Rhodium-catalysed synthesis of fused pyrimidine derivatives employing N-sulfonyl-1,2,3-triazoles as a 1-aza-[4C] synthon

Article abstract of DOI:10.1016/j.tetlet.2019.06.023

A new synthetic application of N-sulfonyl-1,2,3-triazoles acting as a 1-aza-[4C] synthon via the 1,2-shift reaction of an α-imine rhodium carbene was developed for the synthesis of fused pyrimidine derivatives. The high reactivity of the strained three-me

Full text of DOI:10.1016/j.tetlet.2019.06.023

Accepted Manuscript
Rhodium-catalysed synthesis of fused pyrimidine derivatives employing N-sul-
fonyl-1,2,3-triazoles as a 1-aza-[4C] synthon
Ze-Feng Xu, Yuehui An, Yidian Chen, Shengguo Duan
PII:
S0040-4039(19)30563-5
https://doi.org/10.1016/j.tetlet.2019.06.023
TETL 50864
DOI:
Reference:
Tetrahedron Letters
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10 June 2019
11 June 2019
Please cite this article as: Xu, Z-F., An, Y., Chen, Y., Duan, S., Rhodium-catalysed synthesis of fused pyrimidine
derivatives employing N-sulfonyl-1,2,3-triazoles as a 1-aza-[4C] synthon, Tetrahedron Letters (2019), doi: https://
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Tetrahedron Letters
jo u r n a l h o m e p a g e : w w w . e ls e v ie r . c o m
Rhodium-catalysed synthesis of fused pyrimidine derivatives employing N-sulfonyl-
1,2,3-triazoles as a 1-aza-[4C] synthon
Ze-Feng Xuab,* , Yuehui Ana, Yidian Chena and Shengguo Duana
aDepartment of Chemistry, Zhejiang Sci-Tech University, Xiasha West Higher Education District, Hangzhou, 310018, China
bKey Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032,
China
ARTICLE INFO
ABSTRACT
Article history:
Received
Received in revised form
Accepted
A new synthetic application of N-sulfonyl-1,2,3-triazoles acting as a 1-aza-[4C] synthon via the
1,2-shift reaction of an α-imine rhodium carbene was developed for the synthesis of fused
pyrimidine derivatives. The high reactivity of the strained three-membered 2H-azirine ring
facilitated the unusual cyclization of electron-deficient dienes with electron-deficient
dienophiles. The compatibility was good with common functionalities tolerated. Excellent
chemoselectivity was observed, and no reactions occurred between the rhodium carbene and 2H-
azirine. The products could be converted into seven-membered multi-functionalized 1H-1,4-
diazepine derivatives, illustrating the potential application of the protocol in medium-sized N-
heterocycle synthesis.
Available online
Keywords:
Triazole
Rhodium carbene
Rearrangement
Tandem reaction
2009 Elsevier Ltd. All rights reserved.
N-Heterocycles, such as pyrroles, pyridines, piperidines and
pyrimidines, are important skeletons in many bioactive
compounds and other valuable molecules.1 In 2008, Fokin,
Gevorgyan and co-workers reported that under Rh2(Oct)4
catalysis, N-sulfonyl-1,2,3-triazole 1 could be converted into α-
imine rhodium carbene 2 (Scheme 1A), which could be
employed as a 1,3-dipole synthon to construct imidazoles.2 Due
to the unique reactivity of α-imine rhodium carbene 2, during the
last decade transition metal (especially rhodium) catalysed
transformations of N-sulfonyl-1,2,3-triazoles have been
intensively investigated,3,4,5 especially for the synthesis of N-
heterocycles.3e
1,2-migration of α-imine rhodium carbenes generated from the
corresponding acetoxy substituted N-sulfonyl-1,2,3-triazoles,
giving 1-azadienes, and various piperidine derivatives were
synthesized via subsequent tandem electrocyclization. A cascade
intermolecular aza-Diels-Alder reaction of acetoxy substituted 1-
azadienes with electron-rich olefins was also reported for the
synthesis of various polysubstituted piperidine derivatives
(Scheme 1B).7d Remarkably, the migration of an acetoxy group
was rapid, and thus, excellent chemoselectivity was observed and
no pyrrole derivatives were detected in the reaction. Such an
advantage provided an opportunity to explore other reactions
employing N-sulfonyl-1,2,3-triazoles as a 1-aza-[4C] synthon in
N-heterocycle synthesis.
Generally, in α-imine rhodium carbene chemistry, 1,2-shift
reactions are not preferable (Scheme 1B). For instance, 1,2-
hydrogen migration of a rhodium carbene led to the failure of
piperidine synthesis from 4-alkyl-N-sulfonyl-1,2,3-triazoles, and
1-azadiene 3 was isolated as the only product.4f Despite this, 1-
azadiene 3 is well known as a powerful intermediate in organic
synthesis which is usually utilized as a 4-atom synthon in the
construction of nitrogen-containing compounds.6 However,
compared to the large number of cases where N-sulfonyl-1,2,3-
triazoles are employed as 1,3-dipoles in N-heterocycle synthesis,
limited examples have been reported using N-sulfonyl-1,2,3-
triazoles as a 4-atom synthon.7
Consequently, a cascade reaction of acetoxy substituted N-
sulfonyl-1,2,3-triazole 1 with 2H-azirine 4 was designed. In fact,
the rhodium catalysed reaction of N-sulfonyl-1,2,3-triazoles with
2H-azirines could produce 3-amino-pyrrole derivatives 5 or 1,2-
dihydropyrazines 6 with the triazole acting as a [2C] synthon or
1-aza-[3C] synthon, respectively (Scheme 1C).8 However, in our
proposal (Scheme 1D), under rhodium catalysis, acyloxy
substituted triazoles could be converted to 1-azadienes first,
which would be employed as a 1-aza-[4C] synthon to cyclize
with 2H-azirines producing fused pyrimidine skeleton 7.
Pyrimidine derivatives are well known motifs in bioactive
molecules exhibiting antiviral, anticonvulsant, antioxidant,
anticancer and anti-inflammatory activities;9 furthermore, the
bridging C-N bond could be cleaved to give an interesting
medium-sized 1H-1,4-diazepine derivative, which is also
widespread in bioactive molecules.10 Herein, we report the
synthesis of fused polysubstituted pyrimidine derivatives via the
In 2015, Tang, Shi and co-workers7a reported a rhodium
catalyzed 1,2-sulfur migration of sulfur-tethered N-sulfonyl-
1,2,3-triazoles producing sulfur substituted 1-azadienes, the
dimerization of which furnished various tetrahydropyridine
derivatives. In 2015, Anbarasan and co-workers7b reported a
similar cascade reaction. In 2017, our group7c reported acetoxy

2
Tetrahedron
Temp
(oC)
Yieldb
(%)
tandem reaction of 4-acyloxymethylene-1-sulfonyl-1,2,3-
Entry
1
[Rh]
Solvent
7
triazoles and 2H-azirines.
1c
1a
1a
1a
1a
1a
1a
1b
1c
1c
1c
1c
1c
1c
1c
1c
1c
1c
1c
Rh2(OAc)4
Rh2(OAc)4
Rh2(OAc)4
Rh2(OAc)4
Rh2(OAc)4
Rh2(OAc)4
Rh2(OAc)4
Rh2(OAc)4
Rh2(OAc)4
Rh2(OAc)4
Rh2(OAc)4
Rh2(OAc)4
Rh2(OAc)4
Rh2(OAc)4
Rh2(oct)4
toluene
toluene
DCE
80
7aa
7aa
7aa
7aa
7aa
7aa
7ba
7ca
7ca
7ca
7ca
7ca
7ca
7ca
7ca
7ca
7ca
7ca
18
23
25
26
35
38
57
64
80
83
64
75
58
67
73
69
59
trace
2
80
3
80
4
CHCl3
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
80
5
80
6
90
7
90
8
90
9d
90
10d
11d
12de
13df
14gh
15d
16d
17d
18d
100
110
100
100
100
100
100
100
100
Rh2(adc)4
Rh2(piv)4
Rh2(tfa)4
aReagents and conditions: 1 (0.4 mmol, 2.0 equiv.), 4a (0.2 mmol, 1.0
equiv.), [Rh] (2 mol%), solvent (2 mL), N2 atmosphere. When the
temperature was higher than the boiling point of the solvent, a sealed tube
reaction was used. bIsolated yield. c1a (0.2 mmol) was used. dSolvent (1 mL)
was used. e[Rh] (1 mol%) was used. fReaction time was 6 h. gReaction time
was 12 h. OAc = acetate, oct = octanoate, adc = 1-adamantanecarboxylate,
piv = pivalate, tfa = trifluoroacetate, DCE = 1,2-dichloroethane.
Scheme 1. Background and reaction design.
(1-Tosyl-1H-1,2,3-triazol-4-yl)methyl acetate (1a)11 and 2,3-
diphenyl-2H-azirine (4a)12 were selected as model substrates to
initiate our investigation with Rh2(OAc)4 (2 mol%) as the catalyst,
which was the most efficient catalyst in the 1,2-migration of the
OAc group according to our previous work.7c-d Screening the
ratio of the substrates as well as the solvent (Table 1, entries 1-6)
illustrated that 2.0 equiv of 1a was necessary and CH2Cl2 was the
most effective solvent at 90 oC (Entry 6, 38% yield of 7aa, the
relative configuration was determined as cis according to 7cc,
whose relative configuration was determined by NOESY
analysis). However, further attempts to improve the yield of 7aa
were not successful. The tosyl group of 1a was replaced with
methanesulfonyl, meaning that 1b was used, and 7ba was
obtained in 57% yield (Entry 7). Furthermore, when benzoate 1c
was employed, 7ca was produced in 64% yield (Entry 8).
Therefore 1c was used as the model substrate for further
optimization. To our delight, doubling the concentration was
beneficial to the reaction and the yield of 7ca increased to 80%
(Entry 9). A slightly higher temperature also improved the yield
of 7ca to 83% (Entries 10-11). Reducing the amount of
Rh2(OAc)4 from 2 mol% to 1 mol% gave 7ca in lower yield
(Entry 12) and shorter or longer reaction times neither benefited
to the reaction with 4a recovered or 7ca decomposed (Entries 13-
14). In accordance with our previous work, other rhodium
catalysts were also less effective than Rh2(OAc)4 (Entries 15-18).
Scheme 2. Reaction scope.
The compatibility of the protocol was then evaluated under the
optimised conditions (Table 1, Entry 10) as depicted in Scheme 2.
Generally, the ester and sulfonyl groups of the triazole
Table 1 Optimization of the reaction conditions.a
significantly influenced the reaction. For example, when R1 was
alkyl (Me), changing the R3 group from an aromatic p-tol to an
aliphatic methyl increased the yield of 7 from 38% yield (7aa) to
57% yield (7ba); the same trend was also observed for 7ca-fa in
which R1 = Ph, and aliphatic sulfonyl substituted triazoles (7ca-

da, 75-83% yield) performed much better than aromatic sulfonyl
substituted triazoles (7ea-ga, 51-72% yield). However, when R2
= Me, aromatic carboxylate triazoles performed better than
aliphatic carboxylate triazoles (7aa vs 7fa, 7ba vs 7ca).
(Scheme 4). Dimroth tautomerization of triazole 1c gives the
corresponding α-diazoimine. Under rhodium catalysis, the α-
diazoimine could extrude nitrogen and coordinate with Rh to
produce α-imine rhodium carbene 2c, in which the nucleophilic
carbonyl oxygen attacks the electrophilic carbene carbon to
produce 1,3-dioxa cyclic intermediate 9c. Departure of Rh and
cleavage of the C-O bond gives the carboxylate migration
product—azadiene 3c. Cycloaddition of 3c with 2H-azirine 4a
finally gives the desired product 7ca.
Substituents (such as methyl, iodide and chloride) on the phenyl
carboxylate were also compatible with the reaction (7ha-ka, 63-
70% yield), but for a nitro group, only trace 7la was detected.
Compound 7ma was formed in 66% yield. Interestingly, the Boc
and carbamate groups were well tolerated and 7na and 7oa were
obtained in 63% and 52% yield, respectively. Heteroaryl
carboxylate 7pa was only formed in 14% yield. Unfortunately,
when R3 = Ph, the more substituted 7qa was not produced. In the
cases of 7la, 7pa and 7qa, the azadiene intermediates were
generated but decomposed gradually during the reaction. Neither
acyclic imines nor larger cyclic imines (five-membered or six-
membered) were compatible with these reaction conditions.
To conclude, N-sulfonyl-1,2,3-triazoles were employed as a 1-
aza-[4C] synthon for the synthesis of fused pyrimidine
derivatives via the 1,2-shift of an α-imine rhodium carbene. The
success of the unusual cyclization of electron-deficient dienes
with electron-deficient dienophiles may be attributed to the high
reactivity of the strained 2H-azirine three-membered ring. The
compatibility was good with common functionalities tolerated.
Excellent chemoselectivity was observed with no pyrrole
derivatives 5 or 1,2-dihydropyrazines 6 generated. The fused
pyrimidine product could be converted to seven-membered multi
functionalized 1H-1,4-diazepine derivatives in good yields,
illustrating the potential application of this protocol in medium-
sized N-heterocycle synthesis. This protocol represent a new
synthetic application of N-sulfonyl-1,2,3-triazoles as a 4-atom
synthon and further investigations in N-heterocycle synthesis are
ongoing in our laboratory.
The scope of the 2H-azirines was also explored. Electron-
donating groups on the phenyl ring of 2H-azirines resulted in
decreased yields (7cb, 49% yield and 7cc, 42% yield), and
weakly electron-withdrawing groups were also tolerated (7cd,
50% yield and 7ce, 45% yield). Unfortunately, the 4-nitrophenyl
substituted 2H-azirine did not provide the desired product, which
might be attributed to the strong electron-withdrawing ability of
the nitro group. Furthermore, aliphatic substituted 2H-azirines
also did not produce the desired products, and only azadiene 3c
was detected in each case along with complete decomposition of
the alkyl 2H-azirines.
Acknowledgments
We are grateful for the support of this work by the National
Natural Science Foundation of China (21801224), the Natural
Science Foundation of Zhejiang province (LQ18B020009) and
the Scientific Research Foundation of Zhejiang Sci-Tech
University (16062193-Y).
References and notes
1. (a) E.G. Brow, Ring Nitrogen and Key Biomolecules: The Biochemistry
of N-Heterocycles; Springer, 1998;
(b) K.C. Majumdar, S.K. Chattopadhyay, Heterocycles in Natural Product
Synthesis: Pyridine and Its Derivatives in Natural Product Synthesis,
Wiley-VCH, Weinheim, 2011.
2. T. Horneff, S. Chuprakov, N. Chernyak, V. Gevorgyan, V. V. Fokin, J.
Am. Chem. Soc. 130 (2008) 14972.
Scheme 3. Synthesis of 1H-1,4-diazepine derivatives.
3. (a) B. Chattopadhyay, V. Gevorgyan, Angew. Chem. Int. Ed. 51 (2012)
862;
The fused ring in 7 could easily be opened to give medium
ring products. For instance, the treatment of 7ca with 1.0 equiv.
Et2O·BF3 in CH2Cl2 gave seven-membered multi functionalized
1H-1,4-diazepine derivative 8ca in 78% yield; 8ea and 8ha could
also be obtained in a similar manner (Scheme 3A). Furthermore,
the one pot synthesis of 1H-1,4-diazepine 8 from triazole 1 and
2H-azirine 4 was developed which gave 8ca in 50% yield
(Scheme 3B). Such transformations illustrate the potential
application of this protocol in the synthesis of N-heterocycles of
medium size.
(b) A.V. Gulevich, V. Gevorgyan, Angew. Chem. Int. Ed. 52 (2013) 1371;
(c) H.M.L. Davies, J.S Alford, Chem. Soc. Rev. 43 (2014) 5151;
(d) P. Anbarasan, D. Yadagiri, S. Rajasekar, Synthesis 46 (2014) 3004;
(e) Y. Jiang, R. Sun, X.-Y. Tang, M. Shi, Chem. - Eur. J. 22 (2016) 17924;
(f) Y. Li, H. Yang, H. Zhai, Chem. - Eur. J. 24 (2018) 12757.
4. (a) T. Miura, T. Nakamuro, C.-J. Liang, M. Murakami, J. Am. Chem. Soc.
136 (2014) 15905;
(b) S.W. Kwok, L. Zhang, N.P. Grimster, V.V. Fokin, Angew. Chem. Int.
Ed. 53 (2014) 3452;
(c) J.-M. Yang, C.-Z. Zhu, X.-Y. Tang, M. Shi, Angew. Chem. Int. Ed. 53
(2014) 5142;
(d) H. Shang, Y. Wang, Y. Tian, J. Feng, Y. Tang, Angew. Chem. Int. Ed.
53 (2014) 5662;
(e) E.E. Schultz, V.N. G. Lindsay, R. Sarpong, Angew. Chem. Int. Ed. 53
(2014) 9904;
(f) Y. Shi, A.V. Gulevich, V. Gevorgyan, Angew. Chem. Int. Ed. 53 (2014)
14191;
(g) V.N.G. Lindsay, H.M.-F. Viart, R. Sarpong, J. Am. Chem. Soc. 137
(2015) 8368;
(h) Y. Yang, M.-B. Zhou, X.-H. Ouyang, R. Pi, R.-J. Song, J.-H. Li,
Angew. Chem. Int. Ed. 54 (2015) 6595;
(i) T. Miura, Y. Fujimoto, Y. Funakoshi, M. Murakami, Angew. Chem.
Int. Ed. 54 (2015) 9967;
Scheme 4. Proposed mechanism.
(j) D.J. Lee, D. Ko, E.J. Yoo, Angew. Chem. Int. Ed. 54 (2015) 13715;
(k) T. Miura, T. Nakamuro, S. Miyakawa, M. Murakami, Angew. Chem.
Int. Ed. 55 (2016) 8732;
According to the literature7 as well as our own knowledge, a
possible mechanism for this transformation was proposed

4
Tetrahedron
(l) D. Yadagiri, A.C.S. Reddy, P. Anbarasan, Chem. Sci. 7 (2016) 5934;
(c) H. Dai, S. Yu, W. Cheng, Z.-F. Xu, C.-Y. Li, Chem. Commun. 53
(2017) 6417;
(m) W. Zhou, M. Zhang, H. Li, W. Chen, Org. Lett. 19 (2017) 10;
(n) T. Nakamuro, K. Hagiwara, T. Miura, M. Murakami, Angew. Chem.
Int. Ed. 57 (2018) 5497;
(d) S. Yu, Y. An, W. Wang, Z.-F. Xu, C.-Y. Li, Adv. Synth. Catal. 360
(2018) 2125.
(o) N. Selander, B.T. Worrell, V.V. Fokin, Angew. Chem. Int. Ed. 51
(2012) 13054.
8. (a) Y.-Z. Zhao, H.-B. Yang, X.-Y. Tang, M. Shi, Chem.-Eur. J. 21 (2015)
3562;
5. (a) R.-Q. Ran, J. He, S.-D. Xiu, K.-B. Wang, C.-Y. Li, Org. Lett. 16 (2014)
3704;
(b) Y. Wang, X. Lei, Y. Tang, Chem. Commun. 51 (2015) 4507;
(c) T. Ryu, Y. Baek, P. H. Lee, J. Org. Chem. 80 (2015) 2376.
9. (a) A. Kumar, S. Sinha, P.M. Chauhan, Bioorg. Med. Chem. Lett. 76
(2012) 667;
(b) R.-Q. Ran, S.-D. Xiu, C.-Y. Li, Org. Lett. 16 (2014) 6394;
(c) W.-B. Zhang, S.-D. Xiu, C.-Y. Li, Org. Chem. Front. 2 (2015) 47;
(d) J. He, Z. Man, Y. Shi, C.-Y. Li, J. Org. Chem. 80 (2015) 4816;
(e) Y. Shi, X. Yu, C.-Y. Li, Eur. J. Org. Chem. (2015) 6429;
(f) J. He, Y. Shi, W. Cheng, Z. Man, D. Yang, C.-Y. Li, Angew. Chem.
Int. Ed. 55 (2016) 4557;
(b) P.G. Baraldi, M.G. Pavani, M.C. Nuñez, P. Brigidi, B. Vitali, R.
Gambari, R. Romagnoli, Biorg. Med. Chem. 10 (2002) 449;
(c) M.N. Nasr, M.M. Gineinah, Arch. Pharm. 335 (2002) 289;
(d) A. Gangjee, A. Vidwans, E. Elzein, J.J. McGuire, S.F. Queener, R.L.
Kisliuk, J. Med. Chem. 44 (2001) 1993;
(e) S.M. Sondhi, M. Johar, S. Rajvanshi, S.G. Dastidar, R. Shukla, R.
Raghubir, J.W. Lown, Aust. J. Chem. 54 (2001) 69;
(f) N. Kumar, G. Singh, A.K. Yadav, Heteroat. Chem, 12 (2001) 52;
(g) K.N. Mohana, B.N. Prasanna Kumar, L. Mallesha, Drug Invention
Today, 5 (2013) 216.
(g) Z. Man, H. Dai, Y. Shi, D. Yang, C.-Y. Li, Org. Lett. 18 (2016) 4962;
(h) W. Cheng, Y. Tang, Z.-F. Xu, C.-Y. Li, Org. Lett. 18 (2016) 6168.
6. (a) D.A. Colby, R.G. Bergman, J.A. Ellman, J. Am. Chem. Soc. 128
(2006) 5604;
(b) D.A. Colby, R.G. Bergman, J.A. Ellman, J. Am. Chem. Soc. 130
(2008) 3645;
(c) J.M. Neely, T. Rovis, J. Am. Chem. Soc. 135 (2013) 66;
(d) T. Yamakawa, N. Yoshikai, Org. Lett. 15 (2013) 196;
(e) S. M. Bachrach, M. Liu, J. Org. Chem. 57 (1992) 6736;
(f) R.C. Clark, S.S. Pfeiffer, D.L. Boger, J. Am. Chem. Soc. 128 (2006)
2587;
10.(a) J. Mravljak, O. Monasson, B. Al-Dabbagh, M. Crouvoisier, A. Bouhss,
C. Gravier-Pelletier, Y. Le Merrer, Eur. J. Med. Chem. 46 (2011) 1582;
(b) J.R. Hill, A.A.B. Robertson, J. Med. Chem. 61 (2018) 6945.
11. Triazole 1 was prepared according to ref 6c.
12. See ESI for the synthesis of 2H-azirine 4.
(g) K. Kanai, S. Kobayashi, K. Kudo, T. Honjo, T. Otani, T. Saito,
Tetrahedron Lett. 56 (2015) 5090;
(h) J. Esquivias, R.G. Arrayás, J.C. Carretero, J. Am. Chem. Soc. 129
(2007) 1480;
Supplementary Material
Supplementary material including procedures as well as
analytical data of new compounds was available.
(i) D.L. Boger, A.M. Kasper, J. Am. Chem. Soc. 111 (1989) 1517;
(j) D.L. Boger, W.L. Corbett, J.M. Wiggins, J. Org. Chem. 55 (1990)
2999;
(k) S. Kobayashi, T. Furuya, T. Otani, T. Saito, Tetrahedron Lett. 49
(2008) 4513.
7. (a) Y. Jiang, X.-Y. Tang, M. Shi, Chem. Commun. 51 (2015) 2122;
(b) D. Yadagiri, P. Anbarasan, Chem. Sci. 6 (2015) 5847;
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Rhodium-Catalysed Synthesis of Fused
Pyrimidine Derivatives Employing N-
Sulfonyl-1,2,3-Triazole as a 1-Aza-[4C]
Synthon
Leave this area blank for abstract info.
Ze-Feng Xu, Yuehui An, Yidian Chen, Shengguo Duan

4
Tetrahedron
Highlights
• N-sulfonyl-1,2,3-triazole was used as a 1-aza-
[4C] synthon.
• Excellent chemoselectivity was observed.
• Fused pyrimidine and seven-membered 1H-1,4-
diazepine were synthesized effectively.