Thioketals Thioketones

Mercaptans are generally prepared by displacement reactions. However. secondary or hindered mercaptans are more difficult to obtain. The dithiolane cleavage icaction is a convenient in situ generation of thioketones which are known to be reduced with butyllithium to secondary mercaptans by p-hydrogen transfer Table I shows a number of mercaptans prepared from saturated thioketals in 78-90% yields. The aryl example gives lower yields partly because of ring metalation. 

Thioketals s. Mercaptals a-Thioketocarboxylic acids s. a-Mercapto-/ ,a-ethylene-carboxylic acids Thioketones... 

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