Conformational features and chemical behavior of 5H, 7H-dibenzo[B,g][1,5] dithiocin oxides: 1,5-Oxygen shift via a dithiodication intermediate

✍ Scribed by Katsuo Ohkata; Keiji Okada; Kin-Ya Akiba

• Book ID: 102847424
• Publisher: John Wiley and Sons
• Year: 1995
• Tongue: English
• Weight: 769 KB
• Volume: 6
• Category: Article
• ISSN: 1042-7163
• DOI: 10.1002/hc.520060208

✦ Synopsis

Abstract

Some 5H,7H‐dibenzo[b,g][1,5]dithiocin oxides (4–8) and their related compounds 9–13 were prepared and the assignment of the most favorable conformation was carried out on the basis of the characteristic ^1^H NMR spectral data. Only a single conformer (BC: boatchair form) exists for 4,5, and 8–13, while two conformers (BC and TB: twist‐boat form) are apparent for 6 and 7. Oxidation and methylation of 4 gave exclusively a single geometrical isomer (8 and 13, respectively). These results are interpreted as a sterically preferential attack of electrophiles on the BC conformer of the starting material. A 1,5‐oxygen shift of 4 occurred smoothly to give 6 in the presence of trifluoroacetic acid in CDCl~3~ solution. The mechanistic investigation is described briefly. Differences in chemical behavior between dibenzodithiocin 12‐oxide 4 and dibenzothiazocine 12‐oxide 2 are also discussed on the basis of the conformational features.