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
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...
Elmentve itt :
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| Dokumentumtípus: | Cikk |
| Megjelent: |
1994
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| Sorozat: | HETEROCYCLES
37 No. 2 |
| Tárgyszavak: | |
| doi: | 10.3987/com-93-s121 |
| mtmt: | 1015658 |
| Online Access: | http://publicatio.bibl.u-szeged.hu/31957 |
| Tartalmi kivonat: | 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. |
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| Terjedelem/Fizikai jellemzők: | 1093-1107 |
| ISSN: | 0385-5414 |