Synthesis of some aldoxime derivatives of 4H-pyran-4-ones

Article abstract of DOI:10.3390/70200239

Aldoxime derivatives of 4H-pyran-4-ones 4-7a,b have been synthesized by the reaction of di(aminoxymethyl) pyranones 3a,b with aromatic aldehydes.

Full text of DOI:10.3390/70200239

Molecules 2002, 7, 239–244
molecules
ISSN 1420-3049
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Synthesis of Some Aldoxime Derivatives of 4H-Pyran-4-ones†
Fateme Abrishami1,*, Reza Teimuri-Mofrad1, Yadollah Bayat1 and Aziz Shahrisa2
1
Chemistry and Chemical Engineering Research Center, Faculty of Materials and Chemical
Engineering, Malek-ashtar University of Technology (MUT), Tehran, P. O. Box 16765-3454, Iran
Fax : +98-21-2936578.
2
Department of Organic Chemistry, Faculty of Chemistry, Tabriz University, Tabriz 51664, Iran
* Author to whom correspondence should be addressed; e-mail: fatemeabrishami@yahoo.com
Received: 26 April 2001 ; in revised form: 26 December 2001/ Accepted: 15 February 2002 /
Published: 28 February 2002
Abstract: Aldoxime derivatives of 4H-pyran-4-ones 4-7a,b have been synthesized by the
reaction of di(aminoxymethyl) pyranones 3a,b with aromatic aldehydes.
Keywords: 4H-pyran-4-one, N-hydroxyphthalimide, Condensation reaction.
Introduction
4H-pyran-4-one derivatives constitute an useful class of heterocyclic compounds which are
widely distributed in nature [1,2]. These compounds display diverse biological activities, acting as
fungicides and herbicides and a variety of pharmacological actions, which could be useful in the
treatment of asthma and allergies [3,4].
Several synthetic routes to 4H-pyran-4-one derivatives have been reported in the literatures [5-7].
However, the synthesis of their aminoxymethyl derivatives have not developed. 2-Aminoxymethyl-5-
benzyloxy-4H-pyran-4-one, which was prepared by Natio and co-workers, has been used as an
intermediate in the synthesis of cephalosporin derivatives [8]. As a followup of their work, we report
here the synthesis of some aldoxime derivatives of 4H-pyran-4-ones, which have been prepared by the
condensation of di(aminoxymethyl) derivatives of 4H-pyran-4-ones with aromatic aldehydes.

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Results and Discussion
The reaction of di(bromomethyl) pyranones 1a,b and N-hydroxyphthalimide gave the di(N-
phthalimidoxymethyl) 4H-pyran-4-one derivatives 2a,b in 82.5 and 52% yields, respectively, which
were hydrazinolysized to produce the corresponding di(aminoxymethyl) pyranones 3a,b in 91 and
67.6% yields. The condensation of the compounds 3a or 3b with benzaldehydes at 0°C led to mixtures
of isomeric pairs of aldoximes 4a,b, 5a,b and 6a,b, 7a,b formed in 9.7-72% yields, which were the
mixture of (E,E) and (Z,Z) isomers of each compound (Scheme 1). Characterization of these
compounds indicated that in each case, the major product was the (E,E) isomer.
Scheme 1
O
O
O
Br
Ph
Br
Ph
O
O N
N
Y
Y
i
+
NOH
O
O
X
Ph
X
Ph
O
2(a,b)
1(a,b)
a) X=O, Y=CO
b) X=CO, Y=O
R
R
ii
H
O
H
O
N
N
ONH
ONH
Ph
2
Y
2
Y
iii or iv
Ph
X
Ph
Ph
X
3(a,b)
4(a,b); (E,E), R=H
5(a,b); (E,Z), R=H
6(a,b);(E,E),R=CH
3
7(a,b); (E,Z), R=CH
3
i) Et N, DMF, r.t.
3
ii) H N-NH , MeOH, 0OC
2
2
iii) C H CHO, CH Cl , 0OC ( 4-5a,b )
6
5
2
2
iv) 4-MeC H CHO, CH Cl , 0OC ( 6-7a,b )
6
4
2
2
The 1H-NMR spectra of the (E,E) isomers 4a,b and 6a,b and the (E,Z) isomers 5a,b and 7a,b were
not identical. The two azomethine protons in the (E,E) isomers 4a,b and 6a,b appeared as a singlet
around 8.1 ppm while in the (E,Z) isomers 5a,b and 7a,b one of these protons appeared in the aromatic

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1
area. The proposed structures have been confirmed by the spectral data (IR, H-NMR and MS) and
elemental analyses.
Conclusions
Several new aldoxime derivatives of 4H-pyran-4-ones 4-7a,b were synthesized and characterized
for the first time. These compounds were prepared by condensation of di(aminoxymethy) pyranones
3a,b with aromatic aldehydes.
Experimental
General
Melting points were determined with an Electrothermal Instrument model 9100 and are
1
uncorrected. IR spectra (KBr disks) were taken on a Shimadzu 8010M spectrophotometer. H-NMR
spectra were recorded for CDCl3 solutions on a FT-NMR Brucker 100 MHz spectrometer. Chemical
shifts are reported in ppm values relative to TMS used as the internal standard. Mass spectra were
obtained on a Shimadzu GC MS-QP 1100 EX. Elemental analyses were performed on a Heareus,
CHN-O-RAPID analyzer.
General procedure for preparation of di(N-phthalimidoxymethyl) pyranones 2a,b.
A mixture of di(bromomethyl)diphenyl-4H-pyran-4-one 1a [9] or 1b [10] (6.0 g, 13.8 mmol),
N-hydroxyphthalimide (4.8 g, 29 mmol), Et3N (4.2 g, 41mmol) and DMF (50 mL) was stirred at room
temperature for 24 hrs. To this mixture was added water (20 mL) and the resulting solid was filtered
and washed with water. The crude product 2a,b was used without any purification in the next step.
3,5-Di(N-phthalimidoxymethy)-2,6-diphenyl-4H-pyran-4-one (2a). Colourless crystals (82.5% yield),
1
m.p. 233-235°C; H-NMR δ: 4.9 (s, 4H, -CH2O-), 7.15-7.85 (m, 18H, phenyl-H). IR: 3075, 2950,
2875, 1790, 1730, 1670, 1635, 1575 cm-1; MS: m/z 598; Anal. Calcd. for C35H22N2O8: C, 70.23; H,
3.70; N, 4.68. Found: C, 69.80; H, 3.80; N, 4.57.
2,6-Di(N-phthalimidoxymethly)-3,5-diphenyl-4H-pyran-4-one (2b). Colourless crystals (52% yield),
m.p. 228-229.5°C; 1H-NMR δ: 4.95 (s, 4H, -CH2O-), 7.1-7.3 (m, 10H, phenyl-H), 7.7 (s, 8H, phenyl-
H); IR: 3094, 2925, 2853, 1790, 1740, 1631, 1620, 1579 cm-1; MS: m/z 598; Anal. Calcd. for
C35H22N2O8: C, 70.23; H, 3.70; N, 4.68. Found: C, 70.12; H, 3.67; N, 4.62.
General procedure for preparation of di(aminoxymethyl) pyranones 3a,b.
Hydrazine hydrate (97%, 1.7 mL) was added dropwise over 20 min. to a stirred suspension of
compound 2a or 2b (4.0 g, 6.6 mmol) in absolute methanol (40 mL) [11] at 0°C under nitrogen. The
mixture was stirred at the same temperature for 1h, then allowed to reach room temperature, and the

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residue was dissolved in dichloromethane. The mixture was cooled, stirred, and filtrated. After
removing of the remaining phthalhydrazide, the filtrate was evaporated to give the crude crystalline
solid 3a,b.
3,5-Di(aminoxymethyl)-2,6-diphenyl-4H-pyran-4-one (3a). Colourless crystals (91.5% yield), m.p.
1
127-129°C; H-NMR δ: 4.65 (s, 4H, -CH2O-), 5.3 (br, 4H, -NH2), 7.35-7.55 (m, 10H, phenyl-H); IR:
3300, 3150, 3050, 2950, 2872, 1643, 1495, 1448 cm-1; MS: m/z 338; Anal. Calcd. for C19H18N2O4: C,
67.44; H, 5.36; N, 8.28. Found: C, 67.28; H, 5.23; N, 8.30.
2,6-Di(aminoxymethyl)-3,5-diphenyl-4H-pyran-4-one (3b). Colourless crystals (67.6% yield), m.p.
1
131.5-133°C; H-NMR δ: 4.64 (s, 4H, -CH2O-), 5.37 (br, 4H, -NH2), 7.23 (m, 10H, phenyl-H); IR:
3300, 3250, 3140, 3050, 2960, 1640, 1622, 1570, 1413 cm-1; MS: m/z 338; Anal. Calcd. for
C19H18N2O4: C, 67.44; H, 5.36; N, 8.28. Found: C, 66.97; H, 5.27; N, 8.20.
General procedure for preparation of aldoxime derivatives of 4H-pyran-4-ones 4-7a,b.
To a stirred suspenion of compound 3a or 3b (0.5 g, 1.47 mmol) and 4Å molecular sieves (1.5g) in
dry dichloromethane (15 mL) at 0°C under nitrogen was slowly added benzaldehyde (0.31 g, 2.9
mmol) or 4-methylbenzaldehyde (0.36 g, 2.9 mmol). When the addition of aldehyde was complete, the
mixture was stirred at room temperature overnight. After filteration, the solvent was evaporated. The
resulting crude product was purified by column chromatography on silicagel, using 9:1 petroleum
ether - ethyl acetate as an eluent.
(E,E)-Benzal[(2,6-diphenyl-3,5-4H-pyran-4-one-diyl)bis(methylene)]dioxime (4a). Yellow oil (70.1 %
yield); 1H-NMR δ: 5.1 (s, 4H, -CH2O-), 7.2-7.85 (m, 20H, phenyl-H), 8.1 (s, 2H, -N=CH-); IR: 3050,
3017, 2983, 2875, 1644, 1607, 1500, 1446 cm-1; MS: m/z 514; Anal. Calcd. for C33H26N2O4: C, 77.03;
H, 5.09; N, 5.44. Found: C, 77.18; H, 5.10; N, 5.38.
(E,E)-Benzal[(3,5-diphenyl-2,6-4H-pyran-4-one-diyl)bis(methylene)]dioxime (4b). Yellow oil (68%
1
yield); H-NMR δ: 5.1 (s, 4H, -CH2O-), 7-7.6 (m, 20H, phenyl-H), 8.1 (s, 2H, -N=CH-); IR: 3050,
3010, 2950, 2900, 1630, 1470, 1405 cm-1; MS: m/z 514; Anal. Calcd. for C33H26N2O4: C, 77.03; H,
5.09; N, 5.44. Found: C, 76.92; H, 5.10; N, 5.30.
(E,Z)-Benzal[(2,6-diphenyl-3,5-4H-pyran-4-one-diyl)bis(methylene)]dioxime (5a). Yellow oil (10.5%
1
yield); H-NMR δ: 5.1 (s, 4H, -CH2O-), 7.1-7.8 (m, 20H, phenyl-H; 1H, -N=CH-), 8.1 (s, 1H,
-N=CH-); IR: 3050, 3010, 2980, 2872, 1640, 1600, 1480, 1440 cm-1; MS: m/z 514; Anal. Calcd. for
C33H26N2O4: C, 77.03; H, 5.09; N, 5.44. Found: C, 77.20; H, 4.92; N, 5.34.
(E,Z)-Benzal[(3,5-diphenyl-2,6-4H-pyran-4-one-diyl)bis(methylene)]dioxime (5b). Yellow oil (10%
1
yield); H-NMR δ: 5.15 (s, 4H, -CH2O-), 7-7.6 (m, 20H, phenyl-H; 1H, -N=CH-), 8.1 (s, 1H,
-N=CH-); IR: 3050, 3010, 2985, 1640, 1600, 1480, 1440 cm-1; MS: m/z 514; Anal. Calcd. for
C33H26N2O4: C, 77.03; H, 5.09; N, 5.44. Found: C, 77.29; H, 5.01; N, 5.32.

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(E,E)-4-Methylbenzal[(2,6-diphenyl-3,5-4H-pyran-4-one-diyl)bis(methylene)]dioxime (6a). Colourless
crystals (60% yield), m.p. 128°C; 1H-NMR δ: 2.2 (s, 6H, -CH3), 5.1 (s, 4H, -CH2O-), 6.9-7.9 (m, 18H,
phenyl-H), 8.1 (s, 2H, -N=CH-); IR: 3060, 3035, 2940, 2890, 1640, 1620, 1570, 1480 cm-1; MS: m/z
542; Anal. Calcd. For C35H30N2O4: C, 77.47; H, 5.57; N, 5.16. Found: C, 77.34; H, 5.47; N, 5.02.
(E,E)-4-Methylbenzal[(3,5-diphenyl-2,6-4H-pyran-4-one-diyl)bis(methylene)]dioxime (6b). Colourless
1
oil (61.5% yield); H-NMR δ: 2.15 (s, 6H, -CH3), 5.2 (s, 4H, -CH2O-), 6.9-7.5 (m, 18H, phenyl-H),
8.1 (s, 2H, -N=CH-); IR: 3050, 3020, 2975, 2880, 1640, 1600, 1480, 1440 cm-1; MS: m/z 542; Anal.
Calcd. for C35H30N2O4: C, 77.47; H, 5.57; N, 5.16. Found: C, 77.27; H, 5.49; N, 5.11.
(E,Z)-4-Methylbenzal[(2,6-diphenyl-3,5-4H-pyran-4-one-diyl)bis(methylene)]dioxime (7a). Colourless
1
crystals (11.2% yield), m.p. 138°C; H-NMR δ: 2.3 (s, 6H, -CH3), 5.2 (s, 4H, -CH2O-), 6.9-7.9 (m,
18H, phenyl-H; 1H, -N=CH-), 8.1 (s, 1H, -N=CH-); IR: 3050, 3020, 2940, 2880, 1630, 1570, 1500
cm-1; MS: m/z 542; Anal. Calcd. for C35H30N2O4: C, 77.47; H, 5.57; N, 5.16. Found: C, 77.51; H, 5.42;
N, 5.12.
(E,Z)-4-Methylbenzal[(3,5-diphenyl-2,6-4H-pyran-4-one-diyl)bis(methylene)]dioxime (7b). Colourless
oil (12.3% yield); 1H-NMR δ: 2.2 (s, 6H, -CH3), 5.2 (s, 4H, -CH2O-), 6.9-7.5 (m, 18H, phenyl-H; 1H,
-N=CH-), 8.1 (s, 1H, -N=CH-); IR: 3050, 3010, 2930, 2890, 1645, 1620, 1480 cm-1; MS: m/z 542;
Anal. Calcd. for C35H30N2O4: C, 77.47; H, 5.57; N, 5.16. Found: C, 77.43; H, 5.39; N, 5.18.
References and Notes
†
Presented in part at the 13th International Conference on Organic Synthesis. (Warsaw, Poland),
2000. Book of Abstracts, p. 192.
1. Moriguchi, T.; Matsuura, H.; Itakura, Y.; Katsuki, H.; Saito, H.; Nishiyama, N. Allixin, a
phytoalexin produced by garlic, and its analogs as novel exogenous substances with neurotrophic
activity. Life Sci. 1997, 61, 1413-1420.
2. Murrary, R. D. H. Naturally occurring oxygen-ring compounds. Aromat. Heteroaromat. Chem.
1978, 5, 472-501.
3. Clark, B. P.; Ross, W. J.; Todd, A. 6-Substituted pyranone compounds for pharmaceutical uses.
Ger Offen., 3,012,584; [Chem. Abstr., 1981, 94, P121322f].
4. Clark, B. P.; Ross, W. J.; Todd, A. 5-Substituted pyranone compounds for pharmaceutical uses.
Ger Offen., 3,012,597; [Chem. Abstr., 1981, 94, P83945b].
5. Shahrisa, A.; Tabrizi, R.; Ahsani, H. R. A novel method for the synthesis of 4H-pyran-4-one
derivatives. Org. Prep. & Proced. Int. 2000, 32, 47-55.
6. Shahrisa, A.; Tabrizi, R. Synthesis and characterization of new macrocyclic polyether-diester
ligands containing a 4H-pyran-4-one subcyclic unit. Iran. J. Chem. & Chem. Eng. 1999, 18, 91-
97.

Molecules, 2002, 7
244
7. Yamamura, S.; Nishiyama, S. Synthetic studies on polypropionate-derived 4-pyrone-containing
marine natural products. Bull. Chem. Soc. Jpn. 1997, 70, 2025-2037.
8. Naito, T.; Kobayashi, H.; Ogura, H.; Zama, K. Preparation of pyranone compounds as intermediate
for cephalosporin derivatives. Jpn. Kokai Tokkyo Koho JP 04 91,088; [Chem. Abstr., 1992, 117,
131069m].
9. Allowhn, J.; Brumm, M.; Frenking, G.; Hornivius, M.; Massa, W.; Steubert, F. W.; Wocadlo, S.
Synthese und konformationsanalysen von pyranophanonen und pyrylophanium-verbinung mit
intraannularen substituenten. J. Prakt. Chem. 1993, 335, 503-514.
10. Massa, W.; Schween, M.; Steuber, F. W.; Wocadlo, S. Konformationsanalysen von pyrolytisch
erzeugten [2.2] phanen des 4-pyranons. Chem. Ber. 1990, 123, 1119-1128.
11. Girard, A. In Organic Synthesis Collective; John Wiley & Sons: Chichester (U.K.), 1943; Vol.2, p.
86.
Sample Availability: Available from the authors.
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