%N 2
%I szgyaoe
%D 1994
%L publicatio31957
%X 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 sigma+ 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 hydrogen-bonding, can change the monomeric character of either the ring or the chain form (or both), leading to deviations from the ideal sigma+ values. X-Ray analysis has demonstrated the chain structures of the products of the reactions of L-(-)-norpseudoephedrine and (+/-)-trans-2-aminomethylcyclohexanol with pyrrole-2-carboxaldehyde.
%T Ring-chain tautomerism and crystal structure of some 1,3-oxazacyclanes, and the electrophilic substituent constants for some heteroaryl groups in solution and in the gas-phase
%P 1093-1107
%V 37
%J HETEROCYCLES
%A  FĂźlĂśp Ferenc
%A  SillanpĂ¤Ă¤ Reijo
%A  Dahlqvist Martti
%A  Pihlaja Kalevi
%A  Vainiotalo Pirjo
%R MTMT:1015658 10.3987/com-93-s121