LaLi3tris -binaphthoxide

LLB = LaLi3tris(binaphthoxide. LPB = LaK3tris(bmaphthoxide). PrSB = PrNa3tris(binaphthoxide). GdSB = GdNa3tris(binaphthoxide). 

Scheme 9.2. (R)-LaLi3tris(binaphthoxide)-catalyzed enantioselective three-component Mannich reaction.

Shibasaki and coworkers have conducted extensive research on the use of hetero-bimetallic complexes as catalysts for asymmetric synthesis [11]. The reactions are catalyzed by heterobimetallic complexes that function as both a Lewis acid and a Bronsted base. Among these, LaLi3tris(binaphthoxide) catalyst 1 (LLB) was proven to be an effective catalyst in direct asymmetric aldol reactions (Fig. 1) [12]. On the basis of this research, Shibasaki et al. reported the first report of a direct catalytic asymmetric Mannich reaction [13],... 

Figure . LaLi3tris(binaphthoxide) catalyst 1 and AlLibis(binaphthoxide) (ALB) 2.

LLB lanthanum-lithium-binaphthoxide complex LaLi3tris(binaphthoxide)... 

LaLi3tris(binaphthoxide) catalysts (LLB catalyst, see Section 7.1) have also been used for this reaction,although the method of preparation of the catalyst is important for very high selectivities. The LLB catalyst (6.107) was prepared by mixing LaCl3.7H20 (1 equiv.) BINOL dilithium salt (2.7 equiv.) and sodium... 

In a one-pot synthetic method for chiral 2,2-disubstituted oxetanes, a sequential addition reaction of a sulfur ylide to ketones and intermediate epoxides was promoted by the heterobimetallic catalyst LaLi3tris(binaphthoxide) (LLB). Chiral amplification was observed in the second reaction and was the key to affording the desired oxetanes with excellent enantioselectivity (Scheme 14). 

In 1999, Shibasaki et al. reported on the direct catalytic asymmetric aldol reaction (Scheme 8.36), which was not necessary to preconvert the ketone moiety into the more reactive species such as an enolate ion and enol ether." The addition of bulky aldehyde 248 into the mixture of ethyl methyl ketone 249 and LaLi3tris(/ -binaphthoxide) [(/ )-LLB)] afforded aldol adduct 250 in excellent stereoselectivity. However, this reaction required a large amount of ketones (50 equiv), and catalyst (20 mol%) were required. They improved the conditions to reduce the amount of ketone (5 equiv) and catalyst (8 equiv) by using the hetero-polymetallic asymmetric catalyst (Scheme 8.37). The addition of the catalytic amount of potassium bis(trimethylsilyl) amide (KHMDS) and H2O was found to be effective to the catalysis. Adduct 253 was converted into ester 254 by the... 

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