Thio-Claisen rearrangement synthetic utility

The Claisen rearrangement of allyloxy heterocycles is another reaction which has been studied in some detail. Yields can be variable and mixtures of N- and C-allyl products are sometimes obtained (e.g. equation 70). In other cases the reaction can be of considerable synthetic utility e.g. equation 71). The thio-Claisen rearrangement has also been studied in many cases the intermediate thiones react further (equation 72), although they can also be trapped, for example with ethyl chloroformate. 

Potentially, the Claisen rearrangement is of greater synthetic utility merely because it is not coirfined to hydrocarbon substrates. However, no palladium-catalyzed thio-Claisen rearrangements have been observed, possibly owing to sulfijr poisoning the catalysts. Nevertheless, thioimidates have been rearranged in the presence of catalytic quantities of [PdCl2(PhCN)2]. 

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See also in sourсe #XX -- [ , ]

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