Tol-BINAP-AgF

The complex -Tol-BINAP-AgF (/>-Tol-BINAP - 2,2 -bis(di-/)-tolylphosphanyl)-l,l -binapthyl) catalyzes the asymmetric addition of allylic trimethoxysilanes to aldehydes (Equation (7)).7 3 The process can provide various optically active homoallylic alcohols with high enantioselectivity (up to 96% ee) and a remarkable 7 and anti- selectivities are observed for the reaction with crotylsilanes, irrespective of the configuration of the double bond ... 

Independently, Yamamoto, Yanagisawa, and others reported the asymmetric aldol reaction using trimethoxysilyl enol ethers.19 The reaction was conducted with aldehydes and trimethoxysilyl enol ethers in the presence of Tol-BINAP-AgF to give the corresponding adducts with high enantioselectivities and diastereoselectiv-ities. They obtained vyra-aldol adducts as major products even when silyl enol ethers derived from cyclic ketones were used. Moreover, when a,(3-unsaturated aldehydes were employed as substrates, 1,2 adducts were obtained exclusively (Table 9.10). From an NMR study and correlation between the E Z ratio of the enol ethers and diastereoselectiviy, they proposed a cyclic transition state (Fig. 9.5). Thus, the reaction of E enol ethers proceeded via a boat form, whereas the reaction of Z enol ethers took place via a chair form. 

As shown in Scheme 10.132 (Section 10.3.1.2), Yamamoto et al. have recently reported highly enantioselective allylation of aromatic and a, -unsaturated aldehydes with allyltrimethoxysilane using (P)-(p-Tol-)BINAP AgF as catalyst [377]. Shibasaki et al., on the other hand, have succeeded in asymmetric allylation of acetophenone with allyltrimethoxysilane by use of a p-Tol-BINAP CuCl-TBAT co-catalyst system (up to 61% ee) [378]. 

Table 18.1 Enantioselective allylation of aldehydes with al-lyltrimethoxysilane (27) catalyzed by (R)-/ -Tol-BINAP- AgF complex. ...

In contrast, Yanagisawa, Yamamoto, and coworkers have studied diverse combinations of BINAP-silver(I) catalysts and silyl enolates and found that high levels of asymmetric induction and isolated product yields were attained in the p-Tol-BINAP-AgF-catalyzed aldol reaction of trimethoxysilyl enolates (38) with aldehydes (39) in methanol (Scheme 18.15) [54]. Table 18.2 summarizes the results... 

Yanagisawa A, Kageyama H, Nakatsuka Y, Asakawa K, Matsumoto Y, Yamamoto H. Enantioselective addition of allylic trimethoxysilanes to aldehydes catalyzed by p-Tol-BINAP - AgF. Angew. Chem. Int. Ed. 1999 38 3701-3703. 

H. Yamamoto reported an enantioselective allylation of aldehydes catalyzed by AgF-p-tol-BINAP complex, [Eq. (13.24)]. High enantioselectivity was obtained... 

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