Chiral Phosphoric Acid Catalyzed Regio- and Enantioselective Reactions of Functionalized Propargylic Alcohols

Propargylic alcohols have been known as useful substrates in a wide range of asymmetric reactions. Particularly, the chiral phosphoric acids (CPAs) catalyzed reactions of functionalized propargylic alcohols opened a robust...

On the synthesis of a novel chiral phosphorodiamidic acid containing the α-phenylethyl moiety: Insights in its conformation and reactivity

A few years ago, the synthesis of chiral phosphoric acids supported on chiral BINOL frameworks was accomplished by T. Akiyama and M. Terada. Subsequent relevant applications demonstrated the importance of chiral phosphoric acids as privileged chiral inducers in asymmetric organocatalysis. In the present report we discuss the development of novel chiral phosphorodiamidic acids derived from C2-symmetric trans-1,2-diaminocyclohexane aliphatic frameworks. The preparation of the new chiral Brønsted acids, based on the intermediacy of a 1,3,2-diheterophospholan-2-oxide moiety, turned out to be challenging since several plausible synthetic methodologies proved to be ineffective. Furthermore, the five membered heterocyclic moiety turned out to be easily hydrolyzed when exposed to nucleophilic alcohols or water. Complementary to the successful multistep synthesis reported here, it was possible to obtain crystals of the key precursor of the desired phosphorodiamidic acid, which proved suitable for X-ray diffraction analysis and hence to establish important conformational characteristics of the novel heterocycle.

Utilization of Galvanic Enterprises Sewage

A method for obtaining refractories based on inorganic glue as a reaction product of sludge from electroplating shops with sulfuric and phosphoric acids, which was tested by the authors in laboratory and industrial conditions in the article, is presents. After drying at a certain temperature, the manufactured samples are tested for strength. Properties of refractories based on inorganic glue are characterized by increased water resistance due to treatment with a cement solution. Based on experimental studies, the authors are presents the results of testing samples for strength with dry and wet aluminum-oxide abrasive. According to the test results, it was found that the specific density of the obtained samples increased from 0,57 to 0,9 g/cm3 with increasing glue content, while the strength decreased. Compositions with a low glue content had for the most strength.

Chiral Phosphoric Acid-Catalyzed Enantioselective [4+3] Cyclization Reaction of 4-Indolylmethanols and Quinone Esters

An asymmetric [4+3] cyclization reaction of racemic 4-indolylmethanols and quinone esters catalyzed by chiral phosphoric acids has been developed. This method provides efficient access to biologically important benzoxepino[5,4,3-cd] indoles featuring both axial and central chirality in good yields with up to 98% ee and essentially single diastereomer in mild reaction conditions.