• Journal of the Korean Chemical Society
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• v.54 no.4
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• pp.437-442
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• 2010

Sodium hydrogen sulphate ($NaHSO_4$), n-tetra butyl ammonium bromide (TBAB) as a phase transfer catalyst (PTC) in water, and 1-butyl-3-methyl imidazolium hydrogen sulphate [bmim]$HSO_4$ as ionic liquid (IL) has been used as a mild reaction promoter for the cyclocondensation of formalin, ${\beta}$-naphthol and aromatic amines to afford respective 2,3-dihydro-2-phenyl-1H-naphtho-[1,2-e] [1,3] oxazine derivatives. The present protocols are greener, high yielding and involved the nonchromatographic isolation procedure.