Reaction of N-methyl-hydrazones as azaenamines with quinones

Article abstract of DOI:10.1016/S0040-4020(00)00185-X

1,4-Naphthoquinone derivatives reacted with N,N- disubstituted hydrazones to give C adducts, whereas N- monoalkylhydrazones yielded N adducts which underwent ring closure to benzindazole-4,9-diones. Michael addition with methoxycarbonylbenzoquinone led to open chain mono- and disubstituted N adducts or phthalazin-1-one derivatives, depending on the hydrazone. N Adducts obtained from dimethylbenzoquinone cyclized by hetero Diels-Alder reaction to benzoxadiazines. (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0040-4020(00)00185-X

TETRAHEDRON
Pergamon
Tetrahedron 56 (2000) 5137±5145
Reaction of N-Methyl-hydrazones as Azaenamines with Quinones
²
Heiko Buff and Uwe Kucklander
*
È
È È È È
Institute of Pharmaceutical Chemistry, Heinrich-Heine-Universitat Dusseldorf, Universitatsstraûe 1, 40225 Dusseldorf, Germany
Received 7 August 1999; revised 28 February 2000; accepted 29 February 2000
AbstractÐ1,4-Naphthoquinone derivatives reacted with N,N-disubstituted hydrazones to give C adducts, whereas N-monoalkylhydrazones
yielded N adducts which underwent ring closure to benzindazole-4,9-diones. Michael addition with methoxycarbonylbenzoquinone led to
open chain mono- and disubstituted N adducts or phthalazin-1-one derivatives, depending on the hydrazone. N Adducts obtained from
dimethylbenzoquinone cyclized by hetero Diels±Alder reaction to benzoxadiazines. q 2000 Elsevier Science Ltd. All rights reserved.
Introduction
position 3 were available.4 Hence the synthesis of new inda-
zolequinones 1b with various substituents in position 3
should be of great interest. We have recently reported two
new syntheses of highly cytotoxic benzocarbazolequi-
nones.6,7 For example 2-methylamino-1,4-naphthoquinones
reacted with 2,3-dimethylbenzoquinone to give 2-hydroxy-
A variety of natural or synthetic compounds containing a p-
quinone moiety show strong biological activity due to their
interference with metabolic processes of herbal and animal
cells.1,2 An outstanding example is given by the anthracy-
cline antibiotics, which because of their antimitotic charac-
ter3 are presently some of the most important agents in the
treatment of human cancers. In another area benzindazole-
quinones 1a (Fig. 1) have been investigated for herbicide
activity.4 In this case the biological effect is based on the
inhibition of photosynthesis.5 The synthesis of benzindazole-
quinones 1 was achieved by reaction of quinone derivatives
with diazomethane. Thus only indazoles 1a unsubstituted in
3,4,5-trimethyl-5H-benzo[b]carbazole-6,11-diones,
with
the naphthoquinones acting as enaminones in a new modi-
®cation6 of the Nenitzescu reaction (Fig. 1). Hydrazones
react similarly to enamines8,9,10,11 and can be regarded as
azaenamines. Therefore it should be possible to achieve an
analogous Michael addition of N 2-substituted hydrazones to
1,4-naphthoquinone followed by ring closure to the desired
interesting indazole derivatives 1b.
Figure 1.
Keywords: hydrazones; quinones; Michael and hetero Diels±Alder reactions; aza-enamines; Nenitzescu reaction.
* Corresponding author. E-mail: kucklaen@uni-duesseldorf.de
È È
Part of intended dissertation of the Mathematisch-Naturwissenschaftliche Fakultat der Heinrich-Heine-Universitat Dusseldorf.
²
È
0040±4020/00/$ - see front matter q 2000 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(00)00185-X

È
H. Buff, U. Kucklander / Tetrahedron 56 (2000) 5137±5145
5138
Figure 2.
Results and Discussion
by Michael addition of the azomethine carbon. (Fig. 3).
Cyclization of the adduct 7 was effected by oxidation lead-
ing directly to the the indazolequinone 8.
Previous studies using the N,N-disubstituted hydrazones 1-
phenyl-4,5-dihydro-pyrazole, methylene-morpholin-4-yl-
amine and N,N-dimethyl-N0-methylene-hydrazine as aza-
enamines in the reaction with quinone 2 have already
shown, that this way azaenamine C adducts 312, 4a and
4b12 are available in methanol at room temperature (Fig. 2).
In contrast to this result we were not able to detect C adducts
13a±d when we carried out the aza-Nenitzescu reaction
with N-methylhydrazones 10a±d and 1,4-naphthoquinone
9 but obtained N adducts 11a±d (Fig. 4). As proof for the
1
structures 11a±d we only mention the H NMR spectrum
A recent publication by Granik13 prompted us to report our
own experiences with azaenamines. Granik has shown that
N-phenylhydrazone 6 is able to act as an azaenamine, too.
e.g. of 11b, in which the NvCH hydrogen at 7.86 ppm and
3-H at 7.05 ppm appeared as singlets and no NH signal was
observed. Also, the UV/VIS spectra of 11a and 4b12 were
similar: both had two maxima at l(log e)ˆ486 nm (3.90)
(11a) resp. 476 nm (3.68) (4b) and lˆ313 nm (4.40) (11a)
Reaction with quinone 5 gave the hydroquinone-C-adduct 7
Figure 3.
Figure 4.

È
H. Buff, U. Kucklander / Tetrahedron 56 (2000) 5137±5145
5139
Figure 5.
resp. 290 nm (4.03) (4b), and agreed with the proposed
structure. Apparently the nitrogen in N-methylhydrazones
10a±d is more nucleophilic than in N-phenylhydrazone 6
and we only observed the formation of N adducts.
10 attacked the quinone component 2 by nucleophilic
addition. Only a singlet at 7.08 ppm was observed for the
NvCH hydrogen in the 1H NMR spectrum e.g. of 14e, and
neither the IR nor the 1H NMR spectrum revealed the
presence of an NH group. Hence we could exclude forma-
tion of the possible C adducts 16a,e. The resulting quinone
adducts 14a,e were successfully cyclized by simple stirring
in acetic acid. In both cases the same 1,3-dimethyl-benzin-
dazole-4,9-dione 15 was obtained. We assumed that the ring
closure proceeded by an intramolecular change of the hydra-
zone group. Thus benzindazole quinones substituted in
position 3, e.g. 12a±d and 15 are now available in good
yield.
Ring closure of 11a±d to benzindazole quinones was pos-
sible under drastic conditions. Heating the adducts above
the melting point or in boiling xylene yielded the benzinda-
zoles 12a±d. The low reactivity is due to the presence of
electron rich nitrogen substituent in position 2 which
weakens the electrophilic character of the C-3 in 11a±d.
Moreover it is well-known that cyclizations of this type
are disfavoured for stereochemical reasons14: the ring
closure of 11a±d can be regarded as a 5-endo-trig reaction,
which is known to be an unfavorable process.
Investigations concerning the herbicide activity of 15 (spray
chamber at a rate equivalent to 3000 g a.i./ha) showed that
21 days after treatment the test plants were destroyed 100%
(Sinapis alba), 85% (Lolium multi¯orum) and 60% (Abutilon
theophrasti). Treating the plants with 15 caused foliar
N-Methylhydrazones 10a,e and acetylnaphthoquinone 2
gave similar products 14a,e in good yields (Fig. 5). We
were able to show that the amine nitrogen of azaenamines
Figure 6.

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H. Buff, U. Kucklander / Tetrahedron 56 (2000) 5137±5145
5140
shifts due to their chemical analogy. However, we found
two different signals at 203.5 ppm (C-10) and 163.3 ppm
(C-1) con®rming the structure of 18.
The phthalazine derivative 18 was successfully transformed
into phthalazine-5,8-dione 20. As a result of the oxidation
the two singlets for the OH hydrogens at 12.04 and
11.07 ppm (18) disappeared. The UV/VIS maximum was
shifted from l(log e)ˆ366 nm (3.95) (18) to 425 nm
(3.54) (20). In this case phthalazine 18 was the product of
a Michael addition of hydrazone structure 10e, with the
carbon atom as active site demonstrating the ambient
reactivity of hydrazones. Again, the benzaldehyde hydra-
zone 10a reacted at the nitrogen leading to the mono- and
disubstituted hydrazino compounds 21 and 22. (Fig. 7).
In addition, we have examined the behavior of 2,3-
dimethyl-benzoquinone 23. This quinone was selected in
order to avoid double reaction which seemed to complicate
the use of simple p-benzoquinone.
Figure 7.
necrosis similar to observations with 1-alkyl-3H-naphthinda-
zole-4,9-diones (1), known to inhibit photosynthesis.5
Reaction of the N-methylhydrazones 10a,c with dimethyl-
benzoquinone 23 in methanol gave only the N adducts 24a,c
and no C adducts. The absence of the NH hydrogen in the 1H
NMR spectrum and the observed singlet due to the N-CH3
group at 3.55 ppm (24a) resp. 3.53 ppm (24c) indicated that
again the N adduct has been formed. The NvCH hydrogen
at 7.78 ppm (24a) resp. 7.75 ppm (24c) and the fact that no
N±H group was present in the IR spectra supported our
conclusion. The UV/VIS spectra showed maxima at
l(log e)ˆ314 nm (4.33) and 510 nm (3.83) (24a) and
312 nm (4.38) and 526 nm (3.93) (24c), respectively. Puri-
fying the resulting crystals by stirring in boiling methanol,
The reaction of 2-methoxycarbonyl-benzoquinone 17 as a
more reactive quinone component with methylhydrazono-
propanone 10e led to a product with mass spectral data
and microanalysis in agreement with the structure of the
phthalazine derivatives 18 or 19 (Fig. 6).
The formation of 18 was corroborated by 13C NMR spectro-
scopy. In the case of the cinnoline derivative 19, carbonyl
carbons 10 and 4 were supposed to show signals with similar
Figure 8.

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H. Buff, U. Kucklander / Tetrahedron 56 (2000) 5137±5145
5141
2-propanol or toluene gave a yellow colored solution from
which the benzoxadiazine derivatives 26a,c were isolated.
2,5-dimethoxy-benzaldehyde (16.60 g, 0.10 mol) in
100 ml diethyl ether. MgSO4 (5 g) was added and the
mixture heated 3 h under re¯ux. The solvent was removed
and the pale yellow oil was puri®ed by Kugelrohr distil-
lation at 2358C/23 mbar to give white crystals (16.5 g,
70%). For identi®cation the unstable hydrazone was stirred
30 min in acetic acid anhydride and then treated with water
to give the acylated product as pale white crystals. Mp 898C.
MS (70 eV): m/z (%): 236 (10) [M1], 193 (3), 178 (4), 163
(100), 148 (34), 135 (11), 121 (9), 107 (7), 91 (11), 77 (20),
43 (91). IR (KBr): nˆ3038, 2998, 2922, 2836, 1666, 1617,
1
The signal for NvCH hydrogen in the H NMR spectrum
was absent; however, an additional signal for OH hydrogen
at 9.07 ppm (26a) or 9.03 ppm (26c) appeared. The IR
spectrum showed OH bands at 3280 and 3480 cm21 instead
of signals for CvO. To prove the structures of 26a,c, the
acetyl derivatives 27a,c were prepared. Apparently the N
adducts 24 suffered ring closure to benzoxadiazine by intra-
molecular hetero Diels±Alder reaction (Fig. 8). Again the
nitrogen in N-methylhydrazones 10 showed a more nucleo-
philic character than in N-arylhydrazones 6.
1
1595, 1571 cm21. H NMR (CDCl3): 2.46 (s 3H, COCH3),
3.36 (s 3H, NCH3), 3.82, 3.85 (d 6H, two OCH3), 6.84±6.95
(m 2H, 30,40-H), 7.46 (d 1H, 60-H), 8.03 (s 1H, NvCH).
Anal. calcd for C12H16N2O3: C, 61.00; H, 6.83; N, 11.86.
Found: C, 61.19; H, 6.84; N, 11.81.
Conclusion
Our results demonstrate the ambient character of the N-alkyl-
hydrazone structure. The reaction of N-alkylhydrazones with
quinones opens new ways to heterocyclic compounds, such
as benzindazolones, benzoxadiazines and phthalazines.
1-Methylhydrazonopropanone (10e). See Ref. 21
2-(N0-benzylidene-N-methyl-hydrazino)-[1,4]naphtho-
quinone (11a). Benzaldehyde methylhydrazone 10a
(2.72 g, 20.4 mmol) in methanol (5 ml) was added slowly
to a suspension of 1,4-naphthoquinone 9 (1.92 g, 12 mmol)
in methanol (15 ml). After being stirred for 15 min the
precipitate (2.50 g, 72%) was ®ltered off, washed with
methanol and dried. Red needles from toluene. Mp 1758C.
MS: m/z (%): 290 (19), 261 (7), 233 (6), 186 (38), 158 (49),
130 (23), 106 (100), 77 (71), 51 (35). IR (KBr): nˆ3075,
3057, 2941, 1672, 1632, 1590, 1557 cm21. UV/VIS
(CH2Cl2): lmax(log e)ˆ313 (4.40), 486 (3.90) nm. 1H
NMR (CDCl3): 3.68 (s 3H, CH3), 7.05 (s 1H, 3-H), 7.37±
7.47 (m 3H, C6H5), 7.62±7.78 (m 4H, C6H5, 6,7-H), 7.86 (s
1H, NvCH), 8.04±8.10 (m 2H, 5,8-H). 13C NMR (CDCl3):
183.92 (s, C-4 or C-1), 182.77 (s, C-1 or C-4), 150.27 (s,
C-2), 140.29 (d, NvCH), 134.75 (s, C-4a), 133.88 (d, C-6
or C-7), 132.56 (d, C-7 or C-6), 132.47 (s, phenyl-C), 132.28
(s, C-8a), 129.84 (d, phenyl-CH), 128.77 (d, phenyl-CH),
127.29 (d, phenyl-CH), 126.61 (d, C-5 or C-8), 125.53 (d,
C-8 or C-5), 115.61 (d, C-3), 36.31 (q, CH3). Anal. calcd for
C18H14N2O2: C, 74.47; H, 4.86; N, 9.65. Found: C, 74.19; H,
4.82; N, 9.55.
Experimental
NMR spectra were recorded using Bruker AC 200 (1H:
200 MHz; 13C: 50 MHz) with TMS as internal standard.
Mass spectra were performed using Finnigan 4000 mass-
spectrometer (EI, 70 eV). IR spectra: Perkin Elmer FT-IR-
1600 spectral photometer. Melting points were measured
with Gallenkamp-apparatus and are uncorrected. TLC-
control: Merck Silica gel 60 F254. Microanalyses were
performed by Zentrale Einrichtung der Chemie/Pharmazie
È
È
-Mikroanalyse- der Heinrich-Heine-Universitat Dusseldorf.
All solvents were puri®ed and dried by known methods.
Chemicals that are not specially mentioned were commer-
cially available products.
2-Acetylnaphthoquinone (2). See Refs. 15,16
Formaldehyde dimethylhydrazone. See Ref. 17
2-Acetyl-3-(dimethyl-hydrazonomethyl)-[1,4]naphtho-
quinone (4a). Formaldehyde dimethylhydrazone (0.25 g,
1.7 mmol) was added slowly to 2 (0.20 g, 1 mmol) in metha-
nol (5 ml) and stirred 1 h. The mixture was cooled overnight
at 2208C and violet crystals (20 mg, 7,5%) were ®ltered off
and dried. Mp 1488C. MS (70 eV): m/z (%): 270 (1) [M1],
227 (1), 212 (2), 182 (1), 157 (1), 127 (2), 101 (1), 58 (44),
1-Methyl-3-phenyl-1H-benzo[f]indazole-4,9-dione (12a).
11a (1.00 g, 3.4 mmol) was dissolved in xylene (50 ml) and
re¯uxed 48 h (TLC control). The solvent was removed and
the residue was suspended in boiling methanol. After 5 min
the mixture was ®ltered and the solution stored at 2208C.
Yellow crystals (0.25 g, 25%). Mp 1308C. MS: m/z (%): 288
(100) [M1], 257 (7), 232 (6), 204 (9), 176 (4), 144 (13), 129
(42), 102 (40), 77 (75), 51 (25). IR (KBr): nˆ3058, 3007,
2949, 1676, 1662, 1594 cm21. UV/VIS (CH2Cl2): lmax(log
e)ˆ246 (4.57), 268 (4.42), 339 (3.75) nm. 1H NMR
(CDCl3): 4.40 (s 3H, CH3), 7.44±7.51 (m 3H, C6H5),
7.72±7.81 (m 2H, 6,7-H), 8.13±8.30 (m 4H, 5,8-H, C6H5).
Anal. calcd for C18H12N2O2: C, 74.99; H, 4.20; N, 9.72.
Found: C, 74.87; H, 4.07; N, 9.68.
43 (100). IR (KBr): nˆ2924, 1699, 1665, 1620, 1590 cm21
.
UV/VIS (CH2Cl2): lmax(log e)ˆ307 (4,51), 506 (4.18) nm.
1H NMR (CDCl3): 2.48 (s 3H; COCH3), 3.20 (s 6H, two
CH3), 7.18 (s 1H, NvCH), 7.75±7.78 (m 2H, 6,7-H), 8.05±
8.12 (m 2H, 5,8-H). Anal. calcd for C15H14N2O2: C, 66.66;
H, 5.22; N, 10.36. Found: C, 66.74; H, 5.33; N, 9.97.
Benzaldehyde methylhydrazone (10a). See Ref. 18
Cinnamaldehyde methylhydrazone (10b). See Ref. 19
Anisaldehyde methylhydrazone (10c). See Ref. 20
2-[N-Methyl-N0-(3-phenyl-allylidene)-hydrazino]-[1,4]-
naphthoquinone (11b). Cinnamaldehyde methylhydrazone
10b (2.72 g, 17 mmol) in methanol (5 ml) was added slowly
to a suspension of 1,4-naphthoquinone 9 (1.60 g, 10 mmol)
in methanol (15 ml). After being stirred for 15 min the
precipitate (2.10 g, 65%) was ®ltered off, washed with
2,5-Dimethoxy-benzaldehyde methylhydrazone (10d).
Methylhydrazine (4.61 g, 0.10 mol) was slowly added to

È
H. Buff, U. Kucklander / Tetrahedron 56 (2000) 5137±5145
5142
methanol and dried to give violet needles from toluene. Mp
1598C. MS: m/z (%): 316 (11) [M1], 289 (4), 259 (4), 225
(11), 197 (3), 187 (22), 158 (18), 130 (100), 129 (25), 115
(24), 103 (30), 89 (33), 82 (35), 77 (66), 63 (17), 51 (47). IR
(KBr): nˆ3026, 1672, 1646, 1630, 1592, 1556 cm21. UV/
to a suspension of 1,4-naphthoquinone 9 (0.64 g, 4 mmol) in
methanol (15 ml) under stirring. After 30 min the violet
precipitate (0.64 g, 46%) was ®ltered off, washed with
methanol and dried. Mp 1868C (methanol). MS: m/z (%):
350 (24) [M1], 319 (24), 293 (7), 263 (5), 236 (2), 187 (36),
163 (32), 148 (100), 105 (47), 77 (97), 50 (64). IR (KBr):
nˆ3068, 3030, 3006, 2948, 2909, 2836, 1667, 1631, 1591,
1555 cm21. UV/VIS (CH2Cl2): lmax(log e)ˆ329 (4.33), 500
(4.02) nm. 1H NMR (CDCl3): 3.69 (s 3H, N-CH3), 3.85 and
3.86 (d 6H, two OCH3), 6.81±6.99 (m 2H, 30,40-H), 7.01 (s
1H, 3-H), 7.54±7.56 (`d' 1H, 60-H), 7.63±7.77 (m 2H, 6,7-
H), 8.04±8.12 (m 2H, 5,8-H), 8.26 (s 1H, NvCH). Anal.
calcd for C20H18N2O4: C, 68.56; H, 5.18; N, 8.00. Found: C,
68.63; H, 5.16; N, 7.85.
1
VIS (CH2Cl2): lmax(log e)ˆ336 (4.33), 500 (3.78) nm. H
NMR (CDCl3): 3.63 (s 3H, N-CH3), 6.88±7.13 (m 3H, allyl
system), 7.31±7.52 (m 5H, C6H5), 7.64±7.73 (m 3H, 6,7-H,
3-H), 8.04±8.10 (m 2H, 5,8-H). Anal. calcd for C20H16N2O2:
C, 75.93; H, 5.10; N 8.85. Found: C, 75.74; H, 5.13; N,8.,82.
1-Methyl-3-(3-phenyl-propenyl)-1H-benzo[f]indazole-
4,9-dione (12b). 11b (0.32 g, 1 mmol) was dissolved in
xylene (50 ml) and stirred 5 days under re¯ux (TLC
control). The solvent was removed, the residue treated
with dichloromethane (1 ml) and chromatographed on silica
gel (0.06±0.2 mm) with eluent dichloromethane. Yellow
needles from methanol. Mp 1448C. MS: m/z (%): 314 (7)
[M1], 285 (1), 245 (1), 231 (2), 215 (1), 172 (9), 149 (9),
129 (100), 102 (43), 76 (32), 51 (53), 43 (24). IR (KBr):
nˆ3060, 3022, 2947, 1673, 1635, 1589, 1576, 1525,
1501 cm21. UV/VIS (CH2Cl2): lmax(log e)ˆ250 (4.51),
3-(2,5-Dimethoxy-phenyl)-1-methyl-1H-benzo[f]indazole-
4,9-dione (12d). 11d (0.35 g, 1 mmol) was dissolved in
xylene (50 ml) and stirred 5 days under re¯ux (TLC
control). The solvent was removed, the residue treated
with dichloromethane (1 ml) and chromatographed on silica
gel (0.06±0.2 mm) with eluent dichloromethane/ethyl
acetate (90/10). Yellow needles from methanol. Mp
2528C. MS: m/z (%): 348 (51) [M1],333 (15), 317 (18),
305 (16), 262 (16), 233 (8), 205 (10), 159 (15), 129 (17),
105 (35), 76 (93), 50 (100). IR (KBr): nˆ3073, 3000, 2950,
2837, 1676, 1590 cm21. UV/VIS (CH2Cl2): lmax(log
1
310 (4.34), 412 (3.78) nm. H NMR (CDCl3): 4.36 (s 3H,
N-CH3), 7.28±7.45 (m 3H), 7.61±7.92 (m 6H) (allyl system,
C6H5, 6,7-H), 8.21±8.30 (m 2H, 5,8-H). Anal. calcd for
C20H14N2O2: C, 76.41; H, 4.49; N, 8.91. Found: C, 76.46;
H, 4.67; N, 8.99.
1
e)ˆ248 (4.61), 267 (4.25), 276 (4.25), 312 (3.93) nm; H
NMR (CDCl3): 3.77 (s 3H, OCH3), 3.81 (s 3H, OCH3), 4.39
(s 3H, N-CH3), 6.98±7.05 (m 3H, 30,40,60-H), 7.72±7.77 (m
2H, 6,7-H), 8.17±8.25 (m 2H, 5,8-H). Anal. calcd for
C20H16N2O4: C, 68.96; H, 4.63; N, 8.04. Found: C, 69.06;
H, 4.64; N, 7.79.
2-[N0-(4-methoxy-benzylidene)-N-methyl-hydrazino]-[1,4]-
naphthoquinone (11c). Anisaldehyde methylhydrazone
10c (2.80 g, 17 mmol) in methanol (5 ml) was added slowly
to a suspension of 1,4-naphthoquinone 9 (1.60 g, 1 mmol) in
methanol (15 ml). After being stirred for 15 min the preci-
pitate (1.40 g, 44%) was ®ltered off, washed with methanol
and dried to give red needles from toluene. Mp 148±1518C.
MS: m/z (%): 320 (49) [M1], 291 (10), 263 (7), 233 (2),
187 (24), 158 (19), 135 (100), 104 (27), 77 (47), 44 (20).
IR (KBr): nˆ3064, 2998, 2975, 2938, 2838, 1673,
1625, 1607, 1593, 1554, 1512 cm21. UV/VIS (CH2Cl2):
2-Acetyl-3-(N0-benzylidene-N-methyl-hydrazino)-[1,4]-
naphthoquinone (14a). To a suspension of 2-acetyl-
naphthoquinone 2 (0.20 g, 1 mmol) in methanol (5 ml)
was added slowly benzaldehyde methylhydrazone 10a
(0.23 g, 1.7 mmol) in methanol (3 ml) and the mixture
was stirred 20 min at 208C. The red precipitate (0.25 g,
75%) was ®ltered off, washed with methanol and dried.
Mp 1728C (methanol). MS: m/z (%): 332 (3) [M1], 317
(1), 289 (25), 261 (1), 228 (11), 213 (7), 186 (30), 158
(6), 129 (11), 105 (34), 77 (65), 43 (100). IR (KBr):
l
max(log e)ˆ304 (4.49), 321 (4.51), 503 (4.03) nm. 1H
NMR (CDCl3): 3.68 (s 3H, N-CH3), 3.87 (s 3H, O-CH3),
6.91±6.98 (`d' 2H, 30,50-H, AA0BB0), 7.03 (s 1H, 3-H),
7.63±7.76 (m 4H, 20,60-H from AA0BB0, 6,7-H), 7.85 (s
1H, NvCH), 8.04±8.10 (m 2H, 5,8-H). Anal. calcd for
C19H16N2O3: C, 71.24; H, 5.03; N, 8.74. Found: C, 71.13;
H, 5.11; N, 8.57.
nˆ3060, 2923, 1700, 1674, 1689, 1617, 1595, 1561 cm21
.
UV/VIS (CH2Cl2): lmax(log e)ˆ312 (4.31), 491 (3.79) nm.
1H NMR (CDCl3): 2.53 (s 3H, acetyl), 3.63 (s 3H, N-CH3),
7.37±7.47 (m 3H), 7.57±7.63 (m 2H) (C6H5), 7.67±7.81 (m
3H, 6,7-H, NvCH), 8.04±8.11 (m 2H, 5,8-H). 13C NMR
(CDCl3): 200.56 (s, COCH3), 183.03 (s, C-1), 182.32 (s,
C-4), 146.19 (s, C-3), 140.94 (d, NvCH), 134.37 (d, C-6
or C-7), 133.99 (s, C-2), 133.10 (d, C-7 or C-6), 131.60 (s,
C-4a or C-C8a), 131.51 (s, C-8a or C-4a), 129.91 (d, phenyl-
CH), 128.77 (d, phenyl-CH), 128.13 (s, phenyl-C), 127.44
(d, phenyl-CH), 126.45 (d, C-5 or C-8), 125.74 (d, C-8 or
C-5), 37.68 (q, N-CH3), 32.64 (q, COCH3). Anal. calcd for
C20H16N2O3: C, 72.28; H, 4.85; N, 8.43. Found: C, 71.82; H,
4.79; N, 8.53.
3-(4-Methoxy-phenyl)-1-methyl-1H-benzo[f]indazole-4,9-
dione (12c). See 12a. Yellow crystals from methanol
(0.27 g, 27%). Mp 1738C. MS: m/z (%): 318 (100) [M1],
303 (21), 275 (20), 247 (2), 219 (3), 190 (3), 165 (4), 159
(8), 114 (5), 105 (6), 76 (15), 50 (14). IR (KBr): nˆ3089,
2940, 2842, 1669, 1609, 1593, 1576 cm21. UV/VIS
(CH2Cl2):
l
max(log e)ˆ248 (4.74), 272 (4.43), 412
1
(3.68) nm. H NMR (CDCl3): 3.88 (s 3H, O-CH3), 4.38 (s
3H, N-CH3), 6.96±7.07 (`d' 2H, 30,50-H AA0BB0), 7.70±
7.84 (m 2H, 6,7-H), 8.17±8.31 (m 4H, 5,8-H and 20,60-H
AA0BB0). Anal. calcd for C19H14N2O3: C, 71.69; H, 4.43; N,
8.80. Found: C, 71.81; H, 4.54; N, 8.64.
2-Acetyl-3-[N-methyl-N0-(2-oxo-propylidene)-hydrazino]-
[1,4]naphthoquinone (14e). 2-Acetyl-naphthoquinone 2
(1.80 g, 9 mmol) in 10 ml toluene was added slowly to a
solution of 1-methyl-hydrazonopropanone 10e (0.91 g,
9 mmol) in 10 ml toluene with stirring at room temperature.
2-[N0-(2,5-dimethoxy-benzylidene)-N-methyl-hydrazino]-
[1,4]naphthoquinone (11d). 2,5-Dimethoxy-benzaldehyde
methylhydrazone 10d (1.32 g, 6.8 mmol) was added slowly

È
H. Buff, U. Kucklander / Tetrahedron 56 (2000) 5137±5145
5143
After 20 min the yellow precipitate (2-acetyl-1,4-di-
hydroxy-naphthalene) was ®ltered off. The solution was
evaporated at room temperature, the residue treated with a
mixture of cyclohexane (2 ml)/ethyl acetate (2 ml) and the
precipitate 14e (0.68 g, 25%) was then ®ltered off and dried.
Red crystals. Mp 1248C. MS: m/z (%): 299 (1) [M111], 256
(5), 228 (3), 213(2), 186 (4), 105 (3), 76 (7), 43 (100). IR
(KBr): nˆ3067, 3008, 2974, 1712, 1673, 1629, 1595, 1572,
1556 cm21. UV/VIS (CH2Cl2): lmax(log e)ˆ298 (4.57), 439
(4.03) nm. 1H NMR (CDCl3): 2.33 (s 3H, CH3), 2.57 (s 3H,
acetyl), 3.43 (s 3H, N-CH3), 7.08 (s 1H, NvCH), 7.77±7.83
(m 2H, 6,7-H), 8.09±8.12 (m 2H, 5,8-H). 13C NMR
(CDCl3): 198.85 (q, COCH3), 196.59 (`quint', COCH3),
182.66 (d, C-4), 181.95 (d, C-1), 146.03 (s, C-3), 136.56
(d, NvCH), 134.77 (m, C-7/C-6), 133.96 (m, C-6/C-7),
133.10 (s, C-4a/C-8a), 131.16 (s, C-8a/C-4a), 131.02 (q,
C-2), 126.73 (m, C-5/C-8), 126.18 (m, C-8/C-5), 38.66 (q,
NCH3), 32.62 (q, COCH3), 25.35 (q, COCH3). Anal. calcd
for C16H14N2O4: C, 64.42; H, 4.73; N, 9.39. Found: C,
64.47; H, 4.60; N, 9.36.
¯ask was then ¯ushed with argon. Na2SO4 (2 g) and Ag2O
(3.00 g, 13 mmol) were added and the mixture stirred 30±
40 min (TLC control). The mixture was ®ltered off and the
solution was evaporated at room temperature. Orange
crystals (0.79 g, 80%). Mp:1468C. MS: m/z (%): 232 (3)
[M1], 217 (3), 162 (1), 133 (1), 104 (4), 78 (10), 43
(100). IR (KBr): nˆ3052, 2931, 1694, 1670, 1640, 1611,
1568 cm21. UV/VIS (CH2Cl2): lmax(log e)ˆ241 (4.25), 428
1
(3.54) nm. H NMR (CDCl3): 2.63 (s 3H, acetyl), 3.91 (s
3
3H, N-CH3), 6.94 and 7.00 (AB 2H, Jˆ10.2 Hz). Anal.
calcd for C11H18N2O4: C, 56.9; H, 3.47; N, 12.06. Found:
C, 56.68; H, 3.45; N, 11.88.
2-(N0-Benzylidene-N-methyl-hydrazino)-3,6-dioxo-cyclo-
hexa-1,4-dienecarboxylic acid methyl ester (21). 17
(0.33 g, 2 mmol) was suspended in methanol (5 ml) and
benzaldehyde methylhydrazone 10a (0.13 g, 1 mmol) was
added slowly under stirring. The mixture was evaporated to
dryness, dissolved in dichloromethane (0.5 ml) and chroma-
tographed on silica gel (0.063±0.200 mm) with eluent
dichloromethane/ethyl acetate (95/5). Violet crystals
(0.09 g, 30%). Mp 1488C. MS: m/z (%): 298 (41) [M1],
267 (88), 239 (83), 197 (11), 162 (56), 136 (44), 113 (41),
104 (21), 82 (100), 77 (74), 54 (43). IR (KBr): nˆ3001,
1,3-Dimethyl-1H-benzo[f]indazole-4,9-dione (15). 14a or
14e (0.10 g) was dissolved in methanol/glacial acetic acid
(10 ml, 10%). After 5 h stirring, the colorless solution was
evaporated and the residue (85%) was recrystallized from
methanol. Mp 1408C (methanol). Lit.24: mp 1588C. MS: m/z
(%): 226 (100) [M1], 197 (11), 169 (8), 158 (14), 129 (44),
102 (46), 76 (73), 50 (54), 43 (22). IR (KBr): nˆ3074, 3032,
1678, 1591. UV/VIS (CH2Cl2): lmax(log e)ˆ266 (4.25),
2948, 1730, 1676, 1644, 1603, 1549 cm21 1H NMR
.
(CDCl3): 3.58 (s 3H, OCH3), 3.64 (s 3H, N-CH3), 6.72
(AB 2H, 5,6-H 3Jˆ10.2 Hz), 7.34±7.47 (m 3H), 7.60±
7.67 (m 2H) (C6H5), 7.76 (s 1H, NvCH). Anal. calcd for
C16H14N2O4: C, 64.42; H, 4.73; N, 9.39; Found: C, 64.69; H,
4.81; N, 9.40.
1
275 (4.30), 329 (3.89) nm. H NMR (CDCl3): 2.65 (s 3H,
CH3), 4.27 (s 3H, N-CH3), 7.69±7.82 (m 2H, 6,7-H), 8.16±
8.25 (m 2H, 5,8-H), 13C NMR (CDCl3): 179.90 (s, C-9),
176.09 (s, C-4), 155.40 (s, C-9a), 148.99 (s, C-3), 137.74
(s, C-4a), 134.18 (d, C-6 or C-7), 133.23 (d, C-7 or C-6),
133.10 (s, C-8a), 126.67 (d, C-51C-8), 119.66 (s, C-3a),
38.69 (q, NCH3), 12.87 (q, CH3). Anal. calcd for
C13H10N2O2: C, 69.02; H, 4.46; N, 12.38. Found: C,
68.88; H, 4.47; N, 12.43.
2,5-Bis-(N0-benzylidene-hydrazino)-3,6-dioxo-cyclohexa-
1,4-dienecarboxylic acid methyl ester (22). 17 (0.33 g,
2 mmol) was suspended in methanol (5 ml) and benzalde-
hyde methylhydrazone 10a (0.27 g, 2 mmol) was added
slowly under stirring. After 1 h the mixture was cooled to
2208C and the precipitate (0.17 g, 29%) was ®ltered off,
washed with methanol and dried. Brown powder. Mp
1668C. MS: m/z (%): 430 (2) [M1], 399 (1), 369 (20), 323
(7), 292 (27), 266 (8), 223 (12), 191 (74), 118 (13), 104 (62),
82 (100), 77 (52), 51 (30), 42 (17). IR (KBr): nˆ3062, 2947,
2911, 1732, 1633, 1596, 1560, 1556 cm21. UV/VIS
(CH2Cl2): lmax(log e)ˆ310 (4.39), 458 (4.42) nm. 1H
NMR (DMSO-d6): 3.52 (s 3H, OCH3), 3.60 (s 3H,
N-CH3), 3.63 (s 3H, N-CH3), 6.50 (s 1H, 4-H), 7.45±7.51
(m 6H), 7.68±7.72 (m 2H), 7.78±7.83 (m 2H), (two C6H5),
8.11 (s 1H, NvCH), 8.20 (s 1H, NvCH). Anal. calcd for
C24H22N4O4: C, 66.97; H, 5.15; N, 13.02. Found: C, 66.95;
H, 4.97; N, 12.94.
2-Methoxycarbonyl-1,4-benzoquinone (17). See Ref. 22
4-Acetyl-5,8-dihydroxy-2-methyl-2H-phthalazine-1-one
(18). 17 (1.00 g, 6 mmol) was dissolved in methanol
(10 ml). 1-methylhydrazono-propanone 10e (1.00 g,
10 mmol) was added and the mixture left at room tempera-
ture over night. The precipitate (0.70 g, 50%) was ®ltered
off, washed with methanol and dried. Yellow needles
(methanol). Mp 1908C. MS: m/z (%): 234 (42) [M1], 219
(5), 191 (11), 162 (8), 161 (5), 135 (3), 107 (5), 78 (10), 51
(10), 43 (100)]. IR (KBr): nˆ3446, 2953, 2802, 1674, 1650,
1613, 1578, 1531 cm21. UV/VIS (CH2Cl2): lmax(log
2,3-Dimethyl-1,4-benzoquinone (23). 2,3-Dimethyl-1,4-
hydroquinone (10.40 g, 75.4 mmol), KBrO3 (5.6 g), sulfuric
acid (5 ml) and water (100 ml) were stirred 10 min at 808C.
The mixture was then cooled 3 h with ice. The resulting
yellow needles (10.00 g, 98%) were ®ltered off, washed
with ice-water and crystallized from petrolether (60/80).
Mp 558C.23
1
e)ˆ238 (4.28), 366 (3.95) nm. H NMR (CDCl3): 2.77 (s
3H, CO±CH3), 3.87 (s 3H, N-CH3), 7.19, 7.34 (AB, 2H,
3Jˆ9 Hz 6,7-H), 11.07 (s 1H, 6-OH), 12.04 (s 1H, 8-OH).
13C NMR (CDCl3): 203.54 (s, COCH3), 163.30 (s, C-1),
154.15 (s, C-8 or C-5), 146.02 (s, C-5 or C-8), 141.61 (s,
C-4), 126.81 (d, C-6 or C-7), 121.60 (d, C-7 or C-6), 113.79
(s, C-8a or C-4a), 110.65 (s, C-4a or C-8a), 39.56 (q, N-CH3),
27.98 (q, COCH3). Anal. calcd for C11H10N2O4: C, 56.41; H,
4.27; N, 11.96. Found: C, 56.2; H, 4.34; N, 11.93.
5-(N0-Benzylidene-N-methyl-hydrazino)-2,3-dimethyl-[1,4]-
benzoquinone (24a). Benzaldehyde methylhydrazone 10a
(0.67 g, 5 mmol) was added slowly to a solution of 2,3-
dimethyl-benzoquinone 23 (0.68 g, 5 mmol) in methanol
(5 ml) under stirring. After 5 min the violet precipitate
4-Acetyl-2-methyl-2H-phthalazine-1,5,8-trione (20). 18
(1.00 g, 4.3 mmol) was dissolved in dry acetone and the

È
H. Buff, U. Kucklander / Tetrahedron 56 (2000) 5137±5145
5144
(0.40 g, 30 %) was ®ltered off, washed with methanol and
dried. Mp 1298C. MS: m/z (%): 268 (18) [M1], 225 (2), 211
(11), 197 (10), 164 (30), 136 (44), 124 (25), 110 (19), 108
(18), 106 (69), 82 (100), 77 (51), 67 (67), 54 (53), 42 (20).
IR (KBr): nˆ3183, 3068, 3003, 2946, 2907, 1662, 1646,
1599, 1574, 1507 cm21. UV/VIS (CH2Cl2): lmax(log
e)ˆ289 (4.33), 314 (4.33), 509 (3.83) nm. 1H NMR
(CDCl3): 2.05 (s 6H, two CH3), 3.55 (s 3H, N-CH3), 6.70
(s 1H, 3-H), 7.21±7.45 (m 3H), 7.69±7.76 (m 2H) (C6H5),
7.78 (s 1H, NvCH). Anal. calcd for C16H16N2O2: C, 71.62;
H, 6.01; N, 10.44. Found: C, 71.61; H, 5.97; N, 10.17.
Acetic acid 1,5,6-trimethyl-3-phenyl-1H-benzo[1,3,4]oxa-
diazin-7-yl ester (27a). 26a (0.10 g) was dissolved in 20 ml
(CH3CO)2O, 2 drops of pyridine were added and the mixture
was stirred 1 h at room temperature. The solvent was
removed and the residue was recrystallized from petroleum
ether 60/80 to give yellow needles (0.10 g 90%). Mp:
1058C. MS: m/z (%): 310 (60) [M1], 268 (88), 239 (1),
206 (1), 164 (36), 136 (21), 124 (100), 108 (9), 82 (73),
67 (22), 42 (45). IR (KBr): nˆ3430, 2923, 1760, 1623,
1598, 1576 cm21. UV/VIS (CH2Cl2): lmax(log e)ˆ248
1
(4.49), 309 (3.71), 361 (3.73) nm. H NMR (CDCl3): 1,98
(s 3H, CH3), 2,23 (s 3H, CH3), 2,31(s 3H, CH3), 3,10 (s 3H,
N-CH3), 6,08 (s 1H, 8-H), 7,36±7,42 (m 3H), 7,83±7,88 (m
2H) (C6H5). Anal. calcd for C18H18N2O3: C, 69,66; H, 5,85;
N, 9,03. Found: C, 69,41; H, 5,82; N, 9,24.
5-[N0-(4-Methoxy-benzylidene)-N-methyl-hydrazino]-2,3-
dimethyl-[1,4]benzoquinone (24c). To a solution of 2,3-
dimethylbenzoquinone 23 (0.68 g, 5 mmol) in methanol
(3 ml) was added 4-methoxy-benzaldehyde methylhydra-
zone 10c (0.82 g, 5 mmol) under stirring. After 5 min the
mixture was cooled at 2208C and the precipitate (0.38 g, 39
%) was ®ltered off, washed with methanol and dried. Mp
1708C (petroleum ether 60/80). MS: m/z (%): 298 (40)
[M1], 283 (3), 255 (4), 227 (12), 212 (3), 188 (16), 164
(21), 135 (85), 124 (44), 108 (22), 92 (19), 82 (100), 77
(38), 55 (40), 42 (21). IR (KBr): nˆ2997, 2960, 2935,
1646, 1598, 1562, 1513 cm21. UV/VIS (CH2Cl2): lmax(log
e)ˆ296 (4.47), 312 (4.38), 526 (3.93) nm. 1H NMR
(CDCl3): 2.04 (s 6H, two CH3), 3.53 (s 3H, N-CH3), 3.88
(s 3H, OCH3), 6.67 (s 1H, 3-H), 6.89±6.96 (`d' 2H,
AA0BB0), 7.62±7.70 (`d' 2H, AA0BB0) (4-methoxy-phenyl),
7.75 (s 1H, NvCH). Anal. calcd for C17H18N2O3: C, 68.44;
H, 6.08; N, 9.39. Found: C, 68.20; H, 6.26; N, 9.64.
Acetic acid 3-(4-methoxy-phenyl)-1,5,6-trimethyl-1H-
benzo[1,3,4]oxadiazin-7-yl ester (27c). 26c (0.10 g) was
dissolved in 20 ml (CH3CO)2O, 2 drops of pyridine were
added and the mixture was stirred 30 min at room tempera-
ture. The solvent was removed and the residue was recrys-
tallized from petroleum ether 60/80 to give yellow needles
(0.10 g, 80%). Mp: 1678C. MS: m/z (%): 340 [M1], 324 (1),
298 (48), 256 (1), 226 (1), 215 (1), 164 (41), 136 (19), 124
(100), 82 (62), 67 (20), 55 (11), 42 (55). IR (KBr): nˆ3446,
2996, 2968, 2934, 1759, 1622, 1607, 1513 cm21. UV/VIS
(CH2Cl2): lmax(log e)ˆ258 (4.18), 330 (3.50) nm. 1H NMR
(CDCl3): 1.98 (s 3H, CH3), 2.22 (s 3H, CH3), 2.31 (s 3H,
CH3 acetyl), 3.08 (s 3H, N-CH3), 3.84 (s 3H, OCH3), 6.10 (s
1H, 8-H), 6.86±6.94 (`d' 2H, AA0BB0), 7.76±7.84 (`d' 2H,
AA0BB0) (4-methoxy-phenyl). Anal. calcd for C19H20N2O4:
C, 67.05; H, 5.92; N, 8.23. Found: C, 67.19; H, 5.83; N,
8.19.
7-Hydroxy-1,5,6-trimethyl-3-phenyl-1H-benzo[1,3,4]oxa-
diazine (26a). 24a (1.00 g, 3.7 mmol) were dissolved in
methanol (50 ml) and boiled 5 min under stirring. The
solvent was evaporated at room temperature and the residue
was recrystallized from petroleum ether 60/80. White±
yellow wool-like crystals (3.50 g, 95%). Mp 1298C. MS:
m/z (%): 268 (88) [M1], 234 (1), 192 (21), 164 (29), 150
(5), 136 (25), 124 (100), 108 (11), 82 (39), 67 (15), 42 (25).
IR (KBr): nˆ3274, 2999, 2960, 2992, 2623, 1590, 1500.
UV/VIS (CH2Cl2): lmax(log e)ˆ254 (5.03), 318 (4.27), 366
(4.32) nm. 1H NMR (DMSO-d6)): 1.97 (s 3H, CH3), 2.15 (s
3H, CH3), 3.03 (s 3H, N-CH3), 6.10 (s 1H, 8-H), 7.44±7.50
(m 3H), 7.76 27.85 (m 2H) (C6H5), 9.07 (s 1H, OH). Anal.
calcd for C16H16N2O2: C, 71.62; H, 6.01; N, 10.44. Found:
C, 71.69; H, 5.87; N, 10.31.
References
1. Inouye, H.; Leistner, E. Biochemistry of quinones. In The
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New York, 1974; Vol. 1, Part 2, pp 683±735.
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7-Hydroxy-3-(4-methoxy-phenyl)-1,5,6-trimethyl-1H-
benzo[1,3,4]oxadiazine (26c). 24c (1.00 g, 3.4 mmol) was
dissolved in methanol (50 ml) and boiled 10 min under
stirring. The mixture was evaporated and the residue was
recrystallized from petroleum ether 68/80. White wool-like
crystals (0.90 g, 90%). Mp 1438C. MS: m/z (%): 298 (40)
[M1], 283 (1), 269 (1), 216 (1), 164 (23), 136 (20), 124
(100), 108 (10), 96 (10), 82 (37), 67 (16), 42 (56). IR
(KBr): nˆ3418, 2961, 2924, 1623, 1610, 15771,
1514 cm21. UV/VIS (CH2Cl2): lmax(log e)ˆ261 (4.55),
4. Ditrich, K.; Hamprecht, G.; Wuerzer, B.; Meyer, N.; West-
phalen, K. O.; Laatsch, H. (BASF A.-G.); Preparation of naphthin-
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È
1
349 (3.83) nm. H NMR (DMSO-d6): 1.97 (s 3H, CH3),
È
2.14 (s 3H, CH3), 3.00 (s 3H, N-CH3), 3.80 (s 3H, OCH3),
6.07 (s 1H, 8-H), 6.97±7.05 (`d' 2H, AA0BB0), 7.71±7.78
(`d' 2H, AA0BB0) (4-methoxy-phenyl), 9.03 (s 1H, OH).
Anal. calcd for C17H18N2O3: C, 68.44; H, 6.08; N, 9.39.
Found: C, 68.48; H, 6.21; N, 9.04.
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