A synthesis of 1,1-disubstituted 1,2,3,4-tetrahydroisoquinolines (6) was achieved in a highly efficient manner via Pictet-Spengler reaction of arylethylamines (1) and acyclic and cyclic ketones (2) using titanium (IV) isopropoxide and acetic-formic anhydride. The cyclization of the in situ formed acyliminium ion (4) to N-formyl 1,2,3,4-tetrahydroisoquinoline (5) was greatly facilitated by using...

Stable TiO2 sols were prepared using two nonaqueous sol–gel processes with titanium n-butoxide and titanium isopropoxide, respectively. Crystallization and phase transitions of powders and thin films were studied by ex situ and in situ X-ray diffraction. For both methods, TiO2 began to crystallize around 320 C in air. Using helium instead of air during heat treatment slowed down the crystalliza...

BACKGROUND Aluminum is considered to be a relatively safe metal for humans. However, there are some reports that aluminum can be toxic to humans and animals. In order to estimate the toxicity of aluminum with respect to humans, we measured the aluminum concentration in urine of aluminum-handling and non-handling workers and investigated the relationships between their urinary aluminum concentra...

The Aluminum Hypothesis, the idea that aluminum exposure is involved in the etiology of Alzheimer disease, dates back to a 1965 demonstration that aluminum causes neurofibrillary tangles in the brains of rabbits. Initially the focus of intensive research, the Aluminum Hypothesis has gradually been abandoned by most researchers. Yet, despite this current indifference, the Aluminum Hypothesis con...

Aluminum has been implicated in several neurodegenerative conditions including Alzheimer's disease. Because the mammalian olfactory system has an unusual capacity for the uptake and transneuronal spread of inhaled substances such as aluminum, whole cell recording techniques were used to examine the actions of aluminum on basic membrane properties and amino acid receptors on rat olfactory bulb m...

Some time ago we reported the oxidation of 2,3-unsaturated hexopyranosides and 2-Cmethylene glycosides with hydrogen peroxide in the presence of molybdenum trioxide catalyst to give the corresponding anomeric hydroperoxides 1-5. Relatively stable hydroperoxides 1-5 were used for enantioselective oxidation of prochiral alcohols and sulfides in the presence of Ti(OiPr)4 with stereoselectivities v...

Cu-doped TiO2 nanopowders were prepared by sonochemical-assisted process via a precursor solution of titanium isopropoxide, copper nitrate trihydrate and sodium hydroxide in the presence of polyvinyl alcohol in combination with calcinations process. The as-synthesized products were calcined at various temperatures ranging from 500-1000°C. The physical microstructures, morphologies and chemical ...