Benzoyl xanthate photolysis

This problem is not so severe when acyl xanthates are used as precursors because these substrates absorb in the visible region, while the products do not (however, the products might still be recycled to the radical pool by radical addition-elimination). Visible light photolysis of benzoyl xanthane (42) and allyl acetate provides (43) in 60% yield. Standard (ionic) 3-elimination of the xanthane is a facile reaction that gives (44). When the tertiary acyl xanthane (45) is irradiated in the presence of W-benzylmaleimide... 

The use of a low-molecular-weight sulphur-containing photoinitiator, such as S-benzoyl O-ethyl xanthate (BEX) is described for the polymerization of MMA [133], Laser flash photolysis of BEX reveals [134] that the primary photoprocess involves a C(=0)-S cleavage to generate both the benzoyl and the ethoxythio-caibonylthiyl radicals which initiate the polymerization (Scheme 34). 

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