The Synthesis of 9-Thiabicyclo[3, 3, 1]nona-3, 7-diene-2, 6-dione from cycloocta-1, 5-diene

Abstract

The recent description¹of the conversino of cyclooctatetraene into 9-thiabicycio[3,3,1]nona-3,7-diene-2,6-dione(1) prompts us to describe our preparation of this intereatin compound from the more readily available cycloocta-1,5-diene. The adduct (2) of this hydrocarbon and sulphur dichloride^2,3 was hydrolysed to the diol (3) and the latter selectively oxidised to the corresponding diketone (4) by chromium trioxide in pyridine-dichloromethane⁴. Treatment of the diketone with acetic anhdride-sulphuric acid^5,6furnished the bis-enolacetate (5). Reaction of (5) with N-bromosuccinirride,⁶ gave in high yield the surprisingly stable crystalline dibromodiacetate (6) which was found by¹ H n.m.r. to have the sterrochemistry as shown .Finally. (6) was quanititatively converted by treatment with pyridine at 70 degree into 9- thiabicyclo[3,3,1] nona-3,7-diene-2,6-dione (1), the spectroscopic properties of which are recorded in the experimental section.