Rearrangements of Derivatives of Benzo[b]thiepin and Benzo[b]thiepin 1,1-Dioxide

✍ Scribed by Priv.-Doz. Dr. H. Hofmann; Dipl.-Chem. H. Westernacher

• Publisher: John Wiley and Sons
• Year: 1967
• Tongue: English
• Weight: 227 KB
• Volume: 6
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/anie.196702552

✦ Synopsis

Whereas free BN radicals with unresolved ESR signals are formed on dehalogenation of pyridine-and 2-alkylpyridinedialkylchloroboranes by lithium in tetrahydrofuran 111 at 0 to 5"C, associated radicals ( I ) , whose ESR spectra show a hyperfine structure of ten lines (distances: 3.83 gauss), are obtained from the adducts of dialkylchloroboranes and 4-alkylpyridines. The resolution can be ascribed to the coupling of the free electron to three boron atoms121. In the spectrum of ( I ) in 10-2 M solution, an additional hyperfine structure (see Fig. 1) also appears, the resolution of which varies with the linewidth associated with the substituent R in the aromatic ring, in the order CH2C6Hs M CH3 w CzHs > C3H7 > CH(CH3)z > C(CH3)3. Simultaneously the association (measured cryoscopically in benzene) decreases from x w 3 to x w 1.5.