Sandro Papaleo

Behaviour of triphenylphosphine-substituted ruthenium carbonyl carboxylates with hydrogen

The reaction between Ru(CO) 2 (MeCO 2 ) 2 (PPh 3 ) 2 , or Ru 2 (CO) 4 (MeCO 2 ) 2 (PPh 3 ) 2 , and hydrogen (100 atm) at temperatures between 80 and 160°C has been investigated. The products formed are ruthenium clusters containing PPh 3 , PPh 2 and PPh ligands. The same products were obtained from Ru 4 ( μ -H) 4 (CO) 8 (PPh 3 ) 4 and hydrogen. Several new complexes were isolated and the crystal structures of Ru 3 ( μ -H) 2 (CO) 8 ( μ 3 -PPh)(PPh 3 ), Ru 4 (CO) 8 ( μ 4 -PPh) 2 ( μ -PPh 2 ) 2 and Ru 4 ( μ -H) 4 (CO) 7 ( μ 4 -PPh)( μ -PPh 2 ) 2 (PPh 3 ) are reported.

Fluoride ion induced reactions of organosilanes: the preparation of mono and dicarbonyl compounds from β-ketosilanes

Abstract β-ketosilanes react with a variety of carbon electrophiles in the presence of CsF to give mono- and dicarbonyl derivatives in reasonably good yields.

4-Nitro-2-phenyloxazole: an electrophilic dienophile for normal Diels–Alder reactions in the oxazole series

The title compound 2, obtained by thermal isomerization of the corresponding nitroisoxazole 1, is found to undergo [2 + 4] cycloaddition processes with 2,3-dimethylbuta-1,3-diene and cyclohexa-1,3-diene, respectively.

Reaction of 1-diethylaminopropyne with difunctionalized 4-nitroisoxazoles: a single step access to the Novel isoxazolo[4,5-c]isoxazole system

The nitroderivatives 1a–c were found to react with the title ynamine 2 under mild conditions to give the corresponding fused isoxazoles 3a–c, as proved by an X-ray diffraction of 3a; a plausible mechanistic pattern for these conversions is presented. Treatment of the nitroderivatives 1a–c with the ynamine 2 afforded the new bicyclic isoxazoles 3a–c as proved by an X-ray analysis of 3a.

Reactions of 3,5-dimethyl-4-nitroisoxazole with cyclic enamines and 1-diethylaminopropyne

3,5-Dimethyl-4-nitroisoxazole (1) was found to undergo tandem condensation-cyclization processes with 4-(1-cylopenten-1-yl)- and 4-(1-cyclohexen-1-yl)morpholine in ethanol solution to give, through the intermediates (4) and (7), the N-oxides (5) and (9) respectively. The reactivity of 1 towards 1-diethylamino-propyne in different solvents was also investigated; the structure of the unexpected acycloxime (13), coming from the above reagents in acetonitrile, was determined by an X-ray analysis. Plausible mechanistic pathways for these new reactions are suggested

Thermal rearrangement of ethyl 5-nitro-4-phenyl-2-oxa-3-azabicyclo[3.1.0]hex-3-ene-1-carboxylate into a quinoxaline system

The title compound 2 is found to undergo thermal isomerization into the quinoxaline derivative 3, as shown by a crystal structure determination of the latter; a mechanistic rationale for this unusual rearrangement is suggested.

New features of isoxazole chemistry. The reaction of ethyl 4-nitro-3-phenylisoxazole-5-carboxylate with 2,3-dimethylbuta-1,3-diene

The title compound (2) was found to undergo a (2 + 4) cycloaddition with 2,3-dimethylbuta-1,3-diene affording the tetrahydro-1,2-benzisoxazole (3), which could be easily converted into the corresponding dihydro derivative (4) by elimination of the NO2 and CO2Et groups.