochromic and thermochromic rearrangements of a novel type of heterocyclic photochromes, derivatives of 2,3-dihydro-2-spiro-4 -(2, 6 -di-iert-butylcyclohexadien-2, 5 -one)perimidine la and its analogs.4 The occurrence of a proton transfer step is in accord with the fact that the AvV -dimethyl derivative of la exhibits no photochromic properties. 

A number of interesting and useful organic reactions involve isomerizations of substances having one or more carbon-carbon double bonds. This chapter deals with the kinetics of reactions of alkenes, cycloalkenes and substituted alkenes which involve migration of carbon-carbon double bonds, with or without structural alteration of the carbon skeleton of the starting materials. These reactions include prototropic and anionotropic rearrangements, several concerted unimolecular isomerizations such as the Cope and Claisen rearrangements, and a number of non-concerted thermal isomerization reactions. 

The prototropic isomerization of allenylphosphonate into 1-propynylphosphonate proceeds partially or completely under the influence of an organic base that is generally present in the reaction mixture in a catalytic amount.When pure dialkyl allenylphosphonates are heated to 2()0°C, they remain unchanged (apart from partial polymerization). In the presence of basic catalysts (EtONa, 03 NaOlI, and at room temperature or Et3N 5 and triethyl phosphite at... 

For completeness. Appendix A.12 contains the 100% atom economical reactions cited in Trost s landmark publication. All were ring-forming reactions such as cycloadditions and prototropic cycloisomerizations, which satisfy the research interests of leading synthetic organic chemists. 

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