Regio- and stereoselective vinylic substitution reactions of α-haloenyne sulfones
作者:Mitsuhiro Yoshimatsu、Junko Hasegawa
DOI:10.1016/0040-4039(96)01682-6
日期:1996.10
The nucleophilicvinylicsubstitution reaction of (E)-α-haloenyne sulfones 2, 5–8 with sodium alkoxides proceeded regioselectively to give (E)-α-alkoxyenyne sulfones 9–17 in high yields with exclusive retention of their configuration.
Diazomethane add to the enyne sulfones 1, 3, 4, 6–11 regio-
and stereo-selectively to give the
4-alkynyl-5-phenylsulfonyl-4,5-dihydro-3H-pyrazoles 12–15
and 17–19, which are converted by MeLi into the
4-alkynyl-1H-pyrazoles 24, 25, 16, 26, 28, 30 in good yields.
4,5-Bis(alkynyl)-1H-pyrazoles 34, 37 are also obtained by the
same procedure.