V K Ahluwalia
Articles written in Proceedings – Section A
Volume 38 Issue 6 December 1953 pp 480-494
The two higher analogues of 5-hydroxy flavone (primuletin) containing two and three methoxyl groups in the side phenyl nucleus have been synthesised and subjected to persulphate oxidation. 5-Hydroxy-3′:4′-dimethoxy flavone gave poor yield of dimethoxy primetin while the higher member could not be oxidised under these conditions. Alternatively, oxidation of 8-hydroxy flavones has been attempted and found to proceed more satisfactorily to yield primetin and its higher members. The required 8-hydroxy flavones have been made from 2:3-dihydroxy acetophenone for the preparation of which a convenient method has been worked out starting from ortho vanillin.
Volume 39 Issue 6 June 1954 pp 296-300
Starting from 2-hydroxy-3: 6-dimethoxy acetophenone a new synthesis of 3-hydroxy primetin has been effected and by alkali fission of the trimethyl ether 2-hydroxy-ω: 3: 6-trimethoxy acetophenone has been prepared. Using the same procedure (modified Kostanecki’s method) 3:5:8:3′: 4′-pentahydroxy flavone, its pentamethyl ether and penta-acetate have been obtained. The properties of these compounds are different from those of the pentahydroxy flavone and its derivatives obtained from Ponderosa Pine Bark.
Volume 44 Issue 1 July 1956 pp 1-5
2-Hydroxy-6-methoxy benzoic acid condenses with orcinol giving rise to (1) 1-hydroxy-3-methyl-8-methoxy xanthone and (2) 1: 8-dihydroxy-3-methyl xanthone. The second is also obtained from γ-resorcylic acid. The first undergoes nuclear oxidation with alkaline persulphate to yield ravenelin-8-methyl ether which is demethylated to ravenelin.
Volume 45 Issue 1 January 1957 pp 15-19
The position of the methoxyl group in dalbergin has been established by synthesis using two methods: (1) partial methylation of 4-phenyl-aesculetin and (2) nuclear oxidation of 4-phenyl umbelliferone methyl ether. By similar methods the 7-benzyl ether of 4-phenyl aesculetin and from it by methylation and debenzylation iso-dalbergin has been prepared. The ethyl ethers of dalbergin and iso-dalbergin have also been obtained.
Volume 45 Issue 5 May 1957 pp 293-297
Though the benzophenone method of synthesis is not quite advantageous for dalbergin and methyl dalbergin, it is more convenient for the preparation of allo-dalbergin (4-phenyl-5-methoxy-6-hydroxy coumarin) and its methyl ether. These compounds and other 4-phenyl coumarins give markedly coloured solutions when treated with alcohol, hydrochloric acid and magnesium; a number of 4-methyl coumarin derivatives also give similar colour reactions. On the other hand 3-phenyl and 3-phenyl-4-methyl coumarin derivatives do not respond to this test which may therefore be of diagnostic value.
Volume 47 Issue 4 April 1958 pp 230-237
In order to get fuller information on the influence of hydroxyl groups on alkali colour reactions a number of flavonols of types uncommon in Nature have been prepared and examined. Though the correlation between structure and alkali colour reactions is complex, when applied with care the reactions can be used for diagnostic purposes. The alkali colour reactions of the flavonols with 2′∶3′ and 2′∶3′∶4′ disposition of hydroxyl groups are not prominent and their fluorescence properties are also very feeble.
Volume 49 Issue 2 February 1959 pp 104-110
The two important characteristics of 4-phenyl coumarin derivatives,