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A molecular recognition mechanism based on dimeric model for cyclic dipeptide Cyclo[(S)-His-(S)-Phe] (abridged CHP) catalyzed autoinduction is proposed according to the inference of previous experimental findings, which is supported by theoretical calculation with Oniom(B3LYP/3-21G*:AM1) method. The most unstable CHP dimer whose intermolecular hydrogen bonds are immensely lessened by two intramolecular hydrogen bonds is defined as the highest active component (IIa) existing in solid among the three possible dimers (Ia, IIa, and IIb). The carbonyl group of benzaldehyde coordinates to CHP dimer (IIa) by a hydrogen bond with Phe–N_αH rather than His–N_αH and HCN interacted with the imidazole moiety of His residue to form cyanide ion. In view of the theoretical calculation and experimental results, the structures of the nine-ring complexes derived from interaction between catalytic active dimer CHP(IIa) and cyanohydrins were postulated to explain the enantioselective autoinduction: The structure of no nitrile involved six-ring complex derived from interaction between catalytic active dimer CHP(IIa) and cyanohydrins were postulated to explain the elimination of enantioselective autoinduction.

Density functional theory (DFT) was used to investigate the reaction mechanisms of ruthenium(II)-catalyzed hydroacylation of isoprene with benzaldehyde, and o-methoxyl, m-methoxyl and p-methoxyl benzaldehyde. All intermediates and transition states were entirely optimized at the B3LYP/6-31G(d,p) level (LANL2DZ(f) for Ru). The results demonstrated that the hydroacylation had two different catalytic cycles (path I and II), path II was more favorable than path I. Ru(II)-catalyzed hydroacylation began from the first catalytic cycle, and the nucleophilic reaction was the rate-determining step. The activation barriers of hydrogen migration were the highest in two catalytic cycles, so the hydrogen migration was the rate-determining step. The activation barrier of hydrogen migration could be broken down to two parts: the free energy of exchange ($\mathrm{\Delta }{G}_{\mathrm{\text{ex}}}$) and the relative free energy of transition state ($\mathrm{\Delta }G$). The ligand exchange energy ($\mathrm{\Delta }{G}_{\mathrm{\text{ex}}}$) had more contribution to the activation barrier than the relative free energy of transition state ($\mathrm{\Delta }G$), so the ligand exchange would control these hydroacylation. Furthermore, our calculations also described the substituent effect, and the results indicated that four aldehydes showed different chemical reactivity, and benzaldehyde and m-methoxyl benzaldehyde were predicted to have the best reactivity in ruthenium hydride-catalyzed hydroacylation.

The aerobic oxidative cleavage of styrene C=C double bonds catalyzed by simple manganese porphyrin is reported. Under the catalysis of chloro(tetraphenylporphinato)manganese, the oxidative cleavage of the carbon-carbon double bond of the styrene with air yields benzaldehyde. Our results show that the oxidative cleavage and the epoxidation of the styrene double bond are the competition reactions in the styrene-manganese porphyrin-air system. The reaction temperature decided the product distribution. Under the conditions of 0.4 MPa air and 30 ppm of chloro(tetraphenylporphinato)manganese, the styrene conversion was 20.0% and the selectivity of benzaldehyde and styrene oxide was 81.7% and 12.7% respectively when the reaction temperature was 110°C. Styrene conversion was 92.5% and the selectivity of benzaldehyde and styrene oxide was 48.1% and 41.2% respectively when the reaction temperature was 120°C.

Toluene oxidation with molecular oxygen as the sole oxidant, and μ-oxo-bis[tetraphenylporphinatoiron(III)] as the catalyst, are reported. Under the reaction conditions of 438 K and 0.8 MPa, the molar total yields for the products benzaldehyde and benzyl alcohol and the turnover number of the catalyst are 4.35% and 21,830 (based on the metal ion), respectively. Compared with the reaction catalyzed by the corresponding monometalloporphyrin TPPFe^IIICl, the total yields of the oxidation products and the catalyst turnover number by the dimeric iron porphyrin were almost twice those by the former. A possible reaction mechanism of the toluene oxidation by μ-oxo-bis[tetraphenylporphinatoiron(III)] is proposed.