Structure of peri-hydroxy- and peri-methoxy-substituted aldehydes and ketones according to spectral data and quantum-chemical calculations

Abstract

The structure of peri-hydroxy-and peri-methoxy-substituted aldehydes and ketones of the naphthalene, acenaphthene, and acenaphthylene series and the nature of intramolecular interactions between the perisubstituents therein were determined by spectral (IR, UV, 1 H NMR), X-ray diffraction, and quantum-chemical methods.Naphthalene derivatives having hydroxy and carbonyl groups in the neighboring peri positions play an important role as potential precursors of peri-fused heterocyclic systems [1][2][3]. In addition, these compounds are unique models for studying so-called [4, 5] "peri effects" (hydrogen bonds, electrophilic interactions, ring-chain tautomerism, and other interactions between the peri substituents) [2][3][4][5][6][7][8][9][10][11][12][13]. While studying the reactivity and predicting chemical properties of peri-hydroxy carbonyl compounds, it is strongly desirable to know specific features of the structure of perihydroxy carbonyl moiety and the nature of peri effects therein.Possible types of intramolecular interactions in peri-hydroxy-and peri-methoxy-substituted aldehydes and ketones are illustrated by structures A-F shown in Scheme 1. Structure A corresponds to classical intramolecular hydrogen bond [14] connecting the two electronegative oxygen atoms with closure of sevenmembered H-chelate ring. Rupture of that hydrogen bond by the action of polar solvents (S) creates conditions for the formation of structure B which reflects intramolecular attractive electrophile-nucleophile interactions between the peri substituents. In this case, lone electron pair on the hydroxy oxygen atom is attracted via electrostatic forces to the electron-deficient

peri-hydroxy acenaphthoyl compounds

“…In the series of peri-hydroxy aldehydes we observed a downfield shift (by 1.08-1.23 ppm) of the OH signal of Xc as compared to aldehydes Xa, Xb, and Ia due to the presence of a nitro group in position 5 (as a result, the acidity of the OH group increases). Despite almost coinciding chemical shifts of the OH protons in peri-hydroxynaphthaldehyde (Xa) and its acenaphthene analog Ia (Table 1), the latter is characterized by stronger intramolecular hydrogen bond (according to the IR data) [17]; this is also confirmed by the calculated H-bond energies, 9 and 13 kcal/mol, respectively [17].…”

“…The hydroxy proton in VII appears at δ 10.5 ppm, indicating formation of intramolecular hydrogen bond of the same type as in peri-hydroxyacenaphthenyl methyl ketone (δ 11.6 ppm) [17]. The hydrogen atom in the hydroxy group of the latter is involved in hydrogen bonding via closure of a planar 7-membered H-chelate ring which is coplanar to the naphthalene core (X-ray diffraction data) [17]. In the reaction of peri-hydroxyacenaphthenyl methyl ketone (Ic) with p-nitrobenzaldehyde in alkaline medium we isolated a poorly soluble amorphous material.…”

“…In keeping with the 1 H NMR data, the double bond in chalcones VII is configured trans (J ab > 15 Hz). The hydroxy proton in VII appears at δ 10.5 ppm, indicating formation of intramolecular hydrogen bond of the same type as in peri-hydroxyacenaphthenyl methyl ketone (δ 11.6 ppm) [17]. The hydrogen atom in the hydroxy group of the latter is involved in hydrogen bonding via closure of a planar 7-membered H-chelate ring which is coplanar to the naphthalene core (X-ray diffraction data) [17].…”

“…According to the 1 H NMR data, compounds IIIa and IIIb have trans configuration at the double bond (J ab > 15 Hz). The chemical shift of H b at the double bond (δ ~9.3 ppm) suggests formation of intramolecular hydrogen bond C-H b · · · O (Scheme 1) which is analogous to intramolecular hydrogen bond in Schiff base IIe and peri-methoxyacenaphthaldehydes [17]. The hydroxy proton resonated in the 1 H NMR spectra of IIIa and IIIb in CDCl 3 at δ ~6.3 ppm, and its signal was displaced downfield (to δ ~10 ppm) in going to dimethyl sulfoxide, presumably due to formation of associates like (CD 3 )S=O · · · H-O-C arom .…”

Pyran derivatives peri-fused to acenaphthene and acenaphthylene

“…The presence of a bromine atom in the ortho position with respect to the hydroxy group induced a downfield shift of the hydroxy proton signal in the 1 H NMR spectrum of compound IV (δ 12.60 ppm) as compared to hydroxy ketone I (δ 11.60 ppm) [10]. These findings suggest stronger intramolecular hydrogen bond in IV due to effect of bulky ortho-substituent on the hydroxy group.…”