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phorus ylide 4 in 91% yield; it underwent spontaneous
intramolecular cyclization into isoindolo[2,1-b]iso-
quinoline-5,7-dione 5 at room temperature. The reac-
tion was more efficient under conditions of refluxing
the phosphorus ylide 4 in dioxane in the presence of a
catalytic amount of benzoic acid, the similar effect has
been noted previously [9]. The tetracyclic product 5
was obtained in a yield of 47%. The structure of the
final product was confirmed by 1H and 13C NMR data.
solution of 0.35 g (1 mmol) of benzyl bromide in
10 mL of anhydrous benzene. The reaction mixture
was stirred during 3 h and then refluxed during one
day. The solvent was then decanted, and the residue
was washed with hot benzene and evaporated. Yield
0.38 g (63%). Found, %: C 67.37; H 4.13; N 2.37; Br
13.15. С34Н25BrNO3Р. Calculated, %: C 67.34; H 4.16;
N 2.31; Br 13.18. P 5.11.
2-{2-[(Triphenylphosphoranylidene)methyl]-
benzoyl}-1Н-isoindole-1,3(2Н)-dione (4). 5 mmol of
sodium hydride was added to a stirred suspension of
0.61 g (1 mmol) of phosphonium salt 3 in 20 mL of
tetrahydrofuran, and the reaction mixture was stirred
during 1.5 h. The precipitate was filtered off, and the
solvent was removed to give red oily product. Yield
In summary, synthesis of isoindolo[2,1-b]isoqui-
noline-5,7-dione via the Wittig intramolecular cycliza-
tion of phosphorus ylide prepared from commercially
available phthalimide and o-bromomethylbenzoate was
performed.
1
2-[2-(Bromomethyl)benzoyl]-1H-isoindole-1,3(2H)-
dione (2). 3.3 mmol of thionyl chloride was added to a
suspension of 0.241 g (1.1 mmol) of o-bromo-
methylbenzoic acid in 20 mL of anhydrous benzene.
The mixture was refluxed until the gas evolution had
ceased (≈ 6 h). After evaporation of the solvent and
excess of thionyl chloride, the resulting acid chloride
was used introduced in further reactions without
additional purification.
0.47 g (91%). H NMR spectrum (CDCl3), δ, ppm
(J, Hz): 4.34 s (1H, CH), 7.30–8.35 m (23H, Ar).
Found, %: C 77.68; H 4.64; N 2.71. С34Н24NO3Р.
Calculated, %: C 77.70; H 4.60; N 2.67; P 5.89; O 9.13.
Isoindolo[2,1-b]isoquinoline-5,7-dione (5). Catalytic
amount of benzoic acid was added to a suspension of
0.53 g (1 mmol) of phosphorus ylide in 10 mL of
anhydrous toluene. The reaction mixture was refluxed
during 5 h under argon. After removal of toluene, the
residue was purified by chromatography on silica gel
(petroleum ether : ethyl acetate = 4 : 1). Yield 116 mg
(47%). IR (nujol), ν, cm–1: 1157, 1641, 1730. 1H NMR
(CDCl3), δ, ppm (J, Hz): 6.61 s (1H, CH), 7.33–7.55 m
(4Н, C6H4), 7.68–8.35 m (4Н, C6H4). 13С NMR spec-
trum, δС, ppm (J, Hz): 105.87 (=CH), 120.33 (=C),
125.78 (CHAr), 125.96 (CHAr), 128.41 (CAr), 129.16
(CAr), 129.57 (CHAr), 131.04 (CHAr), 131.91 (CHAr),
132.75 (CHAr), 134.79 (CHAr), 136.73 (CHAr), 137.48
(CAr), 140.08(CAr), 162.52 (С=О), 167.55 (С=О). Mass
spectrum: m/z = 345 [M + H]+. Found, %: С 77.74; Н
3.63; N 5.70. С16Н9NO2. Calculated, %: С 77.72; Н
3.67; N 5.67.
A solution of the acid chloride in 5 mL of
tetrahydrofuran was added dropwise upon stirring and
cooling to a solution of 1 mmol of the phthalimide and
1.1 mmol of triethylamine in 20 mL of tetrahydrofuran
over 10 min. The reaction mixture was then heated to
ambient stirred during 2 h. The precipitate was filtered
off; the filtrate was poured into 50 mL of dilute
hydrochloric acid and then extracted with methylene
chloride. The organic layer was dried over MgSO4 and
evaporated. The residue was purified by chromato-
graphy on silica gel (chloroform : acetone = 9 : 1).
1
Yield 0.31 g (89%). H NMR spectrum (CDCl3), δ,
ppm (J, Hz): 5.01 m (2Н, CH2), 7.42–8.29 m (4Н,
С6Н4). 13С NMR spectrum, δС, ppm: 30.34 (CH2),
123.62 (CHAr), 128.85 (2CHAr), 129.02 (CHAr), 131.94
(CHAr), 132.17 (CAr), 133.41 (CAr), 134.34 (CHAr),
134.59 (2CHAr), 139.77 (CAr), 168.07 (2С=О), 170.44
(С=О). Mass spectrum: m/z = 345 [M + H]+. Found,
%: С 55.87; Н 2.95; N 4.03; Br 23.23. С16Н10BrNO3.
Calculated, %: С 55.84; Н 2.93; N 4.07; Br 23.22.
IR spectra were recorded using a Specord M-80
instrument (thin layer or with paraffin oil). NMR
spectra were obtained with a Bruker AM-500 spectro-
meter operating at 500.13 (1H) or 125.76 (13C) MHz.
The reaction progress was monitored by TLC using
Sorbfil PTLC-AF-A plates. Mass spectra (APCI) were
taken using a LCMS-2010EV Shimadzu GC–MS
instrument. Elemental analysis was performed with a
EURO EA-3000 CHNS-analyzer. Column chromato-
graphy was carried out using Chemapol silica gel
(40/100 and 100/160 mesh).
{2-[(1,3-Dioxo-1,3-dihydro-2Н-isoindol-2-yl)car-
bonyl]benzyl}(triphenyl)phosphonium bromide (3).
A solution of 1.1 mmol of triphenylphosphine in 3 mL
of benzene was added in a single portion to a stirred
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 85 No. 11 2015
Gumerov
