Intramolecular Aldol Reaction Starting from Triketones

2 Intramolecular Aldol Reaction Starting from Triketones 

The intramolecular aldol reaction of triketones with asymmetric desymmetrization has been known for a long time. When Eder, Sauer, and Wiechert [97, 98], and in parallel Hajos and Parrish [99-101] reported this reaction in the early 1970s it was the first example of an asymmetric catalytic aldol reaction, and one of the first examples of an organocatalytic asymmetric synthesis [104]. 

The Danishefsky group reported the use of an organocatalytic intramolecular aldol reaction in the synthesis of a key intermediate, 108, for preparation of optically active estrone and commercially relevant 19-norsteroids [118, 119]. In the presence 

Although the highest enantiomeric excess of the products was 43% only, in principle this route is an interesting and promising means of produdng cydic enones with a chiral center by use of a readily available catalyst. 

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