Bridged Sulfides by Addition of Sulfur Dichloride to Dienes

Bridged Sulfides by Addition of Sulfur Dichloride to Dienes 

An interesting addition reaction of sulfur dichloride has been discovered that allows the preparation in good yield of bridged cyclic sulfides from cyclic dienes. Two examples of the reaction have been described ( S) employing in one case 1,3-cyclo-octadiene and in the other 1,5-cyclooctadiene. The former sequence is shown in the scheme. The experimental details of the latter sequence are given below. 

5-Cyclooctane Sulfide (9-Thiabicyclo[3.3.1]nonane) from 1,5-Cyclooctadiene 

5-Cyclooctane Sulfide To 12.5 g (0.06 mole) of the dichlorosulfide in 150 ml of ether is added 1.2 g (0.03 mole) of lithium aluminum hydride in 60 ml of ether at a rate so as to maintain a gentle reflux (about 20 minutes). The mixture is allowed to stand overnight and is then cautiously treated with water to decompose the excess hydride. The mixture is mixed with fuller s earth (Floridin) and is filtered, and the filtrate is dried over anhydrous magnesium sulfate. Filtration of the solution and evaporation of the solvent (rotary evaporator) gives about 7 g of the colorless crystalline solid, mp 170-171°. It may be recrystallized from aqueous methanol, mp 172-173°. 

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