Zirconium-catalyzed asymmetric carboalumination

Zirconium-catalyzed asymmetric carboalumination of alkenes (ZACA reaction) 272... 

Figure 8.12 Stereo- and enantioselective synthesis of (S,f ,f ,S,f ,S)-4,6,8,10,16,18-hexa-methyldocosane via iterative zirconium-catalyzed asymmetric carboalumination of alkenes (ZACA reaction).

Zirconium-Catalyzed Asymmetric Carboalumination of Alkenes (ZACA Reaction)... 

ZACA Zirconium-catalyzed Asymmetric Carboalumination of Alkenes anj CH2R are very similar... 

In the last decade, zirconium-catalyzed asymmetric carboalumination of alkenes (ZACA) has been developed [65]. Most commonly used catalyst is bis... 

Negishi reported the zirconium-catalyzed enantioselective carboalumination of alkenes, which consisted of a hydroalumination/alkylalumination tandem process.133-135 This permits the asymmetric syntheses of methyl-substituted alkanols and other derivatives, typically with >90% ee, which represents an increase in ee value by 15% from the previously obtained 70-80%.136-138 The hydroalumination/zirconium-catalyzed enantioselective carboalumination of alkenes was carried out using (—)-bis(neomenthylindenyl)zirconium dichloride as the catalyst (Table 15).133... 

The carbometalation reaction has been reviewed recently [28-30]. Negishi has demonstrated that zirconium(TV) complexes catalyze the carboalumination of MesAl to various alkynes and enynes [31]. Also the Zr-catalyzed asymmetric carboalumination of aUcenes (ZACA reaction) [32-34] has found important applications in the synthesis of natural products [35-37]. Especially efficient was the asymmetric synthesis of insect pheromones such as (S. / ./ ,S. / ,S)-4,6,8,10,16,18-hexamethyl-docosane (88) (Scheme 8) [38]. 

Negishi coupling reactions can be combined with asymmetric carboalumination, a process that was also discovered by the Negishi group (Scheme 5-87). The asymmetric induction of this zirconium-catalyzed enantioselective methylalumination process ( ZACA ) stems from a chiral zirconium catalyst precursor, namely dichlorobis(neomenthylindenyl)zirconium [(NM aZrCb]. The stereoinduction is very high. 

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