Claisen rearrangement iodonio

Thio- [546] and even iodonio-Claisen rearrangements are known [547]. 

Alkenyl(phenyl)iodine(III) compounds can also serve as starting materials in rearrangements. Allenyl(aryl)iodine(III) compounds of type 86 can be synthesized from (diacetoxyiodo) derivatives 85 and propargylsilanes [145]. It depends on the leaving group ability of the aromatic substituent on iodine in 86 as to whether the reaction proceeds via nucleophilic substitution to compounds of type 87 or by an iodonio-Claisen rearrangement to compounds 88, Scheme 37 [146,147]. The easy access to propynyl compounds 87 has been shown [148] and solvent effects in these reactions have been investigated as well [149,150]. 

The reaction of o-iodosylbenzoic acid with l-(trimethylsilyl)-2-propyne led to a reductive iodonio-Claisen rearrangement (Section 3.8.3), permitting the preparation of 2-iodo-3-prop-2-ynylbenzoic acid [7] ... 

It is possible to incorporate other heteroatoms instead of the oxygen atom. For example, an iodonio-Claisen rearrangement of an in situ generated aUenyliodonio intermediate 68 was reported by Ochiai et al. [61],... 

The reaction of (diacetoxy)aryl-X -iodanes 105 with (trimethyl)aUylsilane in the presence of BF3 -Et20 results in an iodonio-Claisen rearrangement yielding ortho-allyliodoarenes 106 as the major product and 107 and 108 as byproducts (Scheme 30) [26]. Two heterocyclic examples have also been reported. The presence of an electron-donating group in the meta-position appears to be necessary for this transformation. 

Keywords Alkyl-shift Hoffman rearrangement Polycyclization and iodonio-Claisen Prins-Pinacol Ring expansions and cmitractions Transposition... 

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