4
Table 3.
References
Synthesis of pyranocoumarins from benzopyrans 5k-r and 5u
and propiolic acid.
1
2
.
.
Pratap R, Ram VJ. Chem. Rev. 2014; 114: 10476-10526.
(a) Nicolaou KC, Pfefferkorn JA, Barluenga S, Mitchell HJ,
Roecker AJ, Cao G-Q. J. Am. Chem. Soc. 2000; 122: 9968-9976.
(b) Dell CP. Curr. Med. Chem. 1998; 5: 179-194.
3
4
.
.
Fan J, Wang Z. Chem. Commun. 2008; 5381-5383.
Aoyama T, Yamamoto T, Miyota S, Hayakawa M, Takido T,
Kodomari M. Synlett. 2014; 25: 1571-1576.
5
6
.
.
El-Sepelgy O, Haseloff S, Alamsetti SK, Schneider C. Angew.
Chem. Int. Ed. 2014; 53: 7923-7927.
Funabiki K, Komeda T, Kubota Y, Matsui M. Tetrahedron 2009;
6
5: 7457-7463.
7
8
.
.
Li M, Zhang B, Gu Y. Green Chem. 2012; 14: 2421-2428.
Bhattacharjee S, Das DK, Khan AT. Synthesis 2014; 46: 0073-
0
080.
9
1
.
Sangsuwan R, Sangher S, Aree T, Mahidol C, Ruchirawat S,
Kittakoop P. RSC Adv. 2014; 4: 13708-13718.
a
Entry
5
Ar
Time
h
7+8 (%) (7:8)
0. (a) Nishibayashi Y, Inada Y, Hidai M, Uemura S. J. Am. Chem.
Soc. 2002; 124: 7900-7901. (b) Liu Y, Qian J, Lou S, Zhu J, Xu Z.
J. Org. Chem. 2010; 75: 1309-1312.
1. Li HJ, Luo DH, Wu QX, Dai CY, Shen ZL, Wu YC. Chin. Chem.
Lett. 2014; 25: 1235-1239.
2. Thadkapally S, Kunjachan AC, Menon RS. Beilstein J. Org.
Chem. 2016; 12: 16-21.
3. van Otterlo WAL, Ngidi EL, Kuzvidza S, Morgans GL, Moleele
SS, de Koning CB. Tetrahedron 2005; 61: 9996-10006.
1
2
3
4
5
6
7
8
5k
5l
C H
30
30
32
30
32
28
30
28
30
60 (1:3.3)
59 (1:3.2)
56 (1:3.6)
61 (1:3.7)
57 (1:3.4)
60 (1:3.3)
61 (1:3.3)
62 (1:3.1)
6
5
1
1
1
4-Cl-C H
4-CN-C H
6 4
4-OMe-C H
2-OH-3-OMe-C H
6 3
2-OH-C H
2-OH-5-Cl-C H
6 4
2-OH-5-Br-C H
6 4
5m
5n
5o
5p
5q
5r
5u
6 4
6 4
14. (a) Fang YW, Li CZ. J. Org. Chem. 2006; 71: 6427-6431. (b)
Malakar CC, Schmidt D, Conrad J, Beifuss U. Org Lett. 2011; 13:
1972-1975.
6
4
b
9 a
C H
6
64
5
b
1
5. Lukashenko AV, Osyanin VA, Osipov DV, Klimochkin YN. J.
Org. Chem. 2017; 82: 1517-1528.
6. Gaudino EC, Tagliapietra S, Martina K, Palmisano G, Cravotto G.
RSC Adv. 2016; 6: 46394-46405.
The product ratio was determined by isolated yields; isolated
yield of 7i.
1
Next, the hydroarylation reaction could be successfully
extended to other substituted benzopyrans 5l-r, affording the
desired pyranocoumarins 7b-h and 8b-h in good yields. These
compounds were separated by column chromatography using
methanol/chloroform (1:99) as eluent as colorless solids. The
reaction time and overall yields with product ratios of
compounds are given in Table 3 (entries 2-8). Similarly,
benzopyran 5u bearing pyrogallol core underwent hydroarylation
reaction smoothly and afforded pyrano[3,2-g]coumarin 7i in 64%
yield (Table 3, entry 9).
1
1
19. Liu Y, Zhu J, Qian J, Jiang B, Xu Z. J. Org. Chem. 2011; 76:
9096-9101.
2
2
0. Kumar V, Niyaz NMM, Saminathan S, Wickramaratne DBM.
Phytochemistry 1998; 49: 215-218.
1. (a) Ahadi S, Zolghadr M, Khavasi HR, Bazgir A. Org. Biomol.
Chem. 2013; 11: 279-286. (b) Gohain M, van Tonder JH,
Bezuidenhoudt BCB. Tetrahedron Lett. 2013; 54: 3773-3776. (c)
Bagdi AK, Majee A, Hazra A. Tetrahedron Lett. 2013; 54: 3892-
3
895. (d) Singh S, Srivastava A, Mobin SM, Samanta S. RSC Adv.
In conclusion, we have disclosed a simple protocol for the
synthesis of benzopyrans in good yields from the corresponding
phenols and benzylidene derivatives via Michael addition. The
reaction features mild reaction conditions, broad substrate scope
and good functional group tolerance. The cyclization strategy
proceeds through the intermediate chroman derivative and is well
supported by its X-ray structure. The synthetic utility of this
protocol was demonstrated by a facile synthesis of angular and
linear pyranocoumarins. The 4H-chromenes synthesized herein
contain valuable functional groups that can be transformed into
other functional groups of synthetic importance. It is hoped that
this strategy may find applications in the synthesis of various
bioactive 4H-chromenes and pyranocoumarins.
2015; 5: 5010-5014.
2. Karami B, Khodabakhshi S, Eskandari K. Tetrahedron Lett. 2012;
2
2
2
5
3: 1445-1446.
3. Pal S, Khan MN, Karamthulla S, Choudhury LH. Tetrahedron
Lett. 2015; 56: 359-364.
4. Kumar A, Maurya RA, Sharma S, Ahmad P, Singh AB, Bhatia G,
Srivastava AK. Bioorg. Med. Chem. Lett. 2009; 19: 6447-6451.
25. (a) Priyanka, Misra S, Misra-Bhattacharya S, Butcher RJ, Katiyar
D. Tetrahedron: Asymmetry 2017; 28: 734-743. (b) Priyanka,
Singh V, Ekta, Katiyar D. Bioorg. Chem. 2017; 71: 120-127. (c)
Misra S, Singh LK, Priyanka, Gupta J, Misra-Bhattacharya S,
Katiyar D. Eur. J. Med. Chem. 2015; 94: 211-217.
26. CCDC 1402647 contains the supplementary crystallographic data
for compound 5a. These data can be obtained free of charge from
The
Cambridge
Crystallographic
Data
Centre
via
www.ccdc.cam.ac.uk/data_request/cif.
2
7. CCDC 1402653 contains the supplementary crystallographic data
for intermediate III. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
Acknowledgments
Authors thank BHU, Varanasi for financial support and CISC,
BHU, Varanasi for the spectral data of synthesized compounds.
DK thanks Department of Science and Technology (DST), New
Delhi (Grant No. EMR/2016/001396) for the funding and
Priyanka thanks Council of Scientific and Industrial Research
28. CCDC 1570784 contains the supplementary crystallographic data
for compound 7a. These data can be obtained free of charge from
The
Cambridge
Crystallographic
Data
Centre
via
www.ccdc.cam.ac.uk/data_request/cif.
2
9. Melliou E, Magiatis P, Mitaku S, Skaltsounis A-L, Chinou E,
Chinou I. J. Nat. Prod. 2005; 68: 78-82.
30. Cao J-L, Shen S-L, Yang P, Qu J. Org. Lett. 2013; 15: 3856-3859.
(CSIR), New Delhi for Senior Research Fellowship.
A. Supplementary Material
Experimental details and spectra for selected synthesized
compounds are given (PDF).