Catalytic stereoselective cascade reactions of quinols with trifluoromethyl ketones: direct access to CF3-containing 1,3-dioxolanes.

A general and efficient synthesis of CF3-containing 1,3-dioxolanes using Et3N-catalyzed ketalization/oxa-Michael cascade of quinols with trifluoromethyl ketones is described. The reaction works efficiently under mild reaction conditions and produces the desired products in 68%-95% yields with acceptable diastereoselectivities. In addition, the reaction proceeds smoothly to give the desired product 3a in 92% yield and with high ee (80%) in the presence of a chiral catalyst (DHQ)2PHAL.

Silver salts and DBU cooperatively catalyzed nucleophilic addition/cyclization of propargylic alcohols with trifluoromethyl ketones.

A general and efficient synthesis of trifluoromethyl substituted 5-alkylidene-1,3-dioxolane using a silver salt and DBU cooperatively catalyzed nucleophilic addition/cyclization of propargylic alcohols and trifluoromethyl ketones is described. The procedure produced 5-alkylidene-1,3-dioxolane derivatives with good to excellent yields and can be used with a broad range of substrates.

Asymmetric Synthesis of P-Stereogenic Phosphinic Amides via Pd(0)-Catalyzed Enantioselective Intramolecular C-H Arylation.

The palladium-catalyzed enantioselective intramolecular C-H arylation of N-(2-haloaryl)-P,P-diphenylphosphinic amides furnishes P-stereogenic phosphine oxide derivatives in 61-99% yield with 88-97% ee. The catalyst generated in situ from a TADDOL-derived phosphoramide ligand and Pd(dba)2 is optimum in terms of yield and enantioselectivities.

Asymmetric synthesis of planar chiral ferrocenes by enantioselective intramolecular C-H arylation of N-(2-haloaryl)ferrocenecarboxamides.

The palladium-catalyzed intramolecular C-H arylation reaction of N-(2-bromoaryl)ferrocenecarboxamides furnishes planar chiral ferrocene derivatives. TADDOL-derived phosphoramide ligands induce enantioselectivities ranging from 91:9 to 98:2 er.

catena-Poly[[[diaqua-iron(II)]-µ-pyridine-2,5-dicarboxyl-ato-[tetra-aqua-iron(II)]-µ-pyridine-2,5-dicarboxyl-ato] tetra-hydrate].

In the crystal structure of the title compound, {[Fe(2)(C(7)H(3)NO(4))(2)(H(2)O)(6)]·4H(2)O}(n), there are two types of coordination for the Fe(II) atoms. One Fe(II) atom is in a distorted octa-hedral N(2)O(4) environment, with two chelating rings from the pyridine-dicarboxyl-ate ligands and two O atoms from the water mol-ecules, while the other is in a distorted octa-hedral O(6) environment with two O atoms from the pyridine-dicarboxyl-ate ligands and four O atoms from the water mol-ecules. Both Fe(II) atoms lie on crystallographic centers of symmetry. The complex possesses an infinite chain structure running along the [101] direction. These chains are inter-connected by the uncoordinated water mol-ecules through O-H⋯O hydrogen bonds.

1,1'-[o-Phenyl-enebis(nitrilo-methyl-idyne)]di-2-naphthol ethanol hemisolvate.

The asymmetric unit of the title compound, C(28)H(20)N(2)O(2)·0.5C(2)H(5)OH, contains two independent mol-ecules of 1,1'-[o-phenyl-enebis(nitrilo-methyl-idyne)]di-2-naphthol, denoted A and B, and one ethanol solvent mol-ecule. The hydr-oxy groups are involved in intra-molecular O-H⋯N hydrogen bonds influencing the mol-ecular conformations, which are slightly different in mol-ecules A and B, where the two bicyclic systems form dihedral angles of 51.93 (9) and 58.52 (9)°, respectively. In the crystal structure, a number of short inter-molecular C⋯C contacts with distances of less than 3.5 Šsuggest the existence of π-π inter-actions, which contribute to the stability of the crystal packing.

Evaluation of enantiopure N-(ferrocenylmethyl)azetidin-2-yl(diphenyl)methanol for catalytic asymmetric addition of organozinc reagents to aldehydes.

A facile and practical approach to preparation of enantiopure N-(ferrocenylmethyl)azetidin-2-yl(diphenyl)methanol was developed from cheap and easily available l-(+)-methionine. Synthetic highlights include the three-step, one-pot construction of the chiral azetidine ring and the development of an improved one-step procedure for the synthesis of the key intermediate l-2-amino-4-bromobutanoic acid. Enantiopure N-(ferrocenylmethyl)azetidin-2-yl(diphenyl)methanol was evaluated for catalytic asymmetric addition of organozinc reagents to aldehydes. The asymmetric ethylation, methylation, arylation, and alkynylation of aldehydes achieved enantioselectivity of up to 98.4%, 94.1%, 99.0%, and 84.6% ee, respectively, in the presence of a catalytic amount of chiral N-(ferrocenylmethyl)azetidin-2-yl(diphenyl)methanol. Our results demonstrated further that the four-membered heterocycle-based backbone was a good potential chiral unit for the catalytic asymmetric induction reaction, and the hindrance of the bulky ferrocenyl group, compared to a phenyl group, played an important role in the enantioselectivities. A possible transition for the catalytic asymmetric addition has been proposed on the basis of the crystal structure of the chiral ligand 3b including two HOAc molecules and previous studies.