Synthesis and application of a new bisphosphite ligand collection for asymmetric hydroformylation of allyl cyanide

A series of mono- and bidentate phosphites was prepared with (S)-5,5',6,6'-tetramethyl-3,3'-di-tert-butyl-1,1'-biphenyl-2,2'-dioxy [(S)-BIPHEN] as a chiral auxiliary and screened in the asymmetric hydroformylation of allyl cyanide. These hydroformylation results were compared with those of two existing chiral ligands, Chiraphite and BINAPHOS, whose utility in asymmetric hydroformylation has been previously demonstrated. Bisphosphite 11 with a 2,2'-biphenol bridge was found to be the best overall ligand for asymmetric hydroformylation of allyl cyanide with up to 80% ee and regioselectivities (branch-to-linear ratio, b/l) of 20 with turnover frequency of 625 [h(-)(1)] at 35 degrees C. BINAPHOS gave enantioselectivities up to 77% ee when the reaction was conducted in either acetone or neat but with poor regioselectivity (b/l 2.8) and activities 7 times lower than that of 11. The product of allyl cyanide hydroformylation using (R,R)-11 was subsequently transformed into (R)-2-methyl-4-aminobutanol, a useful chiral building block. Single-crystal X-ray structures of (S,S)-11 and its rhodium complex 19 were determined.     

Asymmetric synthesis of axially chiral biaryls via desymmetrization of 2,2',6,6'-tetrahydroxybiphenyl using 1,4-Di-O-benzyl-L-threitol as a chiral template

Sequential etherification of 2,2',6,6'-tetrahydroxybiphenyl (1) with 1,4-di-O-benzyl-L-threitol under Mitsunobu conditions gives desymmetrized biphenyldiol 9 of S-axial chirality exclusively. Cyclization of 9 with 1,omega-dibromoalkanes followed by removal of the chiral auxiliary yields (S)-2,2'-biphenyldiols 14 with alkylenedioxy bridges at the 6 and 6' positions. (S)-6,6'-Dialkyl- and -diphenyldiols 20 are obtained in an efficient manner via Pd(0)-catalyzed cross-coupling of bis(triflate) derivative 17 with organozinc reagents. Bis(triflate) 17 also serves as an intermediate for asymmetric synthesis of axially chiral biphenyldicarboxylic acid 23, terphenylcarboxylic acid 28, lactone 26, and lactam 30.     

Synthesis of Novel Chiral Biphenylamine Ligand 6,6'‐Dimethoxy‐2,2′‐diaminobiphenyl

A new chiral ligand 6,6′‐dimethoxy‐2,2′‐diaminobiphenyl was successfully prepared from 3‐nitrophenol via iodination, Ullmann coupling, and reduction. The resolving reagent (2R, 3R)‐ or (2S,3S)‐2,3‐di (phenylaminocarbonyl)tartaric acid was prepared from commercially available tartaric acid in large scale and was used to resolve the racemic 6,6′‐dimethoxy‐2,2′‐diaminobiphenyl. The chiral 6,6′‐ dimethoxy‐2,2′‐diaminobiphenyl obtained was proved to be enantiomerically pure.     

Pd(Oac)2/(S)-P-PHOS催化的丙烯与CO交替共聚合成手性功能高分子

以丙烯和CO为原料,Pd(OAc)2/(S)-P-PHOS为手性催化剂,在有机溶剂中,经不对称交替共聚反应合成了手性功能高分子聚酮.当过量的还原剂LiAlH4和NaBH4分别还原聚酮时,手性聚醇产率达90%;当NaBH4/羰基摩尔比分别为0.5,1和2,紫外光谱(200～400am)检测证明,手性聚酮中羰基的29%,7...     

New Chiral Ligand N—Toluenesulfony1—2,2‘—dimethoxy—6,6’—di—aminobiphenyl for Catalytic Asymmetric Transfer Hydrogenation of Ketones

A new chiral ligand N‐p‐toluenesulfonyl‐2,2′‐dimethoxy‐6,6′‐diaminobiphenyl (Ts‐DMBDPPA) was prepared from 2,2′‐dimethoxy‐6,6′‐diaminobiphenyl via N‐tosylation. Its Ru(II) complex was effective catalysts for catalytic asymmetric transfer hydrogenation of aromatic ketones (with ee's up to 69.3%).     

Alkylidene and metalacyclic complexes of tungsten that contain a chiral biphenoxide ligand. synthesis,asymmetric ring-closing metathesis,and mechanistic investigations

Two complexes that contain the racemic or enantiomerically pure (S) form of the 3,3'-di-tert-butyl-5,5',6,6'-tetramethyl-1,1'-biphenyl-2,2'-diolate (Biphen(2-)) ligand, W(NAr)(CHCMe(2)Ph)(Biphen) (2a) and W(NAr')(CHCMe(2)Ph)(Biphen) (2b) (Ar = 2,6-i-Pr(2)C(6)H(3); Ar' = 2,6-Me(2)C(6)H(3)), were prepared and shown to be viable catalysts for several representative ring-closing reactions to give products in good yields in most cases and high % ee in asymmetric reactions. Exploration of the reaction between 2a and a stoichiometric amount of one desymmetrization substrate allowed two intermediate tungstacyclobutane complexes to be observed, in addition to the final and quite stable tungstacyclobutane complex formed in a reaction between the ring-closed product and a tungsten methylene complex. Reactions involving (13)C labeled ethylene allowed for the observation of an unsubstituted tungstacyclobutane complex, an ethylene complex, an unsubstituted tungstacyclopentane complex, and a heterochiral dimeric form of a methylene complex. The tungstacyclopentane complex was found to catalyze the dimerization of ethylene to 1-butene slowly.     

Synthesis of New Chiral Bis(BINOL) Substituted 2,2''''-Bipyridine Ligands

Chiral 2,2'-bipyridines have been reported to be highly efficient catalysts and useful building blocks of supramolecular.[1,2] Chirality of bipyridines was introduced by chiral substituents. Because 1,1'-binaphthyl (BINOL) and its derivatives belong to the most important components of asymmetric catalysts, we would like to synthesize 5,5'-and 6,6'-positions substituted chiral bipyridine-type ligands, the chiral moieties of ligands originate from enationpure 1, 1'-binapthyl units.     

Catalytic asymmetric α-alkylation of ketones and aldehydes with N-benzylic sulfonamides through carbon-nitrogen bond cleavage

A range of ketones and aldehydes smoothly undergo asymmetric S(N)1 α-alkylation with N-benzylic sulfonamides in the presence of 10 mol % of a chiral imidazolidinone and trifluoroacetic acid to give the corresponding products in good to excellent yields and with good enantioselectivity. This chemistry has been successfully extended to the asymmetric desymmetrization of 4-substituted cyclohexanones, which exhibits greater than 99:1 diastereoselectivity and good enantioselectivity.     

Novel Chiral Aminophosphine Ligand:Synthesis and Application in Saymmetric Catalytic Hydrogenation Reaction

A new chiral aminophosphine ligand 6,6′-dimethoxy-2,2′-bis(diphenylphosphinoamino)biphenyl(DMBDPPABP) was prepared and its rhodium complex was found to be an effective catalyst for the asymmetric hydrogenation of amidoacrylic acid and its dervatives.The effects of solvent and reaction temperature on enantioselectivity were also studied.     

C(2)-Symmetric bis-sulfoxide: A novel chiral auxiliary for asymmetric desymmetrization of cyclic meso-1,2-diols

A new heterocyclic compound, C(2)-symmetric bis-sulfoxide 1, has been found to be an efficient chiral auxiliary for asymmetric desymmetrization of cyclic meso-1,2-diols via diastereoselective acetal fission. Both (R,R)- and (S,S)-1 are readily synthesized with high optical purity via asymmetric oxidation of 1, 5-benzodithiepan-3-one (2). After acetalization of meso-1,2-diols 6a-e and a mono-TMS ether 6f with this chiral auxiliary 1, the resulting acetals 7a-f were subjected to base-promoted acetal fission upon treatment with potassium hexamethyldisilazide (KHMDS) followed by acetylation or benzylation to give the desymmetrized diol derivatives 8a-f with high diastereoselectivity. The chiral auxiliary 1 is readily removed by acid-promoted hydrolysis and can be recovered without a loss in enantiomeric excess.     

Chiral nematic liquid crystals with helix inversion from (R)-1,1′-binaphthyl and cholesteryl ester moieties

In this study, on the concept of intramolecular chiral conflict between the (R)-1,1′-binaphthyl and cholesteryl ester moieties, we have designed and synthesised a new liquid crystal (LC) (R)-dicholesteryl 6,6′-[1,1′-binaphthyl-2,2′-diylbis(oxy)]dihexanoate [(R)-DC]. A helix inversion could be observed for the chiral nematic liquid crystal (N*-LC) comprising the commercial nematic LC (N-LC) host SLC1717 and (R)-DC on heating. As a comparison, (S)-dicholesteryl 6,6′-[1,1′-binaphthyl-2,2′-diylbis(oxy)]dihexanoate [(S)-DC] was also prepared. Due to the intramolecular chiral superposition between the (S)-1,1′-binaphthyl and cholesteryl ester moieties, the N*-LC comprising SLC1717 and (S)-DC also exhibited excellent temperature sensitivity.     

A novel axially chiral 2,2'-bipyridine N,N'-dioxide. Its preparation and use for asymmetric allylation of aldehydes with allyl(trichloro)silane as a highly efficient catalyst

[reaction: see text] New axially chiral 2,2'-bipyridine N,N'-dioxides were obtained by a new method that does not involve any procedures for the separation of enantiomers. One of the dioxides, (R)-3,3'-bis(hydroxymethyl)-6,6'-diphenyl-2,2'-bipyridine N,N'-dioxide, exhibited extremely high catalytic activity for the asymmetric allylation of aldehydes with allyl(trichloro)silane. The allylation of aromatic aldehydes proceeded in the presence of 0.01 or 0.1 mol % of the dioxide catalyst to give the corresponding homoallyl alcohols of up to 98% ee.     

Catalytic asymmetric synthesis of vicinal diamine derivatives through enantioselective N-allylation using chiral pi-allyl Pd-catalyst

[reaction: see text] N-monoallylation of meso-vicinal diamine bistrisylamides using a chiral pi-allyl-Pd catalyst proceeded in an enantioselective manner (up to 90% ee) to give desymmetrization products in good yields. The product was converted to the known sigma-receptor agonist in short steps. In addition, the present catalytic asymmetric N-allylation was applied to kinetic resolution of racemic-diamide.     

An enantiodivergent and formal synthesis of paroxetine enantiomers by asymmetric desymmetrization of 3-(4-fluorophenyl)glutaric anhydride with a chiral SuperQuat oxazolidin-2-one

The asymmetric desymmetrization of 3-(4-fluorophenyl)glutaric anhydride 9 with lithiated chiral oxazolidin-2-one 8 has been studied. The desymmetrized product was formed with >90% de and converted into known intermediates for both (+)- and (?)-paroxetines.     

Asymmetric total synthesis of the proposed structure of the medicinal alkaloid jamtine using the chiral base approach

[reaction: see text] A highly step-economic asymmetric synthesis of the tetracyclic structure assigned to the medicinal alkaloid jamtine has been accomplished using a chiral lithium amide base desymmetrization of a ring-fused imide. The structure synthesized appears to be different from that of the natural product originally reported.     

Rhodium-catalyzed linear cross-trimerization of two different alkynes with an alkene and two different alkenes with an alkyne

Crossing paths with rhodium: A cationic Rh(I)/H(8)-BINAP complex has been found to catalyze the linear cross-trimerization of terminal alkynes, acetylenedicarboxylates, and acrylamides to give substituted trienes. The asymmetric linear cross-trimerization, giving substituted chiral dienes, has also been achieved by using monosubstituted alkenes and (R)-BINAP instead of terminal alkynes and H(8)-BINAP (see scheme; H(8)-BINAP = 2,2'-bis(diphenylphosphino)-5,5',6,6',7,7',8,8'-octahydro-1,1'-binaphthyl; BINAP = 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl]).     

8-Oxabicyclo[3.2.1]oct-6-en-3-ones: application to the asymmetric synthesis of polyoxygenated building blocks

The development and design of reliable and efficient methods for the construction of chiral building blocks are crucial in modern natural product synthesis. 8-Oxabicyclo[3.2.1]oct-6-en-3-ones are readily accessible scaffolds with defined stereochemical features which have been exploited for non-aldol approaches to the preparation of chiral building blocks. Strategies for their enantioselective synthesis, including asymmetric cycloaddition methods, desymmetrization protocols, and "racemic switch operations", are presented and evaluated.     

消旋的有机二磺酸三邻菲咯啉锌配合物(英)

Compound [Zn(phen)₃][BDA] (1) (BDA=6,6′-dibromo-2,2′-dimethoxy-1,1′-binaphthylene-4,4′-disulfonate, phen= 1,10-phenanthroline) composes of the anion part (racemic-(R,S)-6,6′-dibromo-2,2′-dimethoxy-1,1′-binaphthylene-4,4′-disulfonate ) and the cation part which consists of a racemic octahedrally coordinated zinc center defined six nitrogen atoms from three phen rings to form an inorganic chirality that can be resolution by chiral organic ligand, the 3D framework was formed through the strong H-bonding interaction between sulfonate and water. CCDC: 277924.     

Stereodivergent Desymmetrization of Simple Dicarboxylates via Branch-Selective Pd/Cu Catalyzed Allylic Substitution

Asymmetric desymmetrization has been demonstrated to be a powerful strategy for building stereocenters in asymmetric synthesis. Herein, a Pd/Cu catalyzed asymmetric desymmetrization reaction with a simple geminal dicarboxylate is reported. A wide scope of imino esters bearing an aryl or heteroaromatic group were compatible with this bimetallic catalytic system. The reactions proceeded smoothly, giving the desired products in good yields with high to excellent regio-, diastereo-, and enantioselectivity (up to 20 : 1 branched:linear, >20 : 1 dr, >99 % ee). Notably, the reaction favored branched selectivity, which is unusual for the Pd-catalyzed allylic alkylation reaction. In addition, the standard product could be easily transformed to other valuable molecules such as chiral allylic alcohols, carbamates, and organic boron compounds. Furthermore, DFT calculations were conducted to explain the origin of the branched selectivity.     

Enantioselective arylation of aldehydes catalyzed by a soluble optically active polybinaphthols ligand

A soluble chiral polymer ligand was synthesized by the polymerization of (R)-6,6′-dibutyl-3,3′-diformyl-2,2′-binaphthol (R-M-1) with 2,5-diaminopyridine (M-2) via a nucleophilic addition-elimination reaction. While arylboronic acids were used as the source of the transferable aryl group, the chiral polybinaphthols ligand in combination with Et₂Zn without Ti(OⁱPr)₄ exhibited higher enantioselectivity in asymmetric addition to aromatic aldehydes than alphatic aldehydes. When aromatic aldehydes with electron-withdrawing groups were chosen as substrates, the resulting diarylmethanols were produced in higher ee values than those with electron-donating groups as substrates. 2-Naphthaldehyde used as a substrate afforded product in 95% ee, which could be ascribed to the steric effect influence on this asymmetric arylation reaction. Moreover, the chiral polymer was easily recovered and reused, but exhibited a decrease of enantioselectivity in the third recycle.