Spiro ligands

Spiro Ligands for Asymmetric Catalysis 85 4.3 Carbon-carbon bond-forming reactions... 

Compared with well-established electrophilic it-allylpalladium chemisty, the catalytic asymmetric reaction via umpolung of jt-allylpalladium has received very limited exploration [93]. Zhou and co-workers investigated the Pd-catalyzed asymmetric umpolung allylation reactions of aldehydes [22a, 94], activated ketones [95], and imines [96] by using chiral spiro ligands (5)-18e, (S)-17c, and (5)-17a, respectively. One representative example is that of the Pd/(5)-18e-catalyzed umpolung allylation of aldehydes with allylic alcohols and their derivatives, which provided synthetically useful homoallylic alcohols from readily available allylic alcohols, with high yields and excellent enantioselectivities (Scheme 33). 

A spiroketal bisphosphine (R R,R)-38a derived chiral Au complex was found to be an efficient catalyst for asymmetric cyclopropanation of diazooxindoles with a broad range of aUcenes, providing a highly diastereo- and enantioselective approach for spiro cyclopropyloxindoles (Scheme 41) [47]. These results further demonstrate the special advantage of rigid spiro ligands in Au-catalyzed reactions. 

Professor Zhou s group from Nankai University reported that chiral spiro ligands developed in their laboratory cooperated with monovalent copper can catalyze intramolecular asymmetric O-H bond insertion, which could be used to construct various ring systems, including five-, six- and seven-membered ring [10]. Catalyzed by copper(I), the a-diazo carbonyl compounds containing primary... 

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