Suzuki asymmetric

Suzuki and co-workers recently applied the asymmetric intramolecular benzoin reaction to the synthesis of the homoisoflavonoid (-F)-sappanone B 122 [54]. The authors found that triazolium salt pre-catalyst 120 gave the best results for the... 

Pu and co-workers incorporated atropisomeric binaphthols in polymer matrixes constituted of binaphthyl units, the macromolecular chiral ligands obtained being successfully used in numerous enantioselective metal-catalyzed reactions,97-99 such as asymmetric addition of dialkylzinc reagents to aldehydes.99 Recently, they also synthesized a stereoregular polymeric BINAP ligand by a Suzuki coupling of the (R)-BINAP oxide, followed by a reduction with trichlorosilane (Figure 10).100... 

The development of chiral catalysts for use in enantioselective rhodium-catalyzed hydroborations was pioneered by Burgess9, Suzuki,77 and Hayashi.78 The chiral diphosphine ligands employed in their preliminary investigations 23-26 (Figures 2(a) and 2(b)), had previously been successfully applied in other catalytic asymmetric transformations. 

H. Sasai, T. Suzuki, S. Arai, T. Arai, M Shibasaki, Basic Character of Rare Earth Metal Alkoxides. Utilization in Catalytic C-C Bond-Forming Reactions and Catalytic Asymmetric Nitroaldol Reactions, J. Am. Chem. Soc 1992,114, 4418-4420. 

H. Sasai, T. Suzuki, N. Itoh, K. Tanaka, T. Date, K. Oka-mura, M Shibasaki, Catalytic Asymmetric Nitroaldol Reaction Using Optically Active Rare Earth BINOL Complex Investigation of the Catalyst Structure, J. Am Chem Soc 1993,115,10372-10373. 

H. Sasai, T. Tokunaga, S. Watanabe, T. Suzuki, N. Itoh, M. Shibasaki, Efficient Diastereoselective and Enantiose-lective Nitroaldol Reactions from Prochiral Starting MaterialsStUtilization of La-Li-6,6 -Disubstituted BINOL Complexes as Asymmetric CatalystsUtJ. Org Chem 1995, 60, 7388-7389. 

Shima, K., Omori, R., and Suzuki, A., 2001, High- Q concentrated directional emission from egg-shaped asymmetric resonant cavities. Opt Lett. 26(ll) 795-797. 

Other important examples of immobilized palladium catalysts (48)-(50) which were employed in Heck, Suzuki-Miyaura and allylic alkylation reactions are summarized in Fig. 4.4 [123]. Catalyst (49) is particularly noteworthy as it is a recyc-able amphiphilic resin-supported P,N-chelating Pd-complex which performs asymmetric allylic alkylations in water. 

The protected diol side-chain of 456 is introduced by asymmetric dihydroxylation and directs diastereoselectivity in the formation of 457 and 458 by lithiation. The most acidic position of 456, between the two methoxy groups, is first protected by silylation. Suzuki coupling of 459 with the boronic acid 460 gives the kinetic product 461—the more severe hindrance to bond rotation in this compound does not allow equilibration to the more stable atropisomer of the biaryl under the conditions of the reaction. 

Quinazolines take part in the same types of reactions as pyrimidines, but because of their additional benzene ring, the products of these reactions may have the added feature of hindered rotation. An example of this is the synthesis of 2-phenyl-Quinazolinap by Guiry and co-workers <99TA2797>. Suzuki coupling of 4-chloro-2-phenylquinazoline (115) with boronic acids 116 led to 117 (R = OMe). These intermediates were parlayed into phosphinamines 117 (R = PPh2) and then subjected to chiral resolution to produce new chiral phosphinamine ligands for asymmetric catalysis. 

Applications in Stereoselective CatalYsis 127 Table 1.4.6 Results of the asymmetric Suzuki coupling. 

S. Akutagawa, Practical Asymmetric Syntheses of (—)-Menthol and Related Terpenoids, in R. Noyori, T. Hiraoka, K. Mori, S. Murahashi, T. Onoda, K. Suzuki, and O. Yonemitsu, eds., Organic Synthesis in Japan Past, Present, and Future, p. 75, Tokyo Kagaku Dozin, Tokyo, 1992. 

Asymmetric induction of central chirality at a carbon atom was achieved by an intramolecular enantioposition-selective asymmetric cross-coupling [12]. Treatment of the prochiral bisbo-rane 46, which was prepared from the alkenyl triflate 45 and 2 equiv. of 9-BBN with 20 mol % of Pd/(S)-(/ )-BPPFOAc (48) catalyst generated in situ in THF, brings about intramolecular Suzuki coupling. The following oxidative workup and p-nitrobcnzoylation affords the chiral cyclopentane derivative (R)-47 in 58% yield and 28% ee (Scheme 8F.14). 

In a related study, the Shibasaki group examined cyclizadon of naphthyl triflate 10.1 (Scheme 8G.10) [23], Cyclization of 10.1 under standard cationic conditions gave Heck product 10.2 in 78% yield and 87% ee. Evidently, the reaction is fairly tolerant of the nature of the aryl group, because both 10.1 and 9.3 behaved similarly. An interesting variation of this reaction was also demonstrated in which Suzuki coupling and asymmetric Heck cyclization were performed in a one-pot operation. Thus, treatment of ditriflate 10.3 with borane 10.4 under standard Heck conditions provided 10.2 in similar enantioselectivity to the stepwise procedure, albeit in quite low yield. Heck product 10.2 was converted in several steps to the natural products, halenaqui-none (10.5) and halenaquinol (10.6). 

Suzuki et al. reported the photochemical reaction of CT crystals, in which cycloaddition reaction of bis(l,2,5-thiadiazolo)tetracyano-quinodimethane 17 (electron acceptor) and 2-divinylstylene 18 (electron donor) is efficiently induced (Scheme 3). [17] A structural feature of the CT crystal is the asymmetric nature of the inclusion lattice because of the adoption of a chiral space group, P2. The [2 + 2] photoadduct 19 was formed via the single crystal-to-single crystal transformation, and the optically active product with 95% ee was obtained. 

Sasai, H. Suzuki, T. Arai, S. Arai, T. Shiba- 446 saki, M. Basic character of rare earth metal alkoxides. Utilization in catalytic C-C bondforming reactions and catalytic asymmetric nitroaldol reactions./. Am. Chem. Soc. 1992,... 

New substituted BINOL ligands have been obtained by directed ort/io-lithiation or Suzuki cross-coupling.104 The ligand (R)-(38) has shown improved catalytic properties for the asymmetric diethylzinc addition to aromatic aldehydes. 

Savizky, R. M., Suzuki, N. and Bove, J. L. The use of sonochemistry in the asymmetric epoxidation of substituted chalcones with sodium perborate tetrahydrate. Tetrahedron Asymmetry, 1998, 9, 3967-3969. 

Hayashi Y, Tsuboi W, Shoji M, Suzuki N (2003a) Application of high pressure induced by water-freezing to the direct catalytic asymmetric three-component List-Barbas-Mannich reaction. J Am Chem Soc 125 11208-11209... 

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