Download (8Mb) - Etheses - Saurashtra University
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N<br />
N<br />
Br<br />
R 2<br />
N<br />
N<br />
3<br />
N<br />
H<br />
N<br />
OH<br />
R1 N 3<br />
n<br />
MeCN, 75 o C,<br />
3 Hrs<br />
N<br />
n 3<br />
+<br />
R 2<br />
1 2<br />
Br<br />
O<br />
R 1<br />
One Pot MW ?<br />
o MW. 100 C<br />
MeCN, 10 min<br />
N2H4 (7 equiv)<br />
Scheme-1 Sequential Synthesis of 2-AI-T Framework<br />
R 2<br />
R 1<br />
R 2<br />
R 1<br />
N<br />
N<br />
H<br />
H<br />
N<br />
N<br />
NH<br />
N<br />
N R3 N<br />
n<br />
MW. 100 o C<br />
Cu(OAc) 2<br />
10 min, 80 %<br />
In continuation of earlier work on two step synthesis of 2-AI-T scaffold with excellent<br />
yield. now an ameliorated and convenient one-pot protocol for the synthesis of 2-AI-T<br />
scaffold under microwave conditions has been reported.<br />
4.2 Optimization Study<br />
Looking to the current exploration in the synthesis and microwave-assisted decoration<br />
of the 2-aminoimidazole 14 and click reaction 15 and preliminary success of the<br />
sequence, it was very interesting to investigate whether one-pot protocol for the<br />
construction of 2-AI-T scaffold should be possible. The test reaction was performed<br />
with hydroxy salt {3} and phenyl acetylene as a model system. Different Cu catalyst,<br />
equiv of NH2NH2.H2O, temperature and reaction time were screened to derive an<br />
optimized protocol (Table 1).<br />
First, the application of Cu(OAc)2 as catalyst for click reaction and different<br />
equivalents of aqueous NH2NH2.H2O for simultaneous dimorth rearrangement (Table-<br />
1, No-1-3) was evaluated. However in case of 1 equiv. of hydrazine used, yield was<br />
only 51 %. (Table-1, No-1). Next study of different reaction time (Table-1, No-3-7)<br />
performed. It was observed that reaction could complete even in very short time<br />
4<br />
NH<br />
5<br />
R 3<br />
N 3<br />
n