Aza-Michael addition of amines to activated alkenes catalyzed by Silica supported perchloric acid under a solvent-free condition

An efficient aza-Michael addition of amines to a series of ,-unsaturated ketones, carboxylic esters, nitriles and chalcones has been carried out using perchloric acid supported over silica gel (HClO4-SiO2) at room temperature in high yields under solvent-free reaction conditions.

Intermolecular crosslinking of fatty acyl chains in phospholipids: Use of photoactivable carbene precursors

Phospholipids containing photolysable carhene precursors (beta-trifluoro-a-diazopropionoxy and m-diazirinophenoxy groups) in w-positions of sn-2 fatty acyl chains were prepared. Photolysis of their vesicles produced crosslinked products in 40-60 % yields. Crosslinking was mostly intermolecular and occurred bv carbene insertion into the C-H bonds of a second fatty acyl chain. Crosslinking products were characterized by (i) their gel permeation behavior, (ii) analysis of produets formed by base-catalyzed transesterification. (iii) degradation with phosphoiipases A2 and C, (iv) gas chromatography/mass spectrometry, and-(v) use of mixtures of phospholipids carrying thf' carhene precursors and a phospholipid containing radioactively labeled fatty acyl groups. Nitrenes generated from the aliphatic or aromatic azido groups in phospholipids were unsatisfactory for forming crosslinks by insertion in C-H bond

Cycloaddition Reactions: Reaction of 3-Methyl-2-phenylpyrrocoline with Dimethyl Acteylenedicarboxylate

Reaction of 3-methyl-2-phenylpyrrocoline(I) and dimethyl acetylenedicarboxylate(II) in refluxing toluene furnishes cis-7',8-dihydro.4,5,8,9-tetramethoxycarbonyl-7'-phenyl-7' -methylazocino(2,1,8-cd]pyrrolizine (III) and trans-7',8-dihydro-4,5,8,9-tetramethoxycarbonyl-7-phenyl-7'-methylazocino[2,1,8-cd]pyrrolizine (IV), while the same reaction at ambient temperature yields 1-[(1,2-trans-dimethoxycarbonyl)vinyl]-3-methyl-2-phenylpyrrocoline (V) and 1-[(1,2-cis-di(methoxycarbonyl)vinyl)--methyl-2- phenylpyirocoUne (V) and 1-[(I,2-cis-di(methoxycarbonyl)Yinyl]-3-metbyl-2-phenylpyrrocoline(VI) as the major products. The structure of IV has been determined by X-ray crystallography.A possible mechanism of formation of these products is also discussed.