In principle, the ring-chain tautomeric ratios of a number of 2-heteroaryl-substituted oxazolidines and tetrahydro-1,3-oxazines are well suited for determination of the Hammett-Brown σ+ constants of heteroaryl substituents such as 2-furyl, 3-furyl, 3-thienyl and 2-pyrrolyl in CDCl3 solution and in the gas phase. However, a number of factors, and especially hydrogenbonding, can change the monomeric character of either the ring or the chain form (or both), leading to deviations from the ideal σ+ values. X-Ray analysis has demonstrated the chain structures of the products of the reactions of l-(-)-norpseudoephedrine and (±)-trans-2-aminomethylcyclo-hexanol with pyrrole-2-carboxaldehyde.
|Number of pages||15|
|Publication status||Published - Mar 3 1994|
ASJC Scopus subject areas
- Analytical Chemistry
- Organic Chemistry