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Zn/NH 4 Cl -Mediated reactions of aldehyde 1 with nitro compounds 2 afford 2-(Nalkyl/arylamino)-3-formylchromones 4, which on heating with 70% H 2 SO 4 produces 9a-d and 11e-h from 4a-d and 4e-h, respectively. The synthesis of the aminochromone class of compounds has received considerable attention because of the wide range of biological activities. 5, 4'-Diaminoflavone and some of its congeners exhibited a remarkable antiproliferative effect against the human breast cancer cell line MCF -7 irrespective of the presence or absence of estrogen. 1 Increasing interest in the 2-aminochromone class of compounds is due to the antiplatelet activity. 2 2-(N, N-Dialkylamino)chromone has been synthesised (i) by reacting salicylic esters with ynamines, 2a (ii) by Vilsmeier condensation of β-aminoester with phenol, 3 (iii) by replacement of sulfoxide group in 2-ethylsulfinyl-5, 8-dimethoxychromone by NHRR

In recent years, the synthesis of xanthone derivatives has attracted special attention due to their many biological activities specially as antitumour agents 1 A small liophilic substituent at the C-5 position of xanthone-4-acetic acid enhances the dose potency as an antitumour agent. 2 The antibiotic bikaverin, 3,4 which contains benzo [b]xanthone skeleton, has a high vacuolation property and is a fungal metabolite. Recently, a number of glycosides linked at the 2-position to 4, 5, 8-trimethoxyxanthone have been isolated from ethanolic solution of rhizome of A. Calamus. 5 In view of the natural occurrence and useful range of biological activity associated with the xanthone moiety, various methods have been developed for their syntheses. Most syntheses have been carried out from benzene derivatives and a few from benzopyran-4-ones. 6 We intended to couple 3-functionalised 4-oxo-4H-1benzopyrans through their 2-positions. This coupled product could serve as a precursor for many oxygenerated polycyclic compounds. We have recently reported 7 that 3formylchromenone 1 fails to produce the desired coupled product when treated with sodium naphthalenide or zinc. Product formation was rationalised by considering the initial addition of electron to the aldehyde function of 1 rather at C-2 of the chromenone moiety. Treatment acetal 2 of sodium naphthalenide produced the same mixture of products as was obtained from 1. An earlier report 8 showed that reactions of nucleophiles either with 1 or with 2 produce the same products. Reaction of sodium naphthalenide with ketone 3 produced 2-salicyloylxanthone as was obtained from base-catalysed transformation of 3. 9 Hydrodimerisation of α, β-unsaturated esters 10 by SmI 2 , cyclodimerisation of α, β-unsaturated esters to cyclopentanone derivatives by Yb 11 or by sodium naphthalenide 12 are known. We used 3-methoxycarbonyl-4-oxo-4H-1-benzopyran 4 as the substrate.

For Abstract see ChemInform Abstract in Full Text.

The title aldehyde 1 gives the bischromones 2, 3 and disalicyloylbenzene 5 with sodium naphthalenide; a mixture of 3 and chromanone 22 with zinc in methanol; 3, carbinol 6 and diol 8 with zinc in acetic acid; and acetates 7 and 9 with Zn^Ac 2 O^AcONa.

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One-Pot Synthesis of 2-Alkyl/Arylamino-4-oxo-4H-1-benzopyran-3-carboxaldehyde from 4-Oxo-4H-1-benzopyran-3-carboxaldehyde. -A facile one-pot synthesis of the title 2-amino-3-formylchromones (III) (8 examples) via Zn/NH4Cl-mediated reaction of aldehydes (I) with nitro compounds (II) is developed. Surprisingly, 2-arylamino-3-formylchromones cyclize on heating with 70% sulfuric acid furnishing benzopyranoquinolines [cf. (IV)], whereas 2-alkylamino-3-formylchromones produce deformylated products [cf. (V)] under analogous conditions. -(BANDYOPADHYAY*, C.; SUR, K. R.; PATRA, R.; BANERJEE, S.; J. Chem. Res., Synop. 2003, 8, 459-460; Dep. Chem., Miss. Vivekananda Cent. Coll., Rahara 743 186, India; Eng.) -M. Schroeter 11-128

Reaction of the title aldehyde 1 with acetylacetone 2 gives benzophenone 8 along with the Knoevenagel-type product 5 under acidic conditions.