Olefins enantioselective synthesis

Kovacik, I., Wicht, D.K., Grewal, N.S., Glueck, D.S., Incarvito, C.D., Guzei, I.A., and Rheingold, A.L., Pt(Me-Duphos)-catalyzed asymmetric hydrophosphination of activated olefins enantioselective synthesis of chiral phosphines,... 

The modification of chiral enamines enables the asymmetric nitro-olefination of oxyin-doles, as shown in Eq. 4.98.124 An enantioselective synthesis of (-)-psudophyrnaminol is accomplished using this reaction. 

Diastereoselective intermolecular nitrile oxide—olefin cycloaddition has been used in an enantioselective synthesis of the C(7)-C(24) segment 433 of the 24-membered natural lactone, macrolactin A 434 (471, 472). Two (carbonyl)iron moieties are instrumental for the stereoselective preparation of the C(8)-C(ii) E,Z-diene and the C(i5) and C(24) sp3 stereocenters. Also it is important to note that the (carbonyl)iron complexation serves to protect the C(8)-C(ii) and C(i6)-C(i9) diene groups during the reductive hydrolysis of an isoxazoline ring. 

Mikami and Hatano70 demonstrated the efficiency of the dicationic [Pd(MeCN)4](BF4)2/BINAP catalyst system in DMSO with the highly enantioselective synthesis of a variety of quinoline derivatives, including spiro-compound 99 (Equation (63)), resulting from olefin isomerization of the Alder-ene product. 

At first, the reaction was characterized as most effective in the epoxidation of cw-disubstituted olefins.86 Later, the scope of this reaction was expanded to include the highly enantioselective synthesis of hYwiv-dis ubstitutcd8 7 and tri-substituted epoxides,88 as well as certain monosubstituted epoxides.89 The first example of nondirect asymmetric epoxidation of tetrasubstituted olefins has also appeared.90... 

Catalytic olefin metathesis, in only a few years, has risen to be one of the most important and reliable processes in organic synthesis. Recently, several reports by Schrock and Hoveydallsbbond forming transformations efficiently and enan-tioselectively. A recent concise and enantioselective synthesis of exo-brevicomin by Burke utilizes chiral catalyst 91 (Scheme 13) to effect the desymmetriza-tion of 90 through a ring-closing metathesis.11531... 

Perlmutter used an oxymercuration/demercuration of a y-hydroxy alkene as the key transformation in an enantioselective synthesis of the C(8 ) epimeric smaller fragment of lb (and many more pamamycin homologs cf. Fig. 1) [36]. Preparation of substrate 164 for the crucial cyclization event commenced with silylation and reduction of hydroxy ester 158 (85-89% ee) [37] to give aldehyde 159, which was converted to alkenal 162 by (Z)-selective olefination with ylide 160 (dr=89 l 1) and another diisobutylaluminum hydride reduction (Scheme 22). An Oppolzer aldol reaction with boron enolate 163 then provided 164 as the major product. Upon successive treatment of 164 with mercury(II) acetate and sodium chloride, organomercurial compound 165 and a second minor diastereomer (dr=6 l) were formed, which could be easily separated. Reductive demercuration, hydrolytic cleavage of the chiral auxiliary, methyl ester formation, and desilylation eventually led to 166, the C(8 ) epimer of the... 

This approach sets the stage for an enantiotopos-differentiating olefin metathesis which would allow the enantioselective synthesis of 258. However, the realization of such an approach has not yet been successful [132]. The second building block (259) containing the A ring was synthesized diastereoselectively by a diastereoface-differentiating intramolecular Heck-Mizoroki reaction of the enantiomerically enriched furan 260 [120]. 

R. Beresis, J.S. Panek, A concise enantioselective synthesis of frans-olefin dipeptide isosteres, Bioorg. Med. Chem. Lett. 3 (1993) 1609-1614. 

The Direct Enantioselective Synthesis of Diols from Olefins using Hybrid Catalysts of Chiral Salen Cobalt Complexes Immobilized on MCM-41 and Titanium-containing Mesoporous Zeolite... 

Organometallic compounds asymmetric catalysis, 11, 255 chiral auxiliaries, 266 enantioselectivity, 255 see also specific compounds Organozinc chemistry, 260 amino alcohols, 261, 355 chirality amplification, 273 efficiency origins, 273 ligand acceleration, 260 molecular structures, 276 reaction mechanism, 269 transition state models, 264 turnover-limiting step, 271 Orthohydroxylation, naphthol, 230 Osmium, olefin dihydroxylation, 150 Oxametallacycle intermediates, 150, 152 Oxazaborolidines, 134 Oxazoline, 356 Oxidation amines, 155 olefins, 137, 150 reduction, 5 sulfides, 155 Oxidative addition, 5 amine isomerization, 111 hydrogen molecule, 16 Oxidative dimerization, chiral phenols, 287 Oximes, borane reduction, 135 Oxindole alkylation, 338 Oxiranes, enantioselective synthesis, 137, 289, 326, 333, 349, 361 Oxonium polymerization, 332 Oxo process, 162 Oxovanadium complexes, 220 Oxygenation, C—H bonds, 149... 

Scheme 15. Enantioselective synthesis of carbocyclic tertiary ethers and spirocycles through Mo-catalyzed asymmetric olefin metathesis...

List B, Lerner RA, Barbas CF 3rd (2000) Proline-catalyzed direct asymmetric aldol reactions. J Am Chem Soc 122 2395-2396 List B, Pojarliev P, Martin HJ (2001) Efficient proline-catalyzed Michael additions of unmodified ketones to nitro olefins. Org Lett 3 2423-2425 List B, Pojarliev P, Biller WT, Martin HJ (2002) The proline-catalyzed direct asymmetric three-component Mannich reaction scope, optimization, and application to the highly enantioselective synthesis of 1,2-amino alcohols. J Am Chem Soc 124 827-833... 

The SMB technology was developed by UOP and its major field of application is in the area of binary separations. For example, SMB has been used in the chemical industry for several separations known as SORBEX processes [1-3], which include, among others, the PAREX process for p-xylene separation from a Cs aromatic fraction [4], the OLEX process for the separation of olefins from paraffins, the SAREX process to separate fructose from glucose [4] and the MOLEX process [5]. Simulated moving bed is being used particularly for separation of enantiomers from racemic mixtures or from the products of enantioselective synthesis [6,7]. It has been used for the production of fine chemicals, and petrochemical intermediates, such as Cg-hydrocarbons [8], food chemistry such as fatty acids [2], or certain sugars from carbohydrate mixtures [8] and protein desalination [9]. 

Nishioka, T., Iwabuchi, Y, Irie, H., and Hatakeyama, S., Concise enantioselective synthesis of (-t)-aspicilin based on a ruthenium catalyzed olefin metathesis reaction. Tetrahedron Lett.. 39, 5597, 1998. Williams, D.R., and Clark, M.P., The macrocyclic domain of phorboxazole A. A stereoselective synthesis of the Cj-Cjj macrolactone. Tetrahedron Lett., 40, 2291. 1999. 

Two successful strategies for the enantioselective synthesis of trans-epoxides by means of oxo-metal catalysis have been discovered. The stereospecific epoxidation of frans-olefins offers a direct route to trans-epoxides, although progress in this area has been limited (see Sect. 2.2.1). Alternatively, the [Mn(salen)]-catalyzed epoxidation of cis-disubstituted olefins in the presence of alkaloid-derived phase-transfer catalysts such as 24 resulted in the formation of the transepoxide as the major, and in some cases nearly exclusive, product (Scheme 6)... 

---