Asymmetric Organocatalysis on a Technical Scale
153
times (Tsogoeva et al. 2002). Advantages of this CMR-concept with soluble polymer-supported oligo(l-Leu) are the high conversions in combination with an elegant catalyst recycling and separation, as well as
high enantioselectivities (Tsogoeva et al. 2002).
3.7
Epoxidation/II: Shi Epoxidation
In addition to the Julia–Colonna epoxidation, also the Shi-epoxidation
received commercial interest. This epoxidation has been developed by
the Shi group in recent years and is based on the use of a d-fructosederived enantiomerically pure ketone 32 as a catalyst (Tu et al. 1996;
Wang et al. 1997; review: Shi 2004). Besides the simple approach to the
catalyst starting from an easily available raw material, the high enantioselectivities and the very broad substrate range are further key advantages of this impressive epoxidation technology. Recently, DSM researchers jointly with Shi reported the application of this efficient Shi
epoxidation technology on commercial scale for the synthesis of an
epoxide derivative of 31 (Ager et al. 2007; Ager 2003). This compound
is of interest as a key intermediate in the synthesis of lactone 33 (Ager
et al. 2007). The multi-step synthesis is shown in Scheme 10. For the
epoxidation key step, the overall yields were around 63%, and the resulting lactone 33 showed a chemical purity of 97% and an enantiomeric
excess of 88% ee. This product quality was sufficient to be used for the
subsequent step without further purification. The overall amount of produced lactone was greater than 100 kg (Ager et al. 2007) Notably, the
overall synthesis of the lactone 33 was accomplished without isolation
of any of the intermediates. It should be added that Ager et al. also reported a large-scale feasible and cost effective method for the synthesis
of the organocatalyst, 32 (Ager et al. 2007).
3.8
Other Reactions
Several other examples in the field of (asymmetric) organocatalysis,
which are not described in more detail in this contribution, have been
reported as well. For example, Fehr and co-workers from Firmenich
reported a very interesting asymmetric protonation reaction based on
the use of an organocatalyst on technical scale (Fehr 2006; C. Fehr,
153
times (Tsogoeva et al. 2002). Advantages of this CMR-concept with soluble polymer-supported oligo(l-Leu) are the high conversions in combination with an elegant catalyst recycling and separation, as well as
high enantioselectivities (Tsogoeva et al. 2002).
3.7
Epoxidation/II: Shi Epoxidation
In addition to the Julia–Colonna epoxidation, also the Shi-epoxidation
received commercial interest. This epoxidation has been developed by
the Shi group in recent years and is based on the use of a d-fructosederived enantiomerically pure ketone 32 as a catalyst (Tu et al. 1996;
Wang et al. 1997; review: Shi 2004). Besides the simple approach to the
catalyst starting from an easily available raw material, the high enantioselectivities and the very broad substrate range are further key advantages of this impressive epoxidation technology. Recently, DSM researchers jointly with Shi reported the application of this efficient Shi
epoxidation technology on commercial scale for the synthesis of an
epoxide derivative of 31 (Ager et al. 2007; Ager 2003). This compound
is of interest as a key intermediate in the synthesis of lactone 33 (Ager
et al. 2007). The multi-step synthesis is shown in Scheme 10. For the
epoxidation key step, the overall yields were around 63%, and the resulting lactone 33 showed a chemical purity of 97% and an enantiomeric
excess of 88% ee. This product quality was sufficient to be used for the
subsequent step without further purification. The overall amount of produced lactone was greater than 100 kg (Ager et al. 2007) Notably, the
overall synthesis of the lactone 33 was accomplished without isolation
of any of the intermediates. It should be added that Ager et al. also reported a large-scale feasible and cost effective method for the synthesis
of the organocatalyst, 32 (Ager et al. 2007).
3.8
Other Reactions
Several other examples in the field of (asymmetric) organocatalysis,
which are not described in more detail in this contribution, have been
reported as well. For example, Fehr and co-workers from Firmenich
reported a very interesting asymmetric protonation reaction based on
the use of an organocatalyst on technical scale (Fehr 2006; C. Fehr,