Source of material3-(4-Bromophenyl)-4-hydroxyfuran-2(5H)-one (127 mg, 0.5 mmol) was prepared according to [1],and was added into a mixture of 4-chloroaniline (76 mg, 0.6 mmol) and p-toluene sulphonic acid (3.4 mg,0.02 mmol). The resulting mixture was heated to 363 Kfor 10 min. 5mLoftoluene were then added and refluxed for 4h.After toluene was removed under reduced pressure, the residue was purified by columnc hromatography on silica gel, eluting with EtOAc/petroleum ether (v/v =1/1).
Experimental detailsThe Hatom bonded to N1 was located in difference Fourier map.
The configuration of N1 could help to explain why d(C10-N1) is shorter than d(C11-N1). The Flack parameter is 0.016(8).
DiscussionMany compounds of g-butyrolactone-core (furanone) show diverseb iologicala ctivities. Fore xample,s omed erivatives of gbutyrolactone (5-alkoxy-4-aminofuran-2(5H)-one) showing good antibacterial activity against multiresistant Staphylococcus aureus were reported [2].4-Alkylamino or 4-arylamino derivatives of 3-arylfuran-2(5H)-one are potent inhibitors against tyrosyl-tRNA synthetase (TyrRS) [1,3], one of the aminoacyltRNA synthetases(aaRSs). In the title compound, the bond C7-C10 (1.375(4) Å) was assigned as ad ouble bond [4,5], and the title compound was thereforeidentified as afuran-2(5H)-one, notafuran-2(3H)-one. Butyrolactone moiety and the attached amino group (H1,N 1, C10 and C11)a re nearly co-planar with ad ihedral angle of 5.2(2)°, indicating theconjugation of p orbitalofN1withthe p molecular orbital of C7-C10,which shortens the bond distance of C10-N1. Additionally, d(C10-N1) is further shortened to 1.342(3) Åbythe strong electron withdrawing effect of the carbonyl group (C8-O1), which is intermediated by p molecular orbital of C7-C10.However, C11-N1 is atypical single bond with the bond length of 1.433(3) Å. The dihedral angle of amino group and 4-chlorobenzene ring is quite large (58.5(2)°). The significant tilting of the amino group therefore breaks the conjugation with its attached 4-chlorobenzene ring. The bond distance d(C7-C10) =1 .355(3) Åi sm uch shorter than d(C7-C8) = 1.450(4) Å. This significantly increases the steric strain between 4-(4-chlorophenylamino) group and 3-(4-bromophenyl) group, whichleads to an increase in angle ÐC1-C7-C10 =129.4(2)°in comparison with ÐC1-C7-C8 =1 23.3(2)°. In the packing, the three independent hydrogen bonds generate at wo-dimensional layer running parallel to (010), in which two kinds of hydrogen bonding patterns could be observed with R 4 3 22 () and R 4 4 21 () rings built from C-H×××Oa nd N-H×××Oh ydrogen bonds. On the one hand,eachmolecule utilizes thetwo Oatoms of lactonemoiety as acceptorsand is hydrogen-bonded to threeothers.Onthe other hand, the same molecule utilizes C5, C16 and N1 as donors and forms hydrogen bonding interactions with another three molecules. Theabove mentioned layers are stacked by van der Waals forces.
