Intramolecular cyclization reactions of 5-halo- and 5-nitro-substituted furans.
[reaction: see text] Intramolecular cyclization reactions of 5-halo- and 5-nitro-substituted furanylamides were examined. The 2-alkoxy-5-bromofuran derivative 2 produced the rearranged dihydroquinone 6 (36%), a product from the rearrangement of the intermediate oxabicycle 3. The 5-halo substituted furoyl amide 18 was converted to the polyfunctional oxabicycle 20 in 82% yield and at a much faster rate than the unsubstituted furanyl system 17. The 5-nitro-substituted furfuryl amide 33b underwent an unusual isomerization-cyclization reaction under microwave conditions to provide 1,4-dihydro-2H-benzo[4,5]furo[2,3-c]pyridin-3-one 34.
Crawford
Kenneth R
KR
Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA.
Bur
Scott K
SK
Straub
Christopher S
CS
Padwa
Albert
A
D000577:Amides / Q000737:chemistry; D002384:Catalysis; D003500:Cyclization; D005663:Furans / Q000737:chemistry*; D006219:Halogens / Q000737:chemistry*; D007536:Isomerism; D009020:Morphine / Q000737:chemistry; D009581:Nitrofurans / Q000737:chemistry*; D011728:Pyridones / Q000737:chemistry; D011809:Quinones / Q000737:chemistry
C403008:1,4-dihydroquinone; D000577:Amides; D005663:Furans; D006219:Halogens; D009581:Nitrofurans; D011728:Pyridones; D011809:Quinones; D009020:Morphine