Aluminum complexes amido

The reaction of methacrolein with cyclopentadiene catalyzed by a chiral menthoxyaluminum complex gives adducts with ee s of up to 72%, but with other dienophiles little, if any, induction was noted.9495 A chiral cyclic amido aluminum complex 2 catalyzes the cycloaddition of cyclopentadiene with the fran.v-crotyl derivative 3 in good yield and enantioselectivity (Scheme 26.2).47 This chiral catalyst can also be easily recovered. 

Tridentate diamidoether (N,0,N) ligands have been used as supports for a series of A1 and Ga complexes with amide and aUcoxide initiators (Figure The A1 ate complexes polymerize rac-LA with moderate heteroselectivity (P =0.65-0.67). In comparison, the related neutral aUcoxy dimer requires more forcing conditions to reach high conversions and is isoselective (P =0.62)J The related aluminum and gallium amido complexes are more active than the alkoxide and can generate PLA with p =0.70. i... 

In 1999, Coates and Ovitt reported the first example of highly syndiotactic PLA (with syndiotacticity up to 96%) formation from the ROP of wieso-LA catalyzed by chiral aluminum isoperoxide complex (R, P)-lb [93], Due to the high degree of stereoregularity, this PLA has a high of 152°C. When catalyzed by achiral metal complexes through a chain-end-control mechanism, the ROP of wieso-LA did not produce highly stereo-controlled PLAs. For example, -diketiminate zinc complex 5a [69] afforded syndiotactic PLA with a P value of 0.76 and yttrium amido complex 6 [94, 95] yielded a moderate syndiotactic PLA material with a P, value of 0.76. 

Several examples of organoaluminum-catalyzed hydroamination of amino-alkenes have been reported recently. The neutral amido bis(anilide) 27 [37] and the aluminum pincer diolate complex 28 [114] displayed low catalytic activity and were only applicable to gem-disubstituted aminopentenes (Fig. 7). 

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