Determination of methoxy group in the C-ring of a flavone using 1 H NMR

IITT College of Engineering, Kala Amb, Sirmour-173 030, Himachal Pradesh, India E-mail : sbkalidhar@gmail.com Manuscript received 21 May 2010. accepted 16 November 2010 When 1H NMR of a 3-methoxyflavone is compared with its 3-demethoxyflavone, H-2' and H-6' are found to be downfield in the former. This general observation is helpful for structural studies In naturally occurring flavones. The two flavones under comparison must have the same substituents in the B-rings; and different substituents in the A-rings do not change this observed trend