Triphen­yl(tetra­hydro­furan)­aluminium(III)

In the title compound, [Al(C6H5)3(C4H8O)], the Al atom has a distorted tetra­hedral geometry. The C—Al—C angles range from 113.25 (7) to 116.27 (8)°, much larger than the O—Al—C angles, which range from 103.39 (7) to 103.90 (6)°. The tetra­hydro­furan ring adopts an envelope conformation. The crystal packing is stabilized by C—H⋯π inter­actions

An efficient nickel-catalyzed alkenylation of functionalized benzylic halides with alkenylaluminum reagents

Highly efficient and simple coupling reactions of benzylic bromides or chlorides with alkenylaluminum reagents catalyzed by NiCl2(PPh3)(2) are reported. The coupling reactions proceed effectively at room temperature employing low loading of catalyst, 0.5 mol% for benzylic bromides having either electron-donating or -withdrawing substituents on the aromatic ring, affording coupling products in excellent yields of up to 94% in short reaction times. The coupling reactions of benzylic chloride require 5 mol% of the catalyst and a longer reaction time of 2 h

A new chiral ligand: 2,6-bis 4(S)-isopropyl-1-phenyl-4,5-dihydro-1H-imidazol-2-yl pyridine

The title compound, C29H33N5, is a new chiral bis(imidazolyl) pyridine derivative with a skeleton similar to the bis(oxazolyl) pyridine derivatives, which have been extensively used as ligands in various asymmetric catalytic reactions. The most prominent feature of the present compound is the considerable sp(2) character of N atoms of the imidazoline rings. The substituents at the Nsp(2) atoms can provide a means for tuning the electronic and conformational properties of the compound

Room Temperature and Highly Enantioselective Additions of Alkyltitanium Reagents to Aldehydes Catalyzed by a Titanium Catalyst of (R)-H-8-BINOL

Three alkyltitanium reagents of RTi(O-i-Pr)(3) (R = Cy (1a), i-Bu (1b), and n-Bu (1c)) were prepared in good yields. The high-resolution mass spectroscopy showed that 1b and 1c in the gas phase are monomeric species. However, the solid state of 1a revealed a dimeric structure. Asymmetric additions of 1a-1c to aldehydes catalyzed by a titanium catalyst of (R)-H-8-BINOL were studied at room temperature. The reactions produced desired secondary alcohols in good yields with good to excellent enantioselectivities of up to 94% ee. Reactivity and enantioselectivity differences, in terms of steric bulkiness of the R nucleophiles, are herein described. The addition reactions of secondary c-hexyl to aldehydes were slower than the reactions of primary i-butyl or n-butyl nucleophiles. For the primary alkyls, lower enantioselectivities were obtained for products from addition reactions of the linear n-butyl as compared with the enantioselectivities of products from the addition reactions of the branched i-butyl group. The same stereochemistry of RTi(O-i-Pr)(3) addition reactions as the addition reactions of organozinc, organoaluminum, Grignard, or organolithium reagents directly supports the argument of that titanium- catalyzed addition reactions of aldehydes involve an addition of an organotitanium nucleophile. Chirality 23:929-939, 2011. (C) 2011 Wiley-Liss, Inc

Synthesis of Allenes via Nickel-Catalyzed Cross-Coupling Reaction of Propargylic Bromides with Grignard Reagents

We describe a convenient method for the synthesis of terminal allenes from cross-coupling of propargylic bromide with Grignard reagent. The reaction of propargylic bromide with 1.2 equivalents of Grignard reagent mediated by Ni(acac)(2) (2 mol%) and Ph3P (4 mol%) in THF may produce terminal allenes in good yields and high regioselectivities at room temperature

Dichlorido(N,N '-dibenzylideneethane-1,2-diamine-kappa N-2,N ') (2,2-dimethyl-1,3-dioxolane-4,5-diyl)bis(diphenylmethan-olato)-kappa O-2,O ' titanium(IV)

The title compound, [TiCl2(C31H28O4)(C16H16N2)], is a titanium(IV) complex of the bidentate 2,2-dimethyl-, alpha,alpha,alpha ',alpha '-tetraphenyl-1,3-dioxolane-4,5-dimethanolate (TAD-DOLate) ligand containing also two chloride ions and a bidentate neutral N,N '-dibenzylideneethane-1,2-diamine ligand. The molecular structure has a distorted octahedral geometry around the titanium metal center. The Ti-N bond lengths of 2.246 ( 2) and 2.2476 ( 17) angstrom are long, indicating weak bonding between the titanium( IV) metal center and the imine N atoms. Though the two chloride ligands are trans to each other, they bend away from the Ti-TADDOLate bonds with a Cl-Ti-Cl angle of 163.96 ( 3)degree

Reactions of Ti(O-i-Pr)Cl-3 with 2-aminophenol and the crystal structure of the zwitterionic complex Ti(O-i-Pr)Cl-3(THF)(-OC6H4NH3+) center dot THF

Ti(O-i-Pr)Cl-3 reacts with 1 molar equivalent of 2-aminophenol (HOC6H4NH2) in CH2Cl2 to afford the likely zwitterionic complex [Ti(O-i-Pr) Cl-3(OC6NH3)](2) (1). However, when the reaction is carried out in THF, another zwitterionic complex [Ti(O-i-Pr)-Cl-3(THF) (OC6H4NH3)].(THF) (2) is obtained. With the addition of Ti(O-i-Pr) Cl-3 to a mixture of 2-aminophenol and NEt3 in CH2Cl2, the reaction gives the likely monomeric complex [Ti(O-i-Pr)Cl-3(OC6H4NH2)](-) (HNEt3)(+) (3). The role of the amino group and the effect of the addition of NEt3 and the coordinating THF solvent are discussed. The molecular structure of 2 reveals a species containing the zwitterionic 2-ammonium phenoxide ligand. Two THF molecules are found in the solid state structure in which one THF coordinates to the titanium metal center and the second THF is held tightly via the hydrogen bonding from one ammonium hydrogen. The molecular structure of 2 suggests that the relative bonding abilities of the ligands are in the order of O--i-Pr > -OAr > Cl- > THF. (C) 1998 Elsevier Science S.A. All rights reserved

Palladium-Catalyzed Cross-Coupling Reaction of AlArEt2(THF) with Aryl Bromides

Efficient cross-coupling reactions of aryl bromides with AlArEt2(THF) (Ar = Ph, 4-MeC6H4, 4-MeOC6H4, 4-Me3SiC6H4, or 2-naphthyl) catalyzed by a catalytic system of 1 mol% Pd(OAc)(2) and 2 mol% PCy3 furnish aryl-aryl coupling products. The system works well for a wide range of aryl bromides regardless of the electronic or steric nature of the substituent on the aryl bromides