Synthesis catalytic enantioselective

Mermerian AH, Fu GC (2003) Catalytic enantioselective synthesis of quaternary stereocenters via intermolecular C-acylation of silyl ketene acetals dual activation of the electrophile and the nucleophile. J Am Chem Soc 125 4050-4051... 

Catalytic enantioselective synthesis of vzc-diols is a challenging issue. Chiral induction using chiral ligands is difficult to achieve. The moderately enantioselective pinacolization of benzaldehyde is demonstrated to be performed by the chiral titanocene catalysts 15 and 16 [42,43]. 

M J. O Donnell, F. Delgado, C. Hostettler, R, Schwesinger, An Efficient Homogeneous Catalytic Enantioselective Synthesis of a-Amino Add Derivatives , Tetrahedron Lett. 1998,39, 8775-8778. 

Bartoni, G. Bosco, M. Carlone, A. Locatelli, M. Massaccesi, M. Melehiorre, P., Sambri, L. (2004) Asymmetric aminolysis of aromatic epoxides A facile catalytic enantioselective synthesis of a z-P-amino aleohols Org. Lett., 6 2173-2176. 

In a related process, Johnson and co-workers have developed an asymmetric metallophosphite-catalyzed intermolecular Stetter-hke reaction employing acyl silanes [81, 82], Acyl silanes are effective aldehyde surrogates which are capable of forming an acyl anion equivalent after a [l,2]-Brook rearrangement. The authors have taken advantage of this concept to induce the catalytic enantioselective synthesis of 1,4-dicarbonyls 118 in 89-97% ee and good chemical yields for a,p-unsaturated amides (Table 11). Enantioselectivities may be enhanced by recrystallization. 

Catalytic enantioselective synthesis of 4,4-dimethyl-l-phenyl-l,2-pentadiene from 4,4-dimethyl-1,2-pentadiene and iodobenzene using 0.4 to 1 mol % of palladium complexes containing chiral phosphane ligands as the catalyst for the enantioselective cross coupling134 is the only example of substoichiometric transition metal catalyzed enantioselective allene synthesis. 

Chirality plays a central role in the chemical, biological, pharmaceutical and material sciences. Owing to the recent advances in asymmetric catalysis, catalytic enantioselective synthesis has become one of the most efficient methods for the preparation of enantiomer-ically enriched compounds. An increased amount of enantiomerically enriched product can be obtained from an asymmetric reaction using a small amount of an asymmetric catalyst. Studies on the enantioselective addition of dialkylzincs to aldehydes have attracted increasing interest. After the chiral amino alcohols were developed, highly enantioselective and reproducible —C bond forming reactions have become possible. 

The results shown in Scheme 6 are representative and point out which ligand provides the highest selectivity for a particular substrate (<2% SN2 product in all cases). The catalytic enantioselective synthesis of quaternary carbons represents a unique and effective method for the regio- and enantioselective prepa-... 

Unlike carbocyclic and oxygen-containing heterocyclic systems, catalytic enantioselective synthesis of eight-membered ring amines proceeds efficiently and with excellent enantioselectivity. These catalytic ARCM reactions can be carried out in the absence of solvent as well. Representative data regarding cat-... 

Scheme 11. Catalytic enantioselective synthesis of amines in the absence of solvent through Mo-catalyzed ARCM...

The ester enolate-imine condensation, also called Gilman-Speeter reaction, is another well-accepted method for (3-lactam synthesis (Scheme 4) [67-69]. In 1997, Tomioka reported the first example of a direct catalytic enantioselective synthesis of (3-lactam by using this method [70]. The active reagent is a ternary complex (comprising LDA, the ester enolate, and tridentate amino diether), which finally affords the (3-lactam compounds in high yields and good ee values. 

Table 5.7 Catalytic enantioselective synthesis of a,a-dialkyl-a-amino acids by phase-transfer alkylation.

Scheme 5. Catalytic, enantioselective synthesis of the polyol fragment of amphotericin B according to Carreira et al. a) 2 mol % TolBINAP-CuFj, -78 X, then CF,COOH b) nBuOH, IlOX c) EtjBOMe,...

Permanganate oxidation of 1,5-dienes to prepare f r-2,5-disubstituted tetrahydrofurans is a well-known procedure (Equation 80). The introduction of asymmetric oxidation methodology has revived interest in this area. Sharpless-Katsuki epoxidation has found widespread application in the catalytic enantioselective synthesis of optically active tetrahydrofurans and the desymmetrization of w ro-tetrahydrofurans <2001COR663>. A general stereoselective route for the synthesis of f-tetrahydrofurans from 1,5-dienes has been developed which uses catalytic amounts of osmium tetroxide and trimethyl amine oxide as a stoichiometric oxidant in the presence of camphorsulfonic acid <2003AGE948>. 

Katsuki, T. (2001) The catalytic enantioselective synthesis of optically active epoxides and tetrahydrofurans. 

Katsuki, T. The Catalytic Enantioselective Synthesis of Optically Active Epoxides and Tetrahydrofurans. Asymmetric Epoxidation, the Desymmetrization of mew-Tetrahydrofurans, and Enantiospecific Ring-Enlargement, Curr. Org. Chem. 2001,5, 663-678. 

Keck, G. E., Li, X.-Y., Krishnamurthy, D. Catalytic Enantioselective Synthesis of Dihydropyrones via Formal Hetero Diels-Alder Reactions of "Danishefsky s Diene" with Aldehydes. J. Org. Chem. 1995, 60, 5998-5999. 

Abe, H., Amii, H. and Uneyama, K. (2001) Pd-catalyzed asymmetric hydrogenation of a-fluo-rinated iminoesters in fluorinated alcohol a new and catalytic enantioselective synthesis of fluoro a-amino acid derivatives. Org. Lett., 3, 313-315. 

Corey EJ, Helal CJ (1996) Catalytic enantioselective synthesis of the second generation histamine agonist cetirizine hydrochloride. Tetrahedron Lett 37 4837-4840... 

Addition to C=X bond. Allylzinc reagents add to the carbonyl group of p-keto phosphonates. With respect to a catalytic enantioselective synthesis of chiral pyrimidyl carbinols, an automultiplication phenomenon is elucidated. ... 

Otera, J., Niiho, Y. and Nozaki, H. (1991) Oxirane ring-opening with alcohol catalysed by organotin phosphate condensates. Complete inversion at tertiary and henzylic centers. Tetrahedron, 47, IClS-lCiA, Corey, E.J. and Helal, C.J. (1993) A catalytic enantioselective synthesis of chiral monosuhstituted oxiranes. Tetrahedron Letters, 34, 5227-5230. 

Biddle, M.M., Lin, M. and Scheidt, K.A. (2007) Catalytic enantioselective synthesis of flavanones and chromanones. Journal of the American Chemical Society, 129, 3830-3831. 

A catalytic enantioselective synthesis of chiral N-(o-f-butylphenyl) indoles 347 has been reported (10CEJ6752). It involved a chiral Pd"-cata-lyzed 5-endo-hydroaminocyclization of N-(o-ferf-butylphenyl)alkynylani-lines 346. 

In spite of the tremendous progress in catalytic asymmetric synthesis [36,177] its use in the syntheses of anthracyclinones is limited, apart from Baker s yeast reduction and Sharpless epoxidation and dihydroxylation. In the recent anthracyclinone literature two contributions have appeared on the application of catalytic enantioselective synthesis. Both are based on the desym-metrization of a meso compoimd, but in entirely different chemical contexts. 

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