Reactions of Chiral Carbonyl Dienophiles with Achiral Dienes

1 Reactions of Chiral Carbonyl Dienophiles with Achiral Dienes 

Reactions of chiral glyoxylates with non-activated dienes such as 2,3-dimethyl-1,3-butadiene or cyclohexadiene have been carried out at high pressure to increase yield and stereoselectivity. 

Among the Lewis acids studied in asymmetric hetero Diels-Alder reactions of carbonyl compounds rare earth cations proved to be mild and efficient catalysts. This is demonstrated by the results observed in reactions of camphor sultam (63) derivatives with achiral 1-methoxy-l,3-butadiene. 

In reactions of phenylmenthyl glyoxylate with 2-trimethylsilyl-oxy-l,3-pentadiene in the presence of a catalytic amount of anhydrous MgBr2 high diastereoselectivities were obtained ( 98 2).  

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