Convenient construction of hexahydrobenzo-[b]furan skeleton containing heteroatoms. Choice of Mn(III)- and Ce(IV)-based radical cyclization

Article abstract of DOI:10.3987/com-00-s(i)14

Hexahydrobenzo[b]furan derivatives were efficiently synthesized by the radical cyclization of 1-arylcyclohexenes, 1-phenylcycloheptene, and 1,1-diarylethenes with barbituric acid derivatives or 5,5-dimethyl-1,3-cyclohexanedione (dimedone) using manganese(III) acetate or cerium(IV) ammonium nitrate (CAN).

Full text of DOI:10.3987/com-00-s(i)14

HETEROCYCLES, Vol. 54, No. 1, 2001, pp. 171 - 183, Received, 23rd March, 2000
CONVENIENT CONSTRUCTION OF HEXAHYDROBENZO-
[b]FURAN SKELETON CONTAINING HETEROATOMS.
CHOICE OF Mn(III)- AND Ce(IV)-BASED RADICAL
CYCLIZATION†
Shougo Kajikawa,a Hiroshi Nishino,b* and Kazu Kurosawac
aDepartment of Environmental Science, Graduate School of Science and Technology,
Kumamoto University, Kurokami 2-39-1, Kumamoto 860-8555, Japan
bInstitute for Fundamental Research of Organic Chemistry, Kyushu University, Hakozaki 6-
10-1, Higashi-ku, Fukuoka 812-8581, Japan
cDepartment of Environmental Science, Faculty of Science, Kumamoto University, Kurokami
2-39-1, Kumamoto 860-8555, Japan
Abstract - Hexahydrobenzo[b]furan derivatives were efficiently synthesized by
the radical cyclization of 1-arylcyclohexenes, 1-phenylcycloheptene, and 1,1-
diarylethenes with barbituric acid derivatives or 5,5-dimethyl-1,3-
cyclohexanedione (dimedone) using manganese(III) acetate or cerium(IV)
ammonium nitrate (CAN).
INTRODUCTION
Polycyclic compounds containing the hexahydrobenzo[b]furan skeleton widely exist in nature and it is
known that some have significant biologically active characteristics. For example, morphine and
codeine are well-known as a plant alkaloid,1 norpinguisone, pinuisone, and pinguisenol are antifungal
agents isolated from some bryophyta,2 piperenone shows a distinct antifeeding activity isolated from
plant leaves,3 and (+)-phyllanthocin is an antitumor inhibitor isolated from a plant root.4 Barbituric
acid derivatives have widespread use as a medical hypnotic drug, and are also present in nature as
†Dedicated to Professor Shô Itô, Professor of Tokushima Bunri University, Japan, on his 77th birthday.

pyrimidine derivatives in nucleic acids.5 Further viewpoint of developing biologically active novel
agents and medical supplies, a convenient one-pot synthesis of hexahydrobenzo[b]furans with a fused
pyrimidine ring was desired. With respect to this work, it was reported that the manganese(III)-based
radical cyclization of alkenes with cyclic 1,3-dicarbonyl compounds gave cyclic peroxides,6
hexahydrobenzo[b]furans,7 4,6-dioxo-5,7-diaza-2,3,4,5,6,7-hexahydrobenzo[b]furan,8 and 4-oxo-6-thia-
2,3,4,5,6,7-hexahydrobenzo[b]furan.9 The reaction was quite useful in some cases, however, it
appeared that the yields should be improved in some cases. Recently, Nair et al. showed that
cerium(IV) ammonium nitrate (CAN) was a superior oxidant to the commonly used manganese(III)
acetate for the radical cyclization.10 With these backgrounds, we embarked on the synthesis of the
hexahydrobenzo[b]furans fused pyrimidine ring using the Mn(III)- or Ce(IV)-based one-pot radical
cyclization.
RESULTS AND DISCUSSION
Reaction of Alkenes (1a-g) with Dimedone (2). In order to confirm the usefulness of using
manganese(III) acetate or CAN for the synthesis of the hexahydrobenzo[b]furans, 1-arylcyclohexenes
(1a-c), 1-phenylcycloheptene (1d), and 1,1-diarylethenes (1e-g) were allowed to react with dimedone (2)
according to the literature7,10 and our modified method.11 As a result, the corresponding hexahydro-
benzo[b]furans (3a-g) were obtained in high yields (Scheme 1 and Table 1). It was proved that both
Scheme 1
Ar
O
O
Me
Me
Ar
O
Me
Me
Mn(OAc)3
or CAN
4
5a
1
n
n
H
O
O
1a-d
2
3a-d
Me
Me
Ar
Ar
Me
Me
O
Mn(OAc)3
or CAN
Ar
Ar
O
O
1e-g
a : Ar = Ph, n = 1
b : Ar = 4-Cl-C6H4, n = 1
c : Ar = 4-Me-C6H4, n = 1
d : Ar = Ph, n = 2
3e-g
2
e
f
g
: Ar = Ph
: Ar = 4-Cl-C6H4
: Ar = 4-Me-C6H4

Table 1. Reaction of Alkenes (1a-g) with Dimedone (2) in the Presence of Manganese(III)
Acetate or Cerium(IV) Ammonium Nitratea
Entry Alkene
Oxidant
Mn(III)
Ce(IV)
Mn(III)
Ce(IV)
Mn(III)
Ce(IV)
Mn(III)
Ce(IV)
Mn(III)
Ce(IV)
Mn(III)
Ce(IV)
Mn(III)
Ce(IV)
Molar ratiob
1:2.9:3
Time/min
Product (Yield/%)c
3a (100)
3a (97)
1
2
1a
1a
1b
1b
1c
1c
1d
1d
1e
1e
1f
3
15
3
1:1.2:2.5
1:3.1:3
3
3b (100)
3b (98)
4
1:1.2:2.4
1:3:3
15
3
5
3c (97)
6
1:1.2:2.4
1:3:3.1
15
3
3c (91)
7
3d (93)
8
1:1.2:2.5
1:3.2:3.2
1:1.3:2.6
1:3:3.1
15
3
3d (98)
9
3e (94)d
3e (81)d
3f (94)e
3f (35)e
3g (97)f
3g (87)f
10
11
12
13
14
15
3
1f
1:2:4
15
3
1g
1g
1:3:3
1:1.2:2.4
15
a
The reaction of the alkene (1) with manganese(III) acetate was carried out in boiling acetic acid (10
b
mL), while the reaction of 1 with CAN was conducted in methanol (15 mL) at 0 °C.
The molar ratio
of alkene (1):dimedone (2):oxidant. c Isolated yield based on the amount of the alkene (1) used.
d Benzophenone (5%) was also isolated. e 4,4’-Dichlorobenzophenone (4%) was also isolated. f 4,4’-
Dimethylbenzophenone (2%) was also isolated.
oxidants were very efficient, but the cyclization using manganese(III) acetate was slightly superior
compared to using CAN. This contrasts with the result reported by Nair et al.10 The stereochemistry
of the aryl group at 5a and the H-9a hydrogen in the ring junction of 3b was determined by an NOE
experiment. That is, it was apparent that the cyclohexane fused benzofuran ring had a cis-configuration
since the irradiation of the aromatic proton that appeared at d 7.30 (4H, s) resulted in a 3.2% increase in
the triplet at δ 3.37 (1H, J = 5.2). Moreover, the simple MOPAC calculation of 3a and 3d also
supported the fact that the formation energy of the cis hexahydrobenzo[b]furan was much lower than
that of the trans one.12 Therefore, it seemed that the stereochemistry of the hexahydrobenzo[b]furans
(3a-d) was the cis-configuration. This stereochemistry result was in accord with that of Nair et al.10
Reaction of Alkenes (1a-g) with Barbituric Acid Derivatives (4,7). On the basis of these results,

Scheme 2
R
N
R
N
R
N
O
n
X
R
Ar
Ar
O
X
R
Ar
O
X
R
Mn(OAc)3
or CAN
N
N
N
n
n
H
O
O
O
1a-d
4: R = Me, X = O
7: R = Et, X = S
5a-d
8a-d
6a-c
R
R
O
N
X
R
Ar
Ar
O
N
X
R
Mn(OAc)3
or CAN
Ar
Ar
N
N
O
O
1e-g
4: R = Me, X = O
7: R = Et, X = S
5e-g
8e-g
barbituric acid derivatives (4,7) instead of 2 were allowed to react with the alkenes (1a-g) in the
presence of manganese(III) acetate in glacial acetic acid or CAN in methanol. The cyclization using
CAN gave the corresponding hexahydrobenzo[b]furans (5a-g, 8a-g) in good yields as the sole product,
while the Mn(III)-based reaction afforded the same cyclization products (5a-f, 8a-f) together with
substitution products (6a-c) (Scheme 2 and Table 2).
Especially, the reaction of 1-(4-
methylphenyl)cyclohexene (1c) with 4 in the presence of manganese(III) acetate mainly gave the
substitution product (6c) (Table 2, Entry 9). In addition, the Mn(III)-based reaction of 1,1-bis(4-
methylphenyl)ethene (1g) with 4 or 7 yielded an intractable mixture and no products were isolated
(Table 2, Entries 25 and 27). Therefore, the ability of CAN was quite superior to that of
manganese(III) acetate with respect to the synthesis of the hexahydrobenzo[b]furans fused pyrimidine
skeleton. The predominance for the cyclization using CAN probably depends on the ability to oxidize
the tertiary carbon radical (A) formed during the reaction (Scheme 3).13 That is, CAN (Ce(IV) + e- →
Ce(III), E0 = 1.61 V) is a much stronger oxidant than manganese(III) acetate (Mn(III) + e- → Mn(II), E0
= 1.51 V).14 Therefore, CAN was able to abstract a hydrogen in the intermediate radical (A) at 0 °C
and the concerted cyclization gave the products (5a-d or 8a-d) as the sole product, however,
manganese(III) acetate allowed the oxidation of A under reflux conditions to give the corresponding
tertiary cation (B)15 which should be transformed by deprotonation to cyclic products (5 or 8) and a
substitution product (6). It was deduced that the stereochemisty of 5a-d and 8a-d was also the same as

Table 2. Reaction of Alkenes (1a-g) with Barbituric Acid Derivatives (4,7) in the Presence of
Manganese(III) Acetate or Cerium(IV) Ammonium Nitratea
Entry Alkene Barbituric acid Oxidant Molar ratiob Time/min
Product (Yield/%)c
1
2
1a
1a
1a
1a
1b
1b
1b
1b
1c
1c
1c
1c
1d
1d
1d
1d
1e
1e
1e
1e
1f
4
4
7
7
4
4
7
7
4
4
7
7
4
4
7
7
4
4
7
7
4
4
7
7
4
4
7
7
Mn(III)
Ce(IV)
Mn(III)
Ce(IV)
Mn(III)
Ce(IV)
Mn(III)
Ce(IV)
Mn(III)
Ce(IV)
Mn(III)
Ce(IV)
Mn(III)
Ce(IV)
Mn(III)
Ce(IV)
Mn(III)
Ce(IV)
Mn(III)
Ce(IV)
Mn(III)
Ce(IV)
Mn(III)
Ce(IV)
Mn(III)
Ce(IV)
Mn(III)
Ce(IV)
1:4:4
3
15
3
5a (68)
5a (78)
8a (82)
8a (97)
5b (57)
5b (81)
8b (83)
8b (91)
5c (4)
6a (23)
6b (30)
6c (75)
1:1.2:2.5
1:4:4.1
1:1.2:2.4
1:4:4.1
1:1.2:2.5
1:4:4
3
4
15
3
5
6
15
3
7
8
1:1.2:2.5
1:4:4
15
3
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25 f
26
27 f
28
1:1.2:2.4
1:4:4.1
1:1.2:2.4
1:4.1:4.1
1:1.2:2.4
1:4:4
15
3
5c (73)
8c (66)
8c (85)
5d (82)
5d (81)
8d (83)
8d (87)
5e (65)d
5e (76)d
8e (73)d
8e (79)d
5f (67)e
5f (81)e
8f (72)e
8f (73)e
15
3
15
3
1:1.2:2.4
1:3.1:3.2
1:1.2:2.4
1:3:3.1
1:1.2:2.4
1:3:3
15
3
15
3
15
3
1f
1:2:4.1
1:3:3
15
3
1f
1f
1:2:4
15
3
1g
1g
1g
1g
1:3:3
1:1.2:2.4
1:3:3
15
3
5g (63)g
8g (68)g
1:1.2:2.4
15
a
The reaction of the alkene (1) with manganese(III) acetate was carried out in boiling acetic acid (10
mL), while the reaction of 1 with CAN was conducted in methanol (15 mL) at 0 °C. b The molar ratio
c
of alkene (1):barbituric acid derivatives (4,7):oxidant.
Isolated yield based on the amount of the
d
e
alkene (1) used.
Benzophenone (4-6%) was also isolated.
4,4’-Dichlorobenzophenone (2-10%)
was also isolated. f The reaction gave an intractable mixture and the corresponding products were not
isolated. g 4,4’-Dimethylbenzophenone (2-6%) was also isolated.

Scheme 3
R
N
Ar
n
O
X
R
CAN
5a-d
8a-d
1a-d
4 or 7
MeOH/0 °C
N
H
O
CAN
Mn(OAc)3 AcOH/boiling
A
R
R
N
Ar
Ar
O
O
N
X
R
X
R
Mn(OAc)3
5a-d
8a-d
6a-c
N
N
AcOH
boiling
n
n
H
H
O
O
A
B
that of 3a-d since the NOE experiments of 5b and 8b revealed similar results to that of 3b (see
EXPERIMENTAL).
CONCLUSION
Nineteen new hexahydrobenzo[b]furans (3b-g, 5a-d,f,g, 8a-g) were synthesized in one-pot by the
convenient Mn(III)- or Ce(IV)-based radical cyclization of alkenes (1a-g) with dimedone (2) and
barbituric acid derivatives (4 and 7). In the reaction with the barbituric acid derivatives (4 and 7), the
ability of CAN was demonstrated by the radical cyclization. Photo-induced benzannulation of these
hexahydrobenzo[b]furans obtained by the radical cyclization gave polycyclic naphthalene derivatives in
high yields.16
EXPERIMENTAL
Measurements. All of the NMR spectra were recorded on a JNM EX400 FT NMR spectrometer at
400 MHz for 1H and at 100 MHz for 13C, a JNM-AL 300 FT NMR spectrometer at 300 MHz for 1H and
13
1
13
at 75 MHz for C, or a JNM EX90 FT NMR spectrometer at 90 MHz for H and at 22.5 MHz for C
with tetramethylsilane as the internal standard. Chemical shifts are shown in d and coupling constants
in Hz. The IR spectra were measured using either a Paragon 1000 FT IR spectrophotometer or a
JASCO A-102 IR spectrophotometer. The IR spectral data are expressed in cm-1. The MS spectra
were measured on either a Shimadzu GCMS QP2000GF or a JMS-BU20 mass spectrometer. All of the
melting points were determined with a Yanaco MP-J3 micromelting-point apparatus and are uncorrected.
Elemental analyses were performed by the Center of Instrumental Analysis, Kumamoto University,
Kumamoto, Japan.

Materials. Manganese(II) acetate tetrahydrate, Mn(OAc)2•4H2O, and cerium(IV) ammonium nitrate
were purchased from Wako Pure Chemical Ind., Ltd., and were used as received. Manganese(III)
acetate dihydrate, Mn(OAc)3•2H2O, was prepared according to the method described in the literature.17
The 1-arylcycloalkenes (1a-d) and 1,1-diarylethenes (1e-g) were prepared by dehydration of the
corresponding alcohols which were synthesized by the Grignard reaction of cycloalkanones and
substituted acetophenones with arylmagnesium bromides. Dimedone (2) and 1,3-dimethylbarbituric
acid (4) were purchased from Tokyo-Kasei Co., Ltd., and 1,3-diethyl-2-thiobarbituric acid (7) was
purchased from Aldrich Chemical Co., Inc., and were used as received.
Manganese(III)-Based Radical Cyclization of Alkenes (1a-g) with Dimedone (2) or Barbituric Acid
Derivatives (4,7). To a boiled solution of the alkene (1) (1 mmol) in glacial acetic acid (10 mL),
dimedone (2) or the barbituric acid derivative (4 or 7) and then manganese(III) acetate dihydrate were
added. The solution was heated under reflux with stirring. The reaction time and the molar ratio of
1:2,4 or 7:manganese(III) acetate are shown in Tables 1 and 2. The dark-brown color of Mn(III)
disappeared within 3 min. Water (60 mL) was added, and the aqueous mixture was extracted with
dichloromethane (3 x 20 mL). The combined extracts were successively washed with water and a
saturated aqueous solution of sodium hydrogencarbonate, and then dried over anhydrous magnesium
sulfate. The dried extract was filtered and concentrated to dryness. The products were separated by
silica gel TLC (Wakogel B-10 or Merck Kieselgel 60F254) using chloroform or ether-hexane (5:5-8:2
v/v) as the developing solvent. Analytical samples were further purified by recrystallization from the
appropriate solvent mentioned below except for the liquid products.
Cerium(IV)-Based Radical Cyclization of Alkenes (1a-g) with Dimedone (2) or Barbituric Acid
Derivatives (4,7). To an ice-cooled solution of the alkene (1) (1 mmol) and dimedone (2) or the
barbituric acid derivative (4 or 7) in methanol (5 mL), a solution of CAN in methanol (10 mL) was
added dropwise. The solution was stirred at 0 °C. The reaction time and the molar ratio of 1:2,4 or
7:CAN are shown in Tables 1 and 2. The reddish brown color of CAN disappeared within 15 min.
Water (60 mL) was added, and the mixture was then extracted with dichloromethane (3 x 20 mL). The
combined extract was washed with brine, and then dried over anhydrous magnesium sulfate. The
extract was filtered and concentrated to dryness. The products were separated by silica gel TLC
(Wakogel B-10 or Merck Kieselgel 60F254) using chloroform or diethyl ether-hexane (5:5-8:2 v/v) as the
developing solvent. Analytical samples were further purified by recrystallization from the appropriate
solvent mentioned below except for the liquid products.
3,3-Dimethyl-5a-phenyl-1,2,3,4,5a,6,7,8,9,9a-decahydrodibenzofuran-1-one (3a):
Light yellow
liquid10; IR (CHCl3) 1627 (C=O); 1H NMR (300 MHz, CDCl3) 7.39-7.21 (5H, m, arom H), 3.44 (1H, tt,
J = 5.1, 1.5 Hz, CH), 2.34 (2H, d, J = 1.5 Hz, H-4), 2.18 (2H, s, H-2), 2.04-1.90 (4H, m, 2 x CH2), 1.63-
1.45 (4H, m, 2 x CH2), 1.13 (3H, s, CH3), 1.07 (3H, s, CH3); 13C NMR (75 MHz, CDCl3) 194.8 (C=O),
175.3 (=C-O), 146.3 (arom C), 128.3 (2C), 127.3, 124.2 (2C) (arom CH), 115.1 (C-9b), 94.0 (C-5a),
51.2 (CH2), 44.3 (CH), 37.9 (CH2), 34.1 (C-3), 33.9 (CH2), 29.2, 28.2 (CH3), 24.1, 18.0, 17.9 (CH2); MS
m/z (rel intensity) 296 (M+, 18), 234 (11), 174 (22), 145 (42), 130 (39), 105 (82), 91 (52), 85 (76), 83
(100), 77 (41).
(5aS*,9aS*)-5a-(4-Chlorophenyl)-3,3-dimethyl-1,2,3,4,5a,6,7,8,9,9a-decahydrodibenzofuran-1-one
1
(3b): Colorless microcrystals (from CH2Cl2-hexane), mp 105-108 °C; IR (CHCl3) 1628 (C=O); H

NMR (300 MHz, CDCl3) 7.30 (4H, s, arom H), 3.37 (1H, tt, J = 5.1, 1.5 Hz, CH), 2.38 (2H, d, J = 1.5
Hz, H-4), 2.19 (2H, s, H-2), 2.04-1.85 (4H, m, 2 x CH2), 1.64-1.44 (4H, m, 2 x CH2), 1.13 (3H, s, CH3),
13
1.08 (3H, s, CH3); C NMR (75 MHz, CDCl3) 194.8 (C=O), 175.2 (=C-O), 144.9, 133.1 (arom C),
128.4 (2C), 125.7 (2C) (arom CH), 115.1 (C-9b), 93.5 (C-5a), 51.1 (CH2), 44.3 (CH), 37.9 (CH2), 34.1
(C-3), 33.9 (CH2), 29.1, 28.1 (CH3), 24.2, 18.0, 17.9 (CH2); MS m/z (rel intensity) 330 (M+, 100), 166
(59), 164 (93), 129 (71), 83 (69). Anal. Calcd for C20H23O2Cl: C, 72.61; H, 7.01. Found: C,
72.44; H, 7.18. HRMS Found: m/z 330.1397. Calcd for C20H23O2Cl: M, 330.1387.
5a-(4-Methylphenyl)-3,3-dimethyl-1,2,3,4,5a,6,7,8,9,9a-decahydrodibenzofuran-1-one (3c):
1
Colorless plates (from CH2Cl2-hexane), mp 92-94 °C; IR (CHCl3) 1625 (C=O); H NMR (300 MHz,
CDCl3) 7.28-7.13 (4H, m, arom H), 3.43 (1H, tt, J = 5.1, 1.5 Hz, CH), 2.37 (2H, d, J = 1.5 Hz, H-4),
2.33 (3H, s, CH3), 2.19 (2H, s, H-2), 2.06-1.84 (4H, m, 2 x CH2), 1.65-1.41 (4H, m, 2 x CH2), 1.13 (3H,
s, CH3), 1.08 (3H, s, CH3); 13C NMR (75 MHz, CDCl3) 194.9 (C=O), 175.4 (=C-O), 143.3, 137.1 (arom
C), 129.0 (2C), 124.2 (2C) (arom CH), 115.2 (C-9b), 94.1 (C-5a), 51.2 (CH2), 44.3 (CH), 38.0 (CH2),
34.1 (C-3), 33.9 (CH2), 29.2, 28.2 (CH3), 24.2 (CH2), 21.0 (CH3), 18.1, 18.0 (CH2); MS m/z (rel
intensity) 310 (M+, 81), 158 (30), 144 (100), 129 (47). Anal. Calcd for C21H26O2: C, 81.25; H, 8.44.
Found: C, 81.46; H, 8.35.
3,3-Dimethyl-5a-phenyl-1,2,3,4,5a,7,8,9,10,10a-decahydro-6H-cyclohepta[b]benzofuran-1-one
1
(3d): Light yellow liquid; IR (CHCl3) 1628 (C=O); H NMR (300 MHz, CDCl3) 7.37-7.20 (5H, m,
arom H), 3.59 (1H, ddt, J = 2.9, 6.2, 1.7 Hz,CH), 2.40 (2H, d, J = 1.7 Hz, H-4), 2.36-1.78 (4H, m, 2 x
CH2), 2.19 (2H, s, H-2), 1.74-1.29 (6H, m, 3 x CH2), 1.15 (3H, s, CH3), 1.08 (3H, s, CH3); 13C NMR (75
MHz, CDCl3) 194.5 (C=O), 174.1 (=C-O), 148.1 (arom C), 128.3 (2C), 127.1, 123.7 (2C) (arom CH),
113.8 (C-10b), 98.1 (C-5a), 51.2 (CH2), 50.6 (CH), 40.8, 37.8 (CH2), 33.9 (C-3), 31.2, 29.3 (CH2), 29.3,
28.3 (CH3), 26.3, 24.2 (CH2); MS m/z (rel intensity) 310 (M+, 100), 219 (39), 165 (37), 91 (39), 83 (36).
HRMS Found: m/z 310.1950. Calcd for C21H26O2: M, 310.1933.
6,6-Dimethyl-2,2-diphenyl-2,3,4,5,6,7-hexahydrobenzo[b]furan-4-one (3e):
Colorless needles
1
(from CH2Cl2-hexane), mp 121-122 °C; IR (CHCl3) 1630 (C=O); H NMR (90 MHz, CDCl3) 7.67-6.90
(10H, m, arom H), 3.56 (2H, t, J = 1.7 Hz, H-3), 2.39 (2H, t, J = 1.7 Hz, H-7), 2.20 (2H, s, H-5), 1.05
(6H, s, 2 x CH3); 13C NMR (22.5 MHz, CDCl3) 193.9 (C=O), 174.0 (C-7a), 144.1 (2C) (arom C), 128.0
(4C), 127.3 (2C), 125.2 (4C) (arom CH), 110.8 (C-3a), 95.2 (C-2), 50.5 (C-3), 40.1 (C-5), 37.5 (C-7),
33.7 (C-6), 28.2 (2 x CH3); MS m/z (rel intensity) 318 (M+, 100), 300 (47), 220 (50), 192 (49), 191 (97),
165 (48), 83 (93). Anal. Calcd for C22H22O2: C, 82.99; H, 6.96. Found: C, 82.75; H, 6.87.
2,2-Bis(4-chlorophenyl)-6,6-dimethyl-2,3,4,5,6,7-hexahydrobenzo[b]furan-4-one (3f):
Colorless
1
microcrystals (from CH2Cl2-hexane), mp 99-101 °C; IR (CHCl3) 1634 (C=O); H NMR (300 MHz,
CDCl3) 7.32-7.24 (8H, m, arom H), 3.49 (2H, t, J = 1.7 Hz, H-3), 2.44 (2H, t, J = 1.7 Hz, H-7), 2.25 (2H,
s, H-5), 1.12 (6H, s, 2 x CH3); 13C NMR (75 MHz, CDCl3) 194.4 (C=O), 174.1 (C-7a), 142.6 (2C), 133.9
(2C) (arom C), 128.7 (4C), 127.0 (4C) (arom CH), 111.2 (C-3a), 94.5 (C-2), 50.9 (C-3), 40.4 (C-5), 37.7
(C-7), 34.2 (C-6), 28.7 (2 x CH3); MS m/z (rel intensity) 386 (M+, 28), 369 (31), 139 (27), 83 (100).
Anal. Calcd for C22H20O2Cl2: C, 68.23; H, 5.20. Found: C, 68.47; H, 5.24.
2,2-Bis(4-methylphenyl)-6,6-dimethyl-2,3,4,5,6,7-hexahydrobenzo[b]furan-4-one (3g): Colorless
1
needles (from CH2Cl2-hexane), mp 124-125 °C; IR (CHCl3) 1631 (C=O); H NMR (300 MHz, CDCl3)
7.24-7.10 (8H, m, arom H), 3.53 (2H, t, J = 1.7 Hz, H-3), 2.41 (2H, t, J = 1.7 Hz, H-7), 2.30 (6H, s, 2 x
CH3), 2.22 (2H, s, H-5), 1.10 (6H, s, 2 x CH3); 13C NMR (75 MHz, CDCl3) 194.5 (C=O), 174.6 (C-7a),

141.7 (2C), 137.4 (2C) (arom C), 129.0 (4C), 125.6 (4C) (arom CH), 111.3 (C-3a), 95.7 (C-2), 50.9 (C-
3), 40.4 (C-5), 37.8 (C-7), 34.1 (C-6), 28.7 (2 x CH3), 21.0 (2 x CH3); MS m/z (rel intensity) 346 (M+,
59), 328 (94), 219 (100), 83 (61). Anal. Calcd for C24H26O2: C, 83.20; H, 7.56. Found: C, 83.32;
H, 7.64.
2,4-Dimethyl-5a-phenyl-2,4-diaza-1,2,3,4,5a,6,7,8,9,9a-decahydrodibenzofuran-1,3-dione (5a):
Colorless liquid; IR (CHCl3) 1702, 1658 (C=O); 1H NMR (300 MHz, CDCl3) 7.44-7.28 (5H, m, arom H),
3.72 (1H, t, J = 5.0 Hz, CH), 3.44 (3H, s, NCH3), 3.29 (3H, s, NCH3), 2.17-1.91 (4H, m, 2 x CH2), 1.66-
1.51 (4H, m, 2 x CH2); 13C NMR (75 MHz, CDCl3) 161.0, 160.4 (C=O), 151.7 (C-4a), 144.3 (arom C),
128.5 (2C), 128.0, 124.3 (2C) (arom CH), 96.9 (C-9b), 89.7 (C-5a), 44.6 (CH), 34.3 (CH2), 29.5, 27.8
(NCH3), 24.3, 18.4, 17.9 (CH2); MS m/z (rel intensity) 312 (M+, 100), 182 (80), 157 (88), 156 (88), 130
(42). HRMS Found: m/z 312.1477. Calcd for C18H20N2O3: M, 312.1474.
(5aS*,9aS*)-5a-(4-Chlorophenyl)-2,4-dimethyl-2,4-diaza-1,2,3,4,5a,6,7,8,9,9a-decahydrodibenzo-
furan-1,3-dione (5b): Colorless microcrystals (from ether), mp 158-160 °C; IR (CHCl3) 1703, 1658
(C=O); 1H NMR (300 MHz, CDCl3) 7.38-7.32 (4H, m, arom H), 3.67 (1H, t, J = 5.0 Hz, CH), 3.45 (3H,
13
s, NCH3), 3.29 (3H, s, NCH3), 2.17-1.89 (4H, m, 2 x CH2), 1.66-1.51 (4H, m, 2 x CH2); C NMR (75
MHz, CDCl3) 160.8, 160.3 (C=O), 151.7 (C-4a), 142.9, 133.8 (arom C), 128.7 (2C), 125.9 (2C) (arom
CH), 96.3 (C-9b), 89.5 (C-5a), 44.6 (CH), 34.2 (CH2), 29.5, 27.8 (NCH3), 24.2, 18.3, 17.9 (CH2); MS
m/z (rel intensity) 346 (M+, 69), 190 (77), 182 (100), 157 (77). Anal. Calcd for C18H19N2O3Cl: C,
62.34; H, 5.52; N, 8.08. Found: C, 62.62; H, 5.78; N, 8.20. HRMS Found: m/z 346.1093. Calcd
for C18H19N2O3Cl: M, 346.1084.
The irradiation of the top of the aromatic proton that appeared at δ 7.38-7.32 resulted in a 3.3% increase
in the triplet at δ 3.67. This was supported by the fact that the stereochemistry of the aryl group and the
H-9a hydrogen involved the syn configuration.
5a-(4-Methylphenyl)-2,4-dimethyl-2,4-diaza-1,2,3,4,5a,6,7,8,9,9a-decahydrodibenzofuran-1,3-
dione (5c): Colorless microcrystals (from diethyl ether), mp 102-104 °C; IR (CHCl3) 1702, 1656
(C=O); 1H NMR (300 MHz, CDCl3) 7.32-7.16 (4H, m, arom H), 3.71 (1H, t, J = 5.0 Hz, CH), 3.43 (3H,
s, NCH3), 3.28 (3H, s, NCH3), 2.33 (3H, s, CH3), 2.17-1.88 (4H, m, 2 x CH2), 1.64-1.49 (4H, m, 2 x
CH2); 13C NMR (75 MHz, CDCl3) 161.0, 160.4 (C=O), 151.7 (C-4a), 141.2, 137.8 (arom C), 129.2 (2C),
124.4 (2C) (arom CH), 96.9 (C-9b), 89.6 (C-5a), 44.6 (CH), 34.2 (CH2), 29.4, 27.7 (NCH3), 24.3 (CH2),
21.0 (CH3), 18.5, 18.1 (CH2); MS m/z (rel intensity) 326 (M+, 88), 170 (100), 157 (72), 144 (61). Anal.
Calcd for C19H22N2O3: C, 69.92; H, 6.79; N, 8.58. Found: C, 70.14; H, 7.04; N, 8.82. HRMS
Found: m/z 326.1667. Calcd for C19H22N2O3: M, 326.1630.
2,4-Dimethyl-5a-phenyl-2,4-diaza-1,2,3,4,5a,7,8,9,10,10a-decahydro-6H-cyclohepta[b]benzofuran-
1,3-dione (5d): Colorless microcrystals (from ether), mp 188-190 °C; IR (CHCl3) 1702, 1664 (C=O);
1H NMR (300 MHz, CDCl3) 7.41-7.24 (5H, m, arom H), 3.86 (1H, dd, J = 2.9, 6.9 Hz, CH), 3.47 (3H, s,
NCH3), 3.27 (3H, s, NCH3), 2.28-1.96 (4H, m, 2 x CH2), 1.74-1.41 (6H, m, 3 x CH2); 13C NMR (75 MHz,
CDCl3) 160.0, 159.6 (C=O), 151.7 (C-4a), 146.1 (arom C), 128.5 (2C), 127.7, 123.8 (2C) (arom CH),
100.9 (C-10b), 88.9 (C-5a), 50.7 (CH), 40.8, 31.0, 29.4 (CH2), 29.4, 27.7 (NCH3), 26.3, 23.9 (CH2); MS
m/z (rel intensity) 326 (M+, 100), 170 (45). Anal. Calcd for C19H22N2O3: C, 69.92; H, 6.79; N, 8.58.
Found: C, 70.14; H, 6.92; N, 8.59. HRMS Found: m/z 326.1641. Calcd for C19H22N2O3: M,
326.1630.
5,7-Dimethyl-2,2-diphenyl-5,7-diaza-2,3,4,5,6,7-hexahydrobenzo[b]furan-4,6-dione (5e):

Colorless needles (from CH2Cl2-hexane), mp 190-191 °C (lit.,8 mp 190-191 °C); IR (CHCl3) 1705, 1663
(C=O); 1H NMR (90 MHz, CDCl3) 7.50-7.15 (10H, m, arom H), 3.80 (2H, s, CH2), 3.45 (3H, s, NCH3),
3.29 (3H, s, NCH3); 13C NMR (22.5 MHz, CDCl3) 159.9, 159.8 (C=O), 151.3 (C-7a), 142.6 (2C) (arom
C), 128.3 (4C), 128.0 (2C), 125.4 (4C) (arom CH), 97.3 (C-3a), 85.6 (C-2), 40.3 (CH2), 29.3, 27.7
(NCH3); MS m/z (rel intensity) 334 (M+, 100), 319 (43), 220 (66), 205 (67), 192 (49), 191 (67), 178 (42).
2,2-Bis(4-chlorodiphenyl)-5,7-dimethyl-5,7-diaza-2,3,4,5,6,7-hexahydrobenzo[b]furan-4,6-dione
1
(5f): Colorless needles (from CH2Cl2-hexane), mp 182-184 °C; IR (CHCl3) 1708, 1666 (C=O); H
NMR (300 MHz, CDCl3) 7.36-7.26 (8H, m, arom H), 3.75 (2H, s, CH2), 3.47 (3H, s, NCH3), 3.31 (3H, s,
NCH3); 13C NMR (75 MHz, CDCl3) 160.0, 159.9 (C=O), 151.5 (C-7a), 141.0 (2C), 134.7 (2C) (arom C),
128.9 (4C), 127.1 (4C) (arom CH), 96.5 (C-3a), 85.7 (C-2), 40.5 (CH2), 29.7, 28.1 (NCH3); MS m/z (rel
intensity) 402 (M+, 100), 273 (40), 225 (57), 189 (48), 176 (43), 94 (42). Anal. Calcd for
C20H16N2O3Cl2: C, 59.57; H, 4.00; N, 6.95. Found: C, 59.39; H, 4.04; N, 6.87.
2,2-Bis(4-methyldiphenyl)-5,7-dimethyl-5,7-diaza-2,3,4,5,6,7-hexahydrobenzo[b]furan-4,6-dione
1
(5g): Colorless microcrystals (from ether), mp 120-122 °C; IR (CHCl3) 1704, 1661 (C=O); H NMR
(300 MHz, CDCl3) 7.25-7.15 (8H, m, arom H), 3.77 (2H, s, CH2), 3.45 (3H, s, NCH3), 3.31 (3H, s,
NCH3), 2.34 (6H, s, 2 x CH3); 13C NMR (75 MHz, CDCl3) 160.3, 160.2 (C=O), 151.7 (C-7a), 140.1 (2C),
138.3 (2C) (arom C), 129.2 (4C), 125.7 (4C) (arom CH), 97.9 (C-3a), 86.0 (C-2), 40.6 (CH2), 29.7, 28.0
(NCH3), 21.0 (2 x CH3); MS m/z (rel intensity) 362 (M+, 100), 347 (83), 233 (49). Anal. Calcd for
C22H22N2O3: C, 72.91; H, 6.12; N, 7.73. Found: C, 73.01; H, 6.36; N, 7.80. HRMS Found: m/z
362.1624. Calcd for C22H22N2O3: M, 362.1630.
5-(2-Phenyl-2-cyclohexenyl)-1,3-dimethylbarbituric Acid (6a): Yellow liquid; IR (CHCl3) 1678
(C=O); 1H NMR (300 MHz, CDCl3) 7.32-7.17 (5H, m, arom H), 5.97-5.93 (1H, m, alkenic H), 3.87-3.79
(1H, m, CH), 3.48 (1H, d, J = 3.0 Hz, H-5), 3.15 (3H, s, NCH3), 3.09 (3H, s, NCH3), 2.22-2.16 (2H, m,
13
CH2), 2.03-1.56 (4H, m, 2 x CH2); C NMR (75 MHz, CDCl3) 168.3, 167.8, 151.2 (C=O), 141.4
(alkenic CH), 138.0 (arom C), 130.3 (alkenic C), 128.3 (2C), 127.2, 126.9 (2C) (arom CH), 51.5 (CH),
41.5 (C-5), 28.2 (2 x NCH3), 27.8, 25.5, 21.0 (CH2); MS m/z (rel intensity) 335 (M++Na, 28), 157 (99),
156 (100). FABHRMS (CHCl3-NBA-NaI) Found: m/z 335.1354. Calcd for C18H20N2O3Na: M,
335.1371.
5-[2-(4-Chlorophenyl)-2-cyclohexenyl]-1,3-dimethylbarbituric Acid (6b):
Yellow liquid; IR
1
(CHCl3) 1681 (C=O); H NMR (300 MHz, CDCl3) 7.30-7.21 (4H, m, arom H), 5.98-5.94 (1H, m,
alkenic H), 3.79-3.71 (1H, m, CH), 3.49 (1H, d, J = 3.0 Hz, H-5), 3.21 (3H, s, NCH3), 3.14 (3H, s,
NCH3), 2.21-2.14 (2H, m, CH2), 1.96-1.57 (4H, m, 2 x CH2); 13C NMR (75 MHz, CDCl3) 168.4, 167.2,
151.3 (C=O), 139.9 (alkenic C), 137.1, 132.9 (arom C), 130.6 (alkenic CH), 128.5 (2C), 128.3 (2C)
(arom CH), 51.0 (CH), 41.1 (C-5), 28.4, 28.2 (NCH3), 26.7, 25.4, 20.7 (CH2); MS m/z (rel intensity) 369
(M++Na, 18), 190 (35), 157 (100). FABHRMS (CHCl3-NBA-NaI) Found: m/z 369.0963. Calcd for
C18H19N2O3ClNa: M, 369.0982.
5-[2-(4-Methylphenyl)-2-cyclohexenyl]-1,3-dimethylbarbituric Acid (6c):
Yellow liquid; IR
1
(CHCl3) 1678 (C=O); H NMR (300 MHz, CDCl3) 7.13-7.06 (4H, m, arom H), 5.93-5.90 (1H, m,
alkenic CH), 3.83-3.75 (1H, m, CH), 3.47 (1H, d, J = 2.8 Hz, H-5), 3.14 (3H, s, NCH3), 3.07 (3H, s,
13
NCH3), 2.29 (3H, s, CH3), 2.22-2.12 (2H, m, CH2), 2.00-1.54 (4H, m, 2 x CH2); C NMR (75 MHz,
CDCl3) 168.3, 167.8, 151.2 (C=O), 138.5 (alkenic C), 137.8, 136.8 (arom C), 129.5 (alkenic CH), 128.9
(2C), 126.8 (2C) (arom CH), 51.4 (CH), 41.7 (C-5), 28.2 (2 x NCH3), 27.8, 25.5 (CH2), 21.0 (CH3 and

CH2); MS m/z (rel intensity) 349 (M++Na, 100), 170 (91), 157 (87). FABHRMS (CHCl3-NBA-NaI)
Found: m/z 349.1519. Calcd for C19H22N2O3Na: M, 349.1528.
2,4-Diethyl-5a-phenyl-2,4-diaza-1,2,3,4,5a,6,7,8,9,9a-decahydrodibenzofuran-1-one-3-thione (8a):
1
Colorless needles (from ether), mp 134-135 °C; IR (CHCl3) 1679, 1652 (C=O, C=S); H NMR (300
MHz, CDCl3) 7.45-7.28 (5H, m, arom H), 4.66-4.43 (4H, m, 2 x NCH2CH3), 3.78 (1H, t, J = 4.6 Hz,
CH), 2.23-1.88 (4H, m, 2 x CH2), 1.67-1.48 (4H, m, 2 x CH2), 1.40 (3H, t, J = 7.0 Hz, NCH2CH3), 1.28
13
(3H, t, J = 7.0 Hz, NCH2CH3); C NMR (75 MHz, CDCl3) 175.6 (C=S), 160.5 (C=O), 158.6 (C-4a),
143.9 (arom C), 128.6 (2C), 128.1, 124.3 (2C) (arom CH), 96.6 (C-9b), 94.4 (C-5a), 44.7 (CH), 44.5,
43.1 (NCH2CH3), 34.1, 23.4, 18.1, 17.7 (CH2), 12.8, 11.7 (NCH2CH3); MS m/z (rel intensity) 356 (M+,
100), 226 (51), 201 (61), 156 (64). Anal. Calcd for C20H24N2O2S: C, 67.38; H, 6.79; N, 7.86. Found:
C, 67.55; H, 7.08; N, 7.75. HRMS Found: m/z 356.1564. Calcd for C20H24N2O2S: M, 356.1558.
(5aS*,9aS*)-5a-(4-Chlorophenyl)-2,4-diethyl-2,4-diaza-1,2,3,4,5a,6,7,8,9,9a-decahydrodibenzo-
furan-1-one-3-thione (8b): Colorless microcrystals (from ether), mp 160-161 °C; IR (CHCl3) 1680,
1652 (C=O, C=S); 1H NMR (300 MHz, CDCl3) 7.37 (4H, s, arom H), 4.66-4.42 (4H, m, 2 x NCH2CH3),
3.73 (1H, t, J = 4.6 Hz, CH), 2.25-1.87 (4H, m, 2 x CH2), 1.67-1.47 (4H, m, 2 x CH2), 1.39 (3H, t, J =
7.0 Hz, NCH2CH3), 1.28 (3H, t, J = 7.0 Hz, NCH2CH3); 13C NMR (75 MHz, CDCl3) 175.5 (C=S), 160.4
(C=O), 158.5 (C-4a), 142.4, 134.0 (arom C), 128.8 (2C), 125.9 (2C) (arom CH), 96.0 (C-9b), 94.3 (C-
5a), 44.7 (CH), 44.5, 43.2 (NCH2CH3), 34.0, 23.4, 18.1, 17.7 (CH2), 12.8, 11.7 (NCH2CH3); MS m/z (rel
intensity) 390 (M+, 100), 226 (91). Anal. Calcd for C20H23N2O2ClS: C, 61.45; H, 5.93; N, 7.17.
Found: C, 61.67; H, 6.20; N, 7.07. HRMS Found: m/z 390.1170. Calcd for C20H23N2O2ClS: M,
390.1169.
The irradiation of the aromatic proton that appeared at δ 7.37 resulted in a 3.1% increase in the triplet at
δ 3.73. It was apparent that the stereochemistry of the aryl group and the H-9a hydrogen also involved
the syn configuration.
2,4-Diethyl-5a-(4-methylphenyl)-2,4-diaza-1,2,3,4,5a,6,7,8,9,9a-decahydrodibenzofuran-1-one-3-
thione (8c): Colorless microcrystals (from ether), mp 131-133 °C; IR (CHCl3) 1679, 1651 (C=O,
C=S); 1H NMR (300 MHz, CDCl3) 7.34-7.18 (4H, m, arom H), 4.64-4.42 (4H, m, 2 x NCH2CH3), 3.77
(1H, t, J = 4.6 Hz, CH), 2.35 (3H, s, CH3), 2.26-1.87 (4H, m, 2 x CH2), 1.67-1.48 (4H, m, 2 x CH2), 1.39
13
(3H, t, J = 7.0 Hz, NCH2CH3), 1.28 (3H, t, J = 7.0 Hz, NCH2CH3); C NMR (75 MHz, CDCl3) 175.5
(C=S), 160.6 (C=O), 158.7 (C-4a), 140.8, 138.0 (arom C), 129.2 (2C), 124.4 (2C) (arom CH), 96.7 (C-
9b), 94.5 (C-5a), 44.7 (CH), 44.4, 43.1 (NCH2CH3), 34.0, 23.5 (CH2), 21.0 (CH3), 18.3, 17.9 (CH2), 12.8,
11.7 (NCH2CH3); MS m/z (rel intensity) 370 (M+, 78), 201 (68), 170 (100), 144 (44). Anal. Calcd for
C21H26N2O2S: C, 68.08; H, 7.07; N, 7.56 Found: C, 68.26; H, 7.09; N, 7.56. HRMS Found: m/z
370.1700. Calcd for C21H26N2O2S: M, 370.1715.
2,4-Diethyl-5a-phenyl-2,4-diaza-1,2,3,4,5a,7,8,9,10,10a-decahydrocyclohepta[b]benzofuran-1-one-
3-thione (8d): Colorless microcrystals (from ether), mp 104-105 °C; IR (CHCl3) 1679, 1652 (C=O,
C=S); 1H NMR (300 MHz, CDCl3) 7.43-7.25 (5H, m, arom H), 4.68-4.44 (4H, m, 2 x NCH2CH3), 3.91
(1H, dd, J = 6.3, 2.3 Hz, CH), 2.35-1.98 (4H, m, 2 x CH2), 1.78-1.45 (6H, m, 3 x CH2), 1.43 (3H, t, J =
7.0 Hz, NCH2CH3), 1.27 (3H, t, J = 7.0 Hz, NCH2CH3); 13C NMR (75 MHz, CDCl3) 175.5 (C=S), 159.3
(C=O), 158.2 (C-4a), 146.0 (arom C), 128.6 (2C), 127.8, 123.7 (2C) (arom CH), 100.6 (C-10b), 94.0 (C-
5a), 50.7 (CH), 44.5, 43.1 (NCH2CH3), 41.1, 30.9, 29.0, 26.3, 24.0 (CH2), 12.8, 11.7 (NCH2CH3); MS
m/z (rel intensity) 370 (M+, 100), 170 (80), 129 (43), 91 (49). Anal. Calcd for C21H26N2O2S: C, 68.08;

H, 7.07; N, 7.56. Found: C, 67.91; H, 7.29; N, 7.40. HRMS Found: m/z 370.1731. Calcd for
C21H26N2O2S: M, 370.1715.
5,7-Diethyl-2,2-diphenyl-5,7-diaza-2,3,4,5,6,7-hexahydrobenzo[b]furan-4-one-6-thione (8e):
Colorless cubes (from CH2Cl2-hexane), mp 109-111 °C; IR (CHCl3) 1682, 1655 (C=O, C=S); 1H NMR
(400 MHz, CDCl3) 7.38-7.32 (10H, m, arom H), 4.58 (2H, q, J = 6.8 Hz, NCH2CH3), 4.55 (2H, q, J =
6.8 Hz, NCH2CH3), 3.84 (2H, s, CH2), 1.40 (3H, t, J = 6.8 Hz, NCH2CH3), 1.29 (3H, t, J = 6.8 Hz,
NCH2CH3); 13C NMR (100 MHz, CDCl3) 175.6 (C=S), 159.9 (C=O), 158.3 (C-7a), 142.7 (2C) (arom C),
128.6 (4C), 128.4 (2C), 125.6 (4C) (arom CH), 97.5 (C-3a), 91.0 (C-2), 44.8, 43.3 (NCH2CH3), 40.6
(CH2), 12.8, 11.6 (NCH2CH3); MS m/z (rel intensity) 378 (M+, 100), 220 (90), 191 (43). Anal. Calcd
for C22H22N2O2S: C, 69.81; H, 5.86; N, 7.40. Found: C, 70.08; H, 5.99; N, 7.42.
2,2-Bis(4-chlorophenyl)-5,7-diethyl-5,7-diaza-2,3,4,5,6,7-hexahydrobenzo[b]furan-4-one-6-thione
1
(8f): Colorless microcrystals (from ether), mp 150-152 °C; IR (CHCl3) 1685, 1655 (C=O, C=S); H
NMR (300 MHz, CDCl3) 7.38-7.27 (8H, m, arom H), 4.58 (2H, q, J = 7.0 Hz, NCH2CH3), 4.53 (2H, q, J
= 7.0 Hz, NCH2CH3), 3.77 (2H, s, CH2), 1.38 (3H, t, J = 7.0 Hz, NCH2CH3), 1.28 (3H, t, J = 7.0 Hz,
13
NCH2CH3); C NMR (75 MHz, CDCl3) 175.6 (C=S), 159.6 (C=O), 158.3 (C-7a), 140.8 (2C), 134.8
(2C) (arom C), 129.0 (4C), 127.1 (4C) (arom CH), 96.4 (C-3a), 90.8 (C-2), 44.8, 43.5 (NCH2CH3), 40.5
(CH2), 12.9, 11.6 (NCH2CH3); MS m/z (rel intensity) 446 (M+, 100), 288 (33), 225 (24), 189 (21). Anal.
Calcd for C22H20N2O2Cl2S: C, 59.06; H, 4.51; N, 6.26. Found: C, 58.79; H, 4.61; N, 6.37. HRMS
Found: m/z 446.0618. Calcd for C22H20N2O2Cl2S: M, 446.0622.
5,7-Diethyl-2,2-bis(4-methylphenyl)-5,7-diaza-2,3,4,5,6,7-hexahydrobenzo[b]furan-4-one-6-thione
(8g): Light yellow liquid; IR (CHCl3) 1679, 1653 (C=O, C=S); 1H NMR (300 MHz, CDCl3) 7.25-7.15
(8H, m, arom H), 4.56 (2H, q, J = 7.0 Hz, NCH2CH3), 4.53 (2H, q, J = 7.0 Hz, NCH2CH3), 3.78 (2H, s,
CH2), 2.34 (6H, s, 2 x CH3), 1.38 (3H, t, J = 7.0 Hz, NCH2CH3), 1.28 (3H, t, J = 7.0 Hz, NCH2CH3); 13C
NMR (75 MHz, CDCl3) 175.6 (C=S), 160.0 (C=O), 158.6 (C-7a), 139.9 (2C), 138.4 (2C) (arom C),
129.3 (4C), 125.7 (4C) (arom CH), 97.9 (C-3a), 91.2 (C-2), 44.8, 43.4 (NCH2CH3), 40.6 (CH2), 21.0
(2C) (CH3), 12.8, 11.7 (NCH2CH3); MS m/z (rel intensity) 406 (M+, 100), 248 (76). Anal. Calcd for
C24H26N2O2S: C, 70.90; H, 6.45; N, 6.89. Found: C, 70.95; H, 6.61; N, 6.76. HRMS Found: m/z
406.1703. Calcd for C24H26N2O2S: M, 406.1715.
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