Ligands chiral binaphthyl ligand

A series of chiral binaphthyl ligands in combination with AlMe3 has been used for the cycloaddition reaction of enamide aldehydes with Danishefsky s diene for the enantioselective synthesis of a chiral amino dihydroxy molecule [15]. The cycloaddition reaction, which was found to proceed via a Mukaiyama aldol condensation followed by a cyclization, gives the cycloaddition product in up to 60% yield and 78% ee. 

The amount of catalyst can be reduced to 5 mol % using the binaphthyl-derived Ti-com-plex 32 [11]. Only 2 mol% of Carreira s [12] catalyst 35 is necessary to obtain good yields and high ee values. However, the chiral binaphthyl ligand for 35 is not commercially available. 

The same group also reported that when cadmium nitrate or perchlorate salts were used in the preparation of the MOF, two different MOF structures can be obtained with the same chiral binaphthyl ligand [130]. This diversity in crystal structures seemed to arise from the participation of the anion accompanying Cd " " in the structure. The chiral MOF prepared from nitrate acts as an efficient heterogeneous catalyst for the room-temperature asymmetric addition of diethylzinc to a series of aromatic aldehydes, with ee values up to 90% at 100% substrate conversion. Conversely, the MOFs derived from the perchlorate salt were inactive under the same conditions. 

The Diels-Alder reaction has not escaped the attention of chemists interested in asymmetric synthesis. A binaphthyl-based chiral aluminium complex (30) catalyses the hetero Diels-Alder cycloaddition between benzaldehyde and the Danishefsky diene (29), providing the dihydropyrone (32) with excellent selectivity after acid hydrolysis of the initial adduct (31). 0 2] (We will see further applications of chiral binaphthyl ligands in section 6.4.)... 

Gong L-Z, Pu L (2000) The asymmetric hetero-Diels-Alder reactitm of enamide aldehydes with Danishefsky s diene and an efficient synthesis of chiral binaphthyl ligands. Tetrahedrrai Lett 41 2327-2331... 

Related catalysts include both a chiral BINAP-type phosphine and a chiral diamine ligand. A wide range of aryl ketones gave more than 95% enantioselectivity when substituted-l,l -binaphthyl and ethylene diamines were used.52... 

Aromatic and vinylic sulfides take part in cross-coupling reactions with Grignard reagents in the presence of Ni catalysts.336,337 This reaction has been applied to the enantioselective synthesis of binaphthyls using a standard chiral oxazoline ligand (Equation (25)) 338... 

The effect of additives on Shibasaki s lanthanide-BINOL catalysts has been investigated by Inanaga and coworkers. From a variety of additives, triphenylphosphine oxide turned out to be the best one improving, for example, the obtained ee for the chalcone epoxide from 73% to 96% (Table 16) . The explanation for the positive effect of the additive was the disruption of the oligomeric structure of the catalyst by coordination of the phosphine oxide. As a consequence, epoxidation takes place in the coordination sphere of the ytterbium where the reaction site might become closer to the chiral binaphthyl ring due to the phosphine oxide ligand with suitable steric buUdness. In contrast to the Shibasaki... 

This type of catalytic strategy has recently been extended to enantio-selective addition of alkyllithiums to certain prochiral imines (Scheme 18) (35). Relevantly, in the presence of a small amount of a chiral ether ligand, 1-naphthyllithium reacts with a sterically hindered imine of l-fluoro-2-naphthaldehyde (conjugate addition/elimination) to afford a binaphthyl compound in greater than 80% ee. 

In 1996, Yamamoto and Yanagisawa reported the allylation reaction of aldehydes with allytributyltin in the presence of a chiral silver catalyst.2 They found that the combination of silver and a phosphine ligand accelerates the allylation reaction between aldehydes and allyltributyltin. After this discovery, they screened several chiral phosphine ligands and found that chiral silver-diphosphine catalysts can effect the reaction in an enantioselective fashion (Table 9.1).2 For example, when benz-aldehyde and allyltributyltin were mixed in the presence of 5 mol% of AgOTf and (S)-2,2 -bis(diphenylphosphino)-1,1 -binaphthyl (BINAP), the corresponding homoallyl alcohol was obtained with 96% ee and 88% yield (Table 9.1). Generally, the reaction with aromatic aldehydes afforded the corresponding homoallyl alcohols in excellent... 

Shi and Wang reported that the catalyst generated from AgOTf and a chiral diphenylthiophosphoramide ligand, which was prepared from chiral 1,1 -binaphthyl-2, 2 -diamine, could promote the allylation reaction of allyltributyltin and aromatic aldehydes (Table 9.4).8 Thus, the reaction of allyltributyltin and aldehyde in the presence of AgOTf and chiral diphenylthiophosphoramide gave the corresponding adducts with up to 98% ee. 

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