New spiro (thio) barbiturates based on cyclohexanone and bicyclo [3.1.1]heptan-6-one by nonconcerted [1+5] cyclo addition reaction and their conformational structures

Article abstract of DOI:10.4314/bcse.v28i3.12

Crossed-aldol condensation reaction of aromatic aldehydes with ketones such as; acetone and cyclohexanone leads to the efficient formation of cross conjugated α,β-unsaturated ketones in excellent yield. The intermolecular and then intramolecular Michael addition reaction of α,β-unsaturated ketones derived from acetone and cyclohexanone with (thio)barbituric acids lead to synthesis new type of 7,11-diaryl-2,4-diazaspiro[5.5]undecane-1,3,5,9-tetraone and 2,4-diaryl-1'H-spiro[bicyclo[3.3.l]nonane-3,5'-pyrimidine]-2',4',6',9(3'H)-tetraone, respectively in good yield. Structure elucidation is carried out by ¹H NMR, ¹³C NMR, FT-IR, UV-Visible, mass spectroscopy and X-ray crystallography techniques. A possible mechanism of the formation is discussed. The structural conformation also demonstrated by coupling constants derived from dihedral angles between vicinal and geminal protons. The ¹H NMR spectra of NH protons of spiro compounds derived from barbituric acid show a broad singlet peak instead, these protons in the spiro compounds derived from thiobarbituric acid show two distinct peaks.

Full text of DOI:10.4314/bcse.v28i3.12

Bull. Chem. Soc. Ethiop. 2014, 28(3), 423-440.
Printed in Ethiopia
DOI: http://dx.doi.org/10.4314/bcse.v28i3.12
ISSN 1011-3924
 2014 Chemical Society of Ethiopia
NEW SPIRO (THIO) BARBITURATES BASED ON CYCLOHEXANONE AND
BICYCLO [3.1.1]HEPTAN-6-ONE BY NONCONCERTED [1+5] CYCLOADDITION
REACTION AND THEIR CONFORMATIONAL STRUCTURES
Nader Noroozi Pesyan1*, Sirous Noori1, Soodabeh Poorhassan1 and Ertan Şahin2
1Faculty of Chemistry, Urmia University, 57159, Urmia, Iran
2Department of Chemistry, Faculty of Science, Atatürk University, 25240 Erzurum, Turkey
(Received July 22, 2013; revised May 7, 2014)
ABSTRACT. Crossed-aldol condensation reaction of aromatic aldehydes with ketones such as; acetone and
cyclohexanone leads to the efficient formation of cross conjugated α,β-unsaturated ketones in excellent yield. The
intermolecular and then intramolecular Michael addition reaction of α,β-unsaturated ketones derived from acetone
and cyclohexanone with (thio)barbituric acids lead to synthesis new type of 7,11-diaryl-2,4-
diazaspiro[5.5]undecane-1,3,5,9-tetraone
and
2,4-diaryl-1'H-spiro[bicyclo[3.3.1]nonane-3,5'-pyrimidine]-
2',4',6',9(3'H)-tetraone, respectively in good yield. Structure elucidation is carried out by 1H NMR, 13C NMR, FT-
IR, UV-Visible, mass spectroscopy and X-ray crystallography techniques. A possible mechanism of the formation
is discussed. The structural conformation also demonstrated by coupling constants derived from dihedral angles
between vicinal and geminal protons. The 1H NMR spectra of NH protons of spiro compounds derived from
barbituric acid show a broad singlet peak instead, these protons in the spiro compounds derived from
thiobarbituric acid show two distinct peaks.
KEY WORDS: Crossed-aldol condensation, Michael addition, [1+5] Cycloaddition, Barbituric acid,
Conformation, Spiro barbiturate
INTRODUCTION
The crossed-aldol condensation reaction is an efficient route for the synthesis of α,α'-
bis(substituted benzylidene)cycloalkanones as precursors for the synthesis of biological
pyrimidine derivatives [1-4] These compounds have gained a lot of attention due to their uses as
agrochemical, pharmaceutical and perfume intermediates [5–8] and as liquid crystal polymer
units [9]. Among these reactions, the aldol condensation reaction is useful for the formation of
carbon–carbon bonds in many kinds of carbonyl compounds [10–12]. Crossed-aldol
condensation can be operated with the aid of strong acids or bases [2, 13]. Several catalytic
methods have been achieved for crossed-aldol condensation [4, 14-31].
Several spiro-(thio)barbituric acid derivatives in which the active methylene carbon of
(thio)barbituric acid is substituted by an unsubstituted cyclobutane or cyclohexane ring [32, 33]
have been synthesized, but no pharmacological data is obtained with these compounds. Spiro
compounds have been reported to possess biological activities that include anti-inflammatory
activity [34], anticonvulsant, CNS depressant [35], narcotic [36], hypotensive, analgesic [37].
Several works have been reported for the synthesis of other spiro barbiturates [38-44].
As we searched in the literature, there are some reports about spiro barbiturates based on
bis-arylideneacetones [36, 45] and no report about spiro barbiturates based on 2,6-bis-
arylidenecyclohexanones. Based on these concepts, in this research, we report a new and facile
route for the synthesis of 5,5-two substituted spiro-barbiturates by the condensation reaction of
N-substituted and unsubstituted (thio)barbituric acids with dibenzalacetone and 2,6-
dibenzylidenecyclohexanone derivatives.
EXPERIMENTAL
General
The drawing and nomenclature of compounds were done by ChemBioDraw Ultra 8.0 version
software. Melting points were measured with a digital melting point apparatus (Electrothermal)
__________
*Corresponding author. E-mail: n.noroozi@urmia.ac.ir ; nnp403@gmail.com

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Nader Noroozi Pesyan et al.
and were uncorrected. IR spectra were determined in the region 4000-400 cm-1 on a NEXUS
1
670 FT IR spectrometer by preparing KBr pellets. The H and 13C NMR spectra were recorded
1
on Bruker 300 FT-NMR at 300 and 75 MHz, respectively (Urmia University, Urmia, Iran). H
and 13C NMR spectra were obtained on solution in DMSO-d6 and/or in CDCl3 as solvents using
TMS as internal standard. The data are reported as (s = singlet, d = doublet, t = triplet, q =
quartet, m = multiplet or unresolved, bs = broad singlet, coupling constant(s) in Hz, integration).
All reactions were monitored by TLC with silica gel-coated plates (EtOAc:cyclohexane, 8:10,
v:v). The mass analysis performed using mass spectrometer (Agilent Technology (HP) type, MS
Model: 5973 Network Mass Selective Detector Electron Impact (EI) 70 eV), ion source
temperature was 230 ºC (Tehran University, Tehran, Iran). The electronic spectra were
performed by T80 UV-Vis (PG Instruments Ltd) spectrometer (Urmia University, Urmia, Iran).
Compounds 3 were synthesized based on reported literature [25]. Compounds 1a-k, 2a', 2c',
4a''-4d'' and used solvents purchased from Merck and Across without further purification.
Synthesis
General procedures for the preparation of 3aa' through 3ka' and 3ab' through 3kb'. In a round
bottom flask equipped with an ice-bath, 2.5 g NaOH dissolved in 20 mL distilled water then
added acetone (1.16 g, 0.02 mol) and benzaldehyde (4.24 g, 0.04 mol) then added 20 mL
ethanol dropwise into the reaction mixture. The reaction progression was completed after 2 h.
The pale yellow precipitate then washed with 10 mL chilled ethanol and recrystallized in
absolute ethanol (yield: 95%, see Table 1).
Table 1. Physical properties of bis-arylideneacetones (3ca'-3ia') and 2,6-bis-arylidenecyclohexanones
(3ab'-3kb').
Entry
Bis-arylideneacetones
M.p. (°C)
Color
(cyclohexanones)
1
2
3
4
5
6
7
8
9
3ca'
3ea'
3fa'
3ga'
3ia'
196-198 (Lit. 192-193 [50])
203-205 (Lit. 211-213 [50])
104-106 (Lit. 104-107 [51])
126-129 (Lit. 121-122 [50])
140-143 (Lit. 141-143 [52])
185-187 (Lit. 188-190 [53])
143-146 (Lit. 147-148 [53])
198-202 (Lit. 201-205 [53])
117-119 (Lit. 117-118 [53])
200-202 (Lit. 203-204 [53])
150-154 [54]
Yellow
Yellow
Pale yellow
Pale yellow
Yellow
Yellow
Yellow
Yellow
Yellow
Yellow
Red
3ab'
3cb'
3eb'
3fb'
3gb'
3ib'
10
11
General procedures for the preparation of 7aa'a'' through 7ka'd'' and 7ab'a'' through 7kb'd''.
In a 50 mL round bottom flask equipped with magnetic stirrer the mixture of 1,3-
dimethylbarbituric acid (1.3 mmol, 0.21 g), dibenzalacetone (1.3 mmol, 0.30 g) and
triethylamine (2.1 mmol, 0.22 g, 0.3 mL) in 10 mL methanol and refluxed for 2-3 h. The yellow
color disappeared and consequently white crystalline solid precipitated, filtered off, washed with
few mL of cold ethanol then dried (0.35 g, 70%).
2,4-Dimethyl-7,11-diphenyl-2,4-diazaspiro[5.5]undecane-1,3,5,9-tetraone (7fa'b'') [45]. White
crystalline solid, m.p. 153-156 °C, IR (KBr, cm-1) 3037 (ar.), 2952 (aliph.), 2923 (aliph.), 1717
1
(C=O), 1675 (C=O), 1450, 1422 (ar. C=C stretch), 1382 (Me bend.), 701(mono subst. ph); H
NMR (300 MHz, CDCl3) δ 2.64 (dd, J = 14.7 Hz, J = 4.5 Hz, 2H, diastereotopic -CH2-), 2.88 (s,
3H, MeN), 3.03 (s, 3H, MeN), 3.75 (t, J = 14.4 Hz, 2H, diastereotopic -CH2-), 4.04 (dd, J = 14.3
Hz, J = 4.2 Hz, 2H, -CH-ph benzylic proton), 7.07-7.28 (m, 10 H, ar.); 13C NMR (75 MHz,
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New spiro (thio)barbiturates based on cyclohexanone and bicyclo[3.1.1]heptan-6-one
425
CDCl3) δ 27.9 (NCH3), 28.3 (NCH3), 42.9 (C8 or C10), 50.5 (C7 or C11), 60.9 (C6), 127.5 (C-ar.),
128.6 (C-ar.), 128.8 (C-ar.), 137.1 (Cipso-ar.), 169.5 (C3), 170.6 (C1 or C5), 176.0 (C1 or C5),
208.2 (C9); MS (m/z, %), 390 (M+, 45), 325 (6), 286 (15), 258 (100, base peak), 235 (12), 173
(10), 146 (45), 129 (20), 104 (55), 77 (25), 51 (10).
7,11-Bis(4-chlorophenyl)-2,4-diazaspiro[5.5]undecane-1,3,5,9-tetraone (7ca'a'') [36]. White
crystalline solid; m.p. 98-100 °C; IR (KBr, cm-1) 3387 (OH and/or NH), 3211 (NH), 3029 (ar.),
1
2839 (aliph.), 1710 (C=O), 1590, 1491, 1408, 1091, 1014, 837, 756, 524 (C-Cl stretch); H
NMR (300 MHz, DMSO-d6) δ 2.44 (dd, J = 14.9 Hz, J = 3.6 Hz, 2H, diastereotopic -CH2-), 3.43
(t, J = 13.8 Hz, 2H, diastereotopic -CH2-, overlapped with DMSO (H2O) peak), 4.01 (dd, J =
13.8 Hz, J = 3.9 Hz, 2H, -CH-ph benzylic proton), 7.10 (d, J = 8.1 Hz, 4H, ar.-H), 7.37 (d, J =
8.1 Hz, 4H, ar.-H), 11.0 (extremely bs, 2H, 2NH); 13C NMR (75 MHz, DMSO-d6) δ 42.8 (C8 or
C10), 48.4 (C7 or C11), 59.1 (C6), 129.2 (C-ar.), 130.1 (C-ar.), 133.2 (C-Cl), 136.9 (Cipso-ar.),
149.2 (C3), 171.0 (C1 or C5), 172.1 (C1 or C5), 207.0 (C9).
7,11-Bis(4-chlorophenyl)-2,4-dimethyl-2,4-diazaspiro[5.5]undecane-1,3,5,9-tetraone (7ca'b'').
White crystalline solid; m.p. 220-222 °C; IR (KBr, cm-1) 3010 (ar.), 2924 (aliph.), 2854 (aliph.),
1
1746 (C=O), 1679 (C=O), 1492, 1421, 1379, 1091, 1015; H NMR (300 MHz, CDCl3) δ 2.59
(dd, J = 14.7 Hz, J = 3.6 Hz, 2H, diastereotopic -CH2-), 2.92 (s, 3H, MeN), 3.06 (s, 3H, MeN),
3.66 (t, 2H, diastereotopic -CH2-), 3.98 (dd, J = 14.1 Hz, J = 3.6 Hz, 2H, -CH-ph benzylic
proton), 7.00 (d, J = 8.1 Hz, 4H, ar.), 7.23 (d, J = 8.1 Hz, 4H, ar.); 13C NMR (75 MHz, CDCl3) δ
28.0 (NCH3), 28.5 (NCH3), 42.8 (C8 or C10), 49.8 (C7 or C11), 60.5 (C6), 128.8 (C-ar.), 129.1 (C-
ar.), 134.6 (C-Cl), 135.4 (Cipso-ar.), 149.3 (C3), 168.7 (C1 or C5), 170.4 (C1 or C5), 207.1 (C9).
7,11-bis(4-chlorophenyl)-3-thioxo-2,4-diazaspiro[5.5]undecane-1,5,9-trione (7ca'c'') [46]. Pale
yellow crystalline solid; m.p. 200 °C (decamps.); IR (KBr, cm-1) 3176 (NH), 2918 (aliph.), 2834
1
(aliph.), 1726 (C=O), 1700 (C=O), 1521, 1492, 1320, 1149, 1014, 831, 519; H NMR (300
MHz, DMSO-d6) δ 2.44 (dd, J = 14.7 Hz, J = 3.6 Hz, 2H, diastereotopic -CH2-), 3.40 (d, J =
13.8 Hz, 2H, diastereotopic -CH2-), 4.00 (dd, J = 13.8 Hz, J = 3.9 Hz, 2H, -CH-ph benzylic
proton), 7.10 (d, J = 8.1 Hz, 4H, ar.), 7.37 (d, J = 8.1 Hz, 4H, ar.), 12.30 (s, 1H, NH), 12.55 (s,
1H, NH); 13C NMR (75 MHz, CDCl3) δ 43.0 (C8 or C10), 48.7 (C7 or C11), 59.7 (C6), 59.7 (C6),
129.3 (C-ar.), 130.1 (C-ar.), 133.3 (C-Cl), 136.7 (Cipso-ar.), 168.7 (C1 or C5), 170.0 (C1 or C5),
177.8 (C3), 206.8 (C9).
7,11-Bis(4-chlorophenyl)-2,4-diethyl-3-thioxo-2,4-diazaspiro[5.5]undecane-1,5,9-trione
(7ca'd'') [46]. Yellow crystalline solid; m.p. 86-90 °C; IR (KBr, cm-1) 3030 (ar.), 2980 (aliph.),
2933 (aliph.), 1706 (C=O), 1673 (C=O), 1492, 1399, 1114, 1092, 856, 518; 1H NMR (300 MHz,
CDCl3) δ 1.12 (t, J = 6.6 Hz, 3H, NCH2Me), 1.25 (t, J = 6.6 Hz, 3H, NCH2Me), 2.60 (dd, J =
14.9 Hz, J = 3.9 Hz, 2H, diastereotopic -CH2-), 3.66 (t, J = 14.4 Hz, 2H, diastereotopic -CH2-),
3.98-4.07 (m, 4H, 2NCH2Me), 4.20-4.30 (m, 2H, -CH-ph benzylic proton), 7.01 (d, J = 8.1 Hz,
4H, ar.), 7.20 (d, J = 8.1 Hz, 4H, ar.); 13C NMR (75 MHz, CDCl3) δ 11.8 (CH3), 11.9 (CH3),
43.0 (NCH2-), 43.3 (NCH2-), 43.7 (C8 or C10), 50.4 (C7 or C11), 60.2 (C6), 129.0 (C-ar.), 129.1
(C-ar.), 134.6 (C-Cl), 135.2 (Cipso-ar.), 166.7 (C1 or C5), 168.6 (C1 or C5), 176.8 (C3), 207.2 (C9).
7,11-Bis(4-bromophenyl)-2,4-diazaspiro[5.5]undecane-1,3,5,9-tetraone (7ea'a''). Pale yellow
crystalline solid; m.p. 220 °C (decomps.); IR (KBr, cm-1) 3418 (OH and/or NH), 3204 (NH),
3097 (ar.), 2844 (aliph.), 1693 (C=O), 1652 (C=O), 1590, 1328, 1074, 1010, 519; 1H NMR (300
MHz, DMSO-d6) δ 2.5 (m, 2H, diastereotopic -CH2-), 3.43 (m, 2H, diastereotopic -CH2-,
overlapped with DMSO (H2O) peak), 3.97 (d, J = 13.8 Hz, 2H, -CH-ph benzylic proton), 7.04
(d, J = 7.8 Hz, 4H, ar.), 7.52 (d, J = 7.8 Hz, 4H, ar.), 11.32 (bs, 2H, 2NH); 13C NMR (75 MHz,
DMSO-d6) δ 42.8 (C8 or C10) 48.5 (C7 or C11), 59.0 (C6), 121.8 (C-Br), 130.5 (C-ar.), 132.2 (C-
ar.), 137.3 (Cipso-ar.), 149.2 (C3), 171.0 (C1 or C5), 172.0 (C1 or C5), 207.0 (C9).
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Nader Noroozi Pesyan et al.
7,11-Bis(4-bromophenyl)-2,4-dimethyl-2,4-diazaspiro[5.5]undecane-1,3,5,9-tetraone (7ea'b'').
White crystalline solid; m.p. 237-239 °C; IR (KBr, cm-1) 3088 (ar.), 2973 (aliph.), 2925 (aliph.),
1
1715 (C=O), 1679 (C=O), 1530, 1378, 1350, 1073, 509; H NMR (300 MHz, CDCl3) δ 2.57
(dd, J = 14.7 Hz, J = 3.9 Hz, 2H, diastereotopic -CH2-), 2.90 (s, 3H, MeN), 3.05 (s, 3H, MeN),
3.64 (t, 2H, diastereotopic -CH2-), 3.97 (dd, J = 14.4 Hz, J = 4.2 Hz, 2H, -CH-ph benzylic
proton), 6.93 (d, J = 8.1 Hz, 4H, ar.), 7.37 (d, J = 8.1 Hz, 4H, ar.); 13C NMR (75 MHz, CDCl3) δ
28.1 (NCH3), 28.5 (NCH3), 42.7 (C8 or C10), 49.8 (C7 or C11), 60.3 (C6), 122.8 (C-Br), 129.2 (C-
ar.), 132.1 (C-ar.), 136.0 (Cipso-ar.), 149.3 (C3), 168.6 (C1 or C5), 170.3 (C1 or C5), 207.0 (C9).
7,11-Bis(4-Bromophenyl)-3-thioxo-2,4-diazaspiro[5.5]undecane-1,5,9-trione (7ea'c'') [46].
Yellow crystalline solid; m.p. 200 °C (decomps.); IR (KBr, cm-1) 3189 (NH), 2919 (aliph.),
1701 (C=O), 1521, 1321, 1148, 1009, 829, 515; 1H NMR (300 MHz, DMSO-d6) δ 2.43 (m, 2H,
diastereotopic -CH2-), 3.46 (m, 2H, diastereotopic -CH2-), 4.00 (dd, J = 13.2 Hz, J = 4.5 Hz, 2H,
-CH-ph benzylic proton), 7.03 (d, J = 8.1 Hz, 4H, ar.), 7.50 (d, J = 8.1 Hz, 4H, ar.), 12.30 (s,
1H, NH), 12.55 (s, 1H, NH); 13C NMR (75 MHz, DMSO-d6) δ 42.9 (C8 or C10), 48.8 (C7 or C11),
59.5 (C6), 121.9 (C-Br), 130.4 (C-ar.), 132.2 (C-ar.), 137.1 (Cipso-ar.), 168.7 (C1 or C5), 170.0 (C1
or C5), 177.8 (C3), 206.7 (C9).
7,11-Bis(4-bromophenyl)-2,4-diethyl-3-thioxo-2,4-diazaspiro[5.5]undecane-1,5,9-trione
(7ea'd'') [46]. Yellow crystalline solid; m.p. 173-175 °C; IR (KBr, cm-1) 3050 (ar.), 2980
1
(aliph.), 2932 (aliph.), 1704 (C=O), 1673 (C=O), 1489, 1398, 1291, 1114, 855, 515; H NMR
(300 MHz, CDCl3) δ 0.90 (t, J = 6.9 Hz, 3H, NCH2Me), 1.11 (t, J = 6.6 Hz, 3H, NCH2Me), 2.60
(dd, J = 15.0 Hz, J = 3.9 Hz, 2H, diastereotopic -CH2-), 3.67 (t, J = 14.4 Hz, 2H, diastereotopic
-CH2-), 3.97-4.18 (m, 4H, 2NCH2Me), 4.20 (m, 2H, -CH-ph benzylic proton), 6.96 (d, J = 8.1
Hz, 4H, ar.), 7.37 (d, J = 8.1 Hz, 4H, ar.); 13C NMR (75 MHz, CDCl3) δ 11.8 (NCH3), 12.0
(NCH3), 42.9 (NCH2-), 43.3 (NCH2-), 43.7 (C8 or C10), 50.5 (C7 or C11), 60.0 (C6), 122.7 (C-Br),
129.5 (C-ar.), 132.0 (C-ar.), 135.7 (Cipso-ar.), 166.7 (C1 or C5), 168.6 (C1 or C5), 176.8 (C3),
207.1 (C9).
7,11-Diphenyl-2,4-diazaspiro[5.5]undecane-1,3,5,9-tetraone (7fa'a'') [36]. White crystalline
solid; m.p. 297-299 °C (decomps.); IR (KBr, cm-1) 3201 (NH), 3087 (ar.), 2928 (aliph.), 2855
1
(aliph.), 1755 (C=O), 1708 (C=O), 1683 (C=O), 1411, 1377, 1242, 704; H NMR (300 MHz,
DMSO-d6) δ 2.42 (d, J = 4.2 Hz, 2H, diastereotopic -CH2-), 3.52 (t, J = 14.1 Hz, 2H,
diastereotopic -CH2-), 3.96 (dd, J = 13.8 Hz, J = 4.5 Hz, 2H, -CH-ph benzylic proton), 7.12 (d, J
= 6.3 Hz, 4H, ar.), 7.26-7.31 (m, 6H, ar.), 11.14 (s, 1H, NH), 11.40 (s, 1H, NH); 13C NMR (75
MHz, DMSO-d6) δ 43.2 (C8 or C10), 49.3 (C7 or C11), 59.3 (C6), 128.2 (C-ar.), 128.5 (C-ar.),
129.2 (C-ar.), 138.0 (Cipso-ar.), 149.2 (C3), 171.3 (C1 or C5), 172.2 (C1 or C5), 207.6 (C9); MS
(m/z, %), 362 (M+, 65), 258 (25), 230 (90), 172 (28), 146 (50), 129 (18), 104 (100, base peak),
77 (40), 51 (15).
7,11-Diphenyl-3-thioxo-2,4-diazaspiro[5.5]undecane-1,5,9-trione (7fa'c'') [46]. Yellow
crystalline solid; m.p. 253-255 °C; IR (KBr, cm-1) 3438 (OH and/or NH), 3140 (NH), 2927
1
(aliph.), 1709 (C=O), 1680 (C=O), 1536, 1333, 1148, 702.9; H NMR (300 MHz, DMSO-d6) δ
2.49 (d, J = 4.5 Hz, 2H, diastereotopic -CH2-), 3.49 (t, J = 14.1 Hz, 2H, diastereotopic -CH2-),
3.96 (dd, J = 14.1 Hz, J = 4.5 Hz, 2H, -CH-ph benzylic proton), 7.11 (d, J = 6.6 Hz, 4H, ar.),
7.29 (d, J = 6.6 Hz, 4H, ar.), 12.15 (s, 1H, NH), 12.43 (s, 1H, NH); 13C NMR (75 MHz, DMSO-
d6) δ 43.3 (C8 or C10), 49.6 (C7 or C11), 59.8 (C6), 128.2 (C-ar.), 128.6 (C-ar.), 129.3 (C-ar.),
137.8 (Cipso-ar.), 169.1 (C1 or C5), 170.3 (C1 or C5), 177.9 (C3), 207.4 (C9).
2,4-Diethyl-7,11-diphenyl-3-thioxo-2,4-diazaspiro[5.5]undecane-1,5,9-trione (7fa'd'') [46].
Yellow crystalline solid; m.p. 130-132 °C; IR (KBr, cm-1) 3033 (ar.), 2979 (aliph.), 2931
1
(aliph.), 1707 (C=O), 1672 (C=O), 1398, 1290, 1113, 700; H NMR (300 MHz, CDCl3) δ 0.87
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New spiro (thio)barbiturates based on cyclohexanone and bicyclo[3.1.1]heptan-6-one
427
(t, J = 7.2 Hz, 3H, NCH2Me), 1.09 (t, J = 6.9 Hz, 3H, NCH2Me), 2.65 (dd, J = 15.0 Hz, J = 3.6
Hz, 2H, diastereotopic -CH2-), 3.75 (t, J = 14.7 Hz, 2H, diastereotopic -CH2-), 3.98-4.09 (m, 4H,
2NCH2Me), 4.18 (q, J = 6.9 Hz, 2H, -CH-ph benzylic proton), 7.02-7.23 (m, 10H, ar.); 13C
NMR (75 MHz, CDCl3) δ 11.7 (CH3), 11.8 (CH3), 43.1 (C8 or C10), 43.2 (C7 or C11), 43.6
(NCH2-), 51.1 (NCH2-), 60.6 (C6), 127.6 (C-ar.), 128.6 (C-ar.), 128.8 (C-ar.), 136.8 (Cipso-ar.),
167.1 (C1 or C5), 169.0 (C1 or C5), 177.3 (C3), 208.2 (C9); MS (m/z, %), 434 (M+, 6), 390 (12),
330 (65), 305 (8), 287 (25), 269 (70), 235 (40), 216 (10), 187 (20), 167 (18), 146 (85), 123 (20),
97 (50), 69 (100, base peak), 41 (27).
7,11-Bis(4-methoxyphenyl)-2,4-diazaspiro[5.5]undecane-1,3,5,9-tetraone
(7ga'a'').
White
crystalline solid; m.p. 150 °C (decomps.); IR (KBr, cm-1) 3228 (NH), 3103 (NH), 2963 (aliph.),
2838 (aliph.), 1710 (C=O), 1611, 1513, 1252, 1031, 836; 1H NMR (300 MHz, DMSO-d6) δ 2.36
(d, J = 13.8 Hz, 2H, diastereotopic -CH2-), 3.46 (t, J = 15.0 Hz, 2H, diastereotopic -CH2-), 3.66
(s, 6H, 2MeO), 3.84 (d, J = 12.9 Hz, 2H, -CH-ph benzylic proton), 6.83 (d, J = 7.2 Hz, 4H, ar.),
7.00 (d, J = 7.2 Hz, 4H, ar.), 7.83 (bs, 2H, 2NH); 13C NMR (75 MHz, DMSO-d6) δ 43.5 (C8 or
C10), 48.5 (C7 or C11), 55.4 (C6), 59.6 (OCH3), 114.4 (C-ar.), 130.0 (C-ar.), 130.7 (Cipso-ar.),
149.7 (C3), 159.2 (C-OCH3), 171.6 (C1 or C5), 172.7 (C1 or C5), 208.0 (C9).
7,11-Bis(4-methoxyphenyl)-2,4-dimethyl-2,4-diazaspiro[5.5]undecane-1,3,5,9-tetraone
(7ga'b''). White crystalline solid; m.p. 65-67 °C; IR (KBr, cm-1) 3020 (ar.), 2956 (aliph.), 2837
1
(aliph.), 1716 (C=O), 1676 (C=O), 1601, 1512, 1423, 1307, 1253, 1032, 833, 753; H NMR
(300 MHz, CDCl3) δ 2.58 (dd, J = 14.4 Hz, J = 3.6 Hz, 2H, diastereotopic -CH2-), 2.91 (s, 3H,
MeN), 3.04 (s, 3H, MeN), 3.76 (s, 6H, 2MeO), 3.63-3.99 (m, 4H, diastereotopic -CH2- and -CH-
ph benzylic proton), 6.75 (d, J = 8.7 Hz, 4H, ar.), 6.99 (d, J = 8.7 Hz, 4H, ar.); 13C NMR (75
MHz, CDCl3) δ 27.9 (NCH3), 28.4 (NCH3), 43.2 (C8 or C10), 49.7 (C7 or C11), 55.2 (C6), 61.3
(OCH3), 114.1 (C-ar.), 128.6 (C-ar.), 130.1 (Cipso-ar.), 159.4 (C3), 165.0 (C-OCH3), 169.2 (C1 or
C5), 170.9 (C1 or C5), 208.5 (C9).
2,4-Diethyl-7,11-bis(4-methoxyphenyl)-3-thioxo-2,4-diazaspiro[5.5]undecane-1,5,9-trione
(7ga'd'') [46]. Yellow crystalline solid; m.p. 120 °C; IR (KBr, cm-1) 3010 (ar.), 2976 (aliph.),
2931 (aliph.), 2837 (aliph.), 1706 (C=O), 1675 (C=O), 1594, 1512, 1399, 1255, 1174, 1105,
1
1031, 833, 532; H NMR (300 MHz, CDCl3) δ 0.91 (t, J = 6.9 Hz, 3H, NCH2Me), 1.11 (t, J =
6.9 Hz, 3H, NCH2Me), 1.24-1.43 (m, 2H, diastereotopic -CH2-), 2.58 (dd, J = 14.7 Hz, J = 3.9
Hz, 2H, diastereotopic -CH2-), 3.71 (t, J = 14.7 Hz, 2H, diastereotopic -CH2-), 3.74 (s, 6H,
2MeO), 3.87-4.08 (m, 4H, 2NCH2Me), 4.20 (dd, J = 13.5 Hz, J = 6.6 Hz, 2H, -CH-ph benzylic
proton), 6.74 (d, J = 8.7 Hz, 4H, ar.), 6.99 (d, J = 8.7 Hz, 4H, ar.); 13C NMR (75 MHz, CDCl3) δ
11.8 (CH3), 11.9 (CH3), 43.2 (C8 or C10), 43.4 (C7 or C11), 43.6 (NCH2-), 50.3 (NCH2-), 55.3
(C6), 61.1 (OCH3), 114.1 (C-ar.), 123.4 (C-ar.), 128.9 (Cipso-ar.), 159.5 (C-OCH3), 167.2 (C1 or
C5), 169.2 (C1 or C5), 177.4 (C3), 208.6 (C9).
4-Bis(4-bromophenyl)-1'H-spiro[bicyclo[3.3.1]nonane-3,5'-pyrimidine]-4',6',9-trione (mixture
of two diastereomers, 7eb'b''). In a 50 mL round bottom flask equipped with magnetically
stirrer the mixture of 1,3-dimethylbarbituric acid (1.3 mmol, 0.21 g), (2E,6E)-2,6-
dibenzylidenecyclohexanone (1.3 mmol, 0.36 g) and triethylamine (2.1 mmol, 0.22 g, 0.3 mL)
in 10 mL ethanol and refluxed for 24 h. The yellow color disappeared and consequently white
crystalline solid precipitated, filtered off, washed with few mL of cold ethanol then dried (0.28
g, 50%). White crystalline solid; m.p. 262 °C; IR (KBr, cm-1) 3010 (ar.), 2925 (aliph.), 2854
1
(aliph.), 1743 (C=O), 1672 (C=O), 1577, 1450, 1383, 751, 461; H NMR (300 MHz, CDCl3) δ
1.2 (m, 1H, diastereotopic -CH2-), 1.60 (m, 2H, diastereotopic -CH2-), 1.79-1.82 (m, 2H,
diastereotopic -CH2-), 2.95 (m, 2H, diastereotopic -CH2-), 3.03 (s, 3H, MeN), 3.21 (s, 3H,
MeN), 3.71 (m, 1H, diastereotopic -CH2-), 3.89 (m, 1H, -CH-ph benzylic proton), 4.43 (m, 1H, -
CH-ph benzylic proton), 7.06-7.80 (m, 10H, ar.); 13C NMR (75 MHz, CDCl3) δ 214.0 (C9),
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Nader Noroozi Pesyan et al.
194.0 (C9), 168.4 (C4' or C6'), 168.1 (C4' or C6'), 151.1 (C2'), 137.0 (Cipso-ar.), 136.2 (Cipso-ar.),
136.0 (C-ar.), 130.4 (C-ar.), 130.3 (C-ar.), 128.8 (C-ar.), 128.6 (C-Br), 128.4 (C-Br), 51.3 (C3 or
C5'), 51.1 (C3 or C5'), 49.2, 40.8 (C1 or C5), 35.6 (C1 or C5), 28.5 (C2 or C4), 28.11 (C2 or C4),
28.06 (C2 or C4), 26.5 (NCH3), 25.1 (NCH3), 23.0 (C6 or C8), 20.5 (C7).
1',3'-Dimethyl-2,4-bis(3-nitrophenyl)-1'H-spiro[bicyclo[3.3.1]nonane-3,5'-pyrimidine]-2',4',6',9
(3'H)-tetraone (mixture of two diastereomers, 7ab'b''). White crystalline solid; m.p. 66-68 °C;
IR (KBr, cm-1) 3082 (ar.), 2953 (aliph.), 2863 (aliph.), 1693 (C=O), 1527, 1434, 1351, 1047,
811, 744, 682; 1H NMR (300 MHz, CDCl3) δ 1.58 (m, 2H, diastereotopic -CH2-), 1.90-2.10 (m,
4H, diastereotopic -CH2-), 2.66 (s, 3H, MeN), 2.82-2.98 (m, 3H, diastereotopic -CH2-), 3.46, (s,
3H, MeN), 4.65 (s, 1H, -CH-ph benzylic proton), 6.97 (s, 1H, ar.), 7.43-8.33 (m, 7H, ar.); 13C
NMR (75 MHz, CDCl3) δ 22.4 (C7), 23.2 (C7), 26.5 (C6 or C8), 28.2 (C6 or C8), 28.4 (C2 or C4),
29.5 (C1 or C5), 64.6 (C3 or C5'), 123.7 (C-ar.), 124.0 (C-ar.), 124.4 (C-ar.), 129.0 (C-ar.), 129.2
(C-ar.), 129.3 (C-ar.), 129.9 (C-ar.), 134.7 (C-ar.), 135.0 (Cipso-ar.), 135.3 (Cipso-ar.), 136.1 (C-
NO2), 137.0 (C-NO2), 146.0 (C2'), 150.0 (C2'), 167.0 (C4' or C6'), 167.2 (C4' or C6'), 190.3 (C9),
213.5 (C9).
2,4-Diphenyl-1'H-spiro[bicyclo[3.3.1]nonane-3,5'-pyrimidine]-2',4',6',9(3'H)-tetraone (7fb'a'').
White crystalline solid; m.p. 150 °C (decomps.); IR (KBr, cm-1) 3423 (NH and/or OH), 3160
(NH), 2988 (aliph.), 2941 (aliph.), 2845, 1684 (C=O), 1583, 1447, 1372, 1158, 776, 697, 528;
1H NMR (300 MHz, DMSO-d6) δ 1.09 (m, 3H, diastereotopic -CH2-), 1.69 (m, 2H,
diastereotopic -CH2-), 2.88 (m, 5H, diastereotopic -CH2- and -CH-ph benzylic proton), 7.03-
7.61 (m, 10H, ar.), 8.50, 8.70 (bs, 1H, NH), 10.00 (s, 1H, NH); 13C NMR (75 MHz, DMSO-d6) δ
21.0 (C7), 22.9 (C6 or C8), 28.3 (C2 or C4), 46.1 (C1 or C5), 51 (C3 or C5'), 129.0 (C-ar.), 129.3
(C-ar.), 130.8 (C-ar.), 136.2 (Cipso-ar.), 162.0 (C2'), 175.0 (C4' or C6'), 189.4 (C4' or C6'), 213.0
(C9).
1',3'-Dimethyl-2,4-diphenyl-1'H-spiro[bicyclo[3.3.1]nonane-3,5'-pyrimidine]-2',4',6',9(3'H)-
tetraone (mixture of two diastereomers, 7fb'b''). White crystalline solid; m.p. 66-68 °C; IR
(KBr, cm-1) 3050 (ar.), 2925 (aliph.), 2854 (aliph.), 1743 (C=O), 1672 (C=O), 1577, 1450, 1383,
1
751; H NMR (300 MHz, CDCl3) δ 0.65-0.80 (m, 1H, diastereotopic -CH2-), 1.60-1.82 (m, 4H,
diastereotopic -CH2-), 2.93-2.97 (m, 2H, diastereotopic -CH2-), 2.99 (s, 3H, MeN), 3.15 (s, 3H,
MeN), 3.71 (t, J = 10.8 Hz, 1H, diastereotopic -CH2-), 3.90 (dd, J = 10.8 Hz, J ≈ 3.5 Hz, 1H,
diastereotopic -CH2-), 4.43 (s, 1H, -CH-ph benzylic proton), 7.35-7.49 (m, 10H, ar.); 13C NMR
(75 MHz, CDCl3) δ 20.5 (C7), 23.0 (C7), 25.1 (C6 or C8), 26.5 (C6 or C8), 28.06 (NCH3), 28.11
(NCH3), 28.5 (C2 or C4), 35.6 (C2 or C4), 40.8 (C1 or C5), 49.2 (C1 or C5), 51.1 (C3 or C5'), 51.3
(C3 or C5'), 128.2 (C-ar.), 128.4 (C-ar.), 128.6 (C-ar.), 128.8 (C-ar.), 130.3 (C-ar.), 130.4 (C-ar.),
136.2 (Cipso-ar.), 137.0 (Cipso-ar.), 151.1 (C2'), 168.1 (C2'), 168.4 (C4' or C6'), 190.4 (C4' or C6'),
215.0 (C9).
2,4-Bis(4-methoxyphenyl)-1',3'-dimethyl-1'H-spiro[bicyclo[3.3.1]nonane-3,5'-pyrimidine]-
2',4',6',9(3'H)-tetraone (7gb'b''). Yellow crystalline solid; m.p. 130-132 °C (decomps.); IR
(KBr, cm-1) 3036 (ar.), 3000 (ar.), 2957 (aliph.), 2935 (aliph.), 1715 (C=O), 1676 (C=O), 1609,
1
1512, 1253, 1180, 1032, 833, 753; H NMR (300 MHz, CDCl3) δ 1.80 (m, 3H, diastereotopic
-CH2-), 2.91 (m, 4H, diastereotopic -CH2-), 3.14-3.35 (m, 1H, diastereotopic -CH2-), 3.39 (s,
3H, MeN), 3.41 (s, 3H, MeN), 3.85 (s, 6H, 2MeO), 3.68-3.91 (m, 1H, -CH-ph benzylic proton),
7.44 (d, J = 7.2 Hz, 4H, ar.), 6.93 (d, J = 7.2 Hz, 4H, ar.); 13C NMR (75 MHz, CDCl3) δ 27.9
(C7), 28.4 (C6 or C8), 41.0 (NCH3), 43.2 (NCH3), 49.7 (C2 or C4), 55.2 (C1 or C5), 55.4 (OCH3),
61.3 (C3 or C5'), 114.1 (C-ar.), 128.6 (C-ar.), 142.7 (Cipso-ar.), 149.8 (C2'), 159.4 (C-OCH3),
169.2 (C4' or C6'), 170.9 (C4' or C6'), 208.4 (C9).
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New spiro (thio)barbiturates based on cyclohexanone and bicyclo[3.1.1]heptan-6-one
429
RESULTS AND DISCUSSION
This article describes the crossed-aldol condensation reaction of aromatic aldehydes (1a-k) with
ketones as: e.g. acetone (2a') and cyclohexanone (2b') then subsequently Michael addition with
(thio)barbituric acids (4a''-4d'') was afforded a new class of spiro compounds 7,11-diaryl-2,4-
diazaspiro[5.5]undecane-1,3,5,9-tetraones (7) (Scheme 1).
O
CHO
MeOH
+
n
2
0 o
C
r.t.
R2 R2
2
R1
1
R2 = H (a')
R2 + R2 = (CH2)3 (b')
n = 0, R1 = m-NO2 (a)
n = 0, R1 = p-CN (b)
n = 0, R1 = p-Cl (c)
n = 0, R1 = 2,4-di-Cl (d)
n = 0, R1 = p-Br (e)
n = 0, R1 = H (f)
O
R2 R2
n
n
n = 0, R1 = p-OMe (g)
n = 0, R1 = p-N(Me)2 (h)
n = 1, R1 = H (i)
R1
R1
3
n = 1, R1 = o-NO2 (j)
n = 1, R1 = p-N(Me)2 (k)
X
R3
N
R3
O
N
4
O
4
reflux,
2-3 hrs
R3 = H, X = O (a'')
X
R3 = Me, X = O (b'')
R3 = H, X = S (c'')
R3 = Et, X = S (d'')
R3
R3
O
N
N
O
Ar
Ar
R2 R2
n
n
O
R2
R2
X
R3
R3
O
N
N
Ar
Ar
n
n
O
O
O
N
N
R1
Ar
Ar
R3
R3
R2 R2
n
Ar =
n
X
5
7
Scheme 1. Crossed-aldol condensation reaction of aromatic aldehydes (1a-k) with ketones (2a'
and 2b') and subsequently reaction with (thio)barbituric acids (4a''–4d'') for the
synthesis of 7.
The reaction of aldehydes 1a-k with acetone 2a' and cyclohexanone 2b' leads to cross-
conjugated aldol condensation products, (1E,4E)-1,5-diarylpenta-1,4-dien-3-ones (3aa'-3ha'),
(2E,6E)-2,6-dibenzylidenecyclohexanones (3ab'-3hb'), (1E,3E,6E,8E)-1,9-diarylnona-1,3,6,8-
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Nader Noroozi Pesyan et al.
tetraen-5-ones (3ia'-3ka') and (2E,6E)-2,6-bis((E)-3-phenylallylidene)cyclohexanones (3ib'-
3kb') (Scheme 1). The reaction between these compounds (3aa'-3ka' through 3ab'-3kb') with
4a''-4d'' were afforded spiro compounds 7. Expectedly, no symmetric zwitterionic type dyes
based on (thio)barbituric acids (5) were obtained. Although, it has been reported the synthesis of
zwitterionic type dyes of barbituric acids (14-16) from the reaction of barbituric acids with
tropolone (11) [47], 4,9-methano[11]annulenone (12) [48] and with 7H-benzo[7]annulen-7-one
(13) [49], respectively (Figure 1).
O
O
O
11
12
13
O
R
O
H
O
Me
N
N
N
O
O
O
N
N
N
O
O
R
O
O
R
O
O
Me
H
R
Me
N
N
N
O
O
O
N
N
N
O
R
O
R
O
Me
15
a: R = Me
b: R = Bu
16
14
a: R = Me
b: R = Et
c: R = Ph
Figure 1. Structures of some zwitterionic type dyes based on barbituric acids [47-49].
Representatively, the mechanism for the formation of 7fa'b'' and/or 7fb'b'' is shown in
Scheme 2. The nucleophilic attack of 1,3-dimethyl barbituric acid 4b'' to β-position of 3fa'
and/or 3fb' as an α,β-unsaturated carbonyl compound (intermolecular Michael addition) [55, 56]
was afforded 6fa'b''[I] and/or 6fb'b''[I] and then formed 6fa'b''[II] and/or 6fb'b''[II]
intermediates. The free-rotation around carbon-carbon single bond in 6fa'b''[II] intermediate
facilitates the second intramolecular Michael addition in the form of 6fa'b''[III] intermediate.
Therefore, intramolecular Michael addition of carbon atom (C-attack) in 6fa'b''[III]
intermediate afforded 2,4-dimethyl-7,11-diphenyl-2,4-diazaspiro[5.5]undecane-1,3,5,9-tetraone
(7fa'b''). In comparison, representatively, the reactivity of 3fb' is lower than that of 3fa' in the
reaction with 4a''-4d'' due to high rigidity and rotational barrier on 6fb'b''[II] than to
6fa'b''[II] intermediate (Scheme 2). For this reason, the reaction of 3fb' with 4a''-4d'' needs to
higher temperature and reaction time to be prolonged (see experimental section).
Representatively, the 1H NMR spectrum of 7fa'b'' shows two singlets for N-CH3 protons at
δ 2.88 and 3.03 ppm, two doublet of doublets at δ 2.65 and 4.05 ppm for two diastereotopic
methylene protons, a triplet at δ 3.75 ppm (essentially, it is doublet of doublets) for benzylic
proton on chiral stereogenic center and a multiplet at δ 7.07-7.28 ppm for aromatic phenyl
protons. 13C NMR spectrum of this compound shows thirteen distinct peaks. One of the
carbonyl peaks was extremely shifted to low field at δ 200.18 ppm that confirms the formation
of saturated ketone (substituted cyclohexanone). The IR spectrum of this compound shows the
C=O frequencies at 1717 and 1675 cm-1 that corresponds to carbonyl groups of spiro
Bull. Chem. Soc. Ethiop. 2014, 28(3)

New spiro (thio)barbiturates based on cyclohexanone and bicyclo[3.1.1]heptan-6-one
431
cyclohexanone and barbituric acid ring moieties, respectively. The UV-Visible spectra of some
cross-conjugated dyes such as 3fa', 3ca' and some corresponding spiro compounds 7fa'b'',
7fa'd'' and 7ca'b'' is shown in Figure 2. Representatively, the 3fa' shows two absorption bonds
at 320 and 384 nm that corresponds to π→π* (K-band) and weak n→π* (R-band), respectively.
O
O
CHO
2
+
1f
3fa' & 3fb'
2a' & 2b'
O
O
H
N
N
Me
Me
O
4b''
O
O
Me
O
Me
Me
N
Me
O
N
N
N
O
O
O
H
O
6fa'b''[II] & 6fb'b''[II]
6fa'b''[I] & 6fb'b''[I]
H
O
O
O
10
11
8
7
9
6
Ph
Ph
Ph
Ph
Ph
Ph
O
O
O
O
H
O
O
5
1
4N
N2
N
N
N
N
Me
Me
3
Me
Me
Me
O
Me
O
O
6fa'b''[III] & 6fb'b''[III]
7fa'b'' & 7fb'b''
Scheme 2. Representatively, proposed mechanism for the formation of 7fa'b'' and/or 7fb'b''
(the rotation mark ( ) is only shown for 6fa'b''[II] intermediate).
In contrast, in 7fa'b'', the allowed π→π* transition was disappeared and the only forbidden
weak n→π* band at 304 nm was observed (see experimental section). Obviously, in dyes 3fa'
and 3ca' the K-band undergoes a small bathochromic shift because of the enone conjugation.
Instead, in 7fa'b'' and 7fa'd'' the K-bank hypsochromically shifted. These data also confirm the
formation of the saturated cyclohexanone (decreasing the conjugated system) in 7fa'b'' and
7fa'd'' as representative. A small absorption at 402 nm for 7fa'd'', corresponds to n→π* band
of thiocarbonyl group (Figure 2).
The proposed mass fragmentation of 7fa'a'' and 7fa'b'' is shown in Scheme 3. The
molecular ion peaks of 7fa'a'' and 7fa'b'' are shown at m/z 362 (65%) and 390 (45%
abundance), respectively. Representatively, the ion molecular of 7fa'a'' cleaved to styrene at
m/z 104 (100% abundance) as a base peak and ion radical fragment of 3-phenyl-6,8-
diazaspiro[3.5]nonane-1,5,7,9-tetraone (A) at m/z 258 (25%). This later fragment (A) converted
to ion radical fragment of 1-phenyl-5,7-diazaspiro[2.5]octane-4,6,8-trione (C) at m/z 230 (90%)
Bull. Chem. Soc. Ethiop. 2014, 28(3)

432
Nader Noroozi Pesyan et al.
Figure 2. UV-Visible spectra of some selected dyes and corresponding spiro compounds.
O
O
Ph
O
O
Ph
Ph
+
O
O
N
N
R3
R3
N
m/z 104 (100%,
base peak)(in 7fa'a'')
m/z 104 (55%)
(in 7fa'b'')
N
O
R3
R3
R3 = H, (A)
O
m/z 258 (25%)
R3 = CH3, (B)
m/z 286 (15%)
R3 = H (7fa'a'')
m/z 362 (65%)
R3 = CH3 (7fa'b'')
m/z 390 (45%)
- CO
Ph
O
- C2H2
R3 = H, (C)
O
m/z 230 (90%)
R3 = CH3, (D)
m/z 258
m/z 51 (15%)
(in 7fa'a'')
m/z 51 (10%)
(in 7fa'b'')
m/z 77 (40%)
(in 7fa'a'')
m/z 77 (25%)
(in 7fa'b'')
N
N
R3
R3
(100%, base peak)
O
- CO
Ph
O
Ph
Ph
- CO
- N2(R3)2
O
N
R3
C
O
N
R3
O
O
m/z 172 (28%)
(in 7fa'a'') G
m/z 172 (5%)
(in 7fa'b'') H
R3 = H, (E)
m/z 202 (5%)
R3 = CH3, (F)
m/z 230 (2%)
m/z 144 (I)
Ph
Ph
Ph
O
+2H
O
OH
m/z 146 (50%) (in 7fa'a'') J
m/z 146 (45%) (in 7fa'b'') K
Scheme 3. Representatively, proposed mass fragmentation of 7fa'a'' and 7fa'b''.
Bull. Chem. Soc. Ethiop. 2014, 28(3)

New spiro (thio)barbiturates based on cyclohexanone and bicyclo[3.1.1]heptan-6-one
433
by loss of carbon monoxide (CO). The twice loss of CO from this fragment generated the
fragment of m/z 202 (E), then the loss of diazene (N2H2) obtained 4-phenylspiro[2.2]pentane-
1,2-dione ion radical (G) at m/z 172 (28%). The ion radical fragment of (2-
phenylcyclopropylidene)methanone (I) at m/z 144 generated from this fragment by loss of CO.
The intramolecular rearrangement of phenylcyclopropylidene)methanone ion radical then
capturing two hydrogen radicals and finally tautomerized to 2-phenylcyclobutanone ion radical
(J) at m/z 146 (50%) (Scheme 3). Similarly, the same fragmentation of 7fa'b'' is also shown in
Scheme 3.
O
O
R3 = H, X = O (a'')
R3 = Me, X = O (b'')
R3 = H, X = S (c'')
R3 = Et, X = S (d'')
Ph
Ph
Ph
Ph
O
O
O
O
(a)
N
N
N
N
R3
R3
R3
R3
X
X
Plane of symmetry Axis of symmetry (C2)
A
B
7fa'a''-d''
R3
O
N
X
R3
X
N
O
Ph
Hc
H
H
Hc
N
R3
N
Ph
H
Ph
R3
Hb
O
(b)
Ph
O
O
Ha
Hb
Ha
O
Plane of symmetry
7fa'a''-d''
CH3
O
N
O
Hc
Ph
N
CH3
Hb
O
(c)
Ph
O
Ha
7fa'b''A
Hb: 2.64 ppm
Hc: 3.75 ppm
Ha: 4.04 ppm
Jbc = 14.7 Hz
Jba = 4.2 Hz
Jca = 14.4 Hz
Jcb = 14.7 Hz
Jac = 14.4 Hz
Jab = 4.2 Hz
Figure 3. Representatively, possible structural conformation of 7fa'a''-d'' (a), the observed
plane of symmetry in 7fa'a''-d'' (b) and the chemical shifts and coupling constants of
assigned protons in 7fa'b''A as representative (c).
Two possible conformers (also diastereomers) of 7fa'a''-d'' is shown in Figure 3a.
Representatively, compound 7fa'b'' can be serves as plane of symmetry (7fa'b''A form) and
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434
Nader Noroozi Pesyan et al.
axis of symmetry, C2 (7fa'b''B form) (Figure 3a). The Newman projection and observed
structural conformers of 7fa'a''-d'' is shown in Figure 3b. Representatively, the predominant
conformer and coupling constants (J) of 7fa'b''A is also shown in Figure 3c. The dependence of
vicinal coupling constants on the dihedral angle, φ, based on Karplus curve – is described [57,
58]. For instance, in 7fa'b''A form, for Ha at δ 4.04 ppm, the dihedral angle of φac and φab are
equals to 180° and 60°, respectively. The corresponding J-values were obtained 14.4 and 4.2
Hz, respectively. For Hb at δ 2.64 ppm, the J-values were obtained 14.7 Hz for two geminal
protons Hb and Hc and 4.2 Hz for vicinal Hb and Ha, respectively (φab = 60°). For Hc, the J-
values were obtained 14.4 and 14.7 Hz for vicinal (Jca) and geminal protons (Jcb), respectively.
O
O
Ar
N
Ar
Ar
N
Ar
N
O
O
H
O
O
N
H
H
H
O
O
O
O
H
O
H
O
H
H
N
N
N
N
O
O
Ar
Ar
Ar
Ar
7A[I]
7[III]
O
O
O
O
Ar
Ar
N
Ar
Ar
N
O
O
O
O
N
N
H
H
H
H
O
O
O
O
H
H
H
H
N
N
N
N
O
O
O
Ar
O
Ar
Ar
Ar
O
O
7[II]
7[VI]
Ar = p-Cl-C6H4 (7ca'a''), p-Br-C6H4 (7ea'a''), p-MeO-C6H4 (7ga'a'')
Scheme 4. Representatively, two intermolecular hydrogen bonds and tautomeric forms of
7ca'a'', 7ea'a'' and 7ga'a''.
These observations indicated that the bulky phenyl substituents lie in equatorial positions in 7
and cyclohexanone ring moiety has chair conformer (Figure 3b,c). In addition, the 1H, 13C
Bull. Chem. Soc. Ethiop. 2014, 28(3)

New spiro (thio)barbiturates based on cyclohexanone and bicyclo[3.1.1]heptan-6-one
435
NMR, IR, mass fragmentation data and conformational analysis confirms the assigned structure
of 7fa'b''A (including a plane of symmetry, σ). These data indicated that representatively,
7fa'a''-7fa'd'' have plane of symmetry and are in 7fa'a''-7fa'd''A forms (Figure 3). No spiro
barbiturates 7fa'a''-7fa'd''B forms consists of axis of symmetry (C2) were observed based on
NMR investigations. The chemical shifts of N-R3 protons to be equivalent in (thio)barbituric
acid ring moiety if the molecule have axis of symmetry (C2).
Another most interesting phenomenon in the spiro-barbiturate derivatives of 4a'' is the
equivalence of the chemical shifts of two NH protons that appeared as an extremely broad
singlet. This phenomenon presumably corresponds to the intermolecular hydrogen bond of NH
protons in the molecule with oxygen atom on amidic carbonyl group of other molecule one
(Scheme 4). Instead, this equivalency of two NH protons was not shown in the spiro-
thiobarbiturate derivatives derived from 4c'' (Figure 4). Representatively, the equivalency of the
NH protons of 7ca'a'' and 7ea'a'' are shown and comparised with the NH protons of 7ca'c'' and
7ea'c'' (thiobarbituric acid derivatives) in Figure 4.
Figure 4. Representatively, expanded 1H NMR spectra of 7ca'a'' (a), 7ea'a'' (b), 7ca'c'' (c) and
7ea'c'' (d) at NH region.
We have developed the reaction of 1a''-1d'' with (2E,6E)-2,6-diarylidenecyclohexanones
(3ab'-3kb') in ethanol in both basic (Et3N) and acidic condition (AcOH). Similar to reaction of
acetone 2a', the reaction between cyclohexanone 2b' with aromatic aldehydes 1a-1k, were
afforded 3ab'-3kb'. The reaction of these dyes with 4a''-4d'' gave 7ab'a''-7kb'a'' through
7ab'd''-7kb'd'' (Scheme 1). Representatively, the reaction of benzaldehyde 1f with
cyclohexanone 2b' afforded 3fb' then its reaction with DMBA 4b'' gave 1',3'-dimethyl-2,4-
diphenyl-1'H-spiro[bicyclo[3.3.1]nonane-3,5'-pyrimidine]-2',4',6',9(3'H)-tetraone (7fb'b''). No
Bull. Chem. Soc. Ethiop. 2014, 28(3)

436
Nader Noroozi Pesyan et al.
symmetrical crossed-conjugated type dye 5-((2E,6E)-2,6-dibenzylidenecyclohexylidene)-1,3-
dimethylpyrimidine-2,4,6(1H,3H,5H)-trione (5fb'b'') and/or its zwitterionic form was observed
(Scheme 5).
EtOH
and/or
AcOH
CHO
O
O
Ph
Ph
2
+
reflux
1f
2b'
3fb'
4b''
Ph
O
O
H
Me
4b''
N
O
N
O
H
Me
H
Ph
O
7fb'b''[III]
Me
Me
O
N
N
O
O
Me
Ph
Ph
O
O
N
6'
5'
4'3'N
9
1'
2'
1
Ph
2
8
3
Me
5fb'b''
Ph
O
5
4
6
H
7
H
7fb'b''
Scheme 5. Representatively, the reaction of benzaldehyde (1f) with cyclohexanone (2b') formed
3fb' and then subsequently reaction mechanism with 1,3-dimethyl barbituric acid
(4b'') formed 7fb'b''.
1
Representatively, the H NMR spectrum of 7fb'b'' shows multiplets at δ 0.65-0.80 ppm
(1H), at δ 1.60-1.82 ppm (4H) and at δ 2.93-2.97 ppm (2H) for diastereotopic protons on spiro
bicyclo scaffold. 1H NMR spectrum of this compound also show two singlets for N-CH3 protons
at δ 2.99 (3H) and 3.15 ppm (3H), a triplet at δ 3.71 ppm (1H, J = 10.8 Hz), a doublet of
doublets at δ 3.90 ppm (1H, J = 10.8 Hz, J ≈ 3.5 Hz), a singlet at δ 4.43 ppm (1H) and a
multiplet at δ 7.35-7.49 ppm for aromatic phenyl protons. Obviously, the 13C NMR spectrum of
this compound shows fifteen distinct peaks. One of the carbonyl peaks was extremely shifted to
low field at δ 215.0 ppm that confirms the formation of saturated ketone (substituted spiro
bicyclo[3.3.1]nonan-9-one scaffold). The IR spectrum of this compound shows the C=O
frequencies at 1743 and 1672 cm-1 that corresponds to carbonyl groups of spiro
bicyclo[3.3.1]nonan-9-one moiety in 7fb'b''. All structures of 7ab'a''-7kb'a'' through 7ab'd''-
7kb'd'' (structures derived from 3ab'-3kb') may have two diastereomers due to having two
1
chiral stereogenic centers. For this reason, the H and 13C NMR spectra of the many of these
compounds are complicated. Possible structural conformations of 7fb'a''-d'' ([I], [II] and [III]
forms) are shown in Figure 5. We have adjourned the conformational studies of these
compounds by means of advanced NMR techniques in the near future.
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New spiro (thio)barbiturates based on cyclohexanone and bicyclo[3.1.1]heptan-6-one
437
R3
N
R3
N
O
O
O
O
X
X
Ph
Ph
N
N
R3
R3
Ph
Ph
O
O
H
H
H
H
(II)
7fb'a''-d'' (I)
R3
N
R3
X
O
X
N
O
H
H
Ph
Ph
N
N
R3
R3
Ph
Ph
O
O
H
H
H
H
O
O
(IV)
(III)
R3 = H, X = O (a'')
R3 = Me, X = O (b'')
R3 = H, X = S (c'')
R3 = Et, X = S (d'')
Figure 5. Representatively, possible structural conformations of 7fb'a''-d''.
X-Ray data for 7ca'b''
For the further study, the crystal structure and packing diagram of compound 7ca'b'' are shown
in Figures 6 and 7, respectively. The cyclohexanone and barbituric acid rings have chair and
nearly planar conformers, respectively. The torsion angle between two phenyls and
cyclohexanone rings obtained in results of 79.93 and 95.57°, respectively.
The summary of crystal date for 7ca'b'': crystal system, space group: tetragonal, P-421c;
unit cell dimensions: a = 21.5533(5), b = 21.5533(5), c = 9.4674(2) Å, α = 90.00, β = 90.00, γ =
90.00, cell volume: 4398.03 Å3; Z = 8. Single crystal of 7ca'b'' was obtained as colorless crystal
by slow evaporation from methanol at room temperature. For the crystal structure determination,
the single-crystal of the compound 7ca'b'' was used for data collection on a four-circle Rigaku
R-AXIS RAPID-S diffractometer (equipped with a two-dimensional area IP detector). The
graphite-monochromatized Mo Kα radiation (λ = 0.71073 Å) and oscillation scans technique
with ∆ω = 5˚ for one image were used for data collection. The lattice parameters were
determined by the least-squares methods on the basis of all reflections with F2 > 2σ(F2).
Integration of the intensities, correction for Lorentz and polarization effects and cell refinement
was performed using CrystalClear (Rigaku/MSC Inc., 2005) software [59]. The structures were
solved by direct methods using SHELXS-97 [60] and refined by a full-matrix least-squares
procedure using the program SHELXL-97 [60]. H-atoms were positioned geometrically and
refined using a riding model. The final difference Fourier maps showed no peaks of chemical
significance. Crystallographic data were deposited in CSD under CCDC-800579 registration
number and are available free of charge upon request to CCDC, 12 Union Road, Cambridge,
UK (fax: +44-1223-336033, e-mail: deposit@ccdc.cam.ac.uk).
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Nader Noroozi Pesyan et al.
Figure 6. Crystal structure of 7ca'b''.
Figure 7. Crystal packing diagram of 7ca'b''.
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New spiro (thio)barbiturates based on cyclohexanone and bicyclo[3.1.1]heptan-6-one
439
CONCLUSION
In summary, the crossed-aldol condensation reaction of aromatic aldehydes bearing electron
donating and electron withdrawing substituents with acetone and cyclohexanone afforded cross-
conjugated type dyes. The inter- and then intramolecular Michael addition reaction of these dyes
with (thio)barbituric acids afforded new type of spiro (thio)barbiturates and bicyclo spiro
(thio)barbiturates, respectively. The structures of spiro (thio)barbiturates derived from acetone
revealed that the spiro cyclohexanone moiety has chair conformer and two phenyl (and/or aryl)
groups on cyclohexanone lies in equatorial position. The crystal structure of the one of spiro
compounds derived from acetone show that the cyclohexanone and barbituric acid rings have
chair and nearly planar conformers, respectively, in solid state.
ACKNOWLEDGEMENTS
We gratefully acknowledge financial support by the Research Council of Urmia University.
Authors also acknowledge to crystallography laboratory management in Atatürk University,
Erzurum, Turkey.
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