Study of the Substituent‐Influenced Anomeric Effect in the Ring‐Chain Tautomerism of 1‐Alkyl‐3‐aryl‐naphth[1,2‐e][1,3]oxazines

Abstract

The stabilities of the trans (B) and cis (C) tautomeric ring forms that are experimentally observed in the ring‐chain tautomeric interconversion of 1‐alkyl‐3‐aryl‐2,3‐dihydro‐1H‐naphth[1,2‐e][1,3]oxazines has been investigated. Stability differences are explained by the analysis of the natural bond orbital results for the lone pairs of electrons that are on the heteroatoms in the oxazine ring system and by regression analysis of the calculated 13C NMR chemical shift values. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Enumeration of Ring–Chain Tautomers Based on SMIRKS Rules

“…Some results on ring–chain tautomerism have been published, including the effect of substituents on the tautomeric equilibria, the effect of the solvent, and synthetic applications. Also, computational studies on ring–chain tautomerism have been performed by using quantum chemical calculations to investigate the key structural factors involved in the ring–chain tautomerism equilibrium. − Many studied examples represent the well-known case of ring–chain tautomerism in N-unsubstituted 1,3-X,N-heterocyclic compounds (X = O, S, NR) . Most of the documented cases of experimentally confirmed ring–chain tautomerism have been obtained by the application of endocyclic transformations.…”

Synthesis and conformational analysis of naphthylnaphthoxazine derivatives

“…Through the use of aliphatic aldehydes, e.g. formaldehyde [13], acetaldehyde, propionaldehyde, butyraldehyde, isobutyraldehyde and pivalaldehyde, 1-(1-aminoalkyl)-2-naphthols have been synthesized [14,15], while from heteroaromatic aldehydes primary aminonaphthols have been prepared and their ring-chain tautomeric behaviour has been studied [16].…”

Microwave-Assisted One-Pot Synthesis of (Aminoalkyl)naphthols and (Aminoalkyl)quinolinols by Using Ammonium Carbamate or Ammonium Hydrogen Carbonate as Solid Ammonia Source

“…[10][11][12][13][14][15] The areas of application of these aminonaphthols depend on the nature of the amino group; the enantiomers of secondary and tertiary aminonaphthols have been successfully applied as chiral catalysts in the enantioselective alkylation or arylation of benzaldehyde, 2-9 while primary aminonaphthols have been transformed into heterocyclic compounds, [10][11][12] subsequent condensation with different aldehydes furnishing interesting model compounds for examining the ring-chain tautomeric behavior of naphthoxazines. [13][14][15][16][17][18] On the other hand, the hypotensive and bradycardiac effects of 1-(aminomethyl)-2-naphthol derivatives have been evaluated, 18 and the syntheses of a wide variety of this type of compounds have recently been achieved through the hydrolysis of 1-(amidomethyl)-2naphthols. 19 The overall yields of the desired aminonaphthols in the classical Betti reaction (starting from naphthol, methanolic ammonia, and the corresponding aldehyde, followed by acidic hydrolysis of the intermediate naphthoxazine) have been slightly improved by means of small modifications in the synthesis, e.g.…”