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Synthesis of 2 H ‐indazole‐4,7‐dione derivatives from 3‐phenylsydnone and p ‐toluquinone. The crystal and molecular structure of 6‐bromo‐5‐methyl‐2‐phenyl‐2 H ‐indazole‐4,7‐dione
Author(s) -
Nan'ya Seiko,
Katsuraya Kaname,
Maekawa Eturǒ,
Kondo Kazumoto,
Eguchi Shoji
Publication year - 1987
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570240415
Subject(s) - indazole , chemistry , monoclinic crystal system , crystal structure , regioselectivity , cycloaddition , molecule , stereochemistry , 1,3 dipolar cycloaddition , crystal (programming language) , crystallography , medicinal chemistry , organic chemistry , catalysis , computer science , programming language
The 1,3‐dipolar cycloaddition of 3‐phenylsydnone with p ‐toluquinone afforded 5‐methyl‐ and 6‐methyl‐2‐phenyl‐2 H ‐indazole‐4,7‐diones 3a and 3b. No regioselectivity was observed in this cycloaddition yielding an equimolar amount of the regioisomers. Reactions of 3a and 3b with bromine gave the corresponding mono‐ 4a and 4b and dibromo derivatives 5a and 5b , respectively. The crystal structure of 6‐bromo‐5‐methyl‐2‐phenyl‐2 H ‐indazole‐4,7‐dione ( 4a ) has been determined by the single crystal X‐ray method. The crystals are monoclinic, space group PI with two molecules in a unit cell of dimensions a = 8.029(1), b = 14.309(1), c = 5.895(1)Å, β = 90.24(1)° and V = 621 Å 3 . The structure has been solved by the direct method using 1827 reflections and refined by full‐matrix least‐squares calculations to R = 0.0739.