of benzene was added slowly 1.88 g (7.6 mmol) of tris (diethylamino )phosphine (2). After 10 min, the benzene was removed under vacuum and the residue chromatographed over silica gel.Elution with 10% chloroform in hexane afforded 50 mg (7%) of 6H, 12H-dibenzo[6,/] [1,5] dithioocin as colorless crystals, mp 172-178°, which after crystallization from ethanol afforded colorless needles, mp 173-175°(lit.24 mp 174-176°).2-Phenyl-l,3-propanedithiol (10).-A solution of 4.6 g (10 mmol) of 2-phenyl-l ,3-propanediol ditosylate26 and 10 g (130 mmol) of thiourea in 50 ml of ethanol was refluxed for 4 hr; the ethanol was removed under vacuum and the residue refluxed under nitrogen with 10 g of sodium hydroxide in 50 ml of water for 12 hr. After careful acidification, the mixture was extracted with chloroform and the extract washed well with water, dried, and evaporated to dryness. The crude oil was fractionally distilled under vacuum to afford 1.0 g (55%) of a pale yellow oil: bp 76-78°( 0.005 mm); nmr (CDClg) r 2.70' (mulitplet, 5 H, aromatic), 6.0-7.4 (multiplet, 5 H), 8.7 (multiplet, 3 H, S-H). This crude dithiol was used without further purification.4-Phenyl-1,2-dithiolane ( 12).-A solution of 1.4 g (7.6 mmol) of the dithiol 10 and 1.8 g (1.8 mmol) of triethylamine in 20 ml of methanol was added dropwise with stirring in a nitrogen atmosphere to a solution of 1.95 g (8 mmol) of iodine in 50 ml of methanol. The resulting solution was rapidly filtered and the filtrate cooled in dry ice until crystals formed. The crystals were filtered and washed well with cold methanol to afford 1.0 g (73%) of yellow crystals, mp 77-83°. Sublimation at 75°and 25-µ pressure afforded 488 mg of yellow crystals: mp 82-84°; ir (KBr) 1600, 1490, 1460, 775, and 705 cm"1 (aromatic); ^ ' 335 µ (e 143); nmr (CDClg) 2.66 (multiplet, 5 H, aromatic), 6.5 (multiplet, 5 H).
