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Highly Efficient Synthesis of 5‐Substituted 1 H ‐Tetrazoles Catalyzed by Cu–Zn Alloy Nanopowder, Conversion into 1,5‐ and 2,5‐Disubstituted Tetrazoles, and Synthesis and NMR Studies of New Tetrazolium Ionic Liquids
Author(s) -
Aridoss Gopalakrishnan,
Laali Kenneth K.
Publication year - 2011
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201100957
Subject(s) - chemistry , ionic liquid , alkylation , catalysis , trifluoromethanesulfonate , onium , cycloaddition , counterion , organic chemistry , medicinal chemistry , polymer chemistry , ion
A series of 5‐substituted 1 H ‐tetrazoles were synthesized through [3+2] cycloaddition reactions between nitriles RCN and NaN 3 in the presence of Cu–Zn alloy nanopowder as catalyst. The 1,5‐dibutyl, 1‐butyl‐5‐hexyl, 2,5‐dibutyl, and 2‐butyl‐5‐hexyl derivatives were then used as building blocks to synthesize several novel tetrazolium ionic liquids (ILs) with EtSO 4 – , OTf – , and NTf 2 – counterions. Whereas alkylation of the 2,5‐dialkyltetrazoles selectively gave the N‐4 alkylated onium salts, with the 1,5‐dialkyl derivatives approximately 1:1 mixtures of two tetrazolium salts were formed by alkylation at N‐3 and N‐4. The triflate and ethyl sulfate salts are room‐temperature ILs that are hydrophilic, whereas the NTf 2 salts are low‐melting ILs and are hydrophobic. The resulting tetrazolium‐based ionic liquids were studied by various multinuclear and 2D NMR techniques including natural abundance 15 N and 1 H/ 15 N correlations.