Environmentally Benign one Pot Synthesis of 1,2-Dihydro-1-(4-Chlorophenyl) -3H-Naphth-(1,2-e) (1,3)-Oxazin-3-one Under Microwave Irradiations.

 

Vinod Bhatt1*, Dr. Sadhana Singh2, Krishna Ranawat1

1Dept. of Chemistry, B.N.P.G. College, MLS University, Udaipur (Raj.).

2Lecturer (S.L. Grade), Govt. College, Dungarpur (Raj.).

*Corresponding Author E-mail: bhattpc21@gmail.com

 

 

ABSTRACT:

An efficient and novel, green pathway for the synthesis of naphthoxazinones applying a three component, facile one-pot condensation reaction of β-naphthol, aromatic aldehyde and urea in the presence of silica supported phosphomolybdic acid as catalyst The present procedure offers several advantage such as an excellent yield, short reaction time, simple work-up and recovery of catalyst.

 

KEY WORDS: Naphthoxazinone, phosphomolybdic acid (PMA), β-naphthol, microwave irradiation, one-pot, multicomponent.

 

INTRODUCTION:

Solid support reagents are unique acid catalyst that have become more popular over the last two-decades. The activity and selectivity of a reagent diffused on the surface of a support is amended as the effective surface area of the reagent is increased multifold and thus they more effective than the individual reagent1. Among various solid supports, silica gel is usually preferred since it displays many advantageous properties such as high surface area, excellent stability (thermal and chemical), good accessibility and organic group can be robustly anchored to the surface to provide catalytic centers2,3.

 

Oxazinone, benzoxazinone and their derivatives are significant class of heterocyclic compounds, because many of these derivatives display biological activities, such as HIV-1 reverse transcriptase inhibitors4 and antibacterial properties5.Fulop et al. reported the condensation of amino alkylnaphthols as precursors with phosgene in the presence of Triethyl amine giving naphthalene condensed 1,3-oxazin-2-one derivative in moderate yield6. Cimarelli and Coworkers used carbonyl diimmidazole instead of phosgene for the synthesis of this compounds7.

 

Recently, the synthesis of naphthoxazine derivatives has been reported in the presence of various catalyst such as p-TSA8, FeCl39, (bmin) Br10, TMSCl / NaI11, HClO4 / SiO212, Silica gel13, ZnO NPs14, Cu NPs15, Thiamine hydrochloride16, TMSCl17.

 

Herein, we present procedure for the synthesis of 1,2-dihydro-1-(4-chlorophenyl)-3H-naphth-(1,2-e)(1,3)-oxazin-3-one under microwave radiation, using silica gel supported phosphomolybdic acid as catalyst. Solid heteropolyacid (HPAs) have been employed in numerous applications as useful and versatile acid catalyst. They are usually solids that are insoluble in non polar solvents but highly soluble in polar ones. They can be used in bulk or supported forms in both homogeneous and heterogeneous system. They are more active catalyst than conventional inorganic and organic acids for various reaction in solution18. Phosphomolybdic acid as a HPA catalyst has become important in industries related to fine chemicals19.

 

In this study, the convenient and practical synthesis of 1,2-dihydro-1-(4-chlorophenyl)-3H-naphth-(1,2-e)(1,3)-oxazin-3-one via the simple and efficient one pot multi component condensation reaction of -naphthol, aromatic aldehyde and urea in presence of catalytic amount of PMA  in solid support media.

 

EXPERIMENTAL:

The progress of reaction was monitored by TLC using 0.2 mm merk silica gel pre coated plates. Melting point measured on an electro thermal apparatus. The IR spectra, 1H-NMR, 13C-NMR spectra were obtained from CDRI Lucknow.

 

General procedure for the synthesis of 1,2-dihydro-1-(4-chlorophenyl)-3H-naphth-(1,2-e) (1,3)-oxazin-3-one.

A mixture of 2-naphthol (0.02 mol), 4-chlorobenzaldehyde (0.02 mol) urea (0.025 mol) and H3Mo12O40P / Silica gel (0. 1 mol%) were grinded and heated in mw oven at 180°C for 7 min. The reaction was monitored by TLC, after cooling the reaction mixture was dissolved in ethyl acetate and extracted with ice cold water. The ethyl acetate extract was dried over anhydrous Na2SO4 and evaporate ethyl acetate and recrystallized by methanol. The aqueous. layer evaporated to recover the PMAs.

 

 

Scheme-I : Green synthesis of naphthoxazinone

 

Table-1 : Physical characterisation of 1,2-dihydro-1-(4-chlorophenyl)-3H-naphth-(1,2-e) (1,3)-oxazin-3-one.(4)

Product

Molecular formula

Molecular weight

m.p. range

Yield %

4

C18 H12O2NCl

309.5

207-210°C

88

 

Spectral Data:

1,2-dihydro-1-(4-chlorophenyl)-3H-naphth-(1,2-e) (1,3)-oxazin-3-one(4). m.p. 207-210°C. IR (KBr, cm-1): 3223, 3145, 1734 cm-1. 1H-NMR [300 MHz, DMSO-d6) d = 6.20 (s, 1H, CH), 7.29-8.15 (m, 10H, Ar-H), 8.88 (s, 1H, NH).13C-NMR [75 MHz, DMSO-d6] d = 53.45, 114.06, 117.38, 123.52, 125.65, 127.89, 128.16, 129.17, 129.28, 129.39, 129.50, 131.0, 133.07, 142.30, 147.70, 149.69.

 

RESULTS AND DISCUSSION:

In this literature, we report a new simple, mild procedure for the one pot synthesis of naphthoxazinones derivatives using PMAs / SiO2 as a recyclable catalyst. This catalyst is safe and easy to handle & environmentally favourable. The reaction was carried out between 4-chlorobenzaldehyde, b-naphthol and urea in presence of solid support P.M.A as acid catalyst. As a result of our experiment, aromatic aldehyde containing both electron withdrawing and electron donating group reacted well to give corresponding naphthoxazinone in good yield (table-1)

 

CONCLUSION:

In conclusion, we have illustrate that silica supported PMA is a new, efficient and green catalyst for the synthesis of naphthoxazin-3-one and their derivatives. The distinguished features of this method are shorter reaction time easy work-up process, eco-friendly, excellent yield, and effective recovery of catalyst than other methods.

 

ACKNOWLEDGEMENT:

The authors are grateful to Dept. of Chemistry, BNPG, College for providing the experimental facilities and CDRI Lucknow for spectral analysis.

 

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Received on 23.08.2012        Modified on 05.09.2012

Accepted on 18.09.2012        © AJRC All right reserved

Asian J. Research Chem. 5(10): October, 2012; Page 1278-1280