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Indazaboles—synthesis and molecular structure
Author(s) -
Wrackmeyer Bernd,
Shahid Khadija,
Kempe Rhett,
Döring Christian,
Milius Wolfgang
Publication year - 2010
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/aoc.1627
Subject(s) - chemistry , diborane , boranes , borane , trimethylsilyl , ring (chemistry) , nuclear magnetic resonance spectroscopy , indazole , crystallography , solid state , stereochemistry , alkylation , gas phase , computational chemistry , medicinal chemistry , organic chemistry , boron , catalysis
The reaction of 1‐trimethylsilyl‐indazole with boranes affords indazaboles accompanied by elimination of trimethysilane. Thus, the two isomers of parent indazabole are formed in a 1:1 ratio using borane in THF (BH 3 /THF), characterized by NMR spectroscopy in solution ( 1 H, 11 B and 13 C NMR). In contrast, the analogous reaction with 1,2‐bis(tetramethylene)diborane(6) proceeds to give a single isomer of the B‐alkylated indazabole via symmetric ring cleavage of the diborane(6), as shown by NMR in solution and X‐ray structural analysis in the solid state. The molecular structure is fluxional in solution. In the solid state, the central B 2 N 4 ring adopts a distorted boat conformation. Calculated gas phase geometries of the parent indazaboles and of the B‐alkylated indazabole were optimized by DFT methods at the B3LYP/6‐311 + G(d,p) level of theory. Copyright © 2010 John Wiley & Sons, Ltd.