Enammonium salt with hydrolysis

When acidic hydrolysis is carried out with the material supposed to be enammonium salt, (+)a-phenylpropionaldehyde is produced in excess. When the same substance is heated at 60°C for several hours, a levorotatory material is produced in excess. 

The chirality is decided when a porton is added to the enamine nitrogen on the amine group. Furthermore, when rearrangement to the iminium salt occurs, the chirality of the iminium proton is decided by this first proton. Upon hydrolysis of the enammonium salt, water is added from the opposite side of the enammonium proton and asymmetry of the recovered carbonyl compounds results. When an iminium salt with established chirality is hydrolyzed, the resultant carbonyl compound will have the reversed chirality because the hydrolysis occurs at the carbon-nitrogen double bond. 

That the rearrangement occurs with the enammonium salt has been confirmed by the fact that N-allyl-A methylisobutenylamine (154), which is stable under the reaction conditions, affords aldehyde 155 by treatment with methyl tosylate followed by hydrolysis (equation 33)103. MeOTs acts as a promoting reagent which facilitates the rearrangement. Other electrophilic reagents110-112 have also been employed to create a quaternary nitrogen center in order to accelerate the 3-aza-Cope rearrangement. 

Important for the hydrolysis is the observation (10) that protonation of enamines with hydrogen chloride does not immediately lead to immonium salts, but in most, if not all, cases first to the formation of the corresponding enammonium ions, which afterward rearrange more or less rapidly to the more stable immonium ions [Eq. (1)] ... 

---

See also in sourсe #XX -- [ ]

---