Synthesis of 3-hydroxy-6-oxo[1,2,4]triazin-1-yl alaninamides, a new class of cyclic dipeptidyl ureas

Article abstract of DOI:10.1021/jo060434y

Cyclohexyl or benzyl isocyanide, benzoyl-, or 4-methoxybenzoylformic acid and semicarbazones underwent Ugi reactions in methanol for 3 days to give the Ugi adducts, which were then stirred with sodium ethoxide in ethanol for 12 h to give 3-hydroxy-6-oxo[1

Full text of DOI:10.1021/jo060434y

Synthesis of 3-Hydroxy-6-oxo[1,2,4]triazin-1-yl Alaninamides, a New
Class of Cyclic Dipeptidyl Ureas
Mar´ıa San˜udo,† Stefano Marcaccini,*,‡ Sara Basurto,† and Toma´s Torroba*,†
Qu´ımica Orga´nica, Facultad de Ciencias, UniVersidad de Burgos, 09001 Burgos, Spain,
and Dipartamento di Chimica Organica “Ugo Schiff”, UniVersita` di Firenze, Via della Lastruccia 13,
I-50121 Sesto Fiorentino (FI) Italy
stefano.marcaccini@unifi.it; ttorroba@ubu.es
ReceiVed March 1, 2006
Cyclohexyl or benzyl isocyanide, benzoyl-, or 4-methoxybenzoylformic acid and semicarbazones
underwent Ugi reactions in methanol for 3 days to give the Ugi adducts, which were then stirred with
sodium ethoxide in ethanol for 12 h to give 3-hydroxy-6-oxo[1,2,4]triazin-1-yl alaninamides. The X-ray
diffraction structure of the first example showed the tautomer having the proton in the O2 atom that was
fixed in the crystal by packing in dimers with a H-bond distance of 1.9 Å. Selected [1,2,4]triazines were
treated with diazomethane for 12 h to get the O-methyl derivatives. Both hydroxy and O-methyl derivatives
obtained by this method constitute a new class of pseudopeptidic [1,2,4]triazines composed of two different
amino acids, arylglycine and alanine derivatives, in which the N-terminal arylglycine and the peptidic
amide nitrogen atoms are bonded through a urea moiety.
Introduction
cognate peptides, as they differ by the addition of a single
backbone atom, being in principle inert to enzymatic hydrolysis.
This class of urea pseudopeptides has been successfully used
for the creation of active site human immunodeficiency virus
(HIV-1) protease inhibitors.3 On the other hand, azapeptides
are peptide analogues in which an R-CH group in a peptide
chain is isoelectronically replaced by nitrogen and have
displayed considerable biological activity as hormone analogues,
protease inhibitors, and active-site titrants.4 Selected examples
are atazanavir,5 an azapeptide protease inhibitor marketed for
HIV treatment, and zoladex,6 an azapeptide analogue of the
peptide hormone luliberin, used for breast and prostate cancer
treatment. Indeed, most azapeptides of therapeutic value bear
the urea moiety in their structure, because they are conceptually
derived from semicarbazone7 and, of course, both structural
The design and synthesis of metabolically stable peptide
analogues that can either mimic or block the bioactivity of
natural peptides or enzymes is an important constituent of
bioorganic and medicinal chemistry research. Isosteric replace-
ment of a scissile peptide bond represents a viable and popular
approach in the rational design of peptidomimetics.1 Peptido-
mimetics find applications as drugs, in protein engineering, and
so on. This is evident from the wealth of therapeutically useful
peptidomimetic leads incorporating any of the peptide isosteres
that are currently available. Between the several types of peptide
isosteres known to date, ureidopeptides and azapeptides are
useful peptidomimetics. Ureidopeptides2 are obtained by the
insertion of a nitrogen atom between the R-carbon and the
carbonyl of the scissile amide bond, therefore, they contain a
urea linkage but retain a strong structural resemblance to their
(3) (a) Myers, A. C.; Kowalski, J. A.; Lipton, M. A. Bioorg. Med. Chem.
Lett. 2004, 14, 5219-5222. (b) Barth, B. S.; Myers, A. C.; Lipton, M. A.
J. Pept. Res. 2005, 65, 352-354.
(4) Zega, A. Curr. Med. Chem. 2005, 12, 589-597.
(5) Piliero, P. J. Drugs Today 2004, 40, 901-912.
(6) Zinner, N. R.; Bidair, M.; Centeno, A.; Tomera, K. Urology 2004,
64, 1177-1181. Mansel, R. E.; Goyal, A.; Preece, P.; Leinster, S.; Maddox,
P. R.; Gateley, C.; Kubista, E.; von Fournier, D. Am. J. Obstet. Gynecol.
2004, 191, 1942-1949.
* To whom correspondence should be addressed.
† University of Burgos. Phone: 34-947-258088. Fax: 34-947-258087.
‡ University of Florence. Phone: 39-055-4573510. Fax: 39-055-4573302.
(1) Venkatesan, N.; Kim, B. H. Curr. Med. Chem. 2002, 9, 2243-2270.
(2) Semetey, V.; Hemmerlin, C.; Didierjean, C.; Schaffner, A. P.; Giner,
A. G.; Aubry, A.; Briand, J. P.; Marraud, M.; Guichard, G. Org. Lett. 2001,
3, 3843-3846.
10.1021/jo060434y CCC: $33.50 © 2006 American Chemical Society
Published on Web 05/11/2006
4578
J. Org. Chem. 2006, 71, 4578-4584

3-Hydroxy-6-oxo[1,2,4]triazin-1-yl Alaninamides
motifs, urea and aza-amino acids, can be combined in the same
molecule.8 1,4,5,6-Tetrahydro-l,2,4-triazin-3(2H)ones have been
prepared as bridged azapeptides by direct cyclization of linear
azapeptides by using ethylene glycol bistriflate.9 1,2,4-Triazine-
3,6-diones have been prepared in the context of aza-urea peptide
nificant biological activities, such as the antibiotic fervenuline,
reumycine, and toxoflavine derivatives,20 showing all a py-
rimido[5,4-e][1,2,4]triazine (7-azapteridine) ring system, and the
imidazo[5,1-f][1,2,4]triazinone scaffold has recently received
attention as the core structure of vardenafil (Levitra), a potent
and effective PDE5 inhibitor for the treatment of erectile
dysfunction.21 Despite the broad interest in this class of
heterocycles, a short and regioselective route to 1,2,4-triazine-
3,6-diones has been lacking. We have recently shown that the
sequences of classical Ugi or Passerini isocyanide multicom-
ponent reactions, followed by post-condensation transformations,
constitute extremely powerful synthetic tools for the preparation
of structurally diverse complex molecules, among them are
heterocyclic compounds with elaborate substitution patterns,
constrained peptides, and peptide mimetics, which are of great
interest in drug discovery programs.22 As a new contribution
of this methodology, we want to report in this paper a new
synthesis of pseudopeptidic 1,2,4-triazines by the sequence of
a semicarbazone Ugi reaction, followed by a carbamide cy-
clization and, in selected cases, methylation of the hydroxyl
group.
mimetics by the reaction of hydrazines with R-lactams.10
A
serious drawback of the synthesis is constituted by reports that
some compounds originally assigned as 1,2,4-triazine-3,6-diones
were actually 3-aminohydantoins; therefore, the reaction is
limited to selected substituted hydrazines.11 3-Aminohydantoins
and 1,2,4-triazine-3,6-diones have been obtained as amino acid
derived urea peptidomimetics, using phoxime resin, amino acids,
and substituted hydrazines, followed by cyclization of the
intermediate carbamate hydrazide resin, but the cyclization
strongly depended on the hydrazine substitution.12 A single
example of 1,2,4-triazine-3,6-dione azapeptide, obtained by a
complex route from an R-isocyanatocarboxylic acid derivative,
is also known.13 1,2,4-Triazine derivatives14 possess biological
activity as selective herbicides15 and have been screened for in
vitro anti-HIV16 and anti-cancer activities.17 Remarkable thera-
peutic tools are tirapazamine (3-amino-1,2,4-benzotriazine 1,4-
dioxide), a bioreductive drug in clinical trials as an anticancer
agent to kill refractory hypoxic cells of solid tumors,18 and
lamotrigine {3,5-diamino-6-(2,3-dichlorophenyl)[1,2,4]triazine},
a sodium-channel blocker, which is in clinical use as an
anticonvulsant.19 Furthermore, pyrimido-triazines possess sig-
Results and Discussion
Cyclohexyl or benzyl isocyanide 2a,b (1 equiv) and ben-
zoylformic or 4-methoxybenzoylformic acid23 3a,b (1 equiv)
were added consecutively to a solution of the corresponding
semicarbazone 1a-e (1 equiv) in methanol, and the mixture
was stirred at room temperature for 3 days until complete
precipitation of the Ugi adducts. The resultant solid products
4a-i were then filtered, recrystallized, and characterized by the
usual spectroscopic and analytical techniques. In turn, com-
pounds 4a-i (1 equiv) were stirred with sodium ethoxide (1.05
equiv) in ethanol for 12 h. Then the solvent was evaporated,
the residue was suspended in isopropyl ether, and the resulting
solid was filtered, dissolved in water, and reprecipitated by the
addition of acetic acid until acidic pH. Solid products 5a-i were
then filtered, recrystallized in dichloromethane/methanol (6:1),
and characterized. Selected products, 5b,c,e-g,i, were treated
with diazomethane in ether/chloroform, stirred for 12 h, and
worked-up to get the O-methyl derivatives 6b,c,e-g,i. Scheme
1 and Table 1 show the complete list of reagents, products, and
yields.
(7) See, for example: (a) Melendez, R. E.; Lubell, W. D. J. Am. Chem.
Soc. 2004, 126, 6759-6764. (b) Bondebjerg, J.; Fuglsang, H.; Valeur, K.
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B. S.; Lauritzen, C.; Petersen, G.; Pedersen, J.; Næruma, L. Bioorg. Med.
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(8) Soth, M. J.; Nowick, J. S. J. Org. Chem. 1999, 64, 276-281.
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6487-6489.
(10) Hoffman, R. V.; Nayyar, N. K. J. Org. Chem. 1995, 60, 5992-
5994 and references therein.
(11) Hoffman, R. V.; Reddy, M. M.; Klumas, C. M.; Cervantes-Lee, F.
J. Org. Chem. 1998, 63, 9128-9130 and references therein.
(12) Hamuro, Y.; Marshall, W. J.; Scialdone, M. A. J. Comb. Chem.
1999, 1, 163-172.
(13) Burger, K.; Schierlinger, C.; Muetze, K.; Hollweck, W.; Koksch,
B. Liebigs Ann. Chem. 1994, 4, 407-414.
(14) Neunhoeffer, H. In ComprehensiVe Heterocyclic Chemistry II;
Katrizky, A. R., Rees, C. W., Scriven, E. F. V., Eds.; Elsevier: Oxford,
1996; Vol. 6, Chapter 6.11, pp 507-573.
(15) See, for example, Metribuzin: Landgraf, M. D.; da Silva, S. C.;
Rezende, M. O. Anal. Chim. Acta 1998, 368, 155-164. Metamitron:
Ludvik, J.; Riedl, F.; Liska, F.; Zuman, P. J. Electroanal. Chem. 1998,
457, 177-190. For a review: Abdel-Rahman, R. M. Pharmazie 2001, 56,
195-204.
Semicarbazones have not been previously employed in Ugi
four-component condensations, but in our experiments, they
reacted smoothly under the usual conditions, in a similar way
to the known examples of Ugi reactions employing hydra-
zones.24 The Ugi adducts 4a-i were obtained as colorless
(16) (a) Vzorova, A. N.; Bhattacharyyab, D.; Marzillib, L. G.; Compansa,
R. W. AntiViral Res. 2005, 65, 57-67. (b) Al-Etaibi, A.; Makhseed, S.;
Al-Awadi, N. A.; Ibrahim, Y. A. Tetrahedron Lett. 2005, 46, 31-35. (c)
For a review, see: Abdel-Rahman, R. M. Pharmazie 2001, 56, 18-22.
(17) (a) Borzilleri, R. M.; Cai, Z.; Ellis, C.; Fargnoli, J.; Fura, A.;
Gerhardt, T.; Goyal, B.; Hunt, J. T.; Mortillo, S.; Qian, L.; Tokarski, J.;
Vyas, V.; Wautlet, B.; Zheng, X.; Bhide, R. S. Bioorg. Med. Chem. Lett.
2005, 15, 1429-1433. (b) Borzilleri, R. M.; Zheng, X.; Qian, L.; Ellis, C.;
Cai, Z.; Wautlet, B. S.; Mortillo, S.; Jeyaseelan, R.; Kukral, D. W.; Fura,
A.; Kamath, A.; Vyas, V.; Tokarski, J. S.; Barrish, J. C.; Hunt, J. T.;
Lombardo, L. J.; Fargnoli, J.; Bhide, R. S. J. Med. Chem. 2005, 48, 3991-
4008. (c) Hunt, J. T.; Mitt, T.; Borzilleri, R.; Gullo-Brown, J.; Fargnoli, J.;
Fink, B.; Han, W. C.; Mortillo, S.; Vite, G.; Wautlet, B.; Wong, T.; Yu,
C.; Zheng, X.; Bhide, R. J. Med. Chem. 2004, 47, 4054-4059.
(18) (a) Anderson, R. F., Shinde, S. S.; Hay, M. P.; Denny, W. A. J.
Am. Chem. Soc. 2006, 128, 245-249. (b) Anderson, R. F., Shinde, S. S.;
Hay, M. P.; Gamage, S. A.; Denny, W. A. Org. Biomol. Chem. 2005, 3,
2167-2174. (c) Shinde, S. S.; Anderson, R. F.; Hay, M. P.; Gamage, S.
A.; Denny, W. A. J. Am. Chem. Soc. 2004, 126, 7865-7874.
(19) (a) Adam, F. M.; Burton, A. J.; Cardwell, K. S.; Cox, R. A.; Henson,
R. A.; Mills, K.; Prodger, J. C.; Schilling, M. B.; Tape, D. T. Tetrahedron
Lett. 2003, 44, 5657-5659. For other potential lead compounds, see: (b)
Chambers, M. S.; Atack, J. R.; Carling, R. W.; Collinson, N.; Cook, S. M.;
Dawson, G. R.; Ferris, P.; Hobbs, S. C.; O’Connor, D.; Marshall, G.;
Rycroft, W.; MacLeod, A. M. J. Med. Chem. 2004, 47, 5829-5832. (c)
Sztanke, K.; Fidecka, S.; Kedzierska, E.; Karczmarzyk, Z.; Pihlaja, K.;
Matosiuk, D. Eur. J. Med. Chem. 2005, 40, 127-134.
(20) See for example: (a) Nagamatsu, T.; Yamasaki, H. J. Chem. Soc.,
Perkin Trans. 1 2001, 130-137. (b) Wang, H.; Lim, K. L.; Yeo, S. L.; Xu,
X.; Sim, M. M.; Ting, A. E.; Wang, Y.; Yee, S.; Tan, Y. H.; Pallen, C. J.
J. Nat. Prod. 2000, 63, 1641-1646.
(21) Heim-Riether, A.; Healy, J. J. Org. Chem. 2005, 70, 7331-7337
and references therein.
(22) Marcaccini, S.; Torroba, T. In Multicomponent Reactions; Zhu, J.,
Bienayme´, H., Eds.; Wiley-VCH: Weinheim, Germany, 2005; Chapter 2,
pp 33-75.
(23) Pirrung, M. C.; Tepper, R. J. J. Org. Chem. 1995, 60, 2461-2465.
J. Org. Chem, Vol. 71, No. 12, 2006 4579

San˜udo et al.
SCHEME 1
TABLE 1
entry R1
cyclization of 4a-i. The obtained dioxo-5-phenyl[1,2,4]triazin-
1-ylglycinamide structures could include different tautomers that
should be compatible with their spectral and analytical data;
therefore, a proper assignation of the right tautomer should need
some structural study. Crystals of 5a were suitable for X-ray
diffraction measurements. The obtained structure is shown in
Figure S2 in the Supporting Information. Only the tautomer
having the proton in the O2 atom was obtained. This tautomer
was fixed in the crystal packing by a hydrogen bond between
O(2)H‚‚‚O(3) of two contiguous molecules, packing in fact in
tight dimers in close proximity at a H-bond distance of 1.9 Å
(See Figure S3 in the Supporting Information). The 1,2,4-
thiazine ring in Figure S2 (Supporting Information) was
completely planar, showing angles around the N(2) of 124 (N3-
N2-CO), 118 (N3-N2-CC), and 118 (CC-N2-CO) degrees,
indicating a sp2 hybridization. A quick search on the CCDC
crystallographic database afforded only three examples of
partially aliphatic 1,2,4-triazine-3,6-dione derivatives, which
were not planar, but a few examples of dehydrogenated 1,2,4-
triazine-6-one derivatives25 showed planarity, indicating that this
is a common feature for this type of heterocycle.
R2
R3
R4
4 (%) 5 (%) 6 (%)
a
b
c
d
e
f
g
h
i
CH3 CH3
CH3 CH3
c-C6H11
c-C6H11
c-C6H11
c-C6H11
H
OCH3
H
50
48
55
73
56
59
46
54
55
56
54
84
54
85
53
84
64
60
83
85
-(CH2)5-
-(CH2)5-
-(CH2)5-
CH3
CH2C6H5
CH2C6H5
OCH3
CH2C6H5 OCH3
87
86
80
H
H
H
H
c-C6H11
c-C6H11
c-C6H11
OCH3
H
OCH3
H
CH2CH2C6H5 c-C6H11
89
crystalline solids, easily characterizable by usual techniques.
The different NH groups appeared as distinct peaks in IR at
around 3400 and 3300 cm-1 and in H NMR at δ 9 (usually
1
two signals) and 6. In the same manner, carbonyl groups were
seen as distinct peaks in IR at 1700-1650 cm-1 and 13C NMR
at δ 150-190. Molecular peaks in mass spectrometry were
sometimes missed and, instead, peaks corresponding to ammonia
or water loss were found, but molecular formulas were
confirmed by microanalyses. Crystals of 4c were suitable for
single-crystal X-ray diffraction measurements. The obtained
structure is shown in Figure S1 in the Supporting Information.
Structure 4c showed a hydrogen bond between N(1)H‚‚‚O(2)
having a H-bond distance of 2.1 Å that formed a half-chair eight-
membered quasicycle. The packing of the molecules in the
crystal was supported by several intermolecular hydrogen bonds
between NH amide groups of one molecule and carbonyl groups
of the adjacent molecules. This fact probably explains the easy
crystallization of the Ugi adducts 4a-i from the reaction
mixtures. The crystal structure of 4c showed molecular disorder
of four carbon atoms of the N-cyclohexyl group that were
located in the middle way between chair and half-chair
alternative dispositions.
The tautomer shown in Figure S2 (Supporting Information)
was also proved by chemistry. In fact, by treating selected
compounds 5b,c,e-g,i with diazomethane (1.5 equiv) in ether/
chloroform, the O-methyl derivatives 6b,c,e-g,i were obtained
as crystalline yellow solids, easily characterized by the usual
techniques. Effectively, the methoxy group from the 1,2,4-
thiazine nucleus in the derivatives 6b,c,e-g,i was seen as a neat
1
peak at δ 4 in their H NMR spectra, the NH proton was
observed as a coupled signal at δ 6-7, and there was no trace
of OH signal. MS, HRMS, and microanalyses confirmed the
molecular formulas. Careful comparison between the spectral
features of the hydrocarbon backbone of all compounds permit-
ted the assignment of spectral patterns common to all types of
structures. Products 5a-i, as well as the methyl derivatives
6b,c,e-g,i, constitute a new class of pseudopeptidic 1,2,4-
triazines, composed of two different amino acids, an arylglycine,
and several natural, as well as nonnatural, achiral or racemic
alanine derivatives, such as alanine (5f, 6f), 2-methylalanine
(5a,b, 6b), phenylalanine (5g,h, 6g), homophenylalanine (5i,
Compounds 5a-i were obtained as crystalline yellow solids,
characterized by spectroscopy and microanalysis. A coupled NH
proton was seen by 1H NMR at δ 7-8, an OH proton between
δ 3-6, and two distinct carbonyl groups were observed by 13
C
NMR and IR. HRMS showed in all studied cases molecular
formulas of 5a-i, corresponding to dehydration and, therefore,
(24) See for example: (a) Marcos, C. F.; Marcaccini, S.; Pepino, R.;
Polo, C.; Torroba, T. Synthesis 2003, 691-694. (b) Marcaccini, S.; Pepino,
R.; Polo, C.; Pozo, M. C. Synthesis 2001, 85-88.
(25) See for example: (a) Garg, N. A.; Stoltz, B. M. Tetrahedron. Lett.
2005, 46, 1997-2000. (b) Wade, P. C.; Vogt, B. R.; Toeplitz, B.; Puar, M.
S.; Gougoutas, J. Z. J. Org. Chem. 1979, 44, 88-99.
4580 J. Org. Chem., Vol. 71, No. 12, 2006

3-Hydroxy-6-oxo[1,2,4]triazin-1-yl Alaninamides
of cyclohexanone semicarbazone 1b (427 mg, 2.75) in methanol
(5 mL) and stirred for 3 days, and the resulting solid was filtered
to give compound 4d (888 mg, 73%) as colorless crystals (MeOH-
CH2Cl2, 1:6), mp 236-237 °C; 1H NMR (400 MHz, DMSO-d6) δ
9.43 (d, 1H, J ) 7.0 Hz), 9.19 (s, 1H), 7.79 (d, 2H, J ) 7.0 Hz),
7.04 (d, 2H, J ) 7.0 Hz), 6.13 (br s, 2H), 3.85 (s, 3H), 3.65 (m,
1H), 2.27 (m, 1H), 1.69 (m, 9H), 1.35 (m, 10H); 13C NMR (100
MHz, DMSO-d6) δ 189.6, 171.9, 169.0, 164.9, 159.8, 132.2, 125.3,
114.6, 68.0, 56.21, 47.4, 32.6, 32.2, 29.6, 25.9, 25.2, 24.2, 22.1;
IR (KBr) V˜ 3402 and 3266 (NH), 3071, 2941, 2919, 2854, 1698,
1687, 1665 and 1648 (CdO), 1263, 1176 cm-1; EIMS m/z 445
(M+ + 1, 4), 426 (8), 383 (6), 340 (10), 300 (55), 290 (72), 135
(100). Anal. Calcd for C23H32N4O5: C, 62.14; H, 7.26; N, 12.60.
Found: C, 62.27; H, 7.15; N, 12.46.
6i), and 2,3-tetramethylenealanine (5c-e, 6c, 6e). In all cases,
both the N-terminal arylglycine and the peptidic amide nitrogen
atoms are bonded through a urea moiety, giving rise to a new
class of cyclic dipeptidyl ureas of high pharmacological interest.
Experimental Section
N-Cyclohexyl-2-[N′-carbamoyl-N-(2-oxo-2-phenylacetyl)hy-
drazino]isobutyramide 4a. Cyclohexylisocyanide 2a (300 mg, 2.75
mmol) and benzoylformic acid 3a (413 mg, 2.75 mmol) were added
consecutively to a solution of acetone semicarbazone 1a (317 mg,
2.75 mmol) in methanol (5 mL) and stirred for 3 days, and the
resulting solid was filtered to give compound 4a (515 mg, 50%)
1
as colorless crystals (MeOH-CH2Cl2, 1:6), mp 229-230 °C; H
N-Benzyl-1-[N′-carbamoyl-N-(2-oxo-2-{p-methoxyphenyl}-
acetyl)hydrazino]cyclohexanecarboxamide 4e. Benzylisocyanide
2b (780 mg, 6.66 mmol) and p-methoxybenzoylformic acid 3b23
(1.20 g, 6.66 mmol) were added consecutively to a solution of
cyclohexanone semicarbazone 1b (1.034 mg, 6.66 mmol) in
methanol (10 mL) and stirred for 3 days, and the resulting solid
was filtered to give compound 4e (1.69 g, 56%) as colorless crystals
(MeOH-CH2Cl2, 1:6), mp 187-188 °C; 1H NMR (400 MHz,
DMSO-d6) δ 9.96 (t, 1H, J ) 5.6 Hz), 9.25 (s, 1H), 7.61 (d, J )
8.4 Hz, 2H), 7.31 (m, 5H), 6.85 (m, 2H), 6.12 (br s, 2H), 4.43 (m,
1H), 4.30 (m, 1H), 3.80 (s, 3H), 2.31 (m, 1H), 1.90 (m, 2H), 1.79
(m, 1H), 1.65 (m, 2H), 1.39 (m, 4H); 13C NMR (100 MHz, DMSO-
d6) δ 189.8, 173.1, 169.3, 164.90, 160.0, 140.0, 132.5, 129.0, 128.2,
127.5, 125.4, 114.8, 68.3, 56.37, 43.3, 32.3, 30.0, 25.4, 22.4, 22.3;
IR (KBr) V˜ 3394 and 3234 (NH), 3071, 2924, 1698, 1661 and 1654
(CdO), 1263, 1173 cm-1; EIMS m/z 434 (M+ - 18, 5), 418 (4),
390 (3), 376 (6), 300 (18), 215 (12), 135 (100), 91 (25). Anal.
Calcd for C24H28N4O5: C, 63.70; H, 6.24; N, 12.38. Found: C,
63.57; H, 6.35; N, 12.24.
NMR (400 MHz, DMSO-d6) δ 9.37 (s, 1H), 9.25 (s, 1H), 7.85 (m,
2H), 7.72 (m, 1H), 7.56 (m, 2H), 6.35 (m, 2H), 3.63 (m, 1H), 1.72
(m, 4H), 1.50 (m, 4H), 1.29 (m, 8H); 13C NMR (100 MHz, DMSO-
d6) δ 190.5, 171.2, 167.9, 159.5, 134.7, 132.0, 128.8, 127.3, 65.3,
46.8, 32.1, 25.4, 24.5, 21.3; IR (KBr) V˜ 3600 and 3222 (NH), 3050,
2928, 1704, 1689, 1674 and 1652 (CdO), 1364, 1226 cm-1; EIMS
m/z 357 (M+ - 17, 10), 328 (2), 302 (4), 115 (75), 72 (100). Anal.
Calcd for C19H26N4O4: C, 60.95; H, 7.00; N, 14.96. Found: C,
61.04; H, 6.89; N, 14.78.
N-Cyclohexyl-2-[N′-carbamoyl-N-(2-oxo-2-{p-methoxy}-
phenylacetyl)hydrazino]isobutyramide 4b. Cyclohexylisocyanide
2a (720 mg, 6.60 mmol) and p-methoxybenzoylformic acid 3b23
(1.19 g, 6.60 mmol) were added consecutively to a solution of
acetone semicarbazone 1a (760 mg, 6.60 mmol) in methanol (10
mL) and stirred for 3 days, and the resulting solid was filtered to
give compound 4b (1.28 g, 48%) as colorless crystals (MeOH-
CH2Cl2, 1:6), mp 246-247 °C; 1H NMR (400 MHz, DMSO-d6) δ
9.25 (m, 2H), 7.81 (d, J ) 8.8 Hz, 2H), 7.06 (d, J ) 8.8 Hz, 2H),
6.27 (s, 2H), 3.86 (s, 3H), 3.61 (m, 1H), 1.76 (m, 2H), 1.67 (m,
2H), 1.45 (m, 4H), 1.27 (m, 8H); 13C NMR (100 MHz, DMSO-d6)
δ 189.0, 171.3, 168.2, 164.2, 159.5, 131.6, 125.0, 114.1, 65.2, 55.7,
46.9, 32.0, 25.4, 23.6, 21.3; IR (KBr) V˜ 3332 (br, NH), 2932, 2850,
(()-N-Cyclohexyl-2-[N′-carbamoyl-N-(2-oxo-2-{p-
methoxyphenyl}acetyl)hydrazino]propionamide 4f. Cyclohexy-
lisocyanide 2a (300 mg, 2.75 mmol) and p-methoxybenzoylformic
acid 3b23 (495 mg, 2.75 mmol) were added consecutively to a
solution of acetaldehyde semicarbazone 1c (278 mg, 2.75 mmol)
in methanol (5 mL) and stirred for 3 days, and the resulting solid
was filtered to give compound 4f (633 mg, 59%) as colorless
1774 and 1709 (CdO), 1420, 1380 cm-1; EIMS m/z 407 (M+
+
3, 15), 391 (35), 310 (22), 239 (25), 162 (100). Anal. Calcd for
C20H28N4O5: C, 59.39; H, 6.98; N, 13.85. Found: C, 59.51; H,
6.83; N, 13.67.
1
crystals (MeOH-CH2Cl2, 1:6), mp 214-215 °C; H NMR (400
N-Cyclohexyl-1-[N′-carbamoyl-N-(2-oxo-2-phenylacetyl)hy-
drazino]cyclohexanecarboxamide 4c. Cyclohexylisocyanide 2a
(900 mg, 8.24 mmol) and benzoylformic acid 3a (1.237 g, 8.24
mmol) were added consecutively to a solution of cyclohexanone
semicarbazone 1b (1.279 g, 8.24 mmol) in methanol (15 mL) and
stirred for 3 days, and the resulting solid was filtered to give
compound 4c (1.88 g, 55%) as colorless crystals (MeOH-CH2-
Cl2, 1:6), mp 243-244 °C; 1H NMR (400 MHz, DMSO-d6) δ 9.46
(s, 1H), 9.26 (s, 1H), 7.86 (d, 2H, J ) 7.5 Hz), 7.73 (d, 1H, J )
7.5 Hz), 7.57 (t, 2H, J ) 7.5 Hz), 6.19 (br s, 2H), 3.65 (m, 1H),
2.34 (m, 1H), 1.77 (m, 9H), 1.40 (m, 10H); 13C NMR (100 MHz,
DMSO-d6) δ 191.2, 171.7, 168.9, 160.0, 135.5, 132.6, 129.9, 129.5,
68.3, 47.5, 32.9, 32.3, 30.0, 26.2, 25.4, 24.4, 22.4, 22.3; IR (KBr)
V˜ 3384 and 3248 (NH), 3085, 2930, 2853, 1697, 1685, 1656 and
1650 (CdO), 1225 cm-1; EIMS m/z 309 (M+ - 105, 8), 271 (15),
260 (42), 156 (25), 105 (100), 77 (23). Anal. Calcd for
C22H30N4O4: C, 63.75; H, 7.30; N, 13.52. Found: C, 63.91; H,
7.19; N, 13.39. Crystal data for 4c: C22H30N4O4; M ) 414.50;
monoclinic, P2(1)/c; a ) 9.071(2) Å, b ) 14.515(3) Å, c ) 17.209-
(4) Å; R ) 90°, â ) 95.318(5)°, γ ) 90°; V ) 2256.3(9) Å3; Z )
4; Dcalc ) 1.220 g cm-1; µ(Mo KR) ) 0.085 mm-1. White needle,
(0.20 × 0.10 × 0.10) mm3, 21 927 measured reflections, 3980
MHz, DMSO-d6) δ 8.50 (br s, 1H), 8.32 (br s, 1H), 7.84 (m, 4H),
6.27 (br s, 2H), 3.84 (s, 3H), 3.59 (m, 1H), 1.71 (m, 4H), 1.28 (m,
9H); 13C NMR (100 MHz, DMSO-d6) δ 189.6, 172.9, 169.5, 164.6,
164.0, 132.1, 125.7, 114.5, 62.5, 56.0, 47.9, 32.5, 30.9, 25.5, 24.5;
IR (KBr) V˜ 3440, 3343 and 3289 (NH), 3098, 2941, 2860, 1703,
1687, 1649 and 1611 (CdO), 1252, 1171 cm-1; EIMS m/z 391
(M+ + 1, 3), 372 (M - 18, 15), 347 (5), 319 (6), 255 (35), 247
(65), 135 (100). Anal. Calcd for C19H26N4O5: C, 58.45; H, 6.71;
N, 14.35. Found: C, 58.37; H, 6.61; N, 14.21.
(()-N-Cyclohexyl-2-[N′-carbamoyl-N-(2-oxo-2-phenylacetyl)-
hydrazino]-3-phenylpropionamide 4g. Cyclohexylisocyanide 2a
(300 mg, 2.75 mmol) and benzoylformic acid 3a (413 mg, 2.75
mmol) were added consecutively to a solution of phenylacetalde-
hyde semicarbazone 1d (487 mg, 2.75 mmol) in methanol (5 mL)
and stirred for 3 days, and the resulting solid was filtered to give
compound 4g (552 mg, 46%) as colorless crystals (MeOH-CH2-
Cl2, 1:6), mp 217-218 °C; 1H NMR (400 MHz, DMSO-d6) δ 8.85
(br s, 0.5H), 8.46 (br s, 0.5H), 8.10 (s, 1H), 7.83 (m, 1H), 7.71 (m,
2H), 7.54 (m, 2H), 7.30 (m, 5H), 6.26 (br s, 2H), 4.82 (s, 0.5H),
4.56 (s, 0.5H), 3.59 (m, 1H, CH), 3.22 (m, 1H), 3.15 (m, 1H), 1.64
(m, 5H), 1.24 (m, 5H); 13C NMR (100 MHz, DMSO-d6) δ 191.1,
169.72, 159.0, 158.6, 138.1, 135.6, 132.8, 130.0, 129.8, 129.6,
129.1, 127.4, 63.4, 48.0, 34.2, 32.6, 26.0, 24.7; IR (KBr) V˜ 3403,
3327 and 3207 (NH), 3071, 2930, 2860, 1703, 1686, 1660 and 1643
(CdO), 1545, 1230, 700 cm-1; EIMS m/z 419 (M+ - 17, 6), 393
(3), 331 (5), 293 (31), 230 (48), 104 (100), 91 (26), 77 (28). Anal.
Calcd for C24H28N4O4: C, 66.04; H, 6.47; N, 12.84. Found: C,
66.16; H, 6.33; N, 12.70.
independent (Rint ) 0.1193), 2003 observed (I > 2σ(I)), R1
0.1820, and wR2 ) 0.3495 (all data). CCDC 602195.
)
N-Cyclohexyl-1-[N′-carbamoyl-N-(2-oxo-2-{p-methoxyphenyl}-
acetyl)hydrazino]cyclohexanecarboxamide 4d. Cyclohexyliso-
cyanide 2a (300 mg, 2.75 mmol) and p-methoxybenzoylformic acid
3b23 (496 mg, 2.75 mmol) were added consecutively to a solution
J. Org. Chem, Vol. 71, No. 12, 2006 4581

San˜udo et al.
(()-N-Cyclohexyl-2-[N′-carbamoyl-N-(2-oxo-2-{p-
methoxyphenyl}acetyl)hydrazino]-3-phenylpropionamide 4h.
Cyclohexylisocyanide 2a (300 mg, 2.75 mmol) and p-methoxy-
benzoylformic acid 3b23 (495 mg, 2.75 mmol) were added
consecutively to a solution of phenylacetaldehyde semicarbazone
1d (487 mg, 2.75 mmol) in methanol (5 mL) and stirred for 3 days,
and the resulting solid was filtered to give compound 4h (693 mg,
54%) as colorless crystals (MeOH-CH2Cl2, 1:6), mp 230-232 °C;
1H NMR (400 MHz, DMSO-d6) δ 8.85 (br s, 0.5H), 8.40 (br s,
0.5H), 8.05 (s, 1H), 7.77 (m, 1H), 7.68 (m, 2H), 7.28 (m, 5H),
7.03 (m, 2H), 6.22 (br s, 2H), 4.78 (s, 0.5H), 4.49 (s, 0.5H), 3.84
(s, 3H), 3.76 (m, 1H), 3.15 (m, 2H), 1.61 (m, 5H), 1.20 (m, 5H);
13C NMR (100 MHz, DMSO-d6) δ 189.4, 169.9, 164.8, 158.9,
158.4, 137.7, 132.2, 129.7, 128.9, 127.0, 125.2, 114.7, 63.2, 56.2,
48.0, 34.2, 32.3, 25.7, 24.6; IR (KBr) V˜ 3397, 3332, 3256, 3196
(NH), 3033, 2930, 2854, 1687, 1665 and 1600 (CdO), 1257, 1176
cm-1; EIMS m/z 449 (M+ - 17, 6), 423 (2), 323 (8), 230 (72),
135 (100). Anal. Calcd for C25H30N4O5: C, 64.36; H, 6.48; N,
12.01. Found: C, 64.49; H, 6.56; N, 11.88.
solvent was evaporated, the residue was treated with isopropyl ether
(5 mL), and the resulting solid was filtered and dissolved in water
(5 mL). The solution was acidified with acetic acid until pH ) 4,
and the resulting solid was filtered to give 5b (104 mg, 54%) as
yellow crystals (MeOH-CH2Cl2, 1:6), mp 109-110 °C; 1H NMR
(400 MHz, DMSO-d6) δ 8.49 (d, J ) 8.8 Hz, 2H), 7.8 (d, J ) 8.4
Hz, 1H), 7.34 (d, J ) 8.8 Hz, 1H), 7.06 (d, J ) 8.8 Hz, 2H), 6.26
(br s, 1H), 3.85 (s, 3H), 3.50 (m, 1H), 1.64 (m, 4H), 1.52 (s, 6H),
1.19 (m, 6H); 13C NMR (100 MHz, DMSO-d6) δ 170.7, 164.9,
163.3, 161.53, 152.9, 132.6, 126.8, 114.4, 67.6, 56.1, 48.7, 32.9,
26.0, 25.7, 24.6; IR (KBr) V˜ 3462, 3359, (NH, OH), 2930, 2860,
1660 and 1611 (CdO), 1556, 1269, 1182 cm-1; EIMS m/z 386
(M+, 21), 261 (65), 162 (64), 134 (100). Anal. Calcd for
C20H26N4O4: C, 62.16; H, 6.78; N, 14.50. Found: C, 62.25; H,
6.69; N, 14.39.
N-Cyclohexyl-1-(3-hydroxy-6-oxo-5-phenyl-6H-[1,2,4]triazin-
1-yl)cyclohexanecarboxamide 5c. Cyclohexanecarboxamide 4c
(500 mg, 1.21 mmol) was stirred at room temperature with sodium
ethoxide (from Na, 29 mg, 1.27 mmol) in ethanol (10 mL) for 12
h. Then the solvent was evaporated, the residue was treated with
isopropyl ether (10 mL), and the resulting solid was filtered and
dissolved in water (10 mL). The solution was acidified with acetic
acid until pH ) 4, and the resulting solid was filtered to give 5c
(403 mg, 84%) as yellow crystals (MeOH-CH2Cl2, 1:6), mp 230-
231 °C; 1H NMR (400 MHz, CD3OD) δ 8.37 (d, J ) 7.2 Hz, 2H),
7.51 (q, J ) 7.2 Hz, 1H), 7.42 (t, J ) 7.2 Hz, 2H), 3.63 (m, 1H),
3.26 (s, 2H), 2.42 (m, 2H), 2.02 (m, 2H), 1.66 (m, 10H), 1.26 (m,
4H), 1.12 (m, 2H); 13C NMR (100 MHz, CD3OD) δ 173.8, 164.7,
154.7, 154.4, 135.1, 133.4, 131.3, 129.3, 71.9, 50.5, 33.6, 32.6,
26.7, 26.6, 26.5, 23.3; IR (KBr) V˜ 3358 and 3063 (OH, NH), 2932,
2852, 1629 (CdO), 1579, 1560, 1541, 1208 cm-1; EIMS m/z (396,
M+, 75), 271 (100), 208 (20), 190 (55), 104 (92); HRMS (EI) calcd
for C22H28N4O3, 396.2161; found, 396.2158. Anal. Calcd for
C22H28N4O3: C, 66.64; H, 7.12; N, 14.13. Found: C, 66.75; H,
7.05; N, 14.03.
N-Cyclohexyl-1-(3-hydroxy-6-oxo-5-{p-methoxyphenyl}-6H-
[1,2,4]triazin-1-yl)cyclohexanecarboxamide 5d. Cyclohexanecar-
boxamide 4d (500 mg, 1.12 mmol) was stirred at room temperature
with sodium ethoxide (from Na, 27 mg, 1.17 mmol) in ethanol (10
mL) for 12 h. Then the solvent was evaporated, the residue was
treated with isopropyl ether (10 mL), and the resulting solid was
filtered and dissolved in water (10 mL). The solution was acidified
with acetic acid until pH ) 4, and the resulting solid was filtered
to give 5d (258 mg, 54%) as yellow crystals (MeOH-CH2Cl2, 1:6),
mp 163-164 °C; 1H NMR (400 MHz, CD3OD) δ 8.46 (d, J ) 9.2
Hz, 2H), 7.29 (br d, J ) 8.4 Hz, 1H), 6.93 (d, J ) 9.2 Hz, 2H),
3.80 (s, 3H), 3.60 (m, 1H), 3.24 (s, 1H), 2.38 (m, 2H), 1.99 (m,
2H), 1.62 (m, 12H), 1.23 (m, 2H), 1.1 (m, 2H); 13C NMR (100
MHz, CD3OD) δ 174.2, 174.1, 165.1, 163.6, 154.97, 133.7, 127.8,
114.9, 71.9, 56.2, 50.7, 33.8, 32.8, 26.9, 26.8, 26.7, 23.5; IR (KBr)
V˜ 3435 and 3381 (OH, NH), 2936, 2860, 1660 and 1605 (CdO),
1551, 1263, 1181 cm-1; EIMS m/z 426 (M+, 20), 328 (5), 301
(93), 220 (40), 134 (100); HRMS (EI) calcd for C23H30N4O4,
426.2267; found, 426.2280. Anal. Calcd for C23H30N4O4: C, 64.77;
H, 7.09; N, 13.14. Found: C, 64.65; H, 7.16; N, 13.06.
(()-N-Cyclohexyl-2-[N′-carbamoyl-N-(2-oxo-2-phenylacetyl)-
hydrazino]-4-phenylbutyramide 4i. Cyclohexylisocyanide 2a (229
mg, 2.10 mmol) and benzoylformic acid 3a (315 mg, 2.10 mmol)
were added consecutively to a solution of 3-phenylpropionaldehyde
semicarbazone 1e (402 mg, 2.10 mmol) in methanol (5 mL) and
stirred for 3 days, and the resulting solid was filtered to give
compound 4i (520 mg, 55%) as colorless crystals (MeOH-CH2-
1
Cl2, 1:6), mp 198-199 °C; H NMR (400 MHz, CD3OD) δ 7.90
(triplet of doublets, J ) 7.0, 1.2 Hz, 2H), 7.64 (m, 1H), 7.49 (triplet
of doublets, J ) 7.0, 1.2 Hz, 2H), 7.18 (m, 5H), 4.50 (t, J ) 7.4
Hz, 1H), 3.69 (m, 1H), 3.30 (s, 1H), 3.26 (s, 3H), 2.71 (m, 2H),
2.12 (m, 2H), 1.88 (m, 2H), 1.76 (m, 2H), 1.60 (m, 1H), 1.31 (m,
5H); 13C NMR (100 MHz, CD3OD) δ 191.8, 182.3, 171.3, 154.8,
142.1, 136.1, 134.0, 130.6, 130.0, 129.7, 129.6, 127.4, 63.7, 48.0,
33.8, 33.6, 31.6, 26.7, 26.1; IR (KBr) V˜ 3424, 3348 and 3310 (NH),
2936, 2854, 1730, 1692, 1676 and 1638 (CdO), 1230, 714 cm-1
;
EIMS m/z 433 (M+ - 17, 6), 432 (M+ - 18, 17), 328 (100), 279
(21), 216 (88), 190 (37), 104 (63), 91 (58). Anal. Calcd for
C25H30N4O4: C, 66.65; H, 6.71; N, 12.44. Found: C, 66.57; H,
6.62; N, 12.31.
N-Cyclohexyl-2-(3-hydroxy-6-oxo-5-phenyl-6H-[1,2,4]triazin-
1-yl)isobutyramide 5a. Isobutyramide 4a (200 mg, 0.53 mmol)
was stirred at room temperature with sodium ethoxide (from Na,
13 mg, 0.56 mmol) in ethanol (5 mL) for 12 h. Then the solvent
was evaporated, the residue was treated with isopropyl ether (5
mL), and the resulting solid was filtered and dissolved in water (5
mL). The solution was acidified with acetic acid until pH ) 4, and
the resulting solid was filtered to give 5a (106 mg, 56%) as yellow
1
crystals (MeOH-CH2Cl2, 1:6), mp 215-216 °C; H NMR (400
MHz, acetone-d6) δ 8.54 (d, J ) 7.2 Hz, 2H), 7.57 (t, J ) 7.2 Hz,
1H), 7.47 (t, J ) 7.2 Hz, 2H), 6.87 (d, J ) 8.0 Hz, 1H), 3.68 (m,
1H), 2.09 (s, 1H), 1.82 (m, 2H), 1.64 (m, 2H), 1.62 (s, 6H), 1.27
(m, 2H), 1.10 (m, 4H); 13C NMR (100 MHz, acetone-d6) δ 172.0,
164.0, 154.6, 154.3, 135.8, 133.7, 131.8, 129.7, 69.3, 50.2, 34.25,
27.2, 26.8, 25.2; IR (KBr) V˜ 3377 (NH, OH), 2931, 2853,
1653 and 1554 (CdO), 1218 cm-1; EIMS m/z 356 (M+, 55),
258 (8), 231 (86), 202 (22), 175 (25), 104 (100); HRMS (EI) calcd
for C19H24N4O3, 356.1848; found, 356.1848. Anal. Calcd for
C19H24N4O3: C, 64.03; H, 6.79; N, 15.72. Found: C, 64.15; H,
6.65; N, 15.61. Crystal data for 5a: C19H24N4O3; M ) 356.42;
monoclinic, P2(1)/n, a ) 11.367(4) Å, b ) 15.514(5) Å, c )
11.871(4) Å; R ) 90°, â ) 116.880(4)°, γ ) 90°; V ) 1867.2(11)
Å3; Z ) 4; Dcalc ) 1.268 gcm-1; µ(Mo KR) ) 0.088 mm-1. Yellow
prism, (0.20 × 0.20 × 0.20) mm3, 18 241 measured reflections,
3472 independent (Rint ) 0.0723), 2047 observed (I > 2σ(I)), R1
) 0.1321, and wR2 ) 0.2488 (all data). CCDC 602196.
N-Benzyl-1-(3-hydroxy-6-oxo-5-{p-methoxyphenyl}-6H-[1,2,4]-
triazin-1-yl)cyclohexanecarboxamide 5e. Cyclohexanecarboxa-
mide 4e (500 mg, 1.10 mmol) was stirred at room temperature with
sodium ethoxide (27 mg, 1.17 mmol) in ethanol (10 mL) for 12 h.
Then the solvent was evaporated, the residue was treated with
isopropyl ether (10 mL), and the resulting solid was filtered and
dissolved in water (10 mL). The solution was acidified with acetic
acid until pH ) 4, and the resulting solid was filtered to give 5e
(407 mg, 85%) as yellow crystals (MeOH-CH2Cl2, 1:6), mp 99-
1
100 °C; H NMR (400 MHz, DMSO-d6) δ 8.51 (d, J ) 9.0 Hz,
N-Cyclohexyl-2-(3-hydroxy-6-oxo-5-(p-methoxyphenyl)-6H-
[1,2,4]triazin-1-yl)isobutyramide 5b. Isobutyramide 4b (200 mg,
0.49 mmol) was stirred at room temperature with sodium ethoxide
(from Na, 12 mg, 0.52 mmol) in ethanol (5 mL) for 12 h. Then the
2H), 8.08 (br t, J ) 6.0 Hz, 1H), 7.23 (d, J ) 4.5 Hz, 4H), 7.18
(quintet, J ) 4.5 Hz, 1H), 7.06 (d, J ) 9.0 Hz, 2H), 4.22 (d, J )
6.0 Hz, 2H), 3.85 (s, 3H), 3.40 (v br s, 1H), 2.42 (br d, J ) 13.6
Hz, 2H), 1.98 (m, 2H), 1.52 (m, 6H); 13C NMR (100 MHz, DMSO-
4582 J. Org. Chem., Vol. 71, No. 12, 2006

3-Hydroxy-6-oxo[1,2,4]triazin-1-yl Alaninamides
d6) δ 171.5, 162.4, 160.6, 152.9, 152.6, 139.9, 131.9, 127.9 126.8,
126.3, 126.2, 113.5, 69.7, 55.4, 42.2, 30.8, 24.9, 21.6; IR (KBr) V˜
3375 (NH, OH), 2930, 2860, 1660 and 1611 (CdO), 1557, 1263,
1182 cm-1; EIMS m/z 434 (M+, 14), 376 (3), 328 (4), 300 (100),
216 (35), 134 (63), 91 (51); HRMS (EI) calcd for C23H30N4O4,
426.2267; found, 426.2280. Anal. Calcd for C24H26N4O5: C, 64.77;
H, 7.09; N, 13.14. Found: C, 64.65; H, 7.16; N, 13.06.
C25H28N4O4: C, 66.95; H, 6.29; N, 12.49. Found: C, 67.13; H,
6.36; N, 12.36.
(()-N-Cyclohexyl-2-(3-hydroxy-6-oxo-5-phenyl-6H-[1,2,4]tri-
azin-1-yl)-4-phenylbutyramide 5i. 4-Phenylbutyramide 4i (200
mg, 0.44 mmol) was stirred at room temperature with sodium
ethoxide (from Na, 11 mg, 0.47 mmol) in ethanol (5 mL) for 12 h.
Then the solvent was evaporated, the residue was treated with
isopropyl ether (5 mL), and the resulting solid was filtered and
dissolved in water (5 mL). The solution was acidified with acetic
acid until pH ) 4, and the resulting solid was filtered to give 5i
(115 mg, 60%) as yellow crystals (MeOH-CH2Cl2, 1:6), mp 97-
(()-N-Cyclohexyl-2-(3-hydroxy-6-oxo-5-{p-methoxyphenyl}-
6H-[1,2,4]triazin-1-yl)propionamide 5f. Propionamide 4f (200 mg,
0.51 mmol) was stirred at room temperature with sodium ethoxide
(from Na, 12 mg, 0.52 mmol) in ethanol (5 mL) for 12 h. Then the
solvent was evaporated, the residue was treated with isopropyl ether
(5 mL), and the resulting solid was filtered and dissolved in water
(10 mL). The solution was acidified with acetic acid until pH ) 4,
and the resulting solid was filtered to give 5f (101 mg, 53%) as
yellow crystals (MeOH-CH2Cl2, 1:6), mp 210-211 °C; 1H NMR
(400 MHz, acetone-d6) δ 8.70 (d, J ) 9.1 Hz, 2H), 7.06 (br s, 1H),
7.05 (d, J ) 9.1 Hz, 2H), 5.39 (q, J ) 7.1 Hz, 1H), 3.91 (s, 3H),
3.66 (m, 1H), 2.84 (br s, 1H), 1.79 (m, 2H), 1.66 (m, 2H), 1.57
1
98 °C; H NMR (300 MHz, DMSO-d6) δ 8.45 (d, J ) 7.5 Hz,
2H), 7.76 (d, J ) 7.5 Hz, 1H), 7.62 (t, J ) 7.5 Hz, 1H), 7.54 (t, J
) 7.5 Hz, 2H), 7.25 (t, J ) 7.5 Hz, 2H), 7.17 (d, J ) 7.5 Hz, 3H),
5.20 (t, J ) 7.5 Hz, 1H), 3.54 (m, 1H), 3.35 (br s, 1H), 2.56 (t, J
) 7.5 Hz, 2H), 2.35 (q, J ) 7.5 Hz, 2H), 1.66 (m, 4H), 1.54 (m,
1H), 1.18 (m, 5H); 13C NMR (75 MHz, DMSO-d6) δ 167.0, 161.7,
153.1, 152.8, 141.0, 133.6, 132.2, 129.9, 128.3, 128.2, 128.1, 125.8,
60.3, 48.0, 35.8, 32.1, 31.0, 30.7, 24.7; IR (KBr) V˜ 3305 (NH, OH),
2935, 2859, 1664 and 1555 (CdO), 1224, 707 cm-1; EIMS m/z
432 (M+, 15), 328 (100), 279 (25), 216 (93), 190 (48), 104 (75),
91 (84); HRMS (EI) calcd for C25H28N4O3, 432.2161; found,
432.2188. Anal. Calcd for C25H28N4O3: C, 69.42; H, 6.53; N, 12.95.
Found: C, 69.31; H, 6.45; N, 12.86.
(m, 1H), 1.54 (d, J ) 7.1 Hz, 3H), 1.28 (m, 2H), 1.13 (m, 3H); 13
C
NMR (100 MHz, acetone-d6) δ 169.6, 165.3, 162.6, 156.5, 155.0,
134.3, 128.4, 115.4, 56.9, 51.6, 48.7, 34.4, 27.3, 26.7, 16.9; IR
(KBr) V˜ 3294 (OH, NH), 2941, 2865, 1660 (CdO), 1611, 1589,
1556, 1252, 845 cm-1; EIMS m/z 372 (M+, 25), 293 (5), 274 (5),
247 (100), 204 (25), 134 (95). Anal. Calcd for C19H24N4O6: C,
61.28; H, 6.50; N, 15.04. Found: C, 61.14; H, 6.62; N, 14.91.
N-Cyclohexyl-2-[3-methoxy-5-(4-methoxyphenyl)-6-oxo-6H-
[1,2,4]triazin-1-yl]isobutyramide 6b. An ethereal solution of
diazomethane (8.2 mg, 0.20 mmol in diethyl ether), freshly prepared
from N-methyl-N-nitroso-p-toluenesulfonamide and titrated as it has
been described,26 was added to a suspension of isobutyramide 5b
(50 mg, 0.13 mmol) in chloroform (15 mL) at 0 °C, and the mixture
was stirred for 12 h at room temperature until a homogeneous
solution was obtained. Then the solvent was evaporated to give 6b
(43 mg, 83%) as yellow crystals (MeOH-CH2Cl2, 1:6), mp 226-
(()-N-Cyclohexyl-2-(3-hydroxy-6-oxo-5-phenyl-6H-[1,2,4]tri-
azin-1-yl)-3-phenylpropionamide 5g. Phenylpropionamide 4g (200
mg, 0.46 mmol) was stirred at room temperature with sodium
ethoxide (11 mg, 0.48 mmol) in ethanol (5 mL) for 12 h. Then the
solvent was evaporated, the residue was treated with isopropyl ether
(5 mL), and the resulting solid was filtered and dissolved in water
(5 mL). The solution was acidified with acetic acid until pH ) 4,
and the resulting solid was filtered to give 5g (162 mg, 84%) as
yellow crystals (MeOH-CH2Cl2, 1:6), mp 220-221 °C; 1H NMR
(300 MHz, DMSO-d6) δ 8.31 (d, J ) 8.4 Hz, 2H), 7.83 (d, J ) 7.8
Hz, 1H), 7.57 (q, J ) 7.8 Hz, 1H), 7.48 (t, J ) 7.8 Hz, 2H), 7.18
(m, 4H), 7.13 (m, 1H), 5.55 (dd, J ) 10.5 Hz, J ) 4.8 Hz, 1H),
3.57 (m, 1H), 3.42 (dd, J ) 14.0 Hz, J ) 4.8 Hz, 1H), 3.26 (dd, J
) 14.0 Hz, J ) 10.5 Hz, 1H), 3.34 (br s, 1H), 1.69 (m, 4H), 1.55
(m, 1H), 1.19 (m, 5H); 13C NMR (75 MHz, DMSO-d6) δ 166.5,
161.7, 152.80, 152.5, 137.5, 133.4, 132.3, 129.7, 128.8, 128.2,
128.1, 126.3, 61.6, 48.2, 35.1, 32.2, 30.7, 24.7; IR (KBr) V˜ 3289
(OH, NH), 3076, 2936, 2860, 1671 and 1643 (CdO), 1573, 1426,
1280, 704 cm-1; EIMS m/z 420 (M+ + 2, 30), 419 (M+ + 1, 27),
418 (M+, 13), 335 (5), 293 (25), 230 (65), 104 (100). Anal. Calcd
for C24H26N4O3: C, 68.88; H, 6.26; N, 13.39. Found: C, 68.95;
H, 6.15; N, 13.29.
(()-N-Cyclohexyl-2-(3-hydroxy-6-oxo-5-{p-methoxyphenyl}-
6H-[1,2,4]triazin-1-yl)-3-phenylpropionamide 5h. Phenylpropi-
onamide 4h (500 mg, 1.07 mmol) was stirred at room temperature
with sodium ethoxide (from Na, 26 mg, 1.13 mmol) in ethanol (10
mL) for 12 h. Then the solvent was evaporated, the residue was
treated with isopropyl ether (10 mL), and the resulting solid was
filtered and dissolved in water (10 mL). The solution was acidified
with acetic acid until pH ) 4, and the resulting solid was filtered
to give 5h (307 mg, 64%) as yellow crystals (MeOH-CH2Cl2, 1:6),
mp 172-173 °C; 1H NMR (400 MHz, CD3OD) δ 8.39 (d, J ) 9.2
Hz, 2H), 7.16 (m, 4H), 7.08 (m, 1H), 6.92 (d, J ) 9.2 Hz, 2H),
5.58 (dd, J ) 10.0, 5.5 Hz, 1H), 3.81 (s, 3H), 3.61 (m, 1H), 3.41
(dd, J ) 13.8, 5.5 Hz, 1H), 3.34 (dd, J ) 13.8, 10.0 Hz, 1H), 1.69
(m, 6H), 1.26 (m, 2H), 1.13 (m, 2H); 13C NMR (100 MHz, CD3-
OD) δ 169.8, 165.0, 163.0, 155.2, 155.1, 138.4, 133.6, 130.3, 129.4,
127.8, 127.5, 114.7, 63.7, 56.0, 50.4, 36.9, 33.5, 26.6, 23.1; IR
(KBr) V˜ 3395 and 3180 (NH, OH), 3084, 2929, 2853, 1691 and
1660 (CdO), 1585, 1250, 1165 cm-1; EIMS m/z 448 (M+, 48),
323 (12), 230 (100), 219 (35), 134 (50); HRMS (EI) calcd
for C25H28N4O4, 448.2111; found, 448.2126. Anal. Calcd for
1
227 °C; H NMR (400 MHz, CDCl3) δ 8.62 (d, J ) 8.5 Hz, 2H),
6.92 (d, J ) 8.5 Hz, 2H), 5.48 (d, J ) 7.8 Hz, 1H), 3.95 (s, 3H),
3.86 (s, 3H), 3.80 (m, 1H), 1.72 (s, 6H), 1.68 (m, 4H), 1.34 (m,
4H), 1.14 (m, 2H); 13C NMR (100 MHz, CDCl3) δ 171.0, 163.5,
162.1, 153.2, 132.8, 128.7, 125.8, 113.7, 67.8, 63.9, 55.4, 48.6,
32.9, 25.5, 24.9, 23.8; IR (KBr) V˜ 3419 (NH), 2920, 2850, 1651
(CdO), 1235, 1164 cm-1; EIMS m/z 400 (M+, 43), 376 (6), 275
(100), 246 (55), 232 (34), 134 (46). Anal. Calcd for C21H28N4O4:
C, 62.98; H, 7.05; N, 13.99. Found: C, 63.11; H, 6.94; N, 13.88.
N-Cyclohexyl-1-(3-methoxy-6-oxo-5-phenyl-6H-[1,2,4]triazin-
1-yl)cyclohexanecarboxamide 6c. An ethereal solution of diaz-
omethane (16 mg, 0.38 mmol in diethyl ether), freshly prepared
from N-methyl-N-nitroso-p-toluenesulfonamide,26 was added to a
suspension of cyclohexanecarboxamide 5c (100 mg, 0.25 mmol)
in chloroform (30 mL) at 0 °C, and the mixture was stirred for 12
h at room temperature until a homogeneous solution was obtained.
Then the solvent was evaporated to give 6c (88 mg, 85%) as yellow
1
crystals (MeOH-CH2Cl2, 1:6), mp 164-165 °C; H NMR (400
MHz, CD3OD) δ 8.38 (doublet of triplets, J ) 7.2, 1.5 Hz, 2H),
7.54 (triplet of triplets, J ) 7.2, 1.5 Hz, 1H), 7.44 (triplet of
doublets, J ) 7.2, 1.5 Hz, 2H), 7.37 (d, J ) 8.1 Hz, 1H), 3.95 (s,
3H), 3.64 (m, 1H), 2.47 (m, 2H), 2.05 (m, 2H), 1.77 (m, 2H), 1.69
(m, 8H), 1.59 (m, 2H), 1.27 (m, 2H), 1.14 (m, 2H); 13C NMR (100
MHz, CD3OD) δ 173.7, 173.6, 165.0, 154.6, 134.9, 133.6, 131.3,
129.3, 72.2, 56.0, 50.6, 33.6, 32.5, 26.7, 26.6, 26.4, 23.3; IR (KBr)
(26) Recent examples of the preparation and titration of diazomethane
are: (a) Gaucher, A.; Dutot, L.; Barbeau, O.; Hamchaoui, W.; Wakselman,
M.; Mazaleyrat, J. P. Tetrahedron: Asymmetry 2005, 16, 857-864. (b)
Bug, T.; Hartnagel, M.; Schlierf, C.; Mayr, H. Chem.sEur. J. 2003, 9,
4068-4076. (c) Brown, E.; Dhal, R.; Papin, N. Tetrahedron 1995, 51,
13061-13072. A general procedure and safety indications can be found
in: (d) Furniss, B. S.; Hannaford, A. J.; Smith, P. W. G.; Tatchell, A. R.
Vogel’s Textbook of Practical Organic Chemistry, 5th edition; Longman
Group: Harlow, U.K., 1989; p 430 (safety indications), p 431 (preparation
of N-methyl-N-nitroso-p-toluenesulfonamide), and pp 432-433 (preparation
of diazomethane).
J. Org. Chem, Vol. 71, No. 12, 2006 4583

San˜udo et al.
V˜ 3296 (NH), 2926, 2853, 1646 (CdO), 1582, 1561, 1368, 1226
cm-1; EIMS m/z 410 (M+, 15), 312 (10), 299 (15), 285 (100), 256
(32), 208 (75), 204 (93), 189 (28); HRMS (EI) calcd for
C23H30N4O3, 410.2318; found, 410.2310. Anal. Calcd for
C23H30N4O3: C, 67.29; H, 7.37; N, 13.65. Found: C, 67.21; H,
7.28; N, 13.58.
(()-N-Cyclohexyl-2-(3-methoxy-6-oxo-5-phenyl-6H-[1,2,4]tri-
azin-1-il)-4-phenylbutyramide 6i. An ethereal solution of diaz-
omethane (15 mg, 0.36 mmol in diethyl ether), freshly prepared
from N-methyl-N-nitroso-p-toluenesulfonamide,26 was added to a
suspension of propionamide 5i (100 mg, 0.23 mmol) in chloroform
(50 mL) at 0 °C, and the mixture was stirred for 12 h at room
temperature until a homogeneous solution was obtained. Then the
solvent was evaporated to give 6i (91 mg, 89%) as yellow crystals
(MeOH-CH2Cl2, 1:6), mp 114-115 °C; 1H NMR (300 MHz,
CDCl3) δ 8.51 (d, J ) 7.5 Hz, 1H), 8.45 (d, J ) 7.5 Hz, 1H), 7.57
(q, J ) 7.5 Hz, 1H), 7.48 (sextet, J ) 7.5 Hz, 2H), 7.15 (m, 5H),
6.37 (br d, J ) 7.5 Hz, 1H), 5.32 (t, J ) 7.0 Hz, 1H), 3.96 (s, 3H),
3.73 (m, 1H), 2.69 (m, 2H), 2.56 (m, 2H), 1.87 (m, 2H), 1.62 (m,
4H), 1.21 (m, 4H); 13C NMR (75 MHz, CDCl3) δ 167.1, 163.0,
154.3, 153.6, 140.4, 133.0, 130.4, 130.3, 128.4, 128.3, 128.2, 126.2,
61.2, 55.6, 48.5, 32.6, 32.3, 30.1, 25.3, 24.6; IR (KBr) V˜ 3419 (NH);
2928, 2854, 1651 (CdO), 1557, 1454, 1230 cm-1; EIMS m/z 446
(M+, 24), 342 (48), 243 (22), 230 (67), 204 (53), 188 (21), 104
(47), 91 (100). Anal. Calcd for C26H30N4O3: C, 69.93; H, 6.77; N,
12.55. Found: C, 70.07; H, 6.88; N, 12.46.
Crystal Structure Determination for Compounds 4c and 5a.
A suitable crystal was mounted on a glass fiber. X-ray measure-
ments were made using a Bruker SMART CCD area-detector
diffractometer with Mo KR radiation (λ ) 0.710 73 Å).27 Intensities
were integrated28 from several series of exposures, each exposure
covering 0.3° in ω, and the total data set being a sphere. Absorption
corrections were applied based on multiple and symmetry-equivalent
measurements.29 The structure was solved by direct methods and
refined by least squares on weighted F2 values for all reflections.30
All nonhydrogen atoms were assigned anisotropic displacement
parameters and refined without positional constraints. All hydrogen
atoms were constrained to ideal geometries and refined with fixed
isotropic displacement parameters. Refinement proceeded smoothly
to give the residuals shown in Table 1. Complex neutral-atom
scattering factors were used.31
N-Benzyl-1-[3-methoxy-5-(4-methoxyphenyl)-6-oxo-6H-[1,2,4]-
triazin-1-yl)cyclohexanecarboxamide 6e. An ethereal solution of
diazomethane (15 mg, 0.36 mmol in diethyl ether), freshly prepared
from N-methyl-N-nitroso-p-toluenesulfonamide,26 was added to a
suspension of cyclohexanecarboxamide 5e (100 mg, 0.23 mmol)
in chloroform (30 mL) at 0 °C, and the mixture was stirred at room
temperature for 12 h until a homogeneous solution was obtained.
Then the solvent was evaporated to give 6e (90 mg, 87%) as yellow
1
crystals (MeOH-CH2Cl2, 1:6), mp 127-129 °C; H NMR (300
MHz, CDCl3) δ 8.63 (d, J ) 8.2 Hz, 2H), 7.26 (m, 5H), 6.94 (d,
J ) 8.2 Hz, 2H), 6.23 (t, J ) 5.2 Hz, 1H), 4.48 (d, J ) 5.2, 2H),
3.93 (s, 3H), 3.88 (s, 3H), 2.65 (m, 2H), 2.11 (m, 2H), 1.72 (m,
2H), 1.60 (m, 4H); 13C NMR (75 MHz, CDCl3) δ 171.9, 163.5,
162.4, 153.5, 153.0, 138.2, 132.8, 128.5, 127.6, 127.2, 125.7, 113.6,
71.0, 55.4, 55.2, 43.6, 31.3, 25.2, 22.1; IR (KBr) V˜ 3412 (NH),
2939, 2849, 1689 (CdO), 1601, 1549, 1510, 1258, 1172 cm-1
;
EIMS m/z 448 (M+, 22), 314 (100), 286 (12), 233 (53), 134 (26),
96 (28), 91 (39). Anal. Calcd for C25H28N4O4: C, 66.95; H, 6.29;
N, 12.49. Found: C, 67.11; H, 6.18; N, 12.36.
(()-N-Cyclohexyl-2-[3-methoxy-5-(4-methoxyphenyl)-6-oxo-
6H-[1,2,4]triazin-1-yl]propionamide 6f. An ethereal solution of
diazomethane (8 mg, 0.19 mmol in diethyl ether), freshly prepared
from N-methyl-N-nitroso-p-toluenesulfonamide,26 was added to a
suspension of propionamide 5f (45 mg, 0.12 mmol) in chloroform
(15 mL), and the mixture was stirred for 12 h at room temp until
a homogeneous solution was obtained. Then the solvent was
evaporated to give 6f (40 mg, 86%) as yellow crystals (MeOH-
1
CH2Cl2, 1:6), mp 175-176 °C; H NMR (300 MHz, CDCl3) δ
8.66 (d, J ) 9.0 Hz, 2H), 6.96 (d, J ) 9.0 Hz, 2H), 6.24 (br d, J
) 7.1 Hz, 1H), 5.45 (q, J ) 7.0 Hz, 1H), 3.94 (s, 3H), 3.88 (s,
3H), 3.75 (m, 1H), 1.85 (m, 2H), 1.64 (d, J ) 7.0 Hz, 3H), 1.60
(m, 2H), 1.32 (m, 2H), 1.13 (m, 4H); 13C NMR (75 MHz, CDCl3)
δ 167.7, 163.7, 153.7, 153.5, 141.7, 132.8, 125.8, 113.8, 57.0, 55.5,
48.4, 47.4, 32.8, 25.4, 24.6, 14.7; IR (KBr) V˜ 3269 (NH), 2937,
2854, 1648 (CdO), 1607, 1576, 1548, 1259, 1179 cm-1; EIMS
m/z 386 (M+, 25), 304 (3), 289 (3), 261 (100), 232 (22), 141 (53),
135 (62), 113 (54). Anal. Calcd for C20H26N4O4: C, 62.16; H, 6.78;
N, 14.50. Found: C, 62.07; H, 6.68; N, 14.43.
CCDC 602195 and 602196 contain the crystallographic data for
this paper. These data can be obtained free of charge via
www.ccdc.cam.ac.uk/conts/retrieving.html (or from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge CB2
1EZ, UK; fax, (+44)1223336033; and e-mail, deposit@ccdc.cam.uk).
Acknowledgment. We gratefully acknowledge financial
support from the Direccio´n General de Investigacio´n of Spain
(Project ref. CTQ2005-07562-C04-02/BQU) and Junta de
Castilla y Leo´n, Consejer´ıa de Educacio´n y Cultura, y Fondo
Social Europeo (Project ref. BU01/03). We thank SCAI for
solving structures 4c and 5a by single-crystal X-ray diffraction.
(()-N-Cyclohexyl-2-(3-methoxy-6-oxo-5-phenyl-6H-[1,2,4]tri-
azin-1-yl)-3-phenylpropionamide 6g. An ethereal solution of
diazomethane (16 mg, 0.38 mmol in diethyl ether), freshly prepared
from N-methyl-N-nitroso-p-toluenesulfonamide,26 was added to a
suspension of propionamide 5g (105 mg, 0.25 mmol) in chloroform
(30 mL) at 0 °C, and the mixture was stirred for 12 h at room
temp until a homogeneous solution was obtained. Then the solvent
was evaporated to give 6g (87 mg, 80%) as yellow crystals
(MeOH-CH2Cl2, 1:6), mp 156-157 °C; 1H NMR (300 MHz,
CDCl3) δ 8.45 (d, J ) 7.8 Hz, 2H), 7.56 (t, J ) 7.8 Hz, 1H), 7.45
(t, J ) 7.8 Hz, 2H), 7.22 (m, 5H), 6.16 (br d, J ) 7.6 Hz, 1H),
5.62 (dd, J ) 8.7, 6.8 Hz, 1H), 3.99 (s, 3H), 3.71 (m, 1H), 3.57
(dd, J ) 14.5, 6.8 Hz, 1H), 3.47 (dd, J ) 14.5, 8.7 Hz, 1H), 1.79
(m, 2H), 1.59 (m, 3H), 1.30 (m, 2H), 1.08 (m, 3H); 13C NMR (75
MHz, CDCl3) δ 166.5, 163.0, 153.5, 153.2, 136.6, 133.0, 130.3,
129.1, 129.0, 128.6, 128.3, 126.8, 62.5, 55.7, 48.5, 32.7, 25.4, 24.6;
IR (KBr) V˜ 3313 (NH), 2931, 2849, 1687 (CdO), 1634, 1549, 1262,
699 cm-1; EIMS m/z 432 (M+, 5), 307 (15), 278 (5), 230 (100),
203 (20), 104 (32), 91 (45). Anal. Calcd for C25H28N4O3: C, 69.42;
H, 6.53; N, 12.95. Found: C, 69.51; H, 6.61; N, 12.87.
Supporting Information Available: Crystallographic informa-
tion file (CIF) and X-ray diffraction structures of 4c and 5a and
X-ray diffraction structures of H-bond dimers of 5a in the solid
state. This material is available free of charge via the Internet at
http://pubs.acs.org.
JO060434Y
(27) SMART; diffractometer control software; Bruker Analytical X-ray
Instruments, Inc.: Madison, WI, 1998.
(28) SAINT; integration software; Siemens Analytical X-ray Instruments,
Inc.: Madison, WI, 1994.
(29) Sheldrick, G. M. SADABS; A program for absorption correction
with the Siemens SMART system; University of Go¨ttingen: Germany, 2001.
(30) SHELXTL, version 5.1; program system; Bruker Analytical X-ray
Instruments, Inc.: Madison, WI, 1998.
(31) International Tables for Crystallography; Kluwer: Dordrecht, 1992;
Vol. C.
4584 J. Org. Chem., Vol. 71, No. 12, 2006