Two new bis-benzoxazines, 2,Z'-ethylene-bis(l.2-dihy- drobenzo[h]-JH-4.2-benzoxazine)(I) and 3,3'-ethylene-bis(3.4dihydrobenza[h]-2H-1.3-benzoxazine) (i1) were oDtained by the Mannich reaction of and d -naphthol with formalaehyde and 1 ethylendiamine.'Their H-nmr spectra were simulated and interpretated using the LAOCN3 computer program.We recently have synthesized some bis-benzoxazines because similar compounds have shown antimicrobial activity against gram-positive bacteria, being better than several common antibiotics such as ampicillin, tetracycline and chloramphenicall ".Bl*l = 1 .7 2 , ~~= 8 .3 1 H z ) , 7.73 ( ~~-~-s y s t e m , 2 H , H -C 7 J = '-hi 8.08 ' -BM J =1 ,72,Jlu=0.13hz),8.17 (ANc<-system,Zh,H-C1O,Ju=l .79.Ja=8.31,JyiX=O.lJHz),13c-nmr s p e c t r a (25.2 MHz, C D C ~~) ; ( o f f r e s o n a n c e ) : 49.9iH-CkL2-N,t), 50.5 ( 4 , t ) , 83.0 ( 2 , t ) , 113.4 ( 4 a , s ) , 119.7 ( 6 , d ) , 121.0 ( 1 0 .d ) , 124.6 ( 1 0 a , s ) , 125.1 (5 and 9 , d ) , 125.7 ( 8 , d ) , 127.4 ( 7 , d ) , 133.1 ( 6 a .s ) .149.0 ( 1 0 b .s ) .