Acid catalysis combined

Recently, the power of designer acid catalysts has generally increased as a result of the development of the catalytic enantioselective versions described here. In particular, combined acid catalysis is still very much in a state of infancy, and there is still much more to learn with regard to new reactivity. The ultimate goal is a more reactive, more selective, and more versatile catalyst. We beheve that the realization of such an objective would be a tremendous benefit for the further development of organic synthesis, including green chemistry. 

Designer acids combined acid catalysis for asymmetric synthesis (H. Yamamoto, 2005) [Id]. 

In contrast to some related reviews, which use reaction class or electrophiles as organizational elements, this chapter is divided into three main sections according to catalyst class (i) Bronsted acid catalysis by phosphoric acid and phosphoramide derivatives, (ii) N—H hydrogen bond catalysis by organic base and ammonium systems, and (iii) combined acid catalysis including Bronsted-acid-assisted Bronsted acid, Lewis-acid-assisted Bronsted acid, and Lewis-acid-assisted Br0nsted acid systems (Figure 5.1). 

Abstract The concept of bifunctional acid catalysis is very helpful for inventing new catalytic asymmetric reactions. Compared with single functional acid catalysts, cooperative effect of two acid components has the potential to fine tune the reactivity as well as the selectivity of desired reaction pathways. This chapter focuses on some representative examples on the recent developments of bifunctional acid catalysis, including combined acid catalysis and other cooperative acid catalysis. 

Keywords Asymmetric synthesis Bifunctional acid catalysis Combined acid catalysis Cooperative acid catalysis Designer acid... 

Beyond the concept of combined acid catalysis, there are also many other bifunctional acid catalysts interacting with nucleophiles and electrophiles simultaneously, and thus benefiting through such cooperative effect. Selected examples on Lewis acid/hydrogen bonding cooperative catalysis and Lewis acid/transition-metal... 

The remaining part of this chapter will highlight some recent examples in which bifunctional acid catalysis does not involve combined acid catalysis, namely, two acid components (either Lewis acid, hydrogen bonding, or transition metal) are... 

Since we have already summarized examples of combined acid catalysis [2], only recent representative examples of such catalysis are discussed with emphasis on the area of asymmetric catalysis in the following sections. 

I ] Recent Advance of Combined Acid Strategy for Asymmetric Catalysis Table 1.1 The general classifications of combined acid catalysis. 

Since the introduction of our review article of combined acid catalysis in 2005 [2], this concept has clearly continued to interpenetrate the area of asymmetric catalysis and rapidly evolving, as is apparent from the summary described herein. 

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