Solvent controlled selective photocatalytic oxidation of benzyl alcohol over Ni@C/TiO2

The oxidation of aromatic alcohols to produce carbonyl compounds is of great significance in fine chemical production. The traditional oxidation produces waste gas and pollutes the environment during the reaction. As a new field, photocatalysis has attracted people's attention because of its environmental friendliness. At present, there have been much research on TiO2, or noble metal modified TiO2 to catalyze alcohol oxidation, but the high cost is not conducive to large-scale production. Herein, a Ni@C/TiO2 catalyst was prepared by in-situ hydrothermal synthesis. This catalyst has a better oxidation effect on benzyl alcohol than Ni@C supported on TiO2 on the market and has a good catalytic effect on aromatic alcohols with different substituents. It is more interesting that the selectivity of the product can be adjusted by choosing different reaction solvents. The highly active catalyst with low cost and wide applicability has certain significance for the large-scale use of photocatalytic alcohol oxidation.

Fe(II)-phthalocyanine supported on chitosan aerogel as a catalyst for oxidation of alcohols and alkyl arenes

Manipulation of materials is considered as one of the eminent strategies to create desirable catalysts. In this regard, increasing surface area and decreasing dimensions of catalysts have been widely employed on account of effectiveness of these methods. Herein, aerogel form of chitosan as a sustainable, and high aspect ratio compound is employed as a green support for the catalytic purposes. Chitosan aerogel was modified with Fe(II)-phthalocyanine to produce a heterogeneous catalyst for oxidation reactions. The synthesized catalyst promoted the oxidation reactions of alcohols and alkyl arenes to the corresponding aldehydes and ketones using H2O2 as an oxidant in 24 h. The reactions for aliphatic and aromatic alcohols gave turnover numbers of 106–109 at 80 °C and 106–117 at room temperature, respectively. The oxidations of alkyl arenes were carried out with turnover numbers laying in the range of 106–117 at 100 °C. The low toxicity, inexpensive nature, and recycling possibility of the catalyst accompanied by the reaction mild conditions, clean oxidant, and excellent yields offer chitosan aerogel modified with Fe(II)-phthalocyanine as a promising catalyst for oxidation reactions.

Phosphonium-mediated synthesis of a new class of indoloquinazoline derivatives bearing C-12 aryloxy ester and spiro-γ-lactone

Indoloquinazolines functionalized at C-12 which are structure analogs of the natural alkaloid cephalanthrin B were readily constructed via a Ph3P-I2 mediated one-pot reaction of isatins with aromatic alcohols. In the presence of excess phenols, the C-12 aryloxy ester products were afforded in moderate to good yields under mild conditions. Moreover, fused bicyclic hydroxyaryl derivatives such as 8-hydroxyquinoline gave rise to novel C-12 spiro-γ-lactone derivatives. Reactive iminium cation species derived from dehydration of the C-12 hydroxy ester precursor is proposed to be transient intermediates responsible for these unprecedented transformations.