YAMAMOTO Chirality Transfer

NAD(P)H. 32. Stereoselective reduction of camphoroquinone by a chiral NAD(P)H model. Bull Chem Soc Jpn 54 3478-3481 Ohno A, Nakai J, Nakamura K, Goto T, Oka S (1981c) Reduction by a model of NAD(P)H. 33. Steric and electronic effects on asymmetric reduction of 2-acylpyridines. Bull Chem Soc Jpn 54 3482-3485 Ohno A, Yamamoto H, Oka S 0 981d) Reduction by a model of NAD(P)H. 35. Spectroscopic detection of charge-transfer intermediate. Bull Chem Soc Jpn 54 3489-3491... 

Yamamoto has reported the intramolecular e%o-hydroamination of N-allenyl sulfonamides and carbamates catalyzed by simple, unligated gold(I) and gold(III) salts. Noteworthy was that cyclization of N-allenyl sulfonamide derivatives that possessed an axially chiral allenyl moiety occurred with highly selective transfer of chirality to the newly formed tetrahedral stereogenic carbon atom [38]. For example, treatment of enantiomerically enriched y-allenyl tosylamide 52 (96% ee) with a catalytic amount of AuCl in THF at room temperature led to isolation of ( )-2-(l-heptenyl)pyrroldine ( )-53 in 99% yield with 94% ee (Eq. (11.28)). 

Nishina and Yamamoto have also reported the gold(I)allenes with alcohols [109]. As an example, treatment of a neat mixture of p-tolyl allene and isopropanol with a catalytic 1 1 mixture of (PPh3)AuCl and AgOTf at 30 °C led to isolation of isopropyl )-3-(4-tolyl)-2-propenyl ether in 98% yield (Eq. (12.39)). The protocol was most effective for monosubstituted and 1,3-disubstituted allenes and gave no transfer of chirality for the hydroalkoxylation of 1-phenyl-l,2-butadiene. Horino has reported the gold(I)-catalyzed intermolecular addition of alcohols to the allenyl moiety of 4-vinylidene-2-oxazolidinones [110]. 

The group of Miyaura [78, 89] applied arylbismuth compounds [88] in these metal-catalyzed reactions. The application of this compound type in such met2il-catalyzed reactions is stiU rare. In fact, as has already been mentioned, Miyaura s group reported the use of chiral phosphane/dicationic palladium(II) complexes (based on (S,S)-Chiraphos and (S,S)-Dipamp) in the 1,4-addition of triaryl-bismuth reagents to cyclic and acyclic enones in aqueous methanol at low temperature (Scheme 5.32). Enantioselectivities of up to 95% ee were achieved for cyclic enones. The use of Cu(BF4)2 to help the reoxidation of Pd(0) to the catalyticaUy active Pd(II) species was an advantage, as well as the efficiency of the aryl transfer, allowing utilization of 2-2.8 of the three phenyl groups on the bismuth atom. Several years ago, Yamamoto, Nishikata, and Miyaura [68c] published a personal account of... 

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