Synthons Claisen rearrangements

The functionally and stereochemistry provided by aldehyde (100) have led to the use of the tandem Cope-Claisen rearrangement for the synthesis of estrone methyl ether (117) and steroid synthons. Thermolysis of triene (115 Scheme 8) provides aldehyde (116) as the major component of a 2/1 mixture ... 

The first report of asymmetric catalysis with a chiral ADC ligand utilized cationic derivatives of isocyanide-derived Pd-bis(ADC) complexes 10 (Scheme 16.3) and 39 (Figure 16.6) [23b]. The catalyst derived from 10 promoted the aza-Claisen rearrangement of allylic benzimidate 42 to chiral allylic amide 43 in 30% ee, although the yield was moderate due to the presence of side products (Scheme 16.13). Replacement of the chiral diaminocyclohexane backbone of 10 with a 1,2-diphenylethane backbone in 39 led to an improvement in the ee to 59%, likely due to the steric influence of the phenyl substituents, although the yield decreased. This study established the value of the isocyanide-based approach for rational modification of chiral ADC ligands by simple variation of the amine synthon. 

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