Hu Ying-he
2006
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Fine chemicals
Abstract
Ethyl 7-bromo-1,4-dihydro-3H-2,3-benzoxazines-3-carboxylate(C) was obtained from ethyl 1,4-dihydro-3H-2,3-benzoxazines-3-carboxylate by nitration at the 7-position,reduction of the nitro group to amino group,diazotation and replacement by bromine atom.Using Cs_2CO_3 and Pd(OAc)_2 /R(+)BINAP as the catalytic system under N_2 protection at 100 ℃,C coupled with aniline,N-methylaniline,4-fluroaniline,4-ethoxyaniline,cyclohexylamine,morpholine,pyrrolidine and piperidine separately for 16~24 h in anhydrous toluene,giving the corresponding eight ethyl 7-amino-substituted 1,4-dihydro-3H-2,3-benzoxazines-3-carboxylate(D1~8) in the yields of 83%,85%,71%,90%,72%,63%,75% and 83%,respectively.Structures of D 1~8 were determined by ~1HNMR,MS and elementary analysis.