Chiral calcium phosphate

The chlorination of ketone derivatives was also explored The Antilla group reported a high yielding and enantioselective chiral calcium phosphate-catalyzed chlorination of 3-substituted oxin-doles with NCS (eq 36). ... 

Table 11 Chiral calcium phosphate-catalyzed asymmetric amination reactions affording optically active a-hydrazinoketones...

Table 13 Chiral calcium phosphate-catalyzed 1,4-addition reactions...

Table 24 Chiral calcium phosphate-catalyzed asymmetric phosphination of imines...

Antilla et al. also investigated chiral calcium BINOL phosphate catalysts [94] for reviews of asymmetric phospination reactitMis, see [95, 96]. This type of calcium catalyst was apphed to asymmetric phosphinatimi reactions (Table 24). Not only a chiral magnesium phosphate but also a chiral calcium phosphate was... 

Mannich Reactions Catalyzed by Chiral Calcium Phosphate... 

The actual catalyst in phosphoric acid-catalyzed Mannich-type reaction of imines with 1,3-dicarbonyl compounds is certainly phosphoric acid itself [74], but metal contaminants, such as alkali or alkaline-earth metals, have interesting effects on the reactivity and stereoselectivity. HCl-washed, metal-free chiral phosphoric acid 149a and chiral calcium phosphate 149b are able to catalyze the Mannich-type reactions. The absolute stereoselectivity of the phosphoric acid catalysis is opposite that of the calcium phosphate catalysis (Scheme 28.16) [75]. 

The same chiral calcium phosphate salt (392) has further been employed in asymmetric benzoyloxylation of 3-aryl-2-oxindoles (393) with benzoyl... 

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