Nickel-catalyzed substitution reactions of propargyl halides with organotitanium reagents.

A simple and mild catalytic coupling reaction of propargyl halides with organotitanium reagents is reported. The reaction of propargyl bromide with organo-titanium reagents mediated by NiCl2 (2 mol%) and PCy3 (4 mol%) in CH2Cl2 afforded coupling product allenes in good to excellent yields (up to 95%) at room temperature. However, NiCl2(PPh3)2 was the best catalyst for substituted propargyl halides to yield allenes or alkynes preferentially.

Interpretation and apportionment source of polycyclic aromatic hydrocarbons from neighboring rivers in Dapeng Bay (Taiwan).

The contents of 16 polycyclic aromatic hydrocarbons (PAHs) and surface sediment properties were analyzed from 31 locations in Dapeng Bay and neighboring rivers (i.e., Kaoping River, Tungkang River, and Lingbeng River) in Taiwan.

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 NiCl(2)(PPh(3))(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.

Room temperature and highly enantioselective additions of alkyltitanium reagents to aldehydes catalyzed by a titanium catalyst of (R)-H8-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 and 1c in the gas phase are monomeric species. However, the solid state of 1a revealed a dimeric structure.

Instantaneous room-temperature and highly enantioselective ArTi(O-i-Pr)3 additions to aldehydes.

Direct asymmetric additions of ArTi(O-i-Pr)(3) to aldehydes catalyzed by a titanium catalyst of (R)-H(8)-BINOL are reported. The reactions proceed instantaneously at room temperature, affording alcohols in ≥90% ee. Importantly, the ArTi(O-i-Pr)(3) reagent differentiates the ligand effectiveness in an order of H(8)-BINOL > BINOL > TADDOL > diol 3 > disulfonamide 2.