Co2(CO)8-mediated endo mode cyclization of epoxy-alcohol: synthesis of 2-ethynyl-3-hydroxy-2-methyltetrahydropyran and 2-ethynyl-3-hydroxy-3-methyltetrahydropyran derivatives.
Successive treatment of 4,5-epoxy-5-methyl-7-trimethylsilyl-6-heptyne-1-ol with Co2(CO)8 at 0 degrees C and a catalytic amount of BF3 x OEt2 at -78 degrees C gave the tetrahydropyran derivatives with the cobalt-complexed moiety. Similarly 4,5-epoxy-4-methyl-7-trimethylsilyl-6-heptyne-1-ol underwent ring closure under the above conditions to provide the corresponding tetrahydropyran derivatives. The preferential endo mode cyclization over the exo one was observed in these experiments.
Mukai
C
C
Faculty of Pharmaceutical Sciences, Kanazawa University, Japan. cmukai@kenroku.kanazawa-u.ac.jp
Yamaguchi
S
S
Kim
I J
IJ
Hanaoka
M
M
D000480:Alkynes / Q000737:chemistry*; D003500:Cyclization; D004852:Epoxy Compounds / Q000737:chemistry*; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D011714:Pyrans / Q000737:chemistry*; D013055:Spectrophotometry, Infrared
C436725:2-ethynyl-3-hydroxy-2-methyltetrahydropyran; D000480:Alkynes; D004852:Epoxy Compounds; D007202:Indicators and Reagents; D011714:Pyrans