Yanghui Lin

Lanthanide-catalyzed cyclocarbonylation and cyclothiocarbonylation: a facile synthesis of benzannulated 1,3-diheteroatom five- and six-membered heterocycles

La[N(SiMe3)2]3 proves to be an efficient catalyst system for the cyclocarbonylation of 1,2-disubstituted benzenes with isocyanates. In this approach, aryl/alkyl isocyanates react with o-phenylenediamine, o-aminophenol, o-aminothiophenol, catechols and anilines ortho-substituted by CH2NH2 and CONH2 to form, respectively, the corresponding benzimidazolones, benzoxazolones, benzothiazolones, benzodioxolones, 3,4-dihydroquinazolin-2(1H)-one, and quinazolinediones. These results represent the first example of lanthanide-catalyzed carbonylation. This methodology is also applicable for the preparation of various benzannulated 1,3-diheteroatom cyclic thioketones starting from aryl/alkyl isothiocyanates or CS2 in good to excellent yields. Based on the results of experiments performed using an o-aminobenzamido dianion lanthanide complex, a general mechanism, involving the tandem reaction of two lanthanide-ligand bonds with one heterocumulene molecule, is proposed as well.

Formation of various types of metallofullerenes by laser ablation of externally doped fullerenes C60Mx (M=Sm, Pt, Ni, La, Y, and Rh)

A photofragmentation study of metal fullerides C60Mx (M=Sm, Pt, Ni, La, Y, and Rh) by excimer laser ablation-TOF mass spectrometry shows that many kinds of metallofullerenes have been observed in both the positive and negative ionic modes. For C60Mx (M=Sm, Pt, and Ni), the metal atom is incorporated into the network of the fullerene cage to replace one carbon atom of the cage forming substitutional metallofullerene. While in the case of metal fullerides C60Mx (M=La, Y), evidence of the encapsulation of La and Y atoms in fullerene cages forming endohedral fullerenes has been observed. Different from the above two cases, the laser ablation of rhodium fulleride C60Rhx(x≈1) produces two sequences of rhodium-containing fullerene clusters C2nRh and C2n+1Rh(2n=50–62). Odd-numbered all-carbon clusters in the fullerene regime are observed in our laser ablation study of all the metal fullerides in the negative ion channel. The structures of metallofullerenes C2n+1M and C2nM with an even and odd number of total atom...

A simple and practical catalytic electron transfer system composed of TiCl4 and metallic Yb: application in carbonyl olefination and insight into the mechanism

The McMurry-type olefinations have become a powerful tool in organic synthesis. However, the use of stoichiometric amounts of unmanageable Ti species and the generation of a large amount of salts limit their applications on the industrial scale. This paper outlines a simple and practical catalytic electron transfer (ET) system composed of TiCl4 and Yb, which turned out to be effective for homo- and cross-deoxygenative coupling of aldehydes and ketones. Specifically, the method is based upon the strategy that the low valent Ti species abstracts oxygen from carbonyl and delivers them to highly oxophilic Yb in an unprecedented manner. Remarkably, the present process is operationally simple, minimizes the generation of chemical waste, and makes the only by-product Yb2O3 as a solid easily removed and utilized; furthermore, the yield improved significantly of that obtained in the stoichiometric version in our system. Our mechanistic data not only provide the direct evidence that Ti(IV) can facilitate the part deoxygenation of pinacol at room temperature, but also demonstrate, for the first time, that for bulky ketones the turnover-limiting step is the Ti-mediated carbonyl coupling rather than the subsequent deoxygenation of the resulting pinacolate intermediates, which are different from the previous observations.

Measurement of third-order optical nonlinearity of C60M2 (M=Pd, Pt, and Sm) organometallic compounds by the femtosecond optically heterodyned optical Kerr effect

Abstract We have measured the real components of the third-order optical nonlinearity of organometallic compound films of C 60 M 2 (M=Pd, Pt, and Sm) by using the femtosecond optically heterodyned optical Kerr effect at 647.0 nm. The results show that there is an enhancement of the real components of the third-order optical nonlinearity of C 60 M 2 films compared to that of pristine C 60 film. We attribute the origin of this enhancement to the charge transfer from the metal atoms to the C 60 molecules.

Femtosecond optically heterodyned optical Kerr effect studies of C60-metal films

By using the femtosecond optically heterodyned optical Kerr effect at 647.0 nm we have measured the magnitudes and signs of the real components of third-order nonlinearity of organometallic compounds films of C60M2 fabricated through a series of reactions of C60 anions with some inorganic compound in solution phase and physical jet deposition technique. We find there is an enhancement of the real components of third-order optical nonlinearities of C60M2 films compared to that of pristine C60 film, which can be attributed to the charge transfer from metal atoms to C60 molecules. The signs of the real components of third-order optical nonlinearity of C60 and C60

Functionalization of multiwalled carbon nanotubes with polystyrene under atom transfer radical polymerization conditions

M(subscript 2 films are negative. We also find the disposition temperature will affect third-order optical nonlinearities of C60M2 films.