SYNTHESIS OF 4H-PYRAN
2303
16. (a) Singh, K.; Singh, J.; Singh, H. A synthetic entry into fused pyran derivatives through
carbon transfer reactions of 1,3-oxazinanes and oxazolidines with carbon nucleophiles.
Tetrahedron 1996, 52, 14273; (b) Wang, X. S.; Shi, D. Q.; Tu, S. J.; Yao, C. S. A
convenient synthesis of 5-oxo-5,6,7,8-tetrahydro-4H-benzo[b]pyran derivatives catalyzed
by KF-alumina. Synth Commun. 2003, 33, 119; (c) Ismail, Z. H.; Aly, G. M.; El-Degwi,
M. S.; Heiba, H. I.; Ghorab, M. M. Synthesis and insecticidal activity of some new
pyranopyrazoles, pyrazolopyranopyrimidines and pyrazolopyranopyridines. Egypt. J.
Biotechnol. 2003, 13, 73; (d) Ipsita, D.; Pulak, J. B. Sodium bromide–catalyzed one-pot
synthesis of tetrahydrobenzo[b]pyrans via a three-component cyclocondensation under
microwave irradiation and solvent-free conditions. Tetrahedron Lett. 2004, 45, 8625.
17. (a) Tu, S. J.; Miao, C. B.; Gao, Y.; Feng, Y. J.; Feng, J. G. Microwave-prompted reaction
of cinnamonitrile derivatives with 5,5-dimethyl-1,3-cyclohexanedione. Chin. J. Chem.
2002, 20, 703; (b) Tu, S. J.; Gao, Y.; Guo, C.; Shi, D. Q.; Lu, Z. S. A convenient synthesis
of 2-amino-5,6,7,8-tetrahydro-5-oxo-4-aryl-7,7-dimethyl-4H-benzo[b]pyran-3-carbonitrile
under microwave irradiation. Synth. Commun. 2002, 32 (14); 2137; (c) Zhou, J. F.; Tu,
S. J.; Zhu, H. Q.; Zhi, S. J. A facile one-pot synthesis of pyrano-[2,3-c]pyrazole derivatives
under microwave irradiation. Synth. Commun. 2002, 32 (21), 3363.
18. (a) Jin, T. S.; Wang, A. Q.; Wang, X.; Zhang, J. S.; Li, T. S. A clean one-pot synthesis of
tetrahydrobenzo[b]pyran derivatives catalyzed by hexadecyltrimethyl ammonium bromide
in aqueous media. Synlett 2004, 871; (b) Jin, T. S.; Wang, A. Q.; Cheng, Z. L.; Zhang, J. S.;
Li, T. S. A clean and simple synthesis of 6-amino-4-aryl-5-cyano-3-methyl-1-phenyl-1,4-
dihydropyrano[2,3-c]pyrazole in water. Synth. Commun. 2005, 35, 137.
19. Kaupp, G.; Naimi-Jamal, M. R.; Schmeyers, J. Solvent-free Knoevenagel condensations
and Michael additions in the solid state and in the melt with quantitative yield. Tetra-
hedron 2003, 59, 3753.
20. (a) Khurana, J. M.; Nand, B.; Saluja, P. DBU: A highly efficient catalyst for one-pot syn-
thesis of substituted 3,4-dihydropyrano[3,2-c]chromenes, dihydropyrano[4,3-b]pyranes,
2-amino-4Hbenzo[h]chromenes and 2-amino-4H-benzo[g]chromenes in aqueous medium.
Tetrahedron 2010, 66, 5637; (b) Guo, S. B.; Wang, S. X.; Li, J. T. D,L-Proline-catalyzed
one-pot synthesis of pyrans and pyrano[2,3-c]pyrazole derivatives by a grinding method
under solvent-free conditions. Synth. Commun. 2007, 37, 2111; (and references therein);
(c) Khurana, J. M.; Nand, B.; Saluja, P. DBU: A highly efficient catalyst for one-pot syn-
thesis of substituted tetrahydro-4H-chromenes, tetrahydro[b]pyrans, pyrano[d]pyrimi-
dines and 4H-pyrans in aqueous medium. J. Het. Chem. In press; (d) Sotgiu, G. Easy
electrochemical synthesis of 2-amino-4-aryl-3-cyano-5-ethoxycarbonyl- 6-methyl-4H-pyr-
ans in the absence of supporting electrolyte. Lett. Org. Chem. 2008, 5, 555.
21. Zhang, Z. Nickel(0) catalysts in organic synthesis. Synlett 2005, 5, 877.
22. Alonso, F.; Riente, P.; Yus, M. Hydrogen-transfer reduction of carbonyl compounds
promoted by nickel nanoparticles. Tetrahedron 2008, 64, 1847.
23. Alonso, F.; Riente, P.; Yus, M. Hydrogen-transfer reduction of carbonyl compounds
catalyzed by nickel nanoparticles. Tetrahedron Lett. 2008, 49, 1939.
24. Alonso, F.; Riente, P.; Yus, M. Hydrogen-transfer reductive amination of aldehydes
catalyzed by nickel nanoparticles. Synlett 2008, 1289.
25. Alonso, F.; Riente P.; Yus, M. Alcohols for the a-alkylation of methyl ketones and indirect
aza-Wittig reaction promoted by nickel nanoparticles. Eur. J. Org. Chem. 2008, 4908.
26. Saxena, A.; Kumar, A.; Mozumdar, S. Ni-nanoparticles: An efficient green catalyst for
chemo-selective oxidative coupling of thiols. J. Mol. Cat. A: Chem. 2007, 269, 35.
27. Sapkal, S. B.; Shelke, K. F.; Shingate, B. B.; Shingare, M. S. Nickel
nanoparticle-catalyzed facile and efficient one-pot synthesis of polyhydroquinoline
derivatives via Hantzsch condensation under solvent-free conditions. Tetrahedron Lett.
2009, 50, 1754.