Thiochromans and Thiochromenes

Thiochromans and Thiochromenes. - Cyclization of /3-(phenylmercapto)-propyl phenyl ketones (228) with perchloric acid gave a mixture of products, the pyrylium salt (229) and the thiochroman (230 R = Me or Ph, R = Ph or Me) predominating. An improved procedure has been developed for the synthesis of 1-thiaphenalene (232) from the acid chloride (231).  

Dehydrogenation of thiochroman is accompanied by rearrangement to 2-methylbenzo[b]thiophen. The thiochroman derivative (45) also rearranges, thermally and photochemically, to a benzothiophen (46). Diben- 

The intramolecular rotation of the aldehyde group of benzaldehyde has been studied in the clathrate compound formed with 4-p-hydroxyphenyl-2,2,4-trimethylthiochroman. This thiochroman can also be used to store 

Viktorova, A. A. Freger, A. V. Egorov, and L. M. Petrova, Khim. geterotsikl. Soedinenii, 

A previous report that 3-bromothiochroman-4-one is reduced by sodium borohydride to the cis-3-bromo-4-hydroxy-compound has been confirmed. Attempts to methylate 3-methylthiochroman-4-one with methyl iodide-potassium t-butoxide failed to produce the expected 3,3-dimethyl derivative instead, the much more complex product (49) is formed. Methylation with other bases present, however, does proceed normally. 

The cyclopropanothiochromanone (50) undergoes stereoselective ring opening when treated with hydrogen chloride in chloroform. 3-Cyanothio-chroman-4-one has been synthesized conventionally from methyl 

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