A New Synthetic Route to Enantiomerically Pure Axially Chiral 2,2‘-Bipyridine <i>N,N</i><i>‘</i>-Dioxides. Highly Efficient Catalysts for Asymmetric Allylation of Aldehydes with Allyl(trichloro)silanes

New axially chiral 2,2‘-bipyridine N,N‘-dioxides 1 were obtained in an enantiomerically pure form by way of cyclic diesters 6 or 7 which were formed by the esterification of diols 2 with (R)-2,2‘-bis(chlorocarbonyl)-1,1‘-binaphthalene (5). Epimerization of the kinetic products at the ester formation (Rnap,Spyr)-6 to the thermodynamically stable isomers (Rnap,Rpyr)-7 was observed in refluxing toluene or in the presence of trifluoroacetic acid. One of the N,N‘-dioxides 1a which is substituted with phenyl groups at the 6 and 6‘ positions was found to be highly catalytically active and enantioselective for the asymmetric allylation of aldehydes with allyl(trichloro)silane giving homoallyl alcohols

Nickel-Catalyzed Asymmetric Grignard Cross-Coupling of Dinaphthothiophene Giving Axially Chiral 1,1‘-Binaphthyls

Asymmetric cross-coupling of dinaphtho[2,1-b:1‘,2‘-d]thiophene with ArMgBr (Ar = Ph, 4-MeC6H4, 4-MeOC6H4) proceeded with high enantioselectivity in THF at 20 °C in the presence of 3 mol % of a nickel catalyst generated from Ni(cod)2 and a chiral oxazoline-phosphine ligand to give high yields of axially chiral 2-mercapto-2‘-aryl-1,1‘-binaphthyls, whose enantiomeric excesses are over 93%. The mercapto group in the chiral binaphthyl was converted into iodo, boryl, and phosphino groups without racemization

A Novel Axially Chiral 2,2‘-Bipyridine <i>N,N</i><i>‘</i>-Dioxide. Its Preparation and Use for Asymmetric Allylation of Aldehydes with Allyl(trichloro)silane as a Highly Efficient Catalyst

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

Facile Preparation of a New BINAP-Based Building Block, 5,5‘-DiiodoBINAP, and Its Synthetic Application

Bis(pyridine)iodonium tetrafluoroborate was successfully used for regioselective iodination of BINAP dioxide to give 5,5‘-diiodoBINAP dioxide in an excellent yield of 92%, with no observed formation of 4,4‘-diiodoBINAP dioxide. A Sonogashira cross-coupling reaction with 5,5‘-diiodoBINAP dioxide gave the desired bis(trimethylsilylethynyl) product in 86% yield. The resulting 5,5‘-disubstituted BINAP dioxides were reduced to the corresponding phosphines, which were used as chiral ligands for rhodium-catalyzed asymmetric 1,4-addition of phenylboronic acid to 2-cyclohexenone to give 3-phenylcyclohexanone in excellent yield with high enantioselectivity

A Novel Axially Chiral 2,2‘-Bipyridine <i>N,N</i><i>‘</i>-Dioxide. Its Preparation and Use for Asymmetric Allylation of Aldehydes with Allyl(trichloro)silane as a Highly Efficient Catalyst

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

Asymmetric Synthesis of Axially Chiral Biaryls by Nickel-Catalyzed Grignard Cross-Coupling of Dibenzothiophenes

Catalytic asymmetric Grignard cross-coupling of 1,9-disubstituted dibenzothiophenes (6a−c) and dinaphthothiophene (6d) with aryl- and alkyl-Grignard reagents (7) proceeded with high enantioselectivity (up to 95% ee) in the presence of a nickel catalyst (3−6 mol %) coordinated with 2-diphenylphosphino-1,1‘-binaphthyl (H-MOP) or oxazoline-phosphine ligand (i-Pr-phox) in THF to give 2-mercapto-2‘-substituted-1,1‘-biphenyls (8a−c) and 2-mercapto-2‘-substituted-1,1‘-binaphthyls (8d) in high yields. The mercapto group in the axially chiral cross-coupling products was converted into several functional groups by way of the methylsulfinyl group. The rate of flipping in dinaphthothiophene was measured by variable-temperature 31P NMR analysis of methylphenylphosphinyldinaphthothiophene derivative (21)

Ni-Catalyzed α‑Selective C–H Borylations of Naphthalene-Based Aromatic Compounds

The ability of α-borylated naphthalene-based aromatic compounds is important because it provides ready access to interesting novel extended π-systems. In this report, we disclose the Ni-catalyzed α-selective C–H borylations of naphthalene-based aromatic compounds. The reaction proceeds with peri-xanthenoxanthene and other aromatic compounds to regioselectively afford the α-borylated products without directing groups. The selectivities of these transformations are different from those of Ir-catalyzed C–H borylation reactions and can be used in a complementary manner

Ni-Catalyzed α‑Selective C–H Borylations of Naphthalene-Based Aromatic Compounds

The ability of α-borylated naphthalene-based aromatic compounds is important because it provides ready access to interesting novel extended π-systems. In this report, we disclose the Ni-catalyzed α-selective C–H borylations of naphthalene-based aromatic compounds. The reaction proceeds with peri-xanthenoxanthene and other aromatic compounds to regioselectively afford the α-borylated products without directing groups. The selectivities of these transformations are different from those of Ir-catalyzed C–H borylation reactions and can be used in a complementary manner

Asymmetric Synthesis of 1-Aryl-1,2-ethanediols from Arylacetylenes by Palladium-Catalyzed Asymmetric Hydrosilylation as a Key Step

Double hydrosilylation of arylacetylenes with trichlorosilane catalyzed first by platinum and second by a chiral monophosphine−palladium complex generated the corresponding 1,2-bis(silyl)-1-arylethanes, the oxidation of which with hydrogen peroxide gave 1-aryl-1,2-diols of high enantiomeric purity (94−98% ee) in high yields

Rhodium-Catalyzed Asymmetric Synthesis of Indanones: Development of a New “Axially Chiral” Bisphosphine Ligand

A rhodium-catalyzed asymmetric isomerization of racemic α-arylpropargyl alcohols to β-chiral indanones has been developed. High enantioselectivity has been realized by the use of a newly developed axially chiral bisphosphine ligand. This ligand is unique in the sense that its axial chirality is fixed to a single configuration upon complexation to a transition metal due to other chiral axes existing within the same molecule