29507-75-3Relevant academic research and scientific papers
Studies in Pyranomethylchromones and Prenylated Pyranomethylchromones
Iyer, P. R.,Iyer, C. S. Rukmani,Prasad, K. J. Rajendra
, p. 535 - 538 (2007/10/02)
5,7-Dihydroxy-2-methylchromone (I) on prenylation with 2-methyl-3-buten-2-ol in the presence of BF3 etherate yields pulverin (II) and peucenin (III), which are separable by column chromatography.Cyclodehydrogenation of II with DDQ in benzene under reflux for 6 hr affords 6-(3,3-dimethylallyl)alloptaeroxylin (IV) and 10-(3,3-dimethylallyl)spatheliachromene (V) while prolonged refluxing (70 hr) yields in addition to IV and V, the bispyranochromone (VI) identified as spatheliabischromene.Pyranochromones IV, V and VI have also been synthesised by alternative routes.Alloptaeroxylin (VII) on prenylation with 2-methyl-3-buten-2-ol in the pres ence of BF3 etherate gives IV.Compound III undergoes cyclodehydrogenation with DDQ to give spatheliachromene (VIII) which on prenylation affords V.Acid-catalysed cyclisation of IV followed by NBS/DDQ dehydrogenation of the resultant dihydrodipyranochromone (IX) furnishes VI.
A Study of the Base-catalysed Wessely-Moser Rearrangement of Angularly Condensed 2,2-Dimethyl-2H-pyrano Derivatives of 5-Hydroxy-2-methylchromones and 2,3-Diphenylchromones and related 1-Hydroxyxanthone
Jain, A. C.,Gupta, Atul,Kumari, Sarita
, p. 365 - 369 (2007/10/02)
2-Methyl group in 5-hydroxy-2,8,8-trimethyl-8H-pyranochromone (4a) does not hinder base-catalysed isomerisation to afford the corresponding linear isomer (5a); whereas the presence of of phenyl group in position 2 and 3 as in 4c brings no such change.Similarly, 6-hydroxy-3,3-dimethyl-3H-pyranoxanthone (8) does not undergo alkali isomerisation. 5,7-Dihydroxy-2-methylchromone (2a) with 2-chloro-2-methyl-3-butyne in the presence of K2CO3, KI and DMF yields both the linear and angular 2,2-dimethyl-2H-pyrano derivatives (5a and 4a respectively) besides the 1,1-dimethylpropargyl ether (3a), the ratio being 2:4:3.However, under similar conditions 5,7-dihydroxy-2,3-diphenylchromone (2b) yields 3b, 4c and 5c in the ratio of only 5:14:1; again the tendency of forming linear isomer (5c) is far less than that of the angular isomer (4c).
A New Synthesis of Alloptaeroxylin, Its Methyl Ether and Related Compounds
Prasad, K. J. Rajendra,Iyer, P. R.
, p. 570 - 571 (2007/10/02)
Claisen condensation of 6-acetyl-5,7-dihydroxy-2,2-dimethylchroman (I) with sodium and ethyl acetate gives isoheteropeucenin (II) and isopeucenin (III).Benzylic bromination of II and III with NBS followed by dehydrobromination with pyridine affords alloptaeroxylin (IV) and dehydroisopeucenin (V) respectively.IV on methylation gives alloptaeroxylin methyl ether (VI).VI has also been synthesized by an alternate route.
A Convenient Synthesis of Linear 2-Methylpyranochromones
Ahluwalia, Vinod Kumar,Jain, Anjula,Gupta, Ranjna
, p. 2649 - 2652 (2007/10/02)
A convenient synthesis of linear 2-methylpyranochromones, viz., spatheliachromen(5-hydroxy-2,2,8-trimethyl-2H,6H-benzodipyran-6-one), O-methylspatheliachromen (5-methoxy-2,2,8-trimethyl-2H,6H-benzodipyran-6-one) (8) and O-methylallopteroxylin (5-methoxy-2,8,8-trimethyl-4H,8H-benzodipyran-4-one> is described by blocking the eighth position of the corresponding 7-propargyl ether derivative 7-(1,1-dimethyl-2-propynyloxy)-8-iodo-5-methoxy-2-methyl-4H-1-benzopyran-4-one with iodine followed by thermal cyclization.The linear pyranochromones 2,2,8-trimethyl-2H,6H-benzodipyran-6-one and 8 are also synthesized starting with the easily available appropriate 3,4-dihydro-2,2-dimethyl-2H-1-benzopyran-7-ols following the steps of Claisen condensation with ethyl acetate, cyclization with ethanolic sulfuric acid followed by dehydrogenation with NBS.
