| 摘要 |
#CMT# #/CMT# Preparing 2-(n-butyl)-5-nitro benzofuran (I) from 1-fluoro-4-nitrobenzene, comprises reacting 1-hexyn-3-ol, and submitting the obtained product to claisen rearrangement and an intramolecular cyclization. #CMT#USE : #/CMT# The process is useful to prepare the 2-(n-butyl)-5-nitro benzofuran. #CMT#ADVANTAGE : #/CMT# The process provides the 2-(n-butyl)-5-nitro benzofuran with high yield. #CMT#ORGANIC CHEMISTRY : #/CMT# Preferred Process: The process further comprises: reacting 1-hexyn-3-ol in 1-halo-4-nitrobenzene after alcohol deprotonation in basic medium; the obtained 4-nitrophenyl-1-ethynyl-n-butylether compound (II) subjected to claisen rearrangement to give 2-(2,3-hexadien-1-yl)-4-nitrophenol compound (III); and the 2-(2,3-hexadien-1-yl)-4-nitrophenol subjected to intramolecular cyclization by thermal activation, in (I). The reaction of the 1-hexyn-3-ol is carried out in the 1-fluoro-4-nitrobenzene or in the 1-chloro-4-nitrobenzene, in the presence of mineral or organic base comprising alkaline hydride or alkaline carbonate. The claisen rearrangement and cyclization are carried out by heating at greater than 180[deg] C. The claisen rearrangement and cyclization are carried out in a solvent of polyethylene glycol 200 or N,N-diethylaniline, in the presence of cesium, at 180-260[deg] C. Preferred Components: The 1-halo-4-nitrobenzene is 1-fluoro-4-nitrobenzene or 1-chloro-4-nitrobenzene. #CMT#EXAMPLE : #/CMT# The 4-nitrophenyl-1-ethynyl-n-butylether and polyethylene glycol 200 (1 ml) were introduced in a container. The mixture was agitated and heated at 200[deg] C. The clear yellow solution was moved rapidly towards orangish brown. The agitation and heating were kept for 4 hours and 30 minutes to give the 2-(n-butyl)-5-nitro benzofuran (52%). |
