Microwave Assists The Reaction of Sodium Azide with Enediynes to Synthesize Triazolopyridines

1
Microwave Assists The Reaction of Sodium Azide
with Enediynes to Synthesize Triazolopyridines
Chih-Wei Tsaib, Ming-Jung Wua, aGraduate
Institute of Pharmaceutical Sciences, Kaohsiung
Medical University, Kaohsiung, Taiwan. bFaculty
of Medicinal and Applied Chemistry, Kaohsiung
Medical University, Kaohsiung, Taiwan. Tel
886-7-3121101 ext 2220 Fax [phone]
E-mail mijuwu_at_cc.kmu.edu.tw
Abstract
Recently, we found that the reaction of enediynes
1 with sodium azide gave triazolopyridines 2 and
3 in modest to good chemical yields1. However,
the reaction time is quite long and large amount
of sodium azide is required. In order to provide
a more efficient reaction conditions, some metal
halides as the catalyst have been employed in
this reaction to improve the selectivity and
chemical yields. It was also found that the
reaction time could be reduced under microwave
reaction conditions.
scheme 2
The synthetic chemical mimicry of the
double-helex structural motif is an interesting
area of research with intense activity in recent
years2. Triazolopyridines have been found new
potential helicating ligands3, however the
synthetic method is few. Recently, we found that
the reaction of enediynes 1 with sodium azide
gave triazolopyridines 2 and 3 in modest to good
chemical yields. Further enedyines were tested
(scheme 1). Under Microwave reaction conditions,
no product was obtained using CH3CN, THF and
toluene as solvent but DMF and DMSO, the reaction
time was reduced and only 1.2 equiv. of
sodium azide is needed. Metal halides were also
employed as an addition and MgBr2 gave the best
chemical yields (scheme 23).
scheme 1
scheme 3
Reference

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  Rev.1992, 48, 10013-10059.
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