2-Bromo-2-methyl-N-(4-methyl-2-oxo-2H-chromen-7-yl)propanamide

In the title compound C14H14BrNO3, the coumarin ring system is almost planar (r.m.s. deviation = 0.008 Å) and an intramolecular C—H⋯O interaction generates an S(6) ring. In the crystal, molecules are linked by N—H⋯O hydrogen bonds, with the C=O unit of the coumarin ring system acting as the acceptor group, generating [010] C(8) chains. The chain connectivity is reinforced by two C—H⋯O interactions.


Comment
The title compound C 14 H 14 Br N O 3 , is a monofunctional coumarin derivative, which is used as an initiator (Sinkel et al., 2008) in Atom Transfer Radical Polymerization (ATRP). We have already reported a similar ATRP initiator (Haridharan et al., 2010) with flourine containing coumarin derivative. The title compound reported here is a similiar derivative with bromo methyl propanamide and with a methyl substitution.
The synthesis of oxygen containing heterocyclic based initiators and their crystal structures are worth while to study due to their interesting properties and diverse bioactivities such as non peptidic HIV protease inhibition and tyrosine kinase inhibition (Thaisrivongs et al., 1994).
In the title compound C 14 H 14 Br N O 3 , the coumarin ring system is plannar and the Br atom in the 2-bromo-2-methyl propanamide moiety is almost perpendicular to the ring.
Experimental 7-Amino-4-methylcoumarin (4 g, 0.022 moles), triethylamine (5.08 g, 0.050 moles) and THF (200 ml) were placed in a 3-neck round bottomed flask. Bromoisobutyrl bromide (11.54 g, 0.050 moles) was added slowly, using a syringe, with stirring, upon which an white precipitate of triethylammonium bromide was formed. The mixture was left to react for 6 h, with stirring. Subsequently, triethylammonium bromide, the precipitate was removed by filtration and the THF was removed by rotary evaporation. The resulting crude product was dissolved in ethyl acetate, washed with bicarbonate solution and then with water thrice followed by brine solution and dried over anhydrous sodium sulfate. The solvent was removed from the resulting solution by rotary evaporation. The product was purified by column chromatography technique using 10% ethyl acetate in hexane as the eluent to obtain pure initiator as a light yellow solid. Recrystallization of the compound from chloroform gave light yellow slabs of (I).

Refinement
The nitrogen H atom was located in a difference Fourier map and refined isotropically. All other hydrogen atoms were fixed geometrically and allowed to ride on the parent carbon atoms, with aromatic C-H = 0.93 Å and methyl C-H = 0.96 Å. The displacement parameters were set for phenyl H atoms at U iso (H) = 1.2U eq (C) and methyl H atoms at U iso (H) = 1.5U eq (C). Fig. 1. The molecular structure of (I) with atoms represented as 30% probability ellipsoids.