The morpholine (1,4-oxazinane) motif attracted significant attention due to its widespread availability in natural products and biologically relevant compounds. This review describes recent advances in the synthesis of morpholines and... more
The morpholine (1,4-oxazinane) motif attracted significant attention due to its widespread availability in natural products and biologically relevant compounds. This review describes recent advances in the synthesis of morpholines and their carbonyl-containing analogs from 1,2-amino alcohols, aziridines, epoxides, and related compounds. Special attention is paid to the syntheses performed in a stereoselective manner and using transition metal catalysis. Selected works published since 2013 are covered.
An investigation of a skeletal WagnereMeerwein rearrangement of variously substituted or quinolineannulated 3a,6;4,5-diepoxyisoindol-1-ones is reported. Optimum reaction conditions (Ac2O, BF3$OEt2, rt) were discovered for the formation of... more
An investigation of a skeletal WagnereMeerwein rearrangement of variously substituted or quinolineannulated 3a,6;4,5-diepoxyisoindol-1-ones is reported. Optimum reaction conditions (Ac2O, BF3$OEt2, rt) were discovered for the formation of the target 4,6-epoxycyclopenta[c]pyridines in 40e80% yields. It was shown that the direction of the sigmatropic rearrangement of 3a,6;4,5-diepoxyisoindol-1-ones depended dramatically on the carboxyl group position (exo-/endo-) in the oxabicyclo[2.2.1]heptane moiety. The spatial structure of previously unknown 7,9-epoxycyclopenta[4,5]pyrido[1,2-a]quinolines derived from WagnereMeerwein rearrangement of 2,11b-epoxyoxireno[6,7]isoindolo[2,1-a]quinolines was established based on the X-ray analysis data. The skeletal rearrangement proceeded regio- and stereospecifically in all the cases examined due to the absence of the epimerization of the carbon atoms adjacent to the carbocation centres.
Amorphous mesoporous materials with a different degree of order in the arrangement of pores are outlined. Particularly, the synthesis of a class of mesoporous silica-alumina (MSA) materials with narrow pore size distribution and a... more
Amorphous mesoporous materials with a different degree of order in the arrangement of pores are outlined. Particularly, the synthesis of a class of mesoporous silica-alumina (MSA) materials with narrow pore size distribution and a disordered arrangement of pores is reported and discussed. Likewise, the preparation of titanium-containing ordered mesoporous silicates (Ti-MCM-41) and disordered mesoporous silica-titania (MST) are also described in detail. The structural properties of the solids are compared by means of X-ray diffraction and UV-Vis diffuse reflectance spectroscopy. The nitrogen adsorption-desorption measurements were performed and the textural properties are evaluated by the BET, DFT, BJH and t-plot methods. The high specific surface area and pore volume, as well as the acidity, make MSA solids interesting catalysts in several petrochemical transformations, i.e. oligomerisation, alkylation, hydroisomerisation, rearrangement reactions. Besides, thanks to the width of the mesopores of such solids, the catalytic activity of titanium-containing silicates may have a potential application in the epoxidation of bulky unsaturated fine chemical substrates.
