ethyl diazoacetate 、
2-甲基-2-戊烯醛 在
(3aS)-1,3,3-triphenyl-3a,4,5,6-tetrahydropyrrolo[1,2-c][1,3,2]oxazaborole;1,1,1-trifluoro-N-(trifluoromethylsulfonyl)methanesulfonamide 作用下,
以
丙腈 为溶剂,
反应 1.0h,
生成
(4S, 5R)-ethyl 4-ethyl-5-formyl-5-methyl-4,5-dihydro-1H-pyrazole-3-carboxylate 、 (4R, 5S)-ethyl 4-ethyl-5-formyl-5-methyl-4,5-dihydro-1H-pyrazole-3-carboxylate