Thiopyran sulphones

Successive treatment of bis-3,3-dimethylallenyl sulphone (357) with butyl-lithium in THF at 0 °C gave a 60% yield of the dithia-adamantane (358), whose structure was confirmed by X-ray crystallography. Photolysis of thietans in the presence of a new triplet sensitizer, l,3-dimethyl-2-thioxoimidazolidine-4,5-dione, has produced interesting results for example, the spiro-xanthone (359) gave the acetate (360), but in u.v. light, and without the sensitizer, the thiopyran (361) was obtained in addition to (360). Among several flavonoids identified in a Chinese plant. Euphorbia lunulata Bge., which is used in the treatment of... 

Thiophosgene reacts with cyclohexa-1,3-diene to yield the adduct (17 R = Cl), which can be hydrolysed to the ketone or reduced with lithium aluminium hydride to the bicyclo[2,2,2]oct-5-ene. The related sulphone (18), made by addition of dimethyl acetylenedicarboxylate to 3-phenyl-2H-thiopyran 1,1-dioxide, undergoes a reverse Diels-Alder reaction at 220 C,... 

Sulphones of the thiopyran series continue to receive attention. The acidities of compounds (34 R = H) and (34 R = Me) have been measured the former is a stronger acid than the acyclic disulphone MeS02CH2S02Me, but a weaker acid than the keto-sulphone MeCOCH2S02Me. Several conjugated systems of types (35) and (36) have been prepared. The electronic situation in the thiopyran rings of these compounds should... 

X-Ray crystallographic data have been reported for two compounds of this series/ one of each type. In both examples, the thiopyran ring is not planar but is boat-shaped the bond lengths indicate appreciable contributions from the dipolar structures, and suggest that the sulphone groups are involved in the ir-electron delocalization. 

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