Thermal decomposition of tert-butyl o-(phenoxy)- and o-(anilino)-phenyliminoxyperacetates

Article abstract of DOI:10.1039/a800868j

Some o-phenoxy- and o-anilino-substituted aryliminyl radicals have been generated by thermal decomposition of suitable tert-butyl iminoxyperacetates. The iminyls show no disposition to give 7-membered cyclisation on the phenyl group. In some cases, products have been found that can be rationalised through a 1,6-spirocyclisation of the iminyl radicals followed by homolytic 1,5-migration of the phenyl group from the aminic to the iminic nitrogen: this seems to be the first instance of such a process. Evidence has been found for the formation of imines through hydrogen abstraction by the iminyls; with two o-phenoxy-substituted peresters these imines have been unexpectedly isolated. The reactions have also afforded significant - in some cases major - amounts of other products (acridine, quinazolinone and indole derivatives) presumably deriving from carbon radicals: mechanisms are suggested to account for the formation of these compounds. The structure of the quinazolinone compound has been determined by X-ray crystallographic analysis.

Full text of DOI:10.1039/a800868j

View Article Online / Journal Homepage / Table of Contents for this issue
Thermal decomposition of tert-butyl o-(phenoxy)- and o-(anilino)-
phenyliminoxyperacetates
Gianluca Calestani,a Rino Leardini,*,b Hamish McNab,c Daniele Nannib and
Giuseppe Zanardib
a Dipartimento di Chimica Generale ed Inorganica, Analitica e Chimica Fisica,
Università di Parma and Centro di Studio per la Strutturistica Diffrattometrica del CNR,
Viale delle Scienze, I-43100 Parma, Italy
b Dipartimento di Chimica Organica “A. Mangini”, Università di Bologna,
Viale Risorgimento 4, I-40136 Bologna, Italy
c Department of Chemistry, The University of Edinburgh, West Mains Road,
Edinburgh, UK EH9 3JJ
Some o-phenoxy- and o-anilino-substituted aryliminyl radicals have been generated by thermal
decomposition of suitable tert-butyl iminoxyperacetates. The iminyls show no disposition to give
7-membered cyclisation on the phenyl group. In some cases, products have been found that can be
rationalised through a 1,6-spirocyclisation of the iminyl radicals followed by homolytic 1,5-migration
of the phenyl group from the aminic to the iminic nitrogen: this seems to be the first instance of such
a process. Evidence has been found for the formation of imines through hydrogen abstraction by the
iminyls; with two o-phenoxy-substituted peresters these imines have been unexpectedly isolated. The
reactions have also afforded significant—in some cases major—amounts of other products (acridine,
quinazolinone and indole derivatives) presumably deriving from carbon radicals: mechanisms are
suggested to account for the formation of these compounds. The structure of the quinazolinone
compound has been determined by X-ray crystallographic analysis.
Iminyl radicals have been generated by many different
Introduction
methodologies, i.e. pyrolytic or photochemical reactions,5,6,8b,d
addition of carbon radicals to nitriles,8c,e,g–m reduction of
N-chloroketimines,4a hydrogen abstraction from imines,4c and
reactions of tin radicals with oxime benzoates,7f,h,i sulfenim-
ides,7e,i xanthic hydrazones,7g,i,j,k Barton esters7c,e,i and benzo-
triazolylimines.8n Although the sulfenimide method has been
widely employed for synthetic purposes, it has been reported
that sulfenimides of aromatic ketones are not readily access-
ible.9 Therefore, according to the method of Forrester,5 we
decided to generate the iminyls 2 by thermal decomposition of
suitable tert-butyl iminoxyperacetates. Here we report the data
obtained by pyrolysis of a series of peresters and we discuss the
fate of the resulting iminyls 2 and the possible intermediacy of
other radical species.10
In the last decades, there has been an extraordinary growth in
the chemistry of organic free-radicals, due to their remarkable
potential in organic synthesis. The availability of a great body
of kinetic data and a fine control of the regioselectivity and,
very recently, the stereoselectivity of radical reactions have
allowed the design of novel, exciting radical-based synthetic
strategies.1
Among the various radical species investigated, we have
drawn special attention to imidoyls; several papers have
appeared dealing both with mechanistic aspects of their chem-
istry and their application to the synthesis of heterocyclic com-
pounds.2 Recently, we have investigated the possibility of 1,6- or
1,7-cyclisation on the aromatic ring of o-aryloxy- and o-aryl-
amino benzimidoyl radicals 1 in the liquid phase.3 The oxygen
X
Ph
Results and discussion
X
Ph
The peracetates 6a–l were prepared from the corresponding
carbonyl compounds 3a–l according to the literature.5 The only
exception was that the esterification was carried out directly by
treatment of the acids with tert-butyl hydroperoxide and N,NЈ-
carbonyldiimidazole (CDI) (Scheme 1).
Thermal decomposition of the peresters 6a–l furnishes the
corresponding iminyls 2a–l according to Scheme 2.
The easy homolysis of the oxygen–oxygen bond of 6a–l fol-
lowed by facile decarboxylation of 7a–l generates radicals 8a–l;
in contrast, the loss of formaldehyde from 8a–l seems to be not
very fast. Indeed, the first attempts at decomposition of 6a–l,
performed under the conditions already reported (i.e. boiling
benzene),5 afforded products 9a–l arising almost exclusively
from coupling between 8a–l and tert-butoxyl radicals (Scheme
3).
N
N
Ar
R
1, X = O, NMe
2
a: X = O, R = H g: X = NMe, R = H
b: X = O, R = Me h: X = NMe, R = Me
c: X = O, R = Ph i: X = NMe, R = Ph
d: X = NH, R = H j: X = NPh, R = H
e: X = NH, R = Me k: X = NPh, R = Me
f: X = NH, R = Ph l: X = NPh, R = Ph
derivatives furnished dibenzoxazepines, via 1,7-ring closure,
and comparable amounts of benzophenones, through 1,6-spiro-
cyclisation followed by 1,5-translocation of an aryl radical.
This result prompted us to address our studies to analogous
iminyl radicals 2. These species, almost completely neglected by
organic chemists till the eighties,4 are growing more popular
mostly due to the work by Forrester,5 McNab6 and Zard,7
who have proved their usefulness in synthetically interesting
transformations.8
Further attempts at higher temperatures showed a decrease
of the yields of 9a–l with concomitant appearance of some
other compounds. Therefore we decided to carry out the
J. Chem. Soc., Perkin Trans. 1, 1998
1813

View Article Online
chromatography and, in fact, analogous derivatives were never
X
R
Ph
X
Ph
NH2OH
isolated from peresters 6d–l (see below). Second, it is amazing
that iminyl radicals can abstract a hydrogen atom in the appar-
ent absence of a true hydrogen donor. A possible explanation
for their reasonable stability might be an efficient six-membered
intramolecular hydrogen bonding between nitrogen and oxygen
atoms. This is strongly supported by spectral evidence, i.e. the
extremely broad N᎐H absorption band in the IR spectrum and
the very high chemical shift value of the N᎐H proton (>14 δ) in
O
N
OH
R
3a–1
4a–1
ClCH2CO2H
1
the H NMR spectrum. Furthermore, the mass spectra of the
X
R
Ph
X
R
Ph
corresponding acids 5b,c show a first important fragmentation
involving loss of carbon dioxide and formaldehyde, which leads
to the radical cations of the imines; it is worth noting that, from
this point on, these spectra are identical to those of the imines
12b,c.12 It remains rather obscure which is the actual species
acting as a hydrogen donor.
When the peresters 6d–l were allowed to decompose under
the same conditions, they afforded a wider set of products, as
shown in Scheme 5.
CDI
ButOOH
N
O
N
OH
O
OBut
O
O
O
6a–1
5a–1
Scheme 1
X
Ph
X
Ph
–CO2
∆
6a–1
–ButO
N
O
N
O
O
6d–l
R
O
R
7a–1
8a–1
–CH2O
2a–1
∆
3d–f (5–16%) + 4g (6%) + 9d–l (15–27%) + 10d,g,j (7–17%) + 11j,k (1–5%) +
Ph
Me
N
N
O
Scheme 2
+
+
+
N
X
R
Ph
N
8a–1 + ButO
Ph
R
Ph
N
O
OBut
13 (R = H, 7–14%)
14 (R = Me, 10–23%)
15 (R = Ph, 5–20%)
16 (7–8%)
17 (45%)
9a–1
Ph
N
Ph
N
Scheme 3
NHMe
+
+
decompositions in boiling 0.02  bromobenzene solutions.11
Under these conditions, the oxygenated peresters 6a–c gave the
compounds shown in Scheme 4.
O
H
Ph
Ph
O
18 (2%)
19j (4%)
20l (16%)
6a–c
Scheme 5
∆
As far as compounds 3, 4, 9, 10 and 11 are concerned, they
can be accounted for as previously reported for the decom-
position of the peresters 6a–c. Nevertheless, it is worth pointing
out that the carbonyl derivatives 3d–f were also obtained from
the peresters 6j–l; this means that the aminic nitrogen has lost
one of the two N-phenyl rings present in the starting materials.
This is probably the result of an ipso-substitution process by the
iminyl, as reported in Scheme 6.
+
+
+
3a–c (8–23%)
4a–c (2–18%)
9a–c (11–19%)
X
Ph
X
Ph
X
Ph
NH
+
+
N
CN
OBut
R
R
10a (42%)
11a,c (1–7%)
12b,c (10–27%)
The spirocyclohexadienyl 21, obtained by 1,6-cyclisation
Scheme 4
With the exception of compounds 9a–c, already discussed,
all the other products can be accounted for through the corre-
sponding iminyls 2a–c. The carbonyl derivatives 3a–c are prob-
ably the result of partial hydrolysis of the imines 12a–c, which
can derive from the iminyls 2a–c by hydrogen abstraction. On
the other hand, 3a–c cannot arise from other imine derivatives,
e.g. 4a–c, 9a–c or 11a–c, because these compounds are com-
pletely stable under chromatographic conditions. The nitrile
10a can be easily rationalised by an assisted β-fragmentation of
the C᎐H bond of iminyl 2a. The oximes 4a–c could be the result
of an oxidation process of the corresponding iminyl radicals,
whereas the recombination of iminyls 2a–c and tert-butoxyl
radicals can lead to the O-tert-butyl oximes 11a–c.
X
X
Ph
N
2j–l
N
R
R
21j–l
22j–l
RH –R
XH
hydrolysis
Ph
N
3d–f
R
As far as the imines 12b,c are concerned, their isolation was
quite astonishing for at least two reasons. First, N-unsubsti-
tuted imines are generally very easily hydrolysed by column
23j–l
Scheme 6
1814
J. Chem. Soc., Perkin Trans. 1, 1998

View Article Online
of the corresponding iminyl, can rearrange through a 1,5-
migration of the phenyl ring from the aminic to the iminic
nitrogen; the resulting aminyl 22 gives rise to the carbonyl
compound 3 by hydrogen abstraction followed by hydrolysis
of the imine 23. An analogous rearrangement has been
already suggested to explain some products obtained from
o-(aryloxy)iminyls by flash vacuum pyrolysis (FVP)10a and
from o-(aryloxy)imidoyls in solution.3a,b Radical migrations of
phenyl rings are in general rather uncommon, particularly when
involving heteroatoms.13 To our knowledge, this result seems to
be the first example concerning a 1,5-radical translocation of a
phenyl group from nitrogen to nitrogen. The very small
amounts of the ketone 18, obtained from the perester 6i, could
also be explained with the same mechanism.
Fig. 1 The X-ray crystal structure of 1,4-diphenyl-1,2-dihydroquin-
azolin-2-one (16) showing the atom-numbering scheme
All the peresters 6d–l gave rise to variable amounts of acrid-
ines 13, 14 and 15; these derivatives are always formed with loss
of the substituent on the aminic nitrogen (H, Me, Ph) and
retention of the substituent on the iminic carbon. The form-
ation of these compounds is a very intriguing problem. The first
mechanism considered was an electrocyclic one, similar to that
initially suggested for analogous derivatives obtained by FVP.10b
Nevertheless, the intervention of such a mechanism under our
conditions is very unlikely. Furthermore, the isolation of com-
pounds 19 and 20 from peresters 6j and 6l, respectively, led us to
invent another pathway that could account for the formation of
all the acridine derivatives (Scheme 7).
addition, in the case of perester 6k a GC-MS analysis of the
reaction mixture showed the presence of trace amounts of
9-methylene-10-phenyl-9,10-dihydroacridine: such a compound
can very likely derive from 27k by hydrogen abstraction from
the methyl group. Finally, the carbene 25l was generated by an
independent route starting from the diazo compound 28. From
this experiment we obtained the dihydroacridine 20l as a major
product (Scheme 8). This result clearly shows the importance
Ph
N
25l
20l (40%)
R′
R′
N2
N
N
Ph
. . .
2d–l
N
N
28
O
O
Scheme 8
R
R
24′d–l
24d–l
of carbene 25 in the formation of the acridine derivatives,
although we cannot exclude the intervention to some extent of
path b.14
The quinazolinone 16, whose structure was confirmed by
X-ray diffractometry (Fig. 1), was obtained from the peresters
6f,i,l. In the case of 6i, 16 could be accounted for by cyclisation
of the carbamoyl radical 30 on an iminic double bond (Scheme
9).
R′
R′
N
R
N
a
–NO
X
–XH
R
H
25d–l
20d–l
XH –X
R′
R′
Ph
N
Ph
N
Ph
N
N
N
O
O
Me
N
Ox.
. . .
b
–NO
N
N
R′
R′
R′
R
NO
R
Ph
Ph
Ph
26d–l
27d–l
29
30
31
–R′
–R′
13, 14, 15
19j
16
Ox.
. . .
Scheme 9
(R = H, R′ = Ph)
Scheme 7
Indeed, it has been reported that, under our conditions, N-Me
moieties are easily oxidised to carbamoyl radicals;3b moreover,
an analogous mechanism has been already suggested for
the formation of similar compounds in the oxidation of
N-arylidene-o-(methylanilino)anilines.3b If this mechanism may
be straightforward for the decomposition of 6i, on the other
hand it is rather difficult to understand how 16 can be formed
from 6f,l. Nevertheless, under these conditions we can postulate
the intervention of such aminyl radicals as 32 (Scheme 10);
these species can be generated from 6f,l by hydrogen abstraction
and 1,5-migration of a phenyl group, respectively (see Scheme
6). Although at such high temperatures tert-butoxyl radicals are
known to generate methyl radicals easily, we did not expect to
find products derived from coupling of the methyl radicals. On
the other hand, the structure of 16 was unambiguously estab-
If the oximes are the result of an oxidation process of the
iminyls, as suggested above, their formation should involve the
iminoxyl radicals 24, whose mesomeric form 24Ј can follow two
different routes. In the first case (path a) 24Ј can lose nitric oxide
leading to the carbene 25, whose cyclisation gives the dihydro-
acridines 20, isolated in the case R = RЈ = Ph (20l). Due to
hydrogen abstraction from 20, which produces radicals 27, the
acridines 13, 14 and 15 can arise by loss of the radical RЈ,
whereas 19j can be the result of an oxidation process. Altern-
atively, 24Ј can cyclise to 26 (path b); loss of nitric oxide from 26
leads to radicals 27 and thence to all the acridine derivatives.
The importance of the mesomeric structure 24Ј is evidenced
by the higher yields of acridines when R is a phenyl group. In
J. Chem. Soc., Perkin Trans. 1, 1998
1815

View Article Online
Ph
N
phenyl group from the aminic nitrogen to the iminic one. This
process resembles the behaviour already reported for o-
(phenoxy)arylimidoyl radicals and, to our knowledge, it is
unprecedented. Evidence was found for the formation of the
imines 12 through hydrogen abstraction by the iminyls; surpris-
ingly, we isolated two of them in the case of iminyls 2b,c. The
presence of hydrogen-abstraction products in a very poor
hydrogen donor medium lets us suppose that the homolytic
aromatic substitution should be a very slow reaction. Finally,
from decomposition of the peresters 6a–l some other products
were isolated, probably as a result of carbon-centred radicals;
mechanisms were suggested to account for their formation.
Studies are underway to investigate the behaviour of the same
iminyl radicals when generated under milder, non-oxidative
conditions, i.e. from the corresponding oxime benzoates with
tributyltin radicals.7f,h,i Studies are also in progress on analo-
gous sulfur-containing iminyls to investigate the possibility of
intramolecular homolytic substitution at the sulfur atom.
Ox.
. . .
Me
29
30
16
N
R′
Ph
32
Scheme 10
lished and, as one can see, it contains one carbon atom more by
comparison with the corresponding iminyls. This suggests that
the aminyls 32 and the methyl radicals fulfil the kinetic condi-
tions of the Ingold–Fischer effect for their coupling.15 It is
worth noting that 16 was exclusively obtained when R was a
phenyl: this is probably due to the greater stability attained by
radical 31 when a phenyl ring is linked to the carbon atom.
The last compound we have to account for is the indole
derivative 17, whose structure was unambiguously confirmed
by spectral data comparison with an authentic specimen. It is
not clear how it can be formed, especially in the light of the fact
that it was isolated exclusively from the perester 6h, i.e. only
when the starting material bears two methyl groups. Our
hypothesis that takes this evidence into account is shown in
Scheme 11.
Experimental
General procedures
Melting points were determined on an Electrothermal capillary
apparatus and are uncorrected. 1H and 13C NMR spectra were
recorded in deuterochloroform on Varian EM 360L (60 MHz),
Gemini 200 (200 MHz) or Gemini 300 (300 MHz) instruments,
using tetramethylsilane as an internal standard. Coupling con-
stants J are given in Hz. Low and high resolution mass spectra
were performed with a VG 7070E spectrometer by electron
impact with a beam energy of 70 eV. GC-MS analyses were
carried out on a Carlo Erba AUTO/HRGC/MS-QMD 1000
instrument equipped with a Quadrex capillary column (007,
25 m × 0.25 mm i.d.) and a NIST/NBS library. IR spectra
were recorded in chloroform solution on a Perkin-Elmer 257
spectrophotometer. Column chromatography was carried out
on silica gel (ICN Silica, 63–200, 60 Å), using light petroleum
(bp 40–70 ЊC) and a light petroleum–diethyl ether gradient
(from 0 up to 100% diethyl ether) as eluent. All the organic
phases were dried over anhydrous sodium sulfate. Previously
reported reaction products were identified by spectral com-
parison and mixed mp determination with authentic specimens.
When elemental analyses were not performed, the purity of the
compounds was confirmed by the absence of any significant
Ph
N
Ph
N
Ph
N
R
CH3
NO
CH3
NO
CH2
H
–RH
–NO
CH3
24′h
CH2
33
CH2
34
1, 5-H shift
Ph
N
Ph
N
CH2
H
. . .
17
CH2
CH2
35
36
Scheme 11
1
extraneous peak in the H NMR spectra and/or by GC-MS
The nitroso radical 24Јh, already suggested for the formation
of the acridine derivatives (see Scheme 7), might undergo
hydrogen abstraction to give the corresponding alkene 33 and,
after loss of nitric oxide, the radical 34; 1,5-hydrogen shift leads
to radical 35, which can account for 17 through a 5-exo-trig
cyclisation process. Although this mechanism is not supported
by any experimental evidence, nevertheless the intermediacy of
radical 24Јh and its possibility of furnishing the alkene 33 have
been shown in the discussion of the acridine compounds. The
formation of 17 could be also accounted for through an intra-
molecular insertion of a carbene (25h) into the N-methyl
group.16 Although the intermediacy of the corresponding
carbenic species has been suggested for the reaction of perester
6l (see above), this conjecture would not explain why an analo-
gous indole derivative was not obtained, for instance, from per-
ester 6i (R = Ph), i.e. when the formation of a carbene should be
more favoured. We believe that the mechanism of Scheme 11 is
the only plausible pathway accounting for the simultaneous
presence of the two methyl groups.
analysis.
Starting materials
2-Chlorobenzophenone, N-methylaniline and 2-chlorobenzoic
acid were commercially available (Aldrich). 2-Phenoxybenz-
aldehyde (3a),17 1-(2-phenoxyphenyl)ethan-1-one oxime (4b),18
2-anilinobenzaldehyde (3d),19 1-(2-anilinophenyl)ethan-1-one
(3e),20 (2-anilinophenyl)(phenyl)methanone (3f),20 1-(2-iodo-
phenyl)ethan-1-one,21 2-(diphenylamino)benzaldehyde (3j),22
[2-(diphenylamino)phenyl](phenyl)methanone (3l)23 and tosyl-
hydrazine24 were prepared according to the literature.
(2-Phenoxyphenyl)(phenyl)methanone 3c
Phenol (18.8 g, 200 mmol) was dissolved in a solution of KOH
(11.2 g, 200 mmol) in absolute ethanol (100 cm3). 2-Chloro-
benzophenone (34.3 g, 159 mmol) was then added and the
solvent was removed under vacuum. The resulting mixture was
kept overnight at 200–210 ЊC. After cooling, dichloromethane
and water were added and the organic phase separated and
dried. The residue was chromatographed to give 3c (20.4 g,
47%) as an oil (Found: C, 83.4; H, 5.15. C19H14O2 requires C,
83.2; H, 5.15%); νmax/cmϪ1 3000, 1670, 1600, 1480, 1450,
1320 and 1300; δH(200 MHz) 6.77–6.86 (2 H, m), 6.94–7.10
(2 H, m), 7.16–7.30 (3 H, m ), 7.36–7.60 (5 H, m) and 7.79–
7.87 (2 H, m); m/z 274.1000 (Mϩ, 100%. C19H14O2 requires
274.0994), 273 (86), 197 (92), 105 (85), 77 (87) and 51 (33).
Conclusions
In the light of these results, we can say that iminyl radicals 2a–l
are unable to give seven-membered cyclisation onto both the
phenoxy and the phenylamino moieties. In a few cases (2i–l)
we observed products that can be accounted for through 1,6-
spirocyclisation followed by homolytic 1,5-migration of a
1816
J. Chem. Soc., Perkin Trans. 1, 1998

View Article Online
N-Methyl-N-phenylanthranilic acid
2.42 (3 H, s, COMe), 3.30 (3 H, s, N-Me), 6.70–6.76 (2 H, m,
Following the procedure by Allen and McKee,25 a mixture of
N-methylaniline (177.7 g, 1.66 mol), 2-chlorobenzoic acid (41.0
g, 0.26 mol), anhydrous potassium carbonate (41.0 g, 0.30 mol)
and copper powder (1.0 g) was kept at 200 ЊC for 3 h. The excess
of N-methylaniline was evaporated off and the residue was
refluxed for 15 min with water (500 cm3) and activated carbon.
The hot suspension was filtered and conc. hydrochloric acid
was added to the filtrate up to a slightly acid pH value. The
solution was extracted with dichloromethane, the organic phase
was dried, the solvent removed and the residue chromato-
graphed to give the title compound (47.2 g, 80%), mp 103–
105 ЊC (lit.,26 104–104.5 ЊC).
Ar-H), 6.79–6.86 (1 H, m, Ar-H), 7.20–7.34 (4 H, m, Ar-H),
7.49–7.56 (1 H, m, Ar-H) and 7.66 (1 H, ddd, J1 7.6, J2 1.5, J3
0.4, Ar-H); m/z 225.1156 (Mϩ, 100%. C15H15NO requires
225.1154), 210 (70), 208 (46), 195 (9), 193 (9), 182 (19), 180 (16),
167 (27) and 77 (39).
[2-(Methylanilino)phenyl](phenyl)methanol
A solution of bromobenzene (5.7 g, 36 mmol) in anhydrous
THF was added dropwise under a nitrogen atmosphere to a
stirred suspension of activated magnesium turnings (0.87 g, 36
mmol) in THF. The resulting mixture was refluxed until a
homogeneous solution was obtained. After cooling with an ice-
bath, a solution of 3g (7.6 g, 36 mmol) in THF was added
dropwise at 0 ЊC. The resulting mixture was refluxed for 2 h and
then quenched with water and aqueous ammonium chloride.
After extraction with diethyl ether, the organic phase was dried,
the solvent was removed and the residue chromatographed to
give the title compound (9.7 g, 93%) as an oil (Found: C, 82.7;
H, 6.6; N, 4.8. C20H19NO requires C, 83.0; H, 6.6; N, 4.8%);
νmax/cmϪ1 3600, 3400, 2980, 2880, 1600 and 1490; δH(300 MHz)
2.63 (1 H, br s, CHOH), 2.90 (3 H, s, N-Me), 5.92 (1 H, s,
CHOH), 6.52–6.59 (2 H, m, Ar-H), 6.77 (1 H, dddd, J1, J2 7.2,
J3, J4 0.7, Ar-H), 7.08–7.40 (10 H, m, Ar-H) and 7.62–7.68 (1 H,
m, Ar-H); m/z 289.1471 (Mϩ, 50%. C20H19NO requires
289.1467), 270 (100), 256 (17), 194 (58), 181 (11), 167 (12), 105
(21), 91 (14) and 77 (35).
Methyl N-methyl-N-phenylanthranilate
Methyl iodide (11.7 g, 87.0 mmol) was added dropwise at r.t. to
a stirred solution of potassium carbonate (10.7 g, 77.9 mmol)
and N-methyl-N-phenylanthranilic acid (17.7 g, 77.9 mmol) in
DMF (174 cm3). The mixture was mechanically stirred for 12 h.
The solvent was evaporated and the residue extracted with
diethyl ether; the organic phase was dried and the solvent
removed to give the title compound (17.8 g, 94%) as an oil
(Found: C, 75.0; H, 6.3; N, 5.8. C15H15NO2 requires C, 74.7; H,
6.3; N, 5.8%); νmax/cmϪ1 3050, 3000, 2950, 2880, 1720 and 1600;
δH(60 MHz) 3.23 (3 H, s, N-Me), 3.53 (3 H, s, COOMe) and
6.53–7.97 (9 H, m, Ar-H); m/z 241.1112 (Mϩ, 100%. C15H15NO2
requires 241.1103), 226 (6), 210 (27), 208 (28), 195 (9), 182 (22),
180 (27), 167 (19) and 77 (25).
[2-(Methylanilino)phenyl](phenyl)methanone 3i
[2-(Methylanilino)phenyl]methanol
Following the procedure previously described for 3g, the ketone
3i was isolated (1.8 g, 31%). Better yields were obtained by
methylation of 3f (see above) according to the following pro-
cedure. Finely powdered potassium hydroxide (15.9 g) was
added to a solution of 3f in acetone (135 cm3) and the resulting
mixture was refluxed for 10 min. After cooling, dimethyl sulfate
(26.8 g) was added dropwise. After a 15 min reflux, the mixture
was poured into water and extracted with diethyl ether. The
organic phase was dried, the solvent was removed and the resi-
due chromatographed to give 3i (14.3 g, 79%), mp 107–108.5 ЊC
(Found: C, 83.9; H, 5.95; N, 4.9. C20H17NO requires C, 83.6; H,
5.95; N, 4.9%); νmax/cmϪ1 3000, 1660, 1600 and 1480; δH(300
MHz) 3.05 (3 H, s, N-Me), 6.46–6.52 (2 H, m, Ar-H), 6.70 (1 H,
dddd, J1, J2 7.2, J3, J4 1.0, Ar-H), 7.02–7.09 (2 H, m, Ar-H),
7.26–7.34 (4 H, m, Ar-H), 7.45 (1 H, dddd, J1 7.3, J2 6.7, J3, J4
1.2, Ar-H) and 7.50–7.58 (4 H, m, Ar-H); m/z 287.1312 (Mϩ,
100%. C20H17NO requires 287.1310), 270 (100), 210 (21), 182
(9), 180 (10), 167 (16), 105 (12), 91 (17) and 77 (49).
A solution of methyl N-methyl-N-phenylanthranilate (23.0 g,
95.7 mmol) in anhydrous THF was added dropwise at 0 ЊC to a
stirred solution of LiAlH4 (4 × 1 g pellets, 105.3 mmol) in THF.
After 1 h, ethyl acetate (30 cm3) and then water (20 cm3) were
added cautiously to the solution. After filtration and removal
of the solvent, the residue was extracted with diethyl ether; the
organic phase was dried and the solvent removed to give the
title compound (16.9 g, 83%) as an oil (Found: C, 79.1; H, 7.1;
N, 6.6. C14H15NO requires C, 78.8; H, 7.1; N, 6.6%); νmax/cmϪ1
3600, 3400, 3050, 2950, 2890, 1600 and 1490; δH(300 MHz) 2.62
(1 H, br s, CH2OH), 3.27 (3 H, s, N-Me), 4.60 (2 H, s, CH2OH),
6.63 (2 H, m, Ar-H), 6.81 (1 H, dddd, J1, J2 7.4, J3, J4 0.9,
Ar-H), 7.17–7.27 (3 H, m, Ar-H), 7.31–7.43 (2 H, m, Ar-H) and
7.54–7.59 (1 H, m, Ar-H); m/z 213.1158 (Mϩ, 98%. C14H15NO
requires 213.1154), 195 (18), 194 (100), 182 (13), 180 (46), 167
(17) and 77 (26).
2-(Methylanilino)benzaldehyde 3g
A solution of [2-(methylanilino)phenyl]methanol (10.0 g, 47.1
mmol) in dichloromethane (95 cm3) was added dropwise at r.t.
to a stirred suspension of CrO3 (28.3 g, 282 mmol) in pyridine
(45 cm3) and dichloromethane (700 cm3). After 1 h, the mixture
was filtered on silica gel, the solvent was evaporated and the
residue chromatographed to give 3g (5.0 g, 50%), mp 39.5–
40.5 ЊC (Found: C, 80.0; H, 6.2; N, 6.6. C14H13NO requires C,
79.6; H, 6.2; N, 6.6%); νmax/cmϪ1 3000, 1690, 1600 and 1480;
δH(60 MHz) 3.28 (3 H, s, N-Me), 6.62–8.10 (9 H, m, Ar-H)
and 10.20 (1 H, s, CHO); m/z 211.0995 (Mϩ, 79%. C14H13NO
requires 211.0997), 198 (18), 197 (37), 181 (28), 180 (100), 168
(47), 167 (21) and 77 (31).
1-[2-(Diphenylamino)phenyl]ethan-1-one 3k
The procedure previously described for 3h was followed (see
above), with the exception that, after 5 days at reflux, additional
5 equiv. of K2CO3, iodobenzene and copper were added and the
mixture was refluxed for another week. Under these conditions,
ketone 3e (13.1 g, 62 mmol) gave 3k (8.1 g, 46%), mp 72–74 ЊC
(from light petroleum) (Found: C, 84.0; H, 5.95; N, 4.9.
C20H17NO requires C, 83.6; H, 5.95; N, 4.9%); νmax/cmϪ1 2920,
1680, 1590, 1570, 1470 and 1440; δH(200 MHz) 2.37 (3 H, s,
Me), 6.93–7.05 (6 H, m, Ar-H), 7.12–7.28 (6 H, m, Ar-H), 7.43
(1 H, ddd, J1 7.8, J2 7.4, J3 1.7, Ar-H) and 7.52 (1 H, dd, J1 7.6,
J2 1.6, Ar-H); m/z 287.1315 (Mϩ, 100%. C20H17NO requires
287.1310), 272 (23), 244 (58), 243 (11), 242 (6), 241 (7), 196 (11),
194 (11), 167 (14), 166 (13) and 77 (7).
1-[2-(Methylanilino)phenyl]ethan-1-one 3h
A mixture of N-methylaniline (35.5 g, 180 mmol), 2-iodoaceto-
phenone (44.1 g, 180 mmol), potassium carbonate (17.7 g),
copper powder (1.5 g) and di-n-butyl ether (125 cm3) was
refluxed for 24 h under a nitrogen atmosphere. The hot mixture
was filtered and the solvent was removed. The residue was
chromatographed to give 3h (37.7 g, 93%) as an oil (Found: C,
80.3; H, 6.7; N, 6.2. C15H15NO requires C, 80.0; H, 6.7; N,
6.2%); νmax/cmϪ1 3000, 1680, 1600, 1480 and 1340; δH(300 MHz)
General procedure for the synthesis of the oximes 4a,c–l
According to a standard procedure,27 a solution of the carbonyl
compound and hydroxylamine hydrochloride (same amount in
weight as the former) in a 10:1 v/v mixture of ethanol and
pyridine (with the latter in the same amount in volume as the
carbonyl derivative) was refluxed under mechanical stirring for
a few hours. The mixture was poured into ice–water, acidified to
J. Chem. Soc., Perkin Trans. 1, 1998
1817

View Article Online
pH ~ 5 with conc. hydrochloric acid and extracted with diethyl
ether. The organic phase was dried, the solvent was removed
and the residue chromatographed or crystallised.
2-Phenoxybenzaldehyde oxime 4a. After 1 h and without
chromatography, 3a (19.0 g, 96 mmol) gave 4a (20.0 g, 98%), mp
78–80 ЊC (from light petroleum–benzene) (Found: C, 73.0; H,
30 min, 3i (9.5 g, 33 mmol) yielded 4i (7.6 g, 80%) as a mixture
of the E- and Z-isomers, which were partially separated by
chromatography (Found: C, 79.65; H, 6.0; N, 9.25. C20H18N2O
requires C, 79.4; H, 6.0; N, 9.3%). Major isomer, mp 119–
121 ЊC; νmax/cmϪ1 3570, 3300, 3000, 1605, 1595 and 1490;
δH(200 MHz) 2.90 (3 H, s, NMe), 6.52–6.60 (2 H, m, Ar-H),
6.70 (1 H, dddd, J1 7.4, J2 7.2, J3, J4 0.9, Ar-H), 7.02–7.12 (2 H,
m, Ar-H), 7.20–7.54 (9 H, m, Ar-H) and 8.22 (1 H, br s, OH);
m/z 302.1422 (Mϩ, 74%. C20H18N2O requires 302.1419), 285
(100), 270 (79), 256 (22), 193 (14), 180 (21), 167 (12), 91 (17) and
77 (31). Minor isomer, mp 182–184 ЊC; νmax/cmϪ1 3580, 3300,
3000, 1605, 1595 and 1500; δH(200 MHz) 2.67 (3 H, s, NMe),
6.26–6.34 (2 H, m, Ar-H), 6.70 (1 H, dddd, J1 7.4, J2 7.2, J3, J4
1.0, Ar-H), 7.03–7.38 (9 H, m, Ar-H), 7.48 (1 H, ddd, J1, J2 7.7,
J3 1.5, Ar-H), 7.63 (1 H, dd, J1 7.1, J2 1.2, Ar-H) and 8.20
(1 H, br s, OH); m/z 302.1423 (Mϩ, 22%. C20H18N2O requires
302.1419), 285 (100), 270 (63), 256 (15), 193 (15), 180 (30), 167
(22), 91 (51) and 77 (71).
5.2; N, 6.6. C13H11NO2 requires C, 73.2; H, 5.2; N, 6.6%); νmax
/
cmϪ1 3580, 3320, 1590, 1480 and 1450; δH(200 MHz) 6.91 (1 H,
dd, J1 8.1, J2 1.0, Ar-H), 6.96–7.02 (2 H, m, Ar-H), 7.08–7.20
(2 H, m, Ar-H), 7.29–7.40 (3 H, m, Ar-H), 7.85 (1 H, dd, J1 7.7,
J 1.6, Ar-H), 8.45 (1 H, br s, OH) and 8.51 (1 H, s, CH᎐N); m/z
᎐
2
213.0786 (Mϩ, 57%. C13H11NO2 requires 213.0790), 196 (50),
181 (22), 167 (15), 91 (100), 77 (61) and 51 (35).
(2-Phenoxyphenyl)(phenyl)methanone oxime 4c. After 1 h and
without chromatography, 3c (20.4 g, 75 mmol) yielded 4c (20.0
g, 93%), mp 138–140 ЊC (from light petroleum–benzene)
(Found: C, 79.1; H, 5.2; N, 4.8. C19H15NO2 requires C, 78.9; H,
5.2; N, 4.8%); νmax/cmϪ1 3580, 3300, 3000, 1600, 1580, 1480,
1450, 1320, 1310, 1160, 990 and 910; δH(200 MHz) 6.87–7.07
(4 H, m, Ar-H), 7.15–7.44 (8 H, m, Ar-H), 7.45–7.53 (2 H, m,
Ar-H) and 8.88 (1 H, br s, OH); m/z 289.1105 (Mϩ, 51%.
C19H15NO2 requires 289.1103), 272 (100), 196 (20), 181 (19),
105 (56), 91 (68), 77 (72) and 51 (42).
2-Anilinobenzaldehyde oxime 4d. After 1 h, 3d (16.8 g, 85
mmol) gave 4d (15.0 g, 83%), mp 47–49 ЊC (Found: C, 73.9;
H, 5.7; N, 13.15. C13H12N2O requires C, 73.6; H, 5.7; N,
13.2%); νmax/cmϪ1 3570, 3300, 3000, 1600, 1570, 1460 and
1320; δH(300 MHz) 6.82 (1 H, ddd, J1, J2 7.1, J3 1.3, Ar-
H), 7.09 (1 H, dddd, J1, J2 7.0, J3, J4 1.0, Ar-H), 7.12–7.40
2-(Diphenylamino)benzaldehyde oxime 4j. After 1 h, 3j (11.9
g, 43 mmol) yielded 4j (10.5 g, 84%), mp 123–125 ЊC (from light
petroleum–benzene) (Found: C, 79.2; H, 5.6; N, 9.7. C19H16N2O
requires C, 79.1; H, 5.6; N, 9.7%); νmax/cmϪ1 3580, 3320, 1590
and 1490; δH(300 MHz) 6.92–7.02 (6 H, m, Ar-H), 7.11–7.26 (6
H, m, Ar-H), 7.34–7.42 (1 H, m, Ar-H), 7.81 (1 H, dd, J1 7.7,
J 1.2, Ar-H) and 8.22–8.28 (2 H, s ϩ br s, N᎐CH ϩ OH); m/z
᎐
2
288.1266 (Mϩ, 100%. C19H16N2O requires 288.1263), 271 (64),
270 (24), 269 (17), 256 (99), 243 (13), 180 (22), 167 (16), 77 (22)
and 51 (21).
1-[2-(Diphenylamino)phenyl]ethan-1-one oxime 4k. After 12 h,
3k (8.1 g, 28 mmol) gave 4k (8.5 g, 99%) as a glassy solid, 5:1
mixture of the E- and Z-isomers (Found: C, 79.6; H, 6.0; N,
9.25. C20H18N2O requires C, 79.4; H, 6.0; N, 9.3%); δH(200
MHz) 1.75 (3 H, s, C-Me, minor isomer), 1.95 (3 H, s, C-Me,
major isomer), 6.90–7.38 (14 H, m, Ar-H) and 7.74 (1 H, br s,
OH, both isomers); m/z 302.1424 (Mϩ, 100%. C20H18N2O
requires 302.1419), 285 (48), 270 (80), 256 (12), 243 (13), 210
(16), 195 (17), 167 (17), 77 (21) and 51 (15).
[2-(Diphenylamino)phenyl](phenyl)methanone oxime 4l. After
24 h, 3l (8.7 g, 25 mmol) yielded 4l (7.0 g, 77%) as a mixture of
the E- and Z-isomers, which were partially separated by chrom-
atography (Found: C, 82.6; H, 5.5; N, 7.7. C25H20N2O requires
C, 82.4; H, 5.5; N, 7.7%). Major isomer, mp 145–147 ЊC (from
light petroleum–benzene); νmax/cmϪ1 3560, 3300, 1590 and 1480;
δH(300 MHz) 6.80–7.42 (19 H, m, Ar-H) and 8.05 (1 H, br s,
OH); m/z 364.1577 (Mϩ, 92%. C25H20N2O requires 364.1576),
347 (36), 332 (100), 272 (20), 256 (13), 196 (10), 167 (12), 77
(16) and 51 (9). Minor isomer, mp 158–159 ЊC (from light
petroleum–benzene); νmax/cmϪ1 3560, 3300, 1590 and 1480;
δH(300 MHz) 6.67–7.50 (19 H, m, Ar-H) and 8.16 (1 H, br s,
OH); m/z 364.1578 (Mϩ, 98%. C25H20N2O requires 364.1576),
347 (39), 332 (100), 272 (22), 256 (12), 196 (10), 167 (11), 77 (13)
and 51 (6).
(8 H, m, Ar-H ϩ OH), 8.30 (1 H, s, CH᎐N) and 8.82 (1 H,
᎐
br s, NH); m/z 212.0947 (Mϩ, 100%. C13H12N2O requires
212.0950), 195 (80), 194 (24), 193 (14), 180 (79), 167 (31), 166
(10) and 77 (21).
1-(2-Anilinophenyl)ethan-1-one oxime 4e. After 1 h, 3e (10.0
g, 47 mmol) yielded 4e (17.2 g, 85%) as an oil (Found: C, 74.6;
H, 6.25; N, 12.35. C14H14N2O requires C, 74.3; H, 6.25; N,
12.4%); νmax/cmϪ1 3580, 3300, 3000, 1600, 1580 and 1450;
δH(300 MHz) 2.40 (3 H, s, Me), 6.87–6.93 (1 H, m, Ar-H), 7.00–
7.06 (1 H, m, Ar-H), 7.16–7.35 (5 H, m, Ar-H), 7.38 (1 H, dd, J1
8.3, J2 1.3, Ar-H), 7.47 (1 H, dd, J1 7.9, J2 1.6, Ar-H), 7.85 (1 H,
br s) and 8.85 (1 H, br s); m/z 226.1108 (Mϩ, 100%. C14H14N2O
requires 226.1106), 209 (74), 208 (31), 207 (35), 194 (60), 180
(38), 167 (46), 166 (21) and 77 (27).
(2-Anilinophenyl)(phenyl)methanone oxime 4f. After 1 h, 3f
(19.2 g, 70 mmol) yielded 4f (17.2 g, 85%), mp 143–145 ЊC
(Found: C, 79.3; H, 5.6; N, 9.75. C19H16N2O requires C, 79.1;
H, 5.6; N, 9.7%); νmax/cmϪ1 3560, 3400, 3000, 1600, 1580, 1500,
1450 and 1310; δH(200 MHz) 6.13 (1 H, br s, OH), 6.85–7.60
(14 H, m, Ar-H) and 9.70 (1 H, br s, NH); m/z 288.1266 (Mϩ,
76%. C19H16N2O requires 288.1263), 269 (100), 256 (38), 196
(17), 167 (28) and 77 (21).
2-(Methylanilino)benzaldehyde oxime 4g. After 30 min and
without chromatography, 3g (10.6 g, 50 mmol) yielded 4g (9.7 g,
86%), mp 107–109 ЊC (from light petroleum–benzene) (Found:
C, 74.6; H, 6.25; N, 12.35. C14H14N2O requires C, 74.3; H, 6.25;
N, 12.4%); νmax/cmϪ1 3580, 3320, 3000, 1600, 1490 and 1340;
δH(300 MHz) 3.25 (3 H, s, Me), 6.60–6.66 (2 H, m, Ar-H), 6.76–
6.82 (1 H, m, Ar-H), 7.16–7.33 (4 H, m, Ar-H), 7.41–7.48 (1 H,
m, Ar-H), 7.88–7.93 (1 H, m, Ar-H), 8.16 (1 H, s, OH) and 8.24
General procedure for the synthesis of the iminoxyacetic acids
5a–l
According to the reported procedure,5b a mixture of oxime
(30 mmol), chloroacetic acid (1.6 equiv.) and sodium hydroxide
(3 equiv.) in water (25 cm3)–ethanol (13 cm3) was refluxed for
several hours. Then it was poured into ice–water and neutral-
ised with conc. hydrochloric acid. The mixture was extracted
with dichloromethane, the organic phase was dried, the solvent
removed and the residue chromatographed.
(1 H, s, N᎐CH); m/z 226.1102 (Mϩ, 39%. C H N O requires
᎐
14 14
2
226.1106), 209 (100), 194 (87), 180 (61) and 77 (26).
1-[2-(Methylanilino)phenyl]ethan-1-one oxime 4h. After 30
min and without chromatography, 3h (19.8 g, 88 mmol) yielded
4h (17.2 g, 81%) as an oil (Found: C, 74.8; H, 6.7; N, 11.65.
C15H16N2O requires C, 75.0; H, 6.7; N, 11.7%); δH(200 MHz)
2.06 (3 H, s, C-Me), 3.19 (3 H, s, N-Me), 6.66–6.83 (3 H, m,
Ar-H), 7.14–7.48 (6 H, m, Ar-H) and 8.78 (1 H, br s, OH); m/z
240.1266 (Mϩ, 31%. C15H16N2O requires 240.1263), 223 (62),
208 (100), 194 (44), 193 (16), 180 (14) and 77 (20).
2-({[1-(2-Phenoxyphenyl)methylidene]amino}oxy)acetic acid
5a. After 16 h, 4a (20.0 g, 94 mmol) gave 5a (21.0 g, 78%), mp
101–103 ЊC (from light petroleum–benzene) (Found: C, 66.5;
H, 4.8; N, 5.1. C15H13NO4 requires C, 66.4; H, 4.8; N, 5.1%);
νmax/cmϪ1 3500, 3050, 1740, 1590, 1480 and 1090; δH(200 MHz)
4.80 (2 H, s, CH2), 6.90–7.05 (3 H, m, Ar-H), 7.10–7.20 (2 H,
m, Ar-H), 7.30–7.45 (3 H, m, Ar-H), 7.93 (1 H, dd, J1 7.8, J2
[2-(Methylanilino)phenyl](phenyl)methanone oxime 4i. After
1.4, Ar-H) and 8.63 (1 H, s, N᎐CH); m/z 271.0851 (Mϩ, 9%.
᎐
1818
J. Chem. Soc., Perkin Trans. 1, 1998

View Article Online
C15H13NO4 requires 271.0845), 197 (73), 196 (100), 195 (84),
181 (13), 167 (32), 120 (10), 77 (67) and 51 (36).
m, Ar-H), 7.15–7.50 (6 H, m, Ar-H) and 8.95 (1 H, br s, OH);
m/z 298 (Mϩ, 1%), 253 (<1), 224 (31), 223 (22), 221 (42), 209
(77), 208 (76), 207 (40), 206 (16), 193 (23), 180 (12), 167 (10),
119 (52), 104 (88) and 77 (100).
2-({[1-(2-Phenoxyphenyl)ethylidene]amino}oxy)acetic acid 5b.
After 16 h, 4b (11.9 g, 52 mmol) yielded 5b (9.50 g, 64%) as a
6.4:1 mixture of the E- and Z-isomers, mp 90–93 ЊC (from light
petroleum–benzene) (Found: C, 67.5; H, 5.3; N, 4.9. C16H15NO4
requires C, 67.4; H, 5.3; N, 4.9%); νmax/cmϪ1 3500, 3060, 1770,
1740, 1600, 1490 and 1100; δH(200 MHz) 2.18 (3 H, s, Me,
minor isomer), 2.28 (3 H, s, Me, major isomer), 4.55 (2 H, s,
CH2, minor isomer), 4.72 (2 H, s, CH2, major isomer), 6.85–
7.40 (9 H, m, Ar-H), 7.46 (1 H, dd, J1 7.5, J2 1.6, Ar-H, major
isomer) and 10.81 (1 H, s, OH); m/z 285.1006 (Mϩ, 14%.
C16H15NO4 requires 285.1001), 211 (47), 210 (100), 196 (59),
120 (18), 91 (16), 77 (51) and 51 (24).
2-({[1-(2-Phenoxyphenyl)-1-phenylmethylidene]amino}oxy)-
acetic acid 5c. After 16 h, 4c (20.0 g, 69 mmol) yielded 5c
(11.4 g, 48%), mp 146–148 ЊC (from light petroleum–benzene)
(Found: C, 72.9; H, 4.9; N, 4.0. C21H17NO4 requires C, 72.6;
H, 4.9; N, 4.0%); νmax/cmϪ1 3340, 3060, 3000, 1770, 1730, 1590,
1580, 1480, 1450, 1350, 1330 and 1090; δH(200 MHz) 4.74 (2 H,
s, CH2), 6.90–7.12 (4 H, m, Ar-H), 7.22–7.47 (8 H, m, Ar-H)
and 7.50–7.58 (2 H, m, Ar-H); m/z 347.1164 (Mϩ, 12%.
C21H17NO4 requires 347.1158), 273 (73), 272 (100), 196 (40),
180 (31), 77 (76) and 51 (29).
2-[({1-[2-(Methylanilino)phenyl]-1-phenylmethylidene}amino)-
oxy]acetic acid 5i. After 16 h, 4i (12.4 g, 41 mmol) yielded 5i
(12.4 g, 84%) as a 2:1 mixture of the E- and Z-isomers, oil
(Found: C, 73.55; H, 5.6; N, 7.8. C22H20N2O3 requires C, 73.3;
H, 5.6; N, 7.8%); νmax/cmϪ1 3500, 3060, 1770, 1730, 1600, 1490,
1350 and 1100; δH(200 MHz) 2.72 (3 H, s, Me, minor isomer),
2.92 (3 H, s, Me, major isomer), 4.68 (2 H, s, CH2, major
isomer), 4.70 (2 H, s, CH2, minor isomer), 6.30–6.37 (2 H, m,
Ar-H, minor isomer), 6.55–6.63 (2 H, m, Ar-H, major isomer),
6.69–6.78 (1 H, m, Ar-H, minor isomer), 7.03–7.14 (1 H, m,
Ar-H, major isomer), 7.20–7.70 (11 H, m, Ar-H) and 10.40
(1 H, br s, COOH); m/z 360.1480 (Mϩ, 11%. C22H20N2O3
requires 360.1474), 285 (28), 270 (69), 269 (100), 165 (29) and 77
(24).
2-[({1-[2-(Diphenylamino)phenyl]methylidene}amino)oxy]-
acetic acid 5j. After 16 h, 4j (9.1 g, 32 mmol) yielded 5j (5.5 g,
50%), mp 134–136 ЊC (from light petroleum–benzene) (Found:
C, 73.15; H, 5.2; N, 8.1. C21H18N2O3 requires C, 72.8; H, 5.2; N,
8.1%); νmax/cmϪ1 3500, 3050, 1780, 1740, 1590, 1490 and 1100;
δH(300 MHz) 4.60 (2 H, s, CH2), 6.92–7.00 (6 H, m, Ar-H), 7.12
(1 H, dd, J1 7.8, J2 1.1, Ar-H), 7.18–7.26 (5 H, m, Ar-H), 7.36–
7.42 (1 H, m, Ar-H), 7.82 (1 H, dd, J1 7.8, J2 1.4, Ar-H) and 8.30
2-({[1-(2-Anilinophenyl)methylidene]amino}oxy)acetic
acid
5d. After 16 h, 4d (14.4 g, 68 mmol) yielded 5d (12.0 g, 65%), mp
143–145 ЊC (from light petroleum–benzene) (Found: C, 66.85;
H, 5.2; N, 10.35. C15H14N2O3 requires C, 66.7; H, 5.2; N,
10.4%); νmax/cmϪ1 3300, 3000, 1740, 1610, 1600, 1570 and 1320;
δH(300 MHz) 4.78 (2 H, s, CH2), 6.81 (1 H, ddd, J1 7.9, J2 7.0, J3
1.2, Ar-H), 7.07 (1 H, dddd, J1, J2 7.0, J3, J4 1.2, Ar-H), 7.18–
(1 H, s, N᎐CH); m/z 346.1320 (Mϩ, 5%. C H N O requires
᎐
21 18
2
3
346.1317), 270 (100), 269 (30), 256 (15), 167 (14), 135 (11), 77
(12) and 51 (11).
2-[({1-[2-(Diphenylamino)phenyl]ethylidene}amino)oxy]acetic
acid 5k. After 9 h, 4k (8.5 g, 28 mmol) gave 5k (6.0 g, 59%) as a
5:1 mixture of the E- and Z-isomers, oil (Found: C, 73.45; H,
7.37 (7 H, m, Ar-H), 8.38 (1 H, s, N᎐CH) and 8.65 (1 H, br s,
᎐
NH); m/z 270.1008 (Mϩ, 71%. C15H14N2O3 requires 270.1004),
195 (100), 194 (32), 180 (24), 167 (36) and 77 (19).
5.6; N, 7.8. C22H20N2O3 requires C, 73.3; H, 5.6; N, 7.8%); νmax/
cmϪ1 3500, 3060, 3000, 1770, 1740, 1590, 1480 and 1100; δH(200
MHz) 1.55 (3 H, s, Me, minor isomer), 2.05 (3 H, s, Me, major
isomer), 4.23 (2 H, s, CH2, minor isomer), 4.40 (2 H, s, CH2,
major isomer) and 6.92–7.42 (14 H, m, Ar-H); m/z 360.1473
(Mϩ, 19%. C22H20N2O3 requires 360.1474), 286 (55), 285 (29),
271 (17), 195 (100), 167 (14), 77 (26) and 51 (14).
2-({[1-(2-Anilinophenyl)ethylidene]amino}oxy)acetic acid 5e.
After 16 h, 4e (9.3 g, 41 mmol) yielded 5e (7.30 g, 63%), mp
103–104 ЊC (from light petroleum–benzene) (Found: C, 67.8; H,
5.7; N, 9.9. C16H16N2O3 requires C, 67.6; H, 5.7; N, 9.85%); νmax
/
cmϪ1 3300, 3000, 1740, 1600 and 1450; δH(300 MHz) 2.40 (3 H,
s, Me), 4.75 (2 H, s, CH2), 6.81–6.88 (1 H, m, Ar-H), 6.89–6.96
(1 H, m, Ar-H), 7.07–7.42 (7 H, m, Ar-H) and 9.00 (2 H, br s,
NH ϩ OH); m/z 284.1163 (Mϩ, 86%. C16H16N2O3 requires
284.1161), 209 (100), 208 (30), 207 (23), 194 (20), 193 (14), 180
(17), 167 (52), 166 (13) and 77 (14).
2-[({1-[2-(Diphenylamino)phenyl]-1-phenylmethylidene}-
amino)oxy]acetic acid 5l. After 21 h, 4l (16.4 g, 45 mmol)
yielded 5l (12.2 g, 64%) as a 4:1 mixture of the E- and
Z-isomers, mp 158–162 ЊC (from light petroleum–benzene)
(Found: C, 77.1; H, 5.25; N, 6.6. C27H22N2O3 requires C, 76.8;
H, 5.25; N, 6.6%); νmax/cmϪ1 3460, 3040, 1760, 1730, 1590, 1430
and 1090; δH(300 MHz) 4.38 (2 H, s, CH2, major isomer), 4.48
(2 H, s, CH2, minor isomer), 6.65–7.51 (19 H, m, Ar-H); m/z
422.1636 (Mϩ, 6%. C27H22N2O3 requires 422.1630), 348 (69),
347 (100), 271 (8), 256 (15), 77 (19) and 51 (6).
2-({[1-(2-Anilinophenyl)-1-phenylmethylidene]amino}oxy)-
acetic acid 5f. After 16 h, 4f (20.0 g, 69 mmol) yielded 5f (16.6 g,
69%), mp 178–180 ЊC (by addition of light petroleum to an ice-
cold diethyl ether solution) (Found: C, 73.1; H, 5.2; N, 8.1.
C21H18N2O3 requires C, 72.8; H, 5.2; N, 8.1%); νmax/cmϪ1 3350,
3000, 1740, 1600, 1500 and 1310; δH(300 MHz) 4.90 (2 H, br
s, CH2), 6.78–7.60 (14 H, m, Ar-H) and 8.57 (2 H, br s,
NH ϩ OH); m/z 346.1322 (Mϩ, 78%. C21H18N2O3 requires
346.1317), 271 (79), 270 (61), 269 (100), 255 (11), 167 (40) and
77 (22).
General procedure for the synthesis of the iminoxyperacetates
6a–l
According to the reported procedure,28 the iminoxyacetic acid
(10 mmol) was added at r.t. and under nitrogen to a stirred
solution of CDI (1 equiv) in anhydrous THF (15 cm3). After
1 h, a solution of tert-butyl hydroperoxide (2.2 equiv.) in light
petroleum (30 cm3) was added dropwise at 0 ЊC and the mixture
was kept at 0–5 ЊC for 4 h. The mixture was poured into water
and extracted with diethyl ether. The organic phase was washed
twice with cold water and dried. After removal of the solvent
the residue was chromatographed. Due to very low (or absent)
molecular ions (with the exception of 6d) and their decompos-
ition hazard, neither high resolution mass spectra nor elemental
analyses were obtained for the peresters 6a–l; their purity was
however confirmed by the complete absence of any significant
extraneous peak in the 1H NMR spectra.
2-[({1-[2-(Methylanilino)phenyl]methylidene}amino)oxy]-
acetic acid 5g. After 16 h, 4g (11.5 g, 50 mmol) yielded 5g
(12.8 g, 91%), mp 87–88 ЊC (Found: C, 67.8; H, 5.7; N, 9.8.
C16H16N2O3 requires C, 67.6; H, 5.7; N, 9.85%); νmax/cmϪ1 3500,
3050, 3000, 2920, 1770, 1730, 1600, 1480, 1340 and 1110; δH(300
MHz) 3.50 (3 H, s, Me), 4.98 (2 H, s, CH2), 6.84–6.89 (2 H, m,
Ar-H), 7.03 (1 H, dddd, J1, J2 7.0, J3, J4 1.0, Ar-H), 7.40–7.57
(4 H, m, Ar-H), 7.67–7.74 (1 H, m, Ar-H), 8.17 (1 H, dd, J1 7.7,
J 1.4, Ar-H) and 8.55 (1 H, s, N᎐CH); m/z 284.1160 (Mϩ, 22%.
᎐
2
C16H16N2O3 requires 284.1161), 209 (100), 208 (48), 207 (32),
194 (67), 180 (46) and 77 (26).
2-[({1-[2-(Methylanilino)phenyl]ethylidene}amino)oxy]acetic
acid 5h. After 16 h, 4h (15.6 g, 65 mmol) gave 5h (16.8 g, 87%),
mp 49–53 ЊC (Found: C, 68.7; H, 6.1; N, 9.35. C17H18N2O3
requires C, 68.4; H, 6.1; N, 9.4%); δH(200 MHz) 2.10 (3 H, s,
C-Me), 3.20 (3 H, s, N-Me), 4.70 (2 H, s, CH2), 6.65–6.85 (3 H,
CAUTION: Since hydroperoxides and peresters are poten-
tially hazardous compounds, they must be handled with due
care; avoid exposure to strong heat or light, mechanical shock,
oxidisable organic materials, or transition metal ions. No par-
J. Chem. Soc., Perkin Trans. 1, 1998
1819

View Article Online
ticular difficulties were experienced in handling any of the new
peresters synthesised in this work using the procedure described
above. Their column chromatography did not give any problems,
even on a 10 g scale; however, we advise performing the separ-
ation with extreme care, evaporating the solvent under reduced
pressure with a water bath kept below 20 ЊC.
Z-isomers, oil; δH(200 MHz) 1.35 (9 H, s, But, minor isomer),
1.37 (9 H, s, But, major isomer), 2.10 (3 H, s, C-Me, major
isomer), 2.32 (3 H, s, C-Me, minor isomer), 3.20 (3 H, s, N-Me,
major isomer), 3.30 (3 H, s, N-Me, minor isomer), 4.77 (2 H, s,
CH2, major isomer), 4.85 (2 H, s, CH2, minor isomer), 6.70–
6.85 (3 H, m, Ar-H) and 7.15–7.70 (6 H, m, Ar-H, both
isomers); m/z 370 (Mϩ, <1%), 326 (6), 296 (1), 223 (33), 208
(100), 207 (49), 206 (34), 194 (10), 77 (14) and 57 (35).
tert-Butyl 2-({[1-(2-phenoxyphenyl)methylidene]amino}oxy)-
peracetate 6a. Starting from 5a (8.1 g, 30 mmol), 6a was
obtained (9.15 g, 89%) as an oil; νmax/cmϪ1 3000, 2940, 1780,
1590, 1480, 1450, 1240 and 1080; δH(200 MHz) 1.33 (9 H, s,
But), 4.78 (2 H, s, CH2), 6.88 (1 H, dd, J1 8.1, J2 1.0, Ar-H),
6.92–7.02 (2 H, m, Ar-H), 7.06–7.16 (2 H, m, Ar-H), 7.28–7.40
(3 H, m, Ar-H), 7.88 (1 H, dd, J1 7.7, J2 1.6, Ar-H) and 8.58
tert-Butyl 2-[({1-[2-(methylanilino)phenyl]-1-phenylmethyl-
idene}amino)oxy]peracetate 6i. Starting from 5i (7.0 g, 20
mmol), 6i was obtained (7.2 g, 85%) as a 2:1 mixture of the
E- and Z-isomers, oil; νmax/cmϪ1 2920, 1780 and 1600; δH(200
MHz) 1.33 (9 H, s, But, both isomers), 2.80 (3 H, s, N-Me,
minor isomer), 2.93 (3 H, s, N-Me, major isomer), 4.68 (2 H, s,
CH2, major isomer), 4.73 (2 H, s, CH2, minor isomer), 6.30–
6.38 (2 H, m, Ar-H, minor isomer), 6.50–6.60 (2 H, m, Ar-H,
major isomer), 6.66–6.76 (1 H, m, Ar-H, minor isomer), 7.00–
7.12 (1 H, m, Ar-H, major isomer) and 7.15–7.70 (11 H, m,
Ar-H, both isomers); m/z 388 (Mϩ Ϫ 44, 19%), 285 (59), 270
(100), 269 (84), 165 (28), 77 (15) and 57 (40).
(1 H, s, N᎐CH); m/z 344 (Mϩ ϩ 1, <1%), 299 (1), 213 (10), 196
᎐
(44), 195 (100), 167 (48), 77 (64) and 57 (31).
tert-Butyl
2-({[1-(2-phenoxyphenyl)ethylidene]amino}oxy)-
peracetate 6b. Starting from 5b (9.5 g, 33 mmol), 6b was
obtained (10.0 g, 84%) as an oil; νmax/cmϪ1 2980, 2930, 1780,
1590, 1480, 1450 and 1370; δH(200 MHz) 1.24 (9 H, s, But), 2.21
(3 H, s, Me), 4.71 (2 H, s, CH2), 6.82 (1 H, dd, J1 7.9, J2 1.1,
Ar-H), 6.86–6.95 (2 H, m, Ar-H), 6.98–7.08 (2 H, m, Ar-H),
7.18–7.34 (3 H, m, Ar-H) and 7.38 (1 H, dd, J1 7.5, J2 1.7, Ar-
H); m/z 357 (Mϩ, <1%), 313 (8), 283 (17), 227 (32), 210 (100),
195 (33), 185 (26), 134 (23), 91 (41), 77 (42) and 57 (100).
tert-Butyl
2-[({1-[2-(diphenylamino)phenyl]methylidene}-
amino)oxy]peracetate 6j. Starting from 5j (9.4 g, 27 mmol), 6j
was obtained (6.8 g, 60%), mp 64–68 ЊC; νmax/cmϪ1 2980, 1780,
1590, 1480 and 1080; δH(200 MHz) 1.30 (9 H, s, But), 4.67 (2 H,
s, CH2), 6.92–7.45 (13 H, m, Ar-H), 7.89 (1 H, dd, J1 7.7, J2 1.6,
tert-Butyl
2-({[1-(2-phenoxyphenyl)-1-phenylmethylidene]-
amino}oxy)peracetate 6c. Starting from 5c (8.7 g, 25 mmol), 6c
was obtained (8.3 g, 79%) as a 11:8 mixture of the E- and
Z-isomers, oil; νmax/cmϪ1 2990, 2970, 2880, 1770, 1590, 1580,
1480, 1450, 1370 and 1090; δH(200 MHz) 1.27 (9 H, s, But,
major isomer), 1.29 (9 H, s, But, minor isomer), 4.68 (2 H, s,
CH2, major isomer), 4.76 (2 H, s, CH2, minor isomer), 6.68–
6.76 (2 H, m, Ar-H, both isomers) and 6.82–7.60 (26 H, m,
Ar-H, both isomers); m/z 345 (Mϩ Ϫ 74, 15%), 289 (19), 272
(100), 196 (53), 105 (28), 77 (42) and 57 (93).
tert-Butyl 2-({[1-(2-anilinophenyl)methylidene]amino}oxy)-
peracetate 6d. Starting from 5d (5.4 g, 20 mmol), 6d was
obtained (6.0 g, 90%), mp 39–41 ЊC; δH(200 MHz) 1.20 (9 H, s,
But), 4.70 (2 H, s, CH2), 6.66–6.76 (1 H, m, Ar-H), 6.93–7.03
Ar-H) and 8.30 (1 H, s, N᎐CH); m/z 375 (Mϩ Ϫ 43, 14%), 345
᎐
(Mϩ Ϫ 73, 11), 271 (100), 270 (34), 257 (30), 167 (12), 77 (14),
57 (26), 51 (11) and 44 (27).
tert-Butyl
2-[({1-[2-(diphenylamino)phenyl]ethylidene}-
amino)oxy]peracetate 6k. Starting from 5k (6.0 g, 17 mmol), 6k
was obtained (5.4 g, 76%) as a 5:1 mixture of the E- and
Z-isomers, oil; νmax/cmϪ1 2980, 1780, 1590, 1480, 1370 and
1090; δH(200 MHz) 1.20 (9 H, s, But, both isomers), 1.73 (3 H, s,
Me, minor isomer), 1.90 (3 H, s, Me, major isomer), 4.18 (2 H, s,
CH2, minor isomer), 4.38 (2 H, s, CH2, major isomer) and 6.82–
7.30 (14 H, m, Ar-H, both isomers); m/z 432 (Mϩ, 1%), 388
(100), 358 (15), 302 (22), 285 (70), 270 (79), 256 (13), 243 (10),
195 (18), 167 (10), 77 (7) and 57 (22).
(1 H, m, Ar-H), 7.06–7.30 (7 H, m, Ar-H), 8.26 (1 H, s, N᎐CH)
tert-Butyl 2-[({1-[2-(diphenylamino)phenyl]-1-phenylmethyl-
idene}amino)oxy]peracetate 6l. Starting from 5l (9.7 g, 23
mmol), 6l was obtained (6.7 g, 59%) as an oil; νmax/cmϪ1 2980,
1770, 1590, 1480, 1370 and 1090; δH(200 MHz) 1.25 (9 H, s,
But), 4.40 (2 H, br s, CH2) and 6.70–7.45 (19 H, m, Ar-H); m/z
451 (Mϩ Ϫ 43, 47%), 421 (Mϩ Ϫ 73, 24), 378 (8), 364 (11), 348
(54), 347 (100), 332 (74), 256 (25), 77 (12) and 57 (9).
᎐
and 8.54 (1 H, br s, NH); m/z 342.1586 (Mϩ, 5%. C19H22N2O4
requires 342.1580), 298 (63), 268 (4), 212 (45), 195 (100), 180
(74), 167 (22) and 57 (82).
tert-Butyl
2-({[1-(2-anilinophenyl)ethylidene]amino}oxy)-
peracetate 6e. Starting from 5e (5.4 g, 19 mmol), 6e was
obtained (6.4 g, 95%), mp 34–35 ЊC; νmax/cmϪ1 3370, 3000, 1780,
1600, 1450, 1370 and 1100; δH(60 MHz) 1.30 (9 H, s, But), 2.10
(3 H, s, Me), 4.67 (2 H, s, CH2), 6.70–7.58 (9 H, m, Ar-H) and
8.88 (1 H, br s, NH); m/z 356 (Mϩ, <1%), 312 (73), 282 (6), 227
(5), 226 (29), 209 (100), 208 (23), 194 (61), 180 (19), 167 (35), 77
(14) and 57 (68).
General procedure for the decomposition of peresters 6a–l
A bromobenzene (50 cm3) solution of the perester (10 mmol)
was added dropwise in 1 h to 450 cm3 of boiling bromobenzene.
After one additional hour at reflux, the solution was cooled, the
solvent was evaporated and the residue chromatographed.
From 6a. Perester 6a (9.5 mmol) gave in order of elution 3a
(0.40 g, 21%); 2-phenoxybenzaldehyde O-(tert-butyl)oxime 11a
(0.03 g, 1%), oil; νmax/cmϪ1 2980, 2930, 1590, 1480, 1450, 1370
and 960; δH(200 MHz) 1.32 (9 H, s, But), 6.86–6.97 (3 H, m,
Ar-H), 7.02–7.18 (2 H, m, Ar-H), 7.24–7.36 (3 H, m, Ar-H),
tert-Butyl
2-({[1-(2-anilinophenyl)-1-phenylmethylidene]-
amino}oxy)peracetate 6f. Starting from 5f (5.4 g, 15 mmol), 6f
was obtained (6.2 g, 96%), mp 94.5–95.5 ЊC; νmax/cmϪ1 3330,
2990, 1780, 1600, 1500, 1450, 1370, 1310 and 1090; δH(200
MHz) 1.37 (9 H, s, But), 4.90 (2 H, s, CH2) and 6.90–7.60 (14 H,
m, Ar-H); m/z 374 (Mϩ Ϫ 44, 2%), 344 (<1), 271 (11), 269 (5),
256 (4), 196 (1), 167 (2), 59 (30) and 44 (100).
7.96 (1 H, dd, J 7.8, J 1.6, Ar-H) and 8.38 (1 H, s, N᎐CH); m/z
᎐
1
2
tert-Butyl
2-[({1-[2-(methylanilino)phenyl]methylidene}-
269.1418 (Mϩ, 15%. C17H19NO2 requires 269.1416), 213 (31),
196 (25), 181 (25), 91 (45), 77 (25) and 57 (100); 2-phenoxy-
benzaldehyde O-(tert-butoxymethyl)oxime 9a (0.32 g, 11%), oil;
νmax/cmϪ1 2980, 1600, 1480, 1450 and 1000; δH(200 MHz) 1.25
(9 H, s, But), 5.34 (2 H, s, CH2), 6.84–7.40 (8 H, m, Ar-H), 8.00
amino)oxy]peracetate 6g. Starting from 5g (7.8 g, 27 mmol), 6g
was obtained (8.8 g, 92%) as an oil; νmax/cmϪ1 2980, 1770, 1600,
1520 and 1180; δH(300 MHz) 1.35 (9 H, s, But), 3.25 (3 H, s,
Me), 4.75 (2 H, s, CH2), 6.58–6.64 (2 H, m, Ar-H), 6.79 (1 H,
dd, J1, J2 7.1, Ar-H), 7.15–7.32 (4 H, m, Ar-H), 7.45 (1 H, ddd,
J1, J2 7.7, J3 1.6, Ar-H), 7.94 (1 H, dd, J1 7.9, J2 1.6, Ar-H) and
(1 H, dd, J 7.9, J 1.6, Ar-H) and 8.46 (1 H, s, N᎐CH); m/z
᎐
1
2
299.1526 (Mϩ, 9%. C18H21NO3 requires 299.1521), 269 (6), 213
(26), 196 (70), 77 (19) and 57 (100); 2-phenoxybenzonitrile 10a
(0.96 g, 42%), oil [lit.,29 bp (6 mbar) 150–154 ЊC]; νmax/cmϪ1
3000, 2230, 1600, 1480, 1450 and 1250; m/z 195 (Mϩ, 100%),
167 (50), 77 (45) and 51 (38); 4a (0.03 g, 2%).
8.30 (1 H, s, N᎐CH); m/z 356 (Mϩ, <1%), 312 (7), 282 (3), 209
᎐
(91), 208 (48), 207 (31), 194 (100), 193 (93), 180 (25), 77 (27), 59
(81), 57 (86) and 44 (70).
tert-Butyl
2-[({1-[2-(methylanilino)phenyl]ethylidene}-
amino)oxy]peracetate 6h. Starting from 5h (7.1 g, 24 mmol), 6h
was obtained (7.5 g, 86%) as a 9:2 mixture of the E- and
From 6b. Perester 6b (10 mmol) yielded in order of elution
1-(2-phenoxyphenyl)ethan-1-imine 12b (0.21 g, 10%), mp 82–
1820
J. Chem. Soc., Perkin Trans. 1, 1998

View Article Online
84 ЊC (Found: C, 80.0; H, 6.2; N, 6.6. C14H13NO requires C,
79.6; H, 6.2; N, 6.6%); νmax/cmϪ1 3000, 1620, 1600, 1580, 1490,
1450, 1370 and 1310; δH(200 MHz) 2.35 (3 H, s, Me), 6.85–6.96
(3 H, m, Ar-H), 7.03 (1 H, dd, J1 8.2, J2 1.1, Ar-H), 7.20 (1 H,
dddd, J1, J2 7.3, J3, J4 1.1, Ar-H), 7.33–7.46 (3 H, m, Ar-H),
7.64 (1 H, dd, J1 8.0, J2 1.6, Ar-H) and 14.32 (1 H, br s, NH);
δC(50 MHz) 17.5, 118.6, 118.7, 120.2, 121.8, 125.3, 129.4, 129.6,
133.5, 147.5, 162.5 and 171.7; m/z 211.1000 (Mϩ, 88%. C14H13-
NO requires 211.0997), 210 (77), 196 (89), 120 (32), 77 (100)
and 51 (40); 3c (0.48 g, 23%); 1-(2-phenoxyphenyl)ethan-1-one
O-(tert-butoxymethyl)oxime 9b (0.60 g, 19%), oil; νmax/cmϪ1
2980, 1590, 1480, 1450, 1370 and 990; δH(200 MHz) 1.24 (9 H, s,
But), 2.21 (3 H, s, Me), 5.35 (2 H, s, CH2), 6.88–7.00 (3 H, m,
Ar-H), 7.03–7.12 (1 H, m, Ar-H), 7.14 (1 H, dd, J1 7.4, J2 1.1,
Ar-H), 7.26–7.37 (3 H, m, Ar-H) and 7.51 (1 H, dd, J1 7.4,
J2 1.8, Ar-H); m/z 313.1680 (Mϩ, 5%. C19H23NO3 requires
313.1678), 283 (10), 227 (20), 210 (80), 195 (20), 185 (18), 134
(16), 91 (31), 77 (21) and 57 (100); 4b (0.40 g, 18%).
From 6c. Perester 6c (10 mmol) afforded in order of elution
(2-phenoxyphenyl)(phenyl)methanimine 12c (0.73 g, 27%), mp
135–137 ЊC (Found: C, 83.7; H, 5.5; N, 5.1. C19H15NO requires
C, 83.5; H, 5.5; N, 5.1%); νmax/cmϪ1 3000, 1600, 1480 and 1450;
δH(200 MHz) 6.70–6.80 (3 H, m, Ar-H), 6.90–7.45 (11 H, m,
Ar-H) and 14.52 (1 H, br s, NH); δC(50 MHz) 118.1, 120.0,
122.5, 124.8, 128.3, 128.6, 128.9, 129.0, 132.4, 133.4, 134.2,
147.0, 162.7 and 173.5; m/z 273.1157 (Mϩ, 100%. C19H15NO
requires 273.1154), 272 (88), 256 (6), 196 (46), 180 (26), 77 (92)
and 51 (33); 3c (0.21 g, 8%); (2-phenoxyphenyl)(phenyl)-
methanone O-(tert-butyl)oxime 11c (0.24 g, 7%), oil; νmax/cmϪ1
2980, 1590, 1580, 1480, 1450, 1400, 1370, 1330, 1150, 1100,
1000, 950 and 870; δH(200 MHz) 1.18 (9 H, s, But), 6.83–7.39
(12 H, m, Ar-H) and 7.50–7.60 (2 H, m, Ar-H); m/z 345.1727
(Mϩ, 12%. C23H23NO2 requires 345.1729), 289 (20), 272 (85),
196 (44), 105 (32), 91 (18), 77 (27) and 57 (100); (2-phenoxy-
phenyl)(phenyl)methanone O-(tert-butoxymethyl)oxime 9c (0.59
g, 16%), oil; νmax/cmϪ1 2980, 1590, 1580, 1480, 1450, 1400, 1370,
1330, 1150, 1100, 1000, 950 and 870; δH(200 MHz) 1.21 (9 H, s,
But), 5.29 (2 H, s, CH2), 6.83–7.40 (12 H, m, Ar-H) and 7.53–
7.62 (2 H, m, Ar-H); m/z 375.1830 (Mϩ, 5%. C24H25NO3
requires 375.1834), 345 (14), 289 (97), 272 (80), 180 (23), 170
(31), 77 (42) and 57 (100); 4c (0.26 g, 9%).
H26N2O2 requires C, 77.0; H, 7.0; N, 7.5%); major isomer, νmax
/
cmϪ1 3400, 2980, 1600, 1580, 1500, 1450, 1310 and 950; δH(200
MHz) 1.32 (9 H, s, But), 5.52 (2 H, s, CH2), 6.20 (1 H, br s, NH),
6.90–7.16 (5 H, m, Ar-H), 7.22–7.44 (6 H, m, Ar-H), 7.53 (1 H,
br d, J 8.0, Ar-H) and 7.62–7.70 (2 H, m, Ar-H); δC(50 MHz)
29.2, 75.7, 93.7, 118.6, 121.3, 125.2, 128.3, 128.7, 128.9, 130.1,
130.3, 136.1, 141.5, 144.0 and 157.5; m/z 374.1999 (Mϩ, 77%.
C24H26N2O2 requires 374.1994), 344 (9), 288 (32), 271 (52), 270
(46), 269 (76), 256 (72), 196 (30), 189 (12), 167 (30), 77 (17) and
57 (100); minor isomer, νmax/cmϪ1 3260, 2960, 1600, 1450, 1320,
1100 and 950; δH(200 MHz) 1.18 (9 H, s, But), 5.32 (2 H, s,
CH2), 6.64–6.72 (1 H, m, Ar-H), 6.90 (1 H, dd, J1 7.6, J2 1.2, Ar-
H), 6.97–7.07 (1 H, m, Ar-H), 7.15–7.52 (11 H, m, Ar-H) and
9.68 (1 H, br s, NH); δC(50 MHz) 29.1, 75.4, 93.1, 115.8, 118.5,
120.8, 121.4, 122.4, 128.5, 129.1, 129.5, 129.7, 130.1, 132.8,
134.7, 142.7, 143.9 and 160.0; m/z 374.1996 (Mϩ, 56%.
C24H26N2O2 requires 374.1994), 344 (2), 288 (22), 273 (35), 272
(49), 271 (64), 270 (65), 269 (100), 256 (47), 196 (24), 180 (10),
167 (44), 77 (31) and 57 (65); 9-phenylacridine 15 (0.51 g,
20%), mp 180–182 ЊC (lit.,33 181–182 ЊC); 1,4-diphenyl-1,2-
dihydroquinazolin-2-one 16 (0.24 g, 8%), mp 180–183 ЊC; νmax
/
cmϪ1 1660, 1600, 1370 and 1320; δH(300 MHz) 6.76 (1 H, d, J
8.4), 7.18–7.28 (1 H, m), 7.36–7.42 (2 H, m), 7.50–7.67 (7 H, m),
7.78–7.84 (2 H, m) and 7.89 (1 H, dd, J1 8.1, J2 1.3); δC(50 MHz)
116.1, 116.4, 122.9, 128.9, 129.1, 129.7, 130.0, 130.2, 130.9,
131.2, 135.3, 137.0, 137.5, 145.7 and 176.2; m/z 298.1105 (Mϩ,
69%. C20H14N2O requires 298.1106), 297 (100), 256 (18) and
77 (10); the structure of 16 was also confirmed by X-ray
diffractometry (Fig. 1): see below for experimental details.
From 6g. Perester 6g (10 mmol) gave in order of elution
2-(methylanilino)benzaldehyde O-(tert-butoxymethyl)oxime 9g
(0.48 g, 15%), oil; νmax/cmϪ1 2950, 1600, 1480 and 1000; δH(300
MHz) 1.50 (9 H, s, But), 3.50 (3 H, s, Me), 5.60 (2 H, s, CH2),
6.82–6.91 (2 H, m, Ar-H), 6.99–7.06 (1 H, m, Ar-H), 7.40–7.58
(4 H, m, Ar-H), 7.64–7.72 (1 H, m, Ar-H), 8.26–8.32 (1 H, m,
Ar-H) and 8.44 (1 H, s, N᎐CH); δ (50 MHz) 28.7, 40.3, 74.8,
᎐
C
92.5, 114.0, 118.0, 126.4, 127.3, 128.0, 129.0, 130.3, 131.5,
147.1, 147.7 and 149.4; m/z 312.1836 (Mϩ, 12%. C19H24N2O2
requires 312.1838), 209 (100), 194 (81), 180 (15), 77 (8) and 57
(49); 2-(methylanilino)benzonitrile 10g (0.14 g, 7%), oil; νmax
/
cmϪ1 3000, 2220, 1600 and 1480; δH(300 MHz) 3.40 (3 H, s,
Me), 6.87–6.93 (2 H, m, Ar-H), 6.97 (1 H, dddd, J1, J2 7.2, J3,
J4 1.0, Ar-H), 7.18 (1 H, ddd, J1, J2 7.6, J3 0.9, Ar-H), 7.24–7.33
(3 H, m, Ar-H), 7.55 (1 H, ddd, J1 8.2, J2 7.4, J3 1.5, Ar-H) and
7.64 (1 H, ddd, J1 7.6, J2 1.6, J3 0.4, Ar-H); m/z 208.1003 (Mϩ,
100%. C14H12N2 requires 208.1001), 207 (52), 194 (15), 192 (11),
180 (8), 167 (7), 131 (16) and 77 (20); 4g (0.14 g, 6%); 13 (0.25 g,
14%).
From 6d. Perester 6d (8.2 mmol) gave in order of elution 3d
(0.08 g, 5%); 2-anilinobenzaldehyde O-(tert-butoxymethyl)oxime
9d (0.46 g, 19%), mp 36–37 ЊC (Found: C, 72.7; H, 7.4; N, 9.35.
C18H22N2O2 requires C, 72.5; H, 7.4; N, 9.4%); δH(200 MHz)
1.40 (9 H, s, But), 5.45 (2 H, s, CH2), 6.82–6.94 (1 H, m, Ar-H),
7.12–7.21 (1 H, m, Ar-H), 7.24–7.50 (7 H, m, Ar-H), 8.37 (1 H,
s, N᎐CH) and 9.22 (1 H, br s, NH); δ (50 MHz) 29.1, 75.1, 93.0,
᎐
C
113.7, 116.2, 118.1, 122.0, 123.3, 129.6, 130.7, 133.3, 141.6,
144.3 and 153.2; m/z 298.1683 (Mϩ, 50%. C18H22N2O2 requires
298.1681), 212 (43), 195 (71), 194 (29), 193 (19), 180 (66), 167
(19), 77 (12) and 57 (100); 2-anilinobenzonitrile 10d (0.16 g,
10%), mp 47–49 ЊC (lit.,30 47–48 ЊC); acridine 13 (0.12 g, 8%),
mp 107–110 ЊC (lit.,31 108–110 ЊC).
From 6e. Perester 6e (10 mmol) yielded in order of elution 3e
(0.27 g, 13%); 1-(2-anilinophenyl)ethan-1-one O-(tert-butoxy-
methyl)oxime 9e (0.69 g, 22%), oil; νmax/cmϪ1 3700, 2980, 1600,
1570, 1500, 1450, 1370, 1320 and 990; δH(200 MHz) 1.30 (9 H, s,
But), 2.35 (3 H, s, Me), 5.40 (2 H, s, CH2), 6.83–6.93 (1 H, m,
Ar-H), 6.95–7.03 (1 H, m, Ar-H), 7.18–7.52 (7 H, m, Ar-H) and
9.57 (1 H, br s, NH); δC(50 MHz) 14.7, 28.9, 75.0, 92.5, 116.1,
118.7, 119.9, 121.7, 121.8, 129.4, 129.5, 142.4, 142.5 and 157.2;
m/z 312.1841 (Mϩ, 85%. C19H24N2O2 requires 312.1838), 282
(4), 226 (35), 209 (100), 208 (27), 207 (17), 194 (64), 180 (23),
167 (35), 77 (15) and 57 (96); 9-methylacridine 14 (0.44 g, 23%),
mp 132–133.5 ЊC (lit.,32 132.5 ЊC).
From 6h. Perester 6h (10 mmol) yielded in order of elution
3-methyl-1-phenyl-1H-indole 17 (0.93 g, 45%), oil;34 3h (0.18 g,
8%); 1-[2-(methylanilino)phenyl]ethan-1-one O-(tert-butoxy-
methyl)oxime 9h (0.49 g, 15%) as a 5.7:1 mixture of the E- and
Z-isomers, oil; νmax/cmϪ1 2960 and 1600; δH(200 MHz) 0.98
(9 H, s, But, minor isomer), 1.00 (9 H, s, But, major isomer),
1.78 (3 H, s, C-Me, major isomer), 1.81 (3 H, s, C-Me, minor
isomer), 2.92 (3 H, s, N-Me, minor isomer), 2.95 (3 H, s, N-Me,
major isomer), 4.91 (2 H, s, CH2, minor isomer), 5.10 (2 H, s,
CH2, major isomer), 6.40–6.58 (3 H, m, Ar-H, both isomers),
6.88–7.30 (6 H, m, Ar-H, both isomers); m/z 326.1999 (Mϩ, 8%.
C20H26N2O2 requires 326.1994), 223 (31), 208 (100), 194 (7), 77
(13) and 57 (30); 14 (0.23 g, 12%).
From 6i. Perester 6i (10 mmol) afforded in order of elution
[2-(methylanilino)phenyl](phenyl)methanone
O-(tert-butoxy-
methyl)oxime 9i (0.66 g, 17%) as a 13:4 mixture of the E- and
Z-isomers, oil; major isomer, νmax/cmϪ1 3000, 1600, 1480, 1350,
1090, 1000 and 950; δH(200 MHz) 1.28 (9 H, s, But), 2.92 (3 H, s,
Me), 5.28 (2 H, s, CH2), 6.54–6.62 (2 H, m, Ar-H), 6.72 (1 H,
dddd, J1, J2 7.2, J3, J4 0.8, Ar-H), 7.04–7.15 (2 H, m, Ar-H) and
7.20–7.52 (9 H, m, Ar-H); m/z 388.2150 (Mϩ, 46%. C25H28N2O2
requires 388.2151), 285 (80), 270 (100), 194 (8), 180 (8), 167 (6),
From 6f. Perester 6f (10 mmol) afforded in order of elution
3f (0.27 g, 10%); (2-anilinophenyl)(phenyl)methanone O-(tert-
butoxymethyl)oxime 9f (1.01 g, 27%) as a 4.4:1 mixture of the
E- and Z-isomers, oil (Found: C, 77.2; H, 7.0; N, 7.5. C24-
J. Chem. Soc., Perkin Trans. 1, 1998
1821

View Article Online
77 (11) and 57 (40); minor isomer, νmax/cmϪ1 3000, 1600, 1490,
1350, 1100, 1010 and 950; δH(200 MHz) 1.20 (9 H, s, But), 2.65
(3 H, s, Me), 5.25 (2 H, s, CH2), 6.28–6.37 (2 H, m, Ar-H), 6.63–
6.72 (1 H, m, Ar-H), 7.03–7.38 (9 H, m, Ar-H), 7.47 (1 H, ddd,
J1, J2 7.3, J3 1.8, Ar-H) and 7.70 (1 H, dd, J1 7.3, J2 1.7, Ar-H);
m/z 388.2153 (Mϩ, 8%. C25H28N2O2 requires 388.2151), 285
(82), 270 (100), 194 (6), 180 (7), 167 (3), 77 (8) and 57 (34); 15
(0.45 g, 18%); [2-(methylamino)phenyl](phenyl)methanone 18
(0.03 g, 2%), mp 68.5–70 ЊC (lit.,35 69 ЊC); 16 (0.22 g, 7%).
From 6j. Perester 6j (9.5 mmol) gave in order of elution 10-
phenyl-9,10-dihydroacridin-9-one 19j (0.10 g, 4%), mp 274–
276 ЊC (lit.,36 276 ЊC); 2-(diphenylamino)benzaldehyde O-(tert-
butyl)oxime 11j (0.15 g, 5%), oil; νmax/cmϪ1 2980, 1590, 1480 and
960; δH(200 MHz) 1.22 (9 H, s, But), 6.90–7.40 (13 H, m, Ar-H),
16 mmol) and conc. hydrochloric acid (2 drops) in absolute
ethanol (30 cm3) was refluxed for 3 days; additional tosylhy-
drazine (~1 g) and conc. HCl (2 drops) were added every 24 h.
After removal of the solvent, the residue was chromatographed
to give mostly starting material and the title compound (0.37 g,
5%), mp 191–194 ЊC (decomp.) (Found: C, 74.25; H, 5.25; N,
8.15; S, 6.2. C32H27N3O2S requires C, 74.25; H, 5.3; N, 8.1; S,
6.2%); νmax/cmϪ1 3300, 1590, 1490, 1380, 1320 and 1160; δH(200
MHz) 2.38 (3 H, s, Me), 6.40–6.55 (4 H, m ϩ A part of
AAЈBBЈ, J 8.3, Ar-H), 6.66–7.40 (17 H, m, Ar-H) and 7.58–
7.74 (3 H, m ϩ B part of AAЈBBЈ, J 8.3, Ar-H); m/z 517.1830
(Mϩ, 6%. C32H27N3O2S requires 517.1824), 489 (6), 362 (<1),
334 (72), 332 (86), 256 (100), 254 (21), 91 (21) and 77 (11).
Decomposition of the above hydrazide via the diazo compound
2837
7.94 (1 H, dd, J 7.8, J 1.5, Ar-H) and 8.14 (1 H, s, N᎐CH); m/z
᎐
1
2
344.1895 (Mϩ, 73%. C23H24N2O requires 344.1889), 288 (7), 271
(33), 256 (100), 180 (10), 77 (8) and 57 (36); 3d (0.25 g, 13%); 3j
(0.35 g, 13%); 2-(diphenylamino)benzaldehyde O-(tert-butoxy-
methyl)oxime 9j (0.60 g, 17%), oil; νmax/cmϪ1 2960, 1590, 1480
and 1000; δH(300 MHz) 1.12 (9 H, s, But), 5.23 (2 H, s, CH2),
6.91–7.28 (12 H, m, Ar-H), 7.38 (1 H, td, Jt 7.5, Jd 1.4, Ar-H),
A solution of methyllithium (1.6 , 0.5 cm3) in anhydrous THF
(5 cm3) was added dropwise at r.t. under a nitrogen atmosphere
to a solution of the hydrazide (0.5 g, 0.9 mmol) in THF (10
cm3). After 4 h, the solution was refluxed for 5 h and kept
overnight at r.t. The mixture was poured into ice–water and
extracted with dichloromethane. The organic phase was dried,
the solvent was removed and the residue chromatographed to
give 20l (0.11 g, 40%) and 0.04 g of an unidentified product,
δH(200 MHz) 5.79 (1 H, s), 6.74–6.88 (6 H, m), 6.95–7.22 (11 H,
m) and 7.42–7.52 (1 H, m); m/z 393 (Mϩ, <1%), 365 (<1), 351
(74), 332 (100), 272 (13), 256 (23), 244 (6), 181 (5), 167 (9), 105
(9) and 77 (15).
7.98 (1 H, dd, J 7.7, J 1.2, Ar-H) and 8.22 (1 H, s, N᎐CH); m/z
᎐
1
2
374.1996 (Mϩ, 38%. C24H26N2O2 requires 374.1994), 271 (31),
270 (14), 256 (100), 77 (7) and 57 (56); 2-(diphenylamino)-
benzonitrile 10j (0.44 g, 17%), mp 106–108 ЊC (Found: C, 84.8;
H, 5.2; N, 10.35. C19H14N2 requires C, 84.4; H, 5.2; N, 10.4%);
νmax/cmϪ1 2220, 1590, 1480, 1440 and 1270; δH(200 MHz) 7.02–
7.35 (12 H, m), 7.43–7.53 (1 H, m) and 7.58 (1 H, dd, J1 7.7, J2
1.6); m/z 270.1155 (Mϩ, 100%. C19H14N2 requires 270.1157),
269 (30), 192 (4), 167 (9), 135 (10), 77 (10) and 51 (11); 13 (0.12
g, 7%).
X-Ray crystal structure analysis of quinazolinone 16
Crystal data. C20H14N2O, M = 298.33. Triclinic, a = 9.287(1),
b = 10.625(2), c = 9.192(2) Å, α = 95.42(3), β = 117.95(2),
γ = 69.42(2)Њ, V = 747.4(2) Å3 (by least squares fitting of the
setting angles of 28 automatically centred reflections in the
From 6k. Perester 6k (8.0 mmol) gave in order of elution
1-[2-(diphenylamino)phenyl]ethan-1-one
O-(tert-butyl)oxime
11k (0.04 g, 1%) as a 5:1 mixture of the E- and Z-isomers, oil;
δH(200 MHz) 1.06 (9 H, s, But, minor isomer), 1.08 (9 H, s, But,
major isomer), 1.70 (3 H, s, Me, minor isomer), 1.90 (3 H, s, Me,
major isomer) and 6.75–7.45 (14 H, m, Ar-H); m/z 358.2044
(Mϩ, 91%. C24H26N2O requires 358.2045), 302 (8), 285 (56), 270
(100), 256 (18), 243 (10), 210 (14), 196 (16), 180 (11), 167 (17),
77 (19), 57 (47) and 51 (11); 3e (0.17 g, 10%); 1-[2-(diphenyl-
amino)phenyl]ethan-1-one O-(tert-butoxymethyl)oxime 9k (0.68
g, 22%) as a 5:1 mixture of the E- and Z-isomers, oil; δH(200
MHz) 1.13 (9 H, s, But, major isomer), 1.15 (9 H, s, But, minor
isomer), 1.78 (3 H, s, Me, minor isomer), 1.99 (3 H, s, Me, major
isomer), 4.85 (2 H, s, CH2, minor isomer), 5.10 (2 H, s, CH2,
major isomer) and 6.85–7.45 (14 H, m, Ar-H, both isomers);
m/z 388.2155 (Mϩ, 21%. C25H28N2O2 requires 388.2151), 285
(44), 270 (78), 256 (12), 167 (16), 77 (26), 57 (100) and 51 (22);
14 (0.15 g, 10%).
From 6l. Perester 6l (8.0 mmol) afforded in order of elution
9,10-diphenyl-9,10-dihydroacridine 20l (0.43 g, 16%), mp 171–
173 ЊC (lit.,36 175–175.5 ЊC); 3f (0.36 g, 16%); 3l (0.08 g, 3%);
[2-(diphenylamino)phenyl](phenyl)methanone O-(tert-butoxy-
methyl)oxime 9l (0.54 g, 15%) as a 13:2 mixture of the E-
and Z-isomers; major isomer, mp 123–126 ЊC (from light
petroleum–benzene) (Found: C, 80.3; H, 6.7; N, 6.2. C30H30-
N2O2 requires C, 80.0; H, 6.7; N, 6.2%); δH(200 MHz) 1.20 (9 H,
s, But), 4.97 (2 H, s, CH2) and 6.72–7.35 (19 H, m, Ar-H); m/z
451 (Mϩ ϩ 1, 94%), 421 (21), 364 (15), 347 (52), 332 (100), 272
(16), 256 (18), 243 (14), 196 (14), 167 (9), 77 (12) and 57 (65);
minor isomer, oil (Found: C, 80.4; H, 6.7; N, 6.2. C30H30N2O2
requires C, 80.0; H, 6.7; N, 6.2%); δH(200 MHz) 1.15 (9 H, s,
But), 5.12 (2 H, s, CH2) and 6.65–7.60 (19 H, m, Ar-H); m/z 451
(Mϩ ϩ 1, 100%), 421 (27), 364 (25), 347 (77), 332 (95), 272 (23),
256 (23), 243 (16), 196 (10), 167 (11), 77 (15) and 57 (63); 15
(0.11 g, 5%); 16 (0.17 g, 7%).
¯
range 15.7 р θ р 40.7Њ), λ = 1.541 78 Å, space group P1, Z = 2,
D = 1.326 g cmϪ3, µ(CuKα) = 0.658 mmϪ1
.
Data collection and processing. Pale yellow prismatic crystal
(0.08 × 0.19 × 0.46 mm3), Siemens AED diffractometer, θ–2θ
scans, scan width (1.2 ϩ 0.34 tan θ)Њ, scan speed 0.05–0.16Њ sϪ1
,
graphite monochromated CuKα radiation (λ = 1.541 78 Å),
crystal orientation and stability checked by two standard reflec-
tions measured every 100 reflections, 2828 reflections collected
(4 р θ р 70Њ, Ϫ11 р h р 11, Ϫ12 р k р 12, 0 р l р 11), of
which 2156 showing I > 2σ(I), no absorption correction
performed.
Structure analysis and refinement. The structure was solved
by direct methods with SIR9238 and refined by full-matrix least
squares on F2 with SHELXL93.39 The hydrogen atoms were
located in a ∆F map and positionally refined with Uiso = 0.1 Å2.
The final residuals were R1 = 0.0385 and wR2 = 0.1077 for 2156
unique reflections having I > 2σ(I) and R1 = 0.0512 and
wR2 = 0.1178, S = 1.00 for all 2828 data and 251 refined param-
eters. Maximal ∆/σ = Ϫ0.002 and maximum and minimum
residual peak in the final difference Fourier map 0.211 and
Ϫ0.124 e ÅϪ3 respectively. The molecular structure is shown in
Fig. 1.40 Atomic coordinates, thermal parameters, bond lengths
and bond angles have been deposited at the Cambridge Crystal-
lographic Data Centre. Full crystallographic details, excluding
structure factor tables, have been deposited at the Cambridge
Crystallographic Data Centre (CCDC). For details of the
deposition scheme, see ‘Instructions for Authors’, J. Chem.
Soc., Perkin Trans. 1, available via the RSC Web page (http://
www.rsc.org/authors). Any request to the CCDC for this
material should quote the full literature citation and the refer-
ence number 207/212.
Acknowledgements
The authors gratefully acknowledge financial support from
MURST, CNR (Rome) and Università di Bologna (Progetto di
NЈ-{1-[2-(Diphenylamino)phenyl]-1-phenylmethylidene}-4-
methylbenzene-1-sulfonohydrazide
A solution of 3l (5.0 g, 14 mmol), tosylhydrazine (2.9 g,
1822
J. Chem. Soc., Perkin Trans. 1, 1998

View Article Online
D. M. O’Shea, S. Gerba and S. W. Westwood, J. Chem. Soc., Chem.
Finanziamento Triennale del Dipartimento di Chimica
Organica “A. Mangini”). They also thank Professor Loris
Grossi for helpful discussions.
Commun., 1987, 666; (h) A. L. J. Beckwith, D. M. O’Shea and
S. W. Westwood, J. Am. Chem. Soc., 1988, 110, 2565; (i) B. W.
Yeung, J. L. M. Contelles and B. Fraser-Reid, J. Chem. Soc., Chem.
Commun., 1989, 1160; (j) J. K. Dickson, Jr., R. Tsang, J. M. Llera
and B. Fraser-Reid, J. Org. Chem., 1989, 54, 5350; (k) S. Knapp,
F. S. Gibson and Y. H. Choe, Tetrahedron Lett., 1990, 31, 5397;
(l) B. B. Snider and B. O. Buckman, J. Org. Chem., 1992, 57, 322;
(m) C.-C. Yang, H.-T. Chang and J.-M. Fang, J. Org. Chem., 1993,
58, 3100; (n) L. Elkaim and C. Meyer, J. Org. Chem., 1996, 61, 1556;
(o) V. Sridar and G. Babu, Synth. Commun., 1997, 27, 323.
9 L. Craine and M. Raban, Chem. Rev., 1989, 89, 689. Even aliphatic
sulfenimides are sometimes difficult to obtain: see ref. 8(o).
10 For a study on analogous iminyl radicals in the gas phase see:
(a) M. Black, J. I. G. Cadogan, R. Leardini, G. McDougald,
H. McNab, D. Nanni, D. Reed and A. Zompatori, J. Chem. Soc.,
Perkin Trans. 1, 1998, 1825. (b) R. Leardini, H. McNab, D. Nanni,
S. Parsons, D. Reed and A. G. Tenan, J. Chem. Soc., Perkin Trans. 1,
1998, 1833.
References
1 B. Giese, Radicals in Organic Synthesis: Formation of Carbon–
Carbon Bonds, Pergamon, Oxford, 1986; D. P. Curran, Synthesis,
1988, 417; 489; D. P. Curran, Comprehensive Organic Synthesis,
ed. B. M. Trost and I. Fleming, Pergamon Press, Oxford, 1991, vol.
4, p. 715; W. B. Motherwell and D. Crich, Free Radical Chain
Reactions in Organic Synthesis, Academic Press, London, 1992;
M. J. Perkins, Radical Chemistry, Ellis Horwood, London, 1994;
D. P. Curran, N. A. Porter and B. Giese, Stereochemistry of Radical
Reactions, VCH, Weinheim, 1996.
2 (a) R. Leardini, G. F. Pedulli, A. Tundo and G. Zanardi, J. Chem.
Soc., Chem. Commun., 1984, 1320; (b) R. Leardini, A. Tundo,
G. Zanardi and G. F. Pedulli, Synthesis, 1985, 107; (c) R. Leardini,
D. Nanni, G. F. Pedulli, A. Tundo and G. Zanardi, J. Chem. Soc.,
Perkin Trans. 1, 1986, 1591; (d) R. Leardini, D. Nanni, A. Tundo
and G. Zanardi, Gazz. Chim. Ital., 1989, 119, 637; (e) R. Leardini,
D. Nanni, A. Tundo and G. Zanardi, J. Chem. Soc., Chem.
Commun., 1989, 757; ( f ) R. Leardini, D. Nanni, M. Santori and
G. Zanardi, Tetrahedron, 1992, 48, 3961; (g) D. Nanni, P. Pareschi,
C. Rizzoli, P. Sgarabotto and A. Tundo, Tetrahedron, 1995, 51, 9045;
(h) D. Nanni, P. Pareschi and A. Tundo, Tetrahedron Lett., 1996, 37,
9337.
11 The yields of 9 were not affected by dilution; this is consistent with
cage recombination of 8 and tert-butoxyl radicals [see ref. 5(b) and
references cited therein].
12 On the other hand, due to the complete absence of the corre-
sponding acids in the starting peresters 6b,c, we can exclude that
imines 12b,c might arise from those acids through a concerted
mechanism similar to the one observed in the mass spectrometer.
13 For radical translocations see: T. A. Lowry and K. S. Richardson,
Mechanism and Theory in Organic Chemistry, 3rd Edition, Harper
& Row, New York, 1987, ch. 9, p. 800; D. C. Nonhebel and
J. C. Walton, Free-Radical Chemistry, Structure and Mechanism,
Cambridge University Press, Cambridge, 1974, ch. 13, p. 498;
J. W. Wilt, Free Radical Rearrangements in Free Radicals, J. K.
Kochi, ed., Wiley, New York, 1973, ch. 8, p. 333; for homolytic aryl
migrations in the liquid phase see: ref. 2(c); E. Lee, C. Lee, J. S. Tae,
H. S. Whang and K. S. Li, Tetrahedron Lett., 1993, 34, 2343; W. B.
Motherwell and A. M. K. Pennell, J. Chem. Soc., Chem. Commun.,
1991, 877; L. Benati, L. Capella, P. C. Montevecchi and P. Spagnolo,
J. Org. Chem., 1994, 59, 2818; L. Capella, P. C. Montevecchi and
D. Nanni, J. Org. Chem., 1994, 59, 3368; R. Leardini, D. Nanni,
G. F. Pedulli, A. Tundo, G. Zanardi, E. Foresti and P. Palmieri,
J. Am. Chem. Soc., 1989, 111, 7723 and references cited therein; for
homolytic aryl migrations in the gas phase see: ref. 6( f ); J. I. G.
Cadogan, H. S. Hutchison and H. McNab, J. Chem. Soc., Perkin
Trans. 1, 1987, 1407; M. Black, J. I. G. Cadogan and H. McNab,
J. Chem. Soc., Chem. Commun., 1990, 395.
14 It is worth noting that when the oxime 4l was treated with lead
tetraacetate in boiling benzene—a well-known source of iminoxyl
radicals (G. Just and K. Dahl, Tetrahedron, 1968, 24, 5251; B. C.
Gilbert and R. O. C. Norman, J. Chem. Soc. B, 1968, 123)—the
reaction furnished small amounts of acridines 15 and 20l, together
with major amounts of ketone 3l (see: R. N. Butler, Chem. Rev.,
1984, 84, 249) and other unidentified products. This result suggests
that iminoxyl radicals 24 might be intermediates in the formation of
the acridine derivatives. As far as the intermediacy of a carbenic
species is concerned, it should be noted that acridine compounds
have been obtained by intramolecular insertion of o-(arylamino)-
phenylcarbenes in the gas phase (W. D. Crow and H. McNab, Aust.
J. Chem., 1981, 34, 1037). The possibility that the acridines could
also arise from cyclisation of other electrophilic species obtained by
further oxidation of 24 should however be taken into account.
15 H. Fischer, J. Am. Chem. Soc., 1986, 108, 3925; B. E. Daikh and
R. G. Finke, J. Am. Chem. Soc., 1992, 114, 2938; D. Griller and
K. U. Ingold, Acc. Chem. Res., 1976, 9, 13.
3 (a) S. Guidotti, R. Leardini, D. Nanni, P. Pareschi and G. Zanardi,
Tetrahedron Lett., 1995, 36, 451; (b) R. Leardini, H. McNab and
D. Nanni, Tetrahedron, 1995, 51, 12 143.
4 (a) M. L. Poutsma and P. A. Ibraria, J. Org. Chem., 1969, 34, 2848;
(b) M. C. R. Symons, Tetrahedron, 1973, 29, 615; (c) D. Griller,
G. D. Mendenhall, W. Van Hoof and K. U. Ingold, J. Am. Chem.
Soc., 1974, 96, 6068; (d) B. P. Roberts and J. Winter, J. Chem. Soc.,
Perkin Trans. 2, 1979, 1353.
5 (a) A. R. Forrester, M. Gill, C. J. Meyer, J. S. Sadd and R. H.
Thomson, J. Chem. Soc., Chem. Commun., 1975, 291; (b) A. R.
Forrester, M. Gill, C. J. Meyer, J. S. Sadd and R. H. Thomson,
J. Chem. Soc., Perkin Trans. 1, 1979, 606; (c) A. R. Forrester,
M. Gill, J. S. Sadd and R. H. Thomson, J. Chem. Soc., Perkin Trans.
1, 1979, 612; (d) A. R. Forrester, M. Gill and R. H. Thomson,
J. Chem. Soc., Perkin Trans. 1, 1979, 616; 621; (e) A. R. Forrester,
M. Gill, R. Napier and R. H. Thomson, J. Chem. Soc., Perkin Trans.
1, 1979, 632; ( f ) A. R. Forrester, M. Gill, C. J. Meyer and R. H.
Thomson, J. Chem. Soc., Perkin Trans. 1, 1979, 637; (g) A. R.
Forrester, R. Napier and R. H. Thomson, J. Chem. Soc., Perkin
Trans. 1, 1981, 984; (h) A. R. Forrester, H. Irikawa, R. H. Thomson
and S.-O. Woo, J. Chem. Soc., Perkin Trans. 1, 1981, 1712; (i)
S. Atmaram, A. R. Forrester, M. Gill and R. H. Thomson, J. Chem.
Soc., Perkin Trans. 1, 1981, 1721.
6 (a) W. D. Crow, H. McNab and J. M. Philip, Aust. J. Chem., 1976,
29, 2299; (b) H. McNab, J. Chem. Soc., Chem. Commun., 1980,
422; (c) H. McNab, J. Chem. Soc., Perkin Trans. 1, 1982, 1941;
(d) H. McNab, J. Chem. Soc., Perkin Trans. 1, 1984, 371; (e)
H. McNab, J. Chem. Soc., Perkin Trans. 1, 1984, 377; ( f ) H. McNab
and G. S. Smith, J. Chem. Soc., Perkin Trans. 1, 1984, 381; (g) C. L.
Hickson and H. McNab, J. Chem. Soc., Perkin Trans. 1, 1984, 1569.
7 (a) J. Boivin, E. Fouquet and S. Z. Zard, Tetrahedron Lett., 1990, 31,
85; 3545; (b) J. Boivin, E. Fouquet and S. Z. Zard, J. Am. Chem.
Soc., 1991, 113, 1054; (c) J. Boivin, E. Fouquet and S. Z. Zard,
Tetrahedron Lett., 1991, 32, 4299; (d) J. Boivin, A.-M. Schiano and
S. Z. Zard, Tetrahedron Lett., 1992, 33, 7849; (e) J. Boivin,
E. Fouquet and S. Z. Zard, Tetrahedron, 1994, 50, 1745; 1757; 1769;
( f ) J. Boivin, A.-M. Schiano and S. Z. Zard, Tetrahedron Lett.,
1994, 35, 249; (g) A.-C. Callier-Dublanchet, B. Quiclet-Sire and
S. Z. Zard, Tetrahedron Lett., 1995, 36, 8791; (h) J. Boivin, A.-C.
Callier-Dublanchet, B. Quiclet-Sire, A.-M. Schiano and S. Z. Zard,
Tetrahedron, 1995, 51, 6517; (i) S. Z. Zard, Synlett, 1996, 1148;
(j) M.-H. Le Tadic-Biadatti, A.-C. Callier-Dublanchet, J. H.
Horner, B. Quiclet-Sire, S. Z. Zard and M. Newcomb, J. Org.
Chem., 1997, 62, 559; (k) A.-C. Callier-Dublanchet, B. Quiclet-Sire
and S. Z. Zard, Tetrahedron Lett., 1997, 38, 2463.
16 W. D. Crow and H. McNab, Aust. J. Chem., 1979, 32, 99.
17 I. Genzo, Pharm. Bull., 1957, 5, 401 [Chem. Abstr., 1958, 52, 9006h].
18 S. Kimoto, K. Asaki and S. Kishi, J. Pharm. Soc. Jpn., 1954, 74, 358
[Chem. Abstr., 1955, 49, 5373h].
19 A. Albert, J. Chem. Soc., 1948, 1225.
20 J. Itier and A. Casadevall, Bull. Soc. Chim. Fr., 1969, 2342.
21 V. Auwers, M. Lechner and H. Bundesmann, Chem. Ber., 1925, 58,
36.
22 M. K. Cooper and D. W. Yaniuk, J. Organomet. Chem., 1981, 221,
231.
8 For other studies on iminyl radicals see also (a) H. Sakuragi,
S.-I. Ishikawa, T. Nishimura, M. Yoshida, N. Inamoto and
K. Tokumaru, Bull. Chem. Soc. Jpn., 1976, 49, 1949; (b) R. F.
Hudson, K. A. F. Record, J. Chem. Soc., Chem. Commun., 1976,
539; (c) D. L. J. Clive, P. L. Beaulieu and L. Set, J. Org. Chem., 1984,
49, 1313; (d) M. Hasebe, K. Kogawa and T. Tsuchiya, Tetrahedron
Lett., 1984, 25, 3887; (e) B. Chenera, C. P. Chuang, D. J. Hart and
L. Y. Hsu, J. Org. Chem., 1985, 50, 5409; ( f ) R. Tsang and B. Fraser-
Reid, J. Am. Chem. Soc., 1986, 108, 2116; (g) A. L. J. Beckwith,
23 B. Staskun, J. Org. Chem., 1968, 33, 3031.
24 Beilsteins Handbuch der Organischen Chemie, 1950, 11 II, 66.
25 C. F. H. Allen and G. H. W. McKee, Organic Syntheses, Wiley, New
York, 1943, Coll. Vol. II, 15.
26 H. Gilman and S. M. Spatz, J. Org. Chem., 1952, 17, 860.
27 Vogel’s Textbook of Practical Organic Chemistry, 4th edn.,
Longman, Harlow, 1988, p. 1150.
28 L. A. Singer and N. P. Kong, J. Am. Chem. Soc., 1967, 89, 5251;
H. A. Staab, Angew. Chem., Int. Ed. Engl., 1962, 1, 351.
J. Chem. Soc., Perkin Trans. 1, 1998
1823

View Article Online
29 M. Tomita and T. Sato, Yakugaku Zasshi, 1957, 77, 1024 [Chem.
Abstr., 1958, 52, 3719b].
30 H. Tiefenthaler, W. Dörscheln, H. Göth and H. Schmid, Helv. Chim.
Acta, 1967, 50, 2244.
31 Commercially available compound (Aldrich).
38 A. Altomare, G. Cascarano, C. Giacovazzo, A. Guagliardi, M. C.
Burla, G. Polidori and M. Camalli, J. Appl. Crystallogr., 1994, 27,
435.
39 G. M. Sheldrick, SHELX93, Program for Crystal Structure
Refinement, University of Göttingen, 1993.
32 Beilsteins Handbuch der Organischen Chemie, 1935, 20, 470.
33 Beilsteins Handbuch der Organischen Chemie, 1935, 20, 514.
34 G. P. Tokmakov and I. I. Grandberg, Tetrahedron, 1995, 51, 2091.
35 H. Nishino and K. Kurosawa, Bull. Chem. Soc. Jpn., 1983, 56, 1682.
36 G. M. Kosolapoff and C. S. Schoepfle, J. Am Chem. Soc., 1954, 76,
1276.
40 The ORTEP representation in Fig. 1 was obtained with ORTEP-3
for Windows. See: L. J. Farrugia, J. Appl. Crystallogr., 1997, 30, 565.
Paper 8/00868J
Received 2nd February 1998
Accepted 19th March 1998
37 R. W. Thies and R. H. Chiarello, J. Org. Chem., 1974, 44, 1342.
1824
J. Chem. Soc., Perkin Trans. 1, 1998