Synthesis of a new series of indolinic aminoxyls. Reaction of indoles, 2-phenylbenzothiazole, 2-phenylbenzoxazole and 2-phenyl1,2-dihydro-4H-3,1-benzoxazin-4-one with organolithium reagents

Article abstract of DOI:10.1039/a904092g

2-Alkyl-2-phenyl-3,3-dimethylindolines. obtained by 1,2 organolithium addition to 2-phenyl-3,3-dimethyl-3H-indole, are converted into a new series of aminoxyls by oxidation with m-chloroperoxybenzoic acid. Attempts to synthesise, in a similar way suitable precursors such as 1,2-dihydro-2-phenyl-2-alkylbenzothiazole, 1,2-dihydro-2-phenyl-2-alkylbenzoxazole and 1,2-dihydro-2-phenyl-2-alkyl-4H-3,1-benzoxazin-4-one for other new aminoxyls failed. In fact, 2-phenylbenzothiazole, 2-phenylbenzoxazole and 2-phenyl-4H-3,1-benzoxazin-4-one react with organolithium reagents affording products deriving from ring opening. Crystal structures of 2,3-dimethyl-3-phenyl-3H-indole and bis(2-triphenylmetriylaminophenyl) disulfide are also described.

Full text of DOI:10.1039/a904092g

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Synthesis of a new series of indolinic aminoxyls. Reaction of
indoles, 2-phenylbenzothiazole, 2-phenylbenzoxazole and 2-phenyl-
1,2-dihydro-4H-3,1-benzoxazin-4-one with organolithium reagents
Giampaolo Tommasi,a Paolo Bruni,a Lucedio Greci,*a Paolo Sgarabotto,b Lara Righib and
Rita Petruccic
a Dipartimento di Scienze dei Materiali e della Terra, Università, via Brecce Bianche,
I-60131 Ancona, Italy
b Dipartimento di Chimica Generale ed Inorganica, Chimica Analitica, Chimica Fisica,
Università, Centro di Studio per la Strutturistica Diffrattometrica del CNR,
Viale delle Scienze, I-43100 Parma, Italy
c Dipartimento di Ingegneria Chimica, Università di Roma “La Sapienza”,
via del Castro Laurenziano 7, I-00161 Roma, Italy
Received (in Cambridge, UK) 21st May 1999, Accepted 22nd July 1999
2-Alkyl-2-phenyl-3,3-dimethylindolines, obtained by 1,2 organolithium addition to 2-phenyl-3,3-dimethyl-3H-indole,
are converted into a new series of aminoxyls by oxidation with m-chloroperoxybenzoic acid. Attempts to synthesise, in
a similar way, suitable precursors such as 1,2-dihydro-2-phenyl-2-alkylbenzothiazole, 1,2-dihydro-2-phenyl-2-alkyl-
benzoxazole and 1,2-dihydro-2-phenyl-2-alkyl-4H-3,1-benzoxazin-4-one for other new aminoxyls failed. In fact,
2-phenylbenzothiazole, 2-phenylbenzoxazole and 2-phenyl-4H-3,1-benzoxazin-4-one react with organolithium
reagents affording products deriving from ring opening. Crystal structures of 2,3-dimethyl-3-phenyl-3H-indole
and bis(2-triphenylmethylaminophenyl) disulfide are also described.
Table 1 EPR hyperfine coupling constants of compounds 5
Introduction
All antioxidants working through hydrogen donation, like
Compound
aN
aH-5,7
aH4,6
aH–R
vitamin E, show a pro-oxidant effect,1 and the lower their pro-
oxidative property the higher their efficiency as an antioxidant.2
The indolinonic 1 and 3-arylimino indolinonic aminoxyls 2,
5a
5b
5c
5d
5e
11.00 (1N)
10.94 (1N)
10.58 (1N)
10.62 (1N)
10.59 (1N)
3.39 (1H)
3.29 (1H)
3.41 (1H)
3.19 (1H)
3.32 (1H)
3.31 (1H)
3.25 (1H)
3.26 (1H)
3.29 (1H)
3.16 (1H)
0.91 (1H)
1.00 (1H)
0.86 (1H)
1.08 (1H)
0.77 (1H)
1.14 (1H)
0.98 (1H)
1.00 (1H)
0.90 (1H)
1.10 (1H)
0.16 (3H)
—
0.22 (1H)
—
0.21 (1H)
previously prepared in our laboratory, possess excellent anti-
oxidant character, being able to trap peroxyl radicals at a rate
constant which ranges between 105–107 l molϪ1 sϪ1 3 and alkyl
radicals at a rate close to the one controlled by diffusion.4 On
the basis of this behaviour, these compounds were successfully
used to prevent peroxidation in lipids,5 proteins,6 low density
lipoproteins7 and, more recently, in the protection of DNA.8 In
the above mentioned studies and applications, a certain pro-
oxidant effect of compounds 1 and 2 was observed and the
extent of this effect was correlated with the aminoxyl structure:
in fact, aminoxyls such as 1, bearing a carbonyl group at C-3,
show a higher pro-oxidant effect than those, such as 2, having a
Scheme 1
formed with m-chloroperoxybenzoic acid (MCPBA); yields are
in the range 20–30%. All mass spectra show two characteristic
peaks, the former corresponding to the molecular mass, the
latter to the loss of an oxygen. EPR spectra show similar
hyperfine coupling constants (see Table 1) and are in agreement
with those aminoxyls having an indoline structure.10
The reaction of isopropyl phenyl ketone with phenyl-
hydrazine leads to two different products 3 and 6, depending on
the experimental conditions (Scheme 2). Compound 6 was
identified by X-ray analysis and its analytical and spectroscopic
data are in agreement with the structure proposed. By compar-
C᎐N double bond in the same position.9
᎐
The aim of the present study was to synthesise aminoxyls
bearing an sp3 carbon in position 3, in order to decrease the
pro-oxidant effect which is, however, an intrinsic property of
all aminoxyls. For the same purpose, attempts to synthesise
aminoxyls with a heteroatom in position 3 were performed.
Results
The indolinic aminoxyls 5 were synthesised from 3H-indole 3
according to Scheme 1. The oxidation of indolines 4 was per-
1
ing the H NMR spectrum of compound 6 with the one of
J. Chem. Soc., Perkin Trans. 2, 1999, 2123–2128
This journal is © The Royal Society of Chemistry 1999
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Scheme 2
compound 3, it was possible to assign the C-2 methyl in com-
pound 6, which falls at δ = 1.68 ppm. At room temperature
compound 3 is an oil and the melting point of its picrate
(mp = 158–160 ЊC) is in agreement with the one reported in the
literature.11
Fig. 1 ORTEP plot of compound 6 showing 50% probability dis-
placement ellipsoids and the atom-numbering scheme. H atoms are
drawn as small circles of arbitrary radii.
Compounds 4, which are the precursors of aminoxyls 5, were
obtained by reacting the 3H-indole 3 with alkyllithium: the
structures of the isolated products are shown in Scheme 1.
1
It is noteworthy that in the H NMR spectra of compounds
4, the two methyl groups at C-3 are not magnetically equivalent
(∆δ = 0.9 ppm); the exception shown for compound 4d, demon-
strates that the magnetic non-equivalency is due to the chiral
C-2. All compounds 4 show in their IR spectrum an absorption
at ca. 1600 cmϪ1 which is typical for indolinic structure.12
3H-Indole 6 does not react with organolithium at C-2
because the tautomeric equilibrium, due to the C-2 methyl
indole structure, is presumably responsible for an acid–base
reaction, as shown with analogous substrates.13
An attempt to obtain thioindolines 9 from 2-phenylbenzo-
thiazole 7 was not successful: reaction with both phenyl and
n-hexyllithium lead only to compounds 12 (Scheme 3). Com-
Scheme 4
Scheme 5
Molecular geometry of 2,3-dimethyl-3-phenyl-3H-indole 6 and
of bis(2-triphenylmethylaminophenyl) disulfide acetone solvate
12a
Figs. 1 and 2 show perspective views of compounds 6 and 12a
respectively, together with the arbitrary numbering schemes
used in the crystal analyses: selected bond distances and angles
are given in Table 2.
Scheme 3
pound 12a was identified by X-ray analysis, while 12b was
characterised by its spectroscopic data, which were strictly
similar to those observed for compound 12a.
The same reactivity of benzothiazole 7 toward phenyllithium
was observed for 2-phenylbenzoxazole 13 (Scheme 4); in this
case too, the attainment of the indoline 14 failed and 16 was the
only isolated product.
The reaction of 2-phenyl-1,2-dihydro-4H-3,1-benzoxazin-4-
one 17 with phenyllithium gives products 19 and 20 instead of
18 (Scheme 5), showing behaviour similar to that observed for
compounds 7 and 13.
For compound 6, bond distances and angles are in reason-
able agreement with those found in analogous indoles previ-
ously studied:14 in particular, the presence of a localised double
bond N(1)᎐C(2) 1.287(4) Å and the angle at N(1) of 106.8(2)Њ
᎐
have been found. The indolic moiety is planar, within the
experimental error; the phenyl and the indolic mean planes
form a dihedral angle of 95.7(1)Њ. In the crystal, the molecules
are held together by van der Waals forces.
The structure of 12a consists of discrete monomeric units of
this compound and of acetone solvate, separated by normal
van der Waals distances.
2124
J. Chem. Soc., Perkin Trans. 2, 1999, 2123–2128

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Fig. 2 ORTEP plot of compound 9a showing 30% probability displacement ellipsoids and the atom-numbering scheme. H atoms are drawn as small
circles of arbitrary radii.
Table
2
Selected bond distance (Å) and angles (degrees) for
compounds 6 and 12a
H(2) ؒ ؒ ؒ S(2) 121(3)Њ]. Contacts responsible for packing corre-
spond to van der Waals interactions.
Compound 6
Discussion
N(1)–C(2)
N(1)–C(9)
C(2)–C(3)
C(2)–C(20)
1.287(3)
C(3)–C(4)
C(3)–C(30)
C(3)–C(31)
C(4)–C(9)
1.506(4)
1.548(4)
1.535(3)
1.394(4)
1.430(3)
1.538(4)
1.489(6)
In the reaction of isopropyl phenyl ketone with phenyl-
hydrazine, the compound formed depends on the experimental
conditions, and this could be explained as shown in Scheme 2.
The Fisher’s intermediate (FI, Scheme 2)17 in refluxing ethanol
(mild conditions) could eliminate ammonia affording com-
pound 3; however, when FI is subjected to stronger conditions
(ZnCl2/190 ЊC), a double Wagner–Meerwein transposition18
occurs, leading to compound 6.
C(2)–N(1)–C(9)
N(1)–C(2)–C(3)
C(2)–C(3)–C(4)
106.8(2)
114.7(2)
99.2(2)
C(3)–C(4)–C(9)
N(1)–C(9)–C(4)
107.7(2)
111.7(2)
Compound 12a
Both aliphatic19 and aromatic20 secondary amines may be
converted into the corresponding aminoxyls by oxidation, as
well as indolines21 and indoxyls.22
Indolines such as 4 may be easily prepared by reaction of
indoles with organolithium when the starting indole is substi-
tuted with a phenyl group at C-2: a tertiary carbon at C-2 could
behave like the phenyl group, whereas the presence of only
one hydrogen bonded to the carbon of the substituent at C-2
could give rise to a tautomeric equilibrium,23 inhibiting the
1,2-addition from organolithium.
S(1)–S(2)
2.068(1)
1.773(4)
1.484(4)
1.376(5)
1.414(6)
S(2)–C(52)
N(2)–C(2)
N(2)–C(51)
C(51)–C(52)
1.774(4)
1.474(5)
1.391(5)
1.413(6)
S(1)–C(12)
N(1)–C(1)
N(1)–C(11)
C(11)–C(12)
S(2)–S(1)–C(12)
S(1)–S(2)–C(52)
C(1)–N(1)–C(11) 127.0(3)
C(2)–N(2)–C(51) 125.4(3)
105.5(1)
104.4(1)
N(1)–C(11)–C(12) 120.4(4)
S(1)–C(12)–C(11) 121.6(3)
N(2)–C(51)–C(52) 119.2(4)
S(2)–C(52)–C(51) 120.8(3)
The conversion of indolines 4 into the corresponding amin-
oxyls is not high because the aminoxyls react further with
MCPBA, forming compounds such as benzoyloxy substituted
aminoxyls and quinone imine N-oxides, which have already
been observed and described in the case of 1.22
The atoms C(12), S(1), S(2), C(52) in the centre of the mole-
cule adopt a skewed non-planar conformation like the one
found in similar disulfide molecules reported in the literature,15
where the S–S bond length in disulfide compounds is correlated
with the C–S–S–C torsion angle, being around 2.03 and 2.07 Å
for angles in the range 75–105 and 0–20Њ, respectively.16 The
value of 2.068(1) Å for S(1)–S(2) with a C(12)–S(1)–S(2)–C(52)
torsion angle of Ϫ91.5(2)Њ shown by 12a could be interpreted in
terms of strain effect imposed by steric interactions between the
bulky substituents at the aminic nitrogens.
The S and N atoms are almost coplanar with their respective
rings, N(1)–C(11)–C(12)–S(1) and N(2)–C(51)–C(52)–S(2)
torsion angles being Ϫ4.8(6) and 6.1(6)Њ, respectively. The
molecule exhibits weak intramolecular hydrogen bonds of
the S ؒ ؒ ؒ N type [N(1)–H(1) 0.81(3), N(1) ؒ ؒ ؒ S(1) 3.058(3),
H(1) ؒ ؒ ؒ S(1) 2.070(4) Å; N(1)–H(1) ؒ ؒ ؒ S(1) 109(3)Њ; N(2)–H(2)
0.87(4), N(2) ؒ ؒ ؒ S(2) 3.018(4), H(2) ؒ ؒ ؒ S(2) 2.48(3) Å; N(2)–
The reaction of 2-phenylbenzothiazole 7 with organolithium
would have been interesting for two reasons: on one hand, thio-
indolines 9 themselves could possess antioxidant properties,
such as those shown by the parent phenothiazine,24 which are,
to some extent, structurally similar; on the other hand, amin-
oxyls prepared by oxidation of 9 could have had antioxidant
properties suitable for biological applications. In our opinion,
the synthesis of thioindolines 9 failed because the anion 8,
formed in the first 1,2 addition, rearranges to the anion 10,
which undergoes the addition of one more molecule of RLi
leading to the di-anion 11 (Scheme 3): the latter is then trans-
formed into compound 12 during the reaction work-up. On the
other hand, it is well known that thiophenols easily undergo
J. Chem. Soc., Perkin Trans. 2, 1999, 2123–2128
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oxidative dimerisation to the corresponding disulfides.25 The
ring opening suggested for the intermediate 8 has already been
observed for similar systems.26
A similar reactivity could be likely invoked for 2-phenyl-
benzoxazole 13, even if in this case the o-aminophenol 15 is
oxidised to the corresponding iminoquinone 16 (Scheme 4).
MHz, CDCl3, 25 ЊC): δ 1.68 (s, 3H), 2.13 (s, 3H), 7.12 (m, 4H),
7.28 (m, 4H), 7.61 (d, 1H, J = 7.8 Hz); MW for C16H15N,
221.29; MS (EIϩ): m/z = 221 (Mϩ, 100), 206 (90), 179 (65), 165
(95). Analysis, calcd. C, 86.84; H, 6.83; N, 6.33. Found C, 86.54;
H, 6.97; N, 6.38%.
The
2-phenyl-1,2-dihydro-4H-3,1-benzoxazin-4-one
17
Synthesis of compounds 4
behaves as a bidentate system towards organometallics; in fact,
organolithium could either give 1,2-addition (path a, Scheme
5), as observed for compounds 7 and 13, leading to compound
19 instead of 18, or attack the carbonyl group in position 4
(path b, Scheme 5), forming compound 20. These results clearly
show that alternative pathways must be found to obtain the
interesting products 9, 14 and 18.
THF solutions of RLi (13.5 mmol) were added dropwise, under
Ar, to a solution of 3 (4.5 mmol) in dry THF (40 ml). After 30
min the mixture was poured in a saturated solution of NH4Cl
(150 ml) and extracted with diethyl ether (2 × 40 ml). The com-
bined organic layers were dried on Na2SO4, concentrated and
chromatographed on an SiO2 column (eluant cyclohexane–ethyl
acetate 95/5). Yields are reported below.
4a: Yield = 93.5%; mp = 70–72 ЊC from ligroin 55–85 ЊC; IR
(KBr), ν/cmϪ1: 3334, 3012, 2921, 1457, 1376; H NMR (200
1
Experimental
MHz, CDCl3, 25 ЊC): δ 0.65 (s, 3H), 1.45 (s, 3H), 1.52 (s, 3H),
6.76 (dq, 2H, J = 7.4 and 1.2 Hz), 7.07 (dq, 2H, J = 7.0 and 1.6
Hz), 7.34 (m, 3H), 7.64 (dd, 2H, J = 8.7 and 1.8 Hz); MW for
C17H19N, 237.33; MS (EIϩ): m/z = 237 (Mϩ, 40), 236 (100), 222
(82), 206 (36). Analysis, calcd. C, 86.03; H, 8.07; N, 5.90. Found
C, 86.10; H, 8.12; N, 5.87%.
Melting points are uncorrected and were measured with an
Electrothermal apparatus. IR spectra were recorded in solid
state on a Nicolet Fourier Transform Infrared 20-SX spectro-
photometer equipped with a Spectra Tech. “Collector” for
DRIFT measurements. H NMR and 13C NMR spectra were
1
4b: Yield = 60.0%; oil at rt; IR (KBr), ν/cmϪ1: 3382, 3080,
2956, 1485, 1386; 1H NMR (200 MHz, CDCl3, 25 ЊC): δ 0.63 (s,
3H), 0.80 (t, 3H, J = 7.5 Hz), 0.98 (m, 2H), 1.22 (m, 2H), 1.48 (s,
3H), 1.90 (m, 2H), 4.15 (broad, 1H), 6.78 (m, 2H), 7.09 (m, 2H),
7.36 (m, 3H), 7.60 (d, 2H, J = 7.3 Hz); MW for C20H25N,
279.41; MS (EIϩ): m/z = 279 (Mϩ, 22), 250 (14), 222 (100), 207
(67).
recorded at room temperature in CDCl3 or C6D6 solution on a
Varian Gemini 200 spectrometer (TMS was taken as reference
peak). Mass spectra were performed on a Carlo Erba QMD
1000 mass spectrometer, equipped with a Fisons GC 8060 gas
chromatograph. EPR spectra were recorded on a Varian E4
spectrometer interfaced with a computer (for acquisition, edit-
ing and simulation of experimental signals) and equipped with
an XL microwave 3120 frequency counter and with a ruby
in the cavity as reference. Isopropyl phenyl ketone, phenyl-
hydrazine, zinc chloride, m-chloroperoxybenzoic acid, alkyl-
lithium reagents and compounds 7, 13 and 17 were purchased
from Aldrich and used without further purification.
4c: Yield = 85.7%; oil at rt; IR (KBr), ν/cmϪ1: 3376, 3054,
2956, 1484, 1386; 1H NMR (200 MHz, CDCl3, 25 ЊC): δ 0.65 (s,
3H), 0.80 (s, 9H), 1.49 (s, 3H), 4.15 (broad, 1H), 6.79 (m, 2H),
7.07 (m, 2H), 7.35 (m, 3H), 7.60 (d, 2H, J = 7.2 Hz); MW for
C20H25N, 279.41; MS (EIϩ): m/z = 279 (Mϩ, 10), 250 (70), 222
(100), 207 (71).
4d: Yield = 45.6%; mp = 90–91 ЊC from ligroin 55–85 ЊC; IR
Synthesis of compound 3
1
(KBr), ν/cmϪ1: 3376, 3053, 2975, 1459, 1390; H NMR (200
A solution of isopropyl phenyl ketone (7.4 g, 50 mmol), phenyl-
hydrazine (5.94 g, 55 mmol) and toluene-p-sulfonic acid (0.5 g,
2.9 mmol) was refluxed in a Dean Stark apparatus until 0.9 ml
of water were produced. After cooling, the mixture was treated
with a saturated solution of NaHCO3 (300 ml) and extracted
with CHCl3 (2 × 40 ml). The combined organic layers were
dried on Na2SO4 and evaporated under vacuum. The residue
was dissolved in absolute ethanol (100 ml) and ZnCl2 (50.3 g,
370 mmol) was added. The solution was refluxed for 24 h, then
concentrated. The residue was treated with a saturated solution
of NaHCO3 (400 ml) and extracted with diethyl ether (3 ×
50 ml). The combined organic layers were dried on Na2SO4,
concentrated and the residue chromatographed on SiO2, using
cyclohexane–ethyl acetate 95/5 as an eluant. Compound 3
is an oil at room temperature. Yield = 42%; mp (picrate) =
159–161 ЊC (lit. 158–160 ЊC);11 IR (KBr), ν/cmϪ1: 3058, 2965,
MHz, CDCl3, 25 ЊC): δ 1.20 (s, 6H), 4.14 (broad, 1H), 6.63 (dd,
1H, J = 7.8 and 1.2 Hz), 6.84 (td, 1H, J = 7.5 and 1.0 Hz), 7.08
(td, 2H, J = 7.1 and 1.3 Hz), 7.26 (m, 6H), 7.40 (m, 4H); MW
for C22H21N, 299.40; MS (EIϩ): m/z = 299 (Mϩ, 58), 284 (12),
269 (10), 222 (100), 207 (19). Analysis, calcd. C, 88.25; H, 7.07;
N, 4.68. Found C, 88.31; H, 7.12; N, 4.71%.
4e: Yield = 41.7%; oil at rt; IR (KBr), ν/cmϪ1: 3378, 3053,
2923, 1460, 1387; 1H NMR (200 MHz, CDCl3, 25 ЊC): δ 0.65 (s,
3H), 0.85 (t, 3H, J = 6.5 Hz), 1.19 (m, 8H), 1.47 (s, 3H), 1.90 (m,
2H), 4.17 (broad, 1H), 6.77 (m, 2H), 7.07 (m, 2H), 7.35 (m, 3H),
7.60 (d, 2H, J = 7.1 Hz); MW for C22H29N, 307.46; MS (EIϩ):
m/z = 307 (Mϩ, 22), 250 (46), 222 (100), 207 (62).
Oxidation of indolines 4 to aminoxyls 5. General procedure
Solid 3-chloroperoxybenzoic acid (1 mmol) was added to a
solution of the indoline (0.1 mmol) in CHCl3 (10 ml). The mix-
ture was stirred for 30 min, then evaporated to dryness and
chromatographed on an SiO2 column (eluant cyclohexane–ethyl
acetate 9/1). Compounds 5 were uncrystallisable. Yields: 20–
30%.
1
1520, 1454, 1386; H NMR (200 MHz, CDCl3, 25 ЊC): δ 1.61
(s, 6H), 7.35 (m, 3H), 7.50 (m, 3H), 7.73 (d, 1H, J = 7.2 Hz),
8.17 (m, 2H); MW for C16H15N, 221.29; MS (EIϩ): m/z = 221
(Mϩ, 100), 206 (57), 144 (45).
5a: IR (KBr), ν/cmϪ1: 3055, 2983, 1475, 1386; MW for C17-
H18NO, 252.32; MS (EIϩ): m/z = 252 (Mϩ, 20), 237 (47), 222
(81), 207 (19).
Synthesis of compound 6
ZnCl2 (50.3 g, 370 mmol), isopropyl phenyl ketone (7.4 g, 50
mmol) and phenylhydrazine (6.48 g, 60 mmol) were heated
under stirring at 190 ЊC for 3 h. After cooling, a solution of
NH4OH 0.1 M (200 ml) was added, and the mixture was
extracted with diethyl ether (5 × 40 ml). The combined organic
layers were dried on Na2SO4 and concentrated to dryness under
vacuum. The residue was chromatographed on an SiO2 column
(eluant cyclohexane–ethyl acetate 8/2). Compound 6 was
crystallised from petroleum ether. Yield = 40%; mp = 70 ЊC; IR
5b: IR (KBr), ν/cmϪ1: 3054, 2973, 1463, 1388; MW for
C20H24NO, 294.40; MS (EIϩ): m/z = 294 (Mϩ, 17), 278 (43), 238
(100), 222 (92), 207 (31).
5c: IR (KBr), ν/cmϪ1: 3063, 2989, 1470, 1380; MW for
C20H24NO, 294.40; MS (EIϩ): m/z = 294 (Mϩ, 11), 278 (10), 238
(86), 222 (100), 207 (44).
5d: IR (KBr), ν/cmϪ1: 3060, 2978, 1485, 1377; MW for
C22H20NO, 314.39; MS (EIϩ): m/z = 314 (Mϩ, 25), 298 (88), 222
(99), 207 (44).
1
(KBr), ν/cmϪ1: 3050, 2960, 1525, 1450, 1378; H NMR (200
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5e: IR (KBr), ν/cmϪ1: 3050, 2968, 1488, 1392; MW for
C22H28NO, 322.45; MS (EIϩ): m/z = 322 (Mϩ, 4), 306 (7), 222
(100), 207 (86).
EPR spectra were recorded on solutions of 5 (0.01 mmol) in
CHCl3 (1 ml), deaerated with Ar for 2 min. Hyperfine coupling
constants are reported in Table 1.
Table 3 Experimental data for the X-ray diffraction studies on crystal-
line compounds 6 and 12a
Compound
6
12a
Formula
Cryst. habit
C16H15N
prism
C50H40N2S2ؒC3H6O
prism
Cryst. colour
FW, F(000)
Cryst. syst.
colourless
221.3, 472
monoclinic
P21/c
yellow
791.1, 1672
monoclinic
P21/n
Reactions of 7 with RLi (R ؍ Ph, n-hexyl)
Space group
RLi (9.4 mmol) in toluene (10 ml) was added dropwise, under
Ar, to a solution of 7 (4.7 mmol) in toluene (40 ml) under
stirring. After 30 min the reaction mixture was poured into
water, treated with 15 g of NH4Cl and extracted with CH2Cl2
(2 × 40 ml). The combined organic layers were dried on Na2SO4
and evaporated to dryness. The residue was then chromato-
graphed on an SiO2 column (eluant cyclohexane–ethyl acetate
from 10/0 to 9/1).
12a: Yield = 87%; mp = 95–96 ЊC from benzene–light ligroin;
IR (KBr), ν/cmϪ1: 3384, 3058, 2960, 1446, 1319; 1H NMR (200
MHz, CDCl3, 25 ЊC): δ 6.17 (d, 2H, J = 8.8 Hz), 6.33 (d, 2H,
J = 7.7 Hz), 6.68 (s, 2H), 6.79 (td, 2H, J = 7.7 and 1.5 Hz),
7.03 (td, 2H, J = 7.5 and 1.2 Hz), 7.27 (m, 18H), 7.40 (m,
10H); MW for C50H40N2S2, 712.82; MS (EIϩ): m/z = 366 (Mϩ/
2, 1), 289 (2), 243 (32), 211 (15), 86 (95), 77 (37). Analysis,
calcd. C, 81.92; H, 5.50; N, 3.82, S, 8.75. Found C, 81.95; H,
5.57; N, 3.86%.
Cell parameters at 295 Ka
a/Å
b/Å
c/Å
α/Њ
8.380(2)
14.909(3)
10.712(2)
90
18.957(4)
10.066(3)
22.422(4)
90
β/Њ
111.2
90
1247.8(10)
4
92.14(8)
90
4275.6(18)
4
γ/Њ
V/Å3
Z
dcalc/g cmϪ3
Cryst. dimen./mm
Linear abs. coeff./cmϪ1
Diffractometer
1.18
1.23
0.24 × 0.37 × 0.47
5.2
Siemens AED
0.25 × 0.38 × 0.48
14.4
Enraf Nonius
Cad4
Scan type
Scan width/Њ
Radiation
ω–2θ
ω–2θ
b
b
c
c
2θ range coll./Њ
hkl range
Unique total data
Criterion of obs.
Unique obs. data (NO)
No. of refined param.
(NV)
6–140
h, k, l
2596
I > 2σ(I)
1237
6–140
h, k, l
8810
I > 2σ(I)
3153
12b: Oil at rt; yield = 85%; IR (KBr), ν/cmϪ1: 3380, 3048,
2952, 1452, 1321; 1H NMR (200 MHz, CDCl3, 25 ЊC): δ 0.82 (t,
12H, J = 5.9 Hz), 1.19 (m, 32H), 1.95 (m, 8H), 5.49 (broad, 2H),
6.05 (dd, 2H, J = 8.4 and 0.9 Hz), 6.39 (td, 2H, J = 7.3 and 0.9
Hz), 6.86 (td, 2H, J = 7.7 and 1.7 Hz), 7.31 (m, 6H), 7.47 (m,
4H); MW for C50H40N2S2, 765.24; MS (EIϩ): m/z = 383 (Mϩ/2,
10), 298 (24), 212 (25), 124 (83), 91 (100).
214
384
Overdeterm. ratio
(NO/NV)
Absorption
Solution
5.8
8.2
d
e
f
d
e
f
H atoms
Crystal structure of 2,3-dimethyl-3-phenyl-3H-indole 6 and of
bis(2-triphenylmethylaminophenyl) disulfide acetone solvate 12a
R
Rw
GOF
0.041
0.046
0.065
0.164
0.038
0.040
0.322
0.304
Table 3 shows the experimental and crystallographic data for 6
and 12a.† The intensities Ihkl were determined by analysing the
reflection profiles by the Lehmann and Larsen30 procedure.
Corrections for Lorentz and polarisation effects were per-
formed; there were no corrections for absorption effects.
Atomic scattering factors were from the International
Tables for X-Ray Crystallography.31 Bibliographic searches
were carried out using the Cambridge Structural Database
Files through the Servizio Italiano di Diffusione Dati Cristallo-
grafici, Parma, Italy.
Largest shift/esd
Largest peak/e ÅϪ3
Computer and programs
0.175
0.185
g
g
a Unit cell parameters were obtained by least-squares analysis of the
setting angles of 30 carefully centred reflections chosen from diverse
regions of reciprocal space. b From (θ Ϫ 0.6)Њ to [θ ϩ (0.6 ϩ ∆θ)]Њ;
∆θ = [(λα2 Ϫ λα1)/λ]tan θ. c Ni-filtered Cu-Kα λ = 1.54178 Å. d No
correction applied. e Direct methods. f Located in ∆F map and iso-
tropically refined. g ENCORE e91, SHELXS86,27 SHELX76,28
2
PARST.29R = Σ|∆F|/Σ|Fo|,Rw = [Σw(∆F2)2/Σw(Fo )2]1/2,GOF = [Σw|∆F |2/
(NO-NV)]1/2
.
Reaction of compound 13 with phenyllithium
ethanol. The filtrate was evaporated to dryness and the residue
chromatographed on an SiO2 column (eluant cyclohexane–ethyl
acetate 9/1) afforded compound 19.
The reaction was carried out by the same procedure used for
compound 7 starting from the same molar quantities. Com-
pound 16 was separated by chromatography on an SiO2 column
(eluant cyclohexane–ethyl acetate 9/1); mp = 143–144 ЊC from
ligroin 55–85 ЊC; yield = 66%; IR (KBr), ν/cmϪ1: 3058, 2952,
19: Oil at rt; yield = 38%; IR (KBr), ν/cmϪ1: 3300–2900, 1679,
1600, 1446; 1H NMR (200 MHz, CDCl3, 25 ЊC): δ 7.10 (td, 1H,
J = 8.0 and 1.3 Hz), 7.59 (m, 10H), 8.04 (dd, 2H, J = 8.0 and 1.8
Hz), 8.52 (dd, 1H, J = 9.0 and 0.8 Hz), 11.95 (broad, 1H); MW
for C20H15NO2, 301.33; MS (EIϩ): m/z = 301 (Mϩ, 65), 284 (11),
224 (23), 196 (100), 167 (58), 105 (90), 77 (92).
1
1726, 1583, 1476; H NMR (200 MHz, CDCl3, 25 ЊC): δ 6.14
(dd, 1H, J = 8.4 and 1.1 Hz), 6.45 (td, 1H, J = 7.9 and 1.5 Hz),
6.72 (dd, 1H, J = 8.4 and 1.5 Hz), 6.88 (m, 3H), 7.13 (m, 3H),
7.43 (m, 8H), 7.81 (dd, 2H, J = 8.4 and 1.2 Hz); MW for
C25H19NO, 349.41; MS (EIϩ): m/z = 349 (Mϩ, 34), 272 (40), 196
(29). Analysis, calcd. C, 85.93; H, 5.48; N, 4.01. Found C, 85.88;
H, 5.50; N, 3.98%.
20: Yield = 54%; mp = 248 ЊC from ethanol; IR (KBr),
1
ν/cmϪ1: 3369, 3060, 2970, 1650, 1583, 1448; H NMR (200
MHz, CDCl3, 25 ЊC): δ 6.63 (dd, 1H, J = 7.9 and 1.4 Hz), 6.98
(td, 2H, J = 7.9 and 1.4 Hz), 7.30 (m, 11H), 8.52 (dd, 1H, J = 8.2
and 1.3 Hz), 9.72 (broad, 1H); MW for C20H15NO2, 301.33; MS
(EIϩ): m/z = 301 (Mϩ, 5), 256 (23), 196 (31), 105 (100), 77 (60).
Analysis, calcd. C, 79.71; H, 5.02; N, 4.65. Found C, 79.85; H,
5.07; N, 4.61%.
Reaction of compound 17 with phenyllithium
The reaction was carried out as observed for compounds 7
and 13, starting from the same molar quantities. The crude
residue was treated with diethyl ether (5 × 10 ml); the insoluble
compound 20 was filtered off and crystallised from absolute
Acknowledgements
We thank the Italian MURST (Rome) and the University of
Ancona for financial support.
† CCDC reference number 188/179.
J. Chem. Soc., Perkin Trans. 2, 1999, 2123–2128
2127

View Article Online
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