Asymmetric epoxidation titanium tartrate catalysis

Finn, F M, Hofmann, K 1976, in Neurath, H, Hill, R L (eds), The Proteins, 3rd edn, Vol II, chapter 2(p 106—237), Academic Press New York London Finn, M G, Sharpless, fC. B 1985, On the Mechanism of Asymmetric Epoxidation with Titanium-Tartrate Catalysts, in Momson, J D (ed), Asymmetric Synthesis, Vol 5 Chiral Catalysis chapter 8, p 247, Academic Press New York Fischer, E 1914, Chem Ber 47,196 Fischer, H, Slangier G 1927, Liebigs, Ann Chem 459, 53 Fischer, H Neber, M 1932. Liebigs Ann Chem 496,1... 

The asymmetric epoxidation of allylic alcohols using titanium tetraisopropoxide/ tartrate ester/terf-butylhydroperoxide was developed by Sharpless during the 1980s to become one of the most important methods of asymmetric catalysis. Whilst there... 

The great synthetic versatility of epoxides has prompted intense efforts to identify reliable enantioselective methods for their synthesis [71]. In 1980, this challenge was met as Sharpless announced the groundbreaking discovery that titanium-tartrate complexes in combination with tert-butyl hydroperoxide readily catalyze enantioselective epoxidations of allylic alcohols [72]. This transformation has rightly earned its prominent place in the history of organic chemistry and asymmetric catalysis. In subsequent investigations it was found that the addition of molecular sieves to the reaction mixture had a beneficial effect on the process. Consequently, under optimal conditions the epoxidation reaction can be performed with only 5-10 mol % of the readily available Ti catalyst [73, 74]. A wide variety of allylic alcohols can be epox-... 

Sharpless epoxidation of allyl alcohols (Sharpless, 1985, 1988 Pfenninger, 1986 Rossiter, 1985 Woodard et al., 1991 Finn and Sharpless, 1991 Corey, I990a,b), an example of which is included in Table 9.6, is perhaps the most recent and one of the most remarkable applications of asymmetric catalysis. The reaction is normally performed at low temperatures (-30 to 0°C) in methylene chloride with a titanium complex consisting of a chiral component [diethyl tartrate (DET) or diisopropyl tartrate (DIPT)] and a titanium salt (titanium tetraisopropoxide) as the catalyst. The beauty of the synthesis is that both enantiomers of the tartrate are available so that either form of the product can be prepared in more than 90% ee. 

---