The treatment of o-(N-acylamino)benzyl alcohols (1) with DAST afforded the dehydrative cyclization product, 4H-3,1-benzoxazines (4) and the hydroxy replacement product, o-(N-acylamino)benzyl fluorides (5). The yields of benzoxazines (4) and fluorides (5) depend on the substituents at alpha-position and acyl groups. The treatment of alpha,alpha-diaryl-o-(N-acylamino)benzyl alcohols (1a-c) with DAST yielded benzoxazines (4a-c) exclusively, while that of alpha-monosubstituted o-(N-acylamino)benzyl alcohols (Id-k) with DAST yielded benzoxazines (4d-k) and fluorides (5d-k). In the reaction of o-(N-acylamino)benzyl alcohol (11) with DAST, the formation of fluoride (51) became predominant and that of benzoxazine (41) was suppressed almost completely.
SCHMIDT, R. R.;BEITZKE, B., CHEM. BER., 1983, 116, N 6, 2115-2135
作者:SCHMIDT, R. R.、BEITZKE, B.
DOI:——
日期:——
Catalyst-Free Synthesis of Functionalized 4-Substituted-4<i>H</i>-Benzo[<i>d</i>][1,3]oxazines via Intramolecular Cyclization of <i>ortho-</i>Amide-<i>N</i>-tosylhydrazones