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Table 2 Thermolysis of isoxazolin-5-ones 8 in the presence and absence of potassium ethoxide

From: N-heteroatom substitution effect in 3-aza-cope rearrangements

# Compounds 8 Conditions Products Yielda(%)
   Temp./Time 9 Others
1 8a: R = H 60°C / 30 m 9a (75) -
2 8b: R = Me 60°C / 10 m 9b (85) -
3 8c: R’ = Me 180°C / 7 h 9c (95)b -
4 8d: R’ = Ph 180°C / 5 h 9d (97)  
5 8e 180°C / 5 h - 12 (80)
6 8e EtOKc,d / RT / 5 h - 13 (80)
7 8d: R’ = Ph EtOKc,d / RT / 10 m - 14 (25) 15 (45)
8 8b: R = Me EtOKc,e / RT / 5 d 9b (55) -
   EtOKc,d / RT / 10 m 9b (30) -
  1. aIsolated yields after flash-chromatography. bSee ref. 11. cIn the presence of 18-crown-6 ether. dIn the presence of EtOK (1.5 eq). eIn the presence of EtOK (0.1 eq).