Allylic benzimidate

On the other hand, when the allylic benzimidate 13 was treated with phenylselenenyl bromide, cyclization occurred to form the intermediate diastereomeric iminium salts 14 which were directly converted in good yield into the corresponding synjanti mixtures of amino alcohol derivatives 15. The stereoselectivity of the cyclization was determined by hydrodeselenation of the purified diastereomeric mixtures, hydrolysis of the benzoate esters and comparison of the resulting amino alcohols with authentic samples245. 

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. 

A related planar chiral Co-based oxazoline palladacycle COP-X (46) was later found to be of higher synthetic utility as it permitted the use of benzimidates, [62] as well as allylic trifluoro- [63] and trichloroacetimidates [64, 65]. 46 was found to be superior to its ferrocene analogue 41 [61] in a number of aspects such as ease of... 

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