R. Perez-Ossorio

A novel aza-di-Π-methane rearrangement the photoreaction of 4,4-dimethyl-1,6,6-triphenyl-2-aza-hexa-2,5-diene

Abstract The synthesis and the novel photochemical aza-di-π-methane reaction of 4,4-dimethyl-1,6,6-triphenyl-2-aza-hexa-2,5-diene are described.

On the reaction of phenylglyoxal with 2-aminopyridine

Abstract A structure of 2-phenyl-1 H -imidazo[1,2-a]pyridinium-3-olate 1 has been assigned to the product of the title reaction instead of the previously reported one. In solution, 1 undergoes photo-oxidation related to that occurring in Cypridina luciferine.

Studies on the scope of the aza-di-π-methane rearrangement of β,γ-unsaturated imines

The syntheses of imines of 2,2,4,4-tetraphenylbut-3-enal, 3,3-dimethyl-5,5-diphenylpent-4-en-2-one, and 2,2-dimethyl-1,4,4-triphenylbut-3-en-1-one are described. The results of the irradiation of these and of 2,2-dimethyl-4,4-diphenylbut-3-enonitrile and 2,2-dimethyl-4,4-diphenylbut-3-enal oxime are discussed. The N-isopropyl imine of 2,2,4,4-tetraphenylbut-3-enal and the N-phenyl and benzyl imines of 3,3-dimethyl-5,5-diphenylpent-4-en-2-one undergo the 1-aza-di-π-methane rearrangement.

Substitution effects on the aza-di-π-methane rearrangement of imines

The u.v. irradiation of several 1-aryl derivatives of 3,3-dimethyl-5,5-diphenyl-1-azapenta-1,4-diene has been carried out. All of them undergo the aza-di-π-methane rearrangement and yield a cyclopropylimine. The influence of substituents on the 1-aryl group has given support for the proposal that imines with a low ionization potential are less efficient at undergoing the aza-di-π-methane process than are imines with a higher ionization potential. This was demonstrated in a quantitative fashion. The involvement of an electron-transfer process in the reaction is discussed.

A novel photochemical 1,2-acyl migration in an enol ester. The synthesis of 3-oxazoline derivatives.

Abstract Irradiation of 3-Aryl-4-benzoyloxy-1,1,4-triphenyl-2-aza-buta-1,3-dienes gives 3-oxazoline derivatives in high yield by a novel 1,2-acyl migration, in clear contrast with the normal behaviour of other enol esters.

Reaction of α-diketones with ethanolamine

Butanedione and ethanolamine react to yield 4-5-diaza-1,5-dioxadecalin 3, 2,3-epoxy-8-aza-1, 4,5-trioxadecalin 4, and 2-hydroxy-1,6-dihydro-oxazine 5a according to the molar ratios of the reagents. With benzil and 1-phenyl-1,2-propanedione only the related oxazines 5. are obtained in equilibrium with their open-chain tautomers.

Stereochemistry of imino-group reduction. Part 3. The hydride reduction of achiral benzil monoimines

The RR,SS:RS,SR ratio of diastereoisomeric amino-alcohols obtained from the lithium aluminium hydride reduction of the monoimines prepared by reaction of benzil and various aliphatic and aromatic achiral amines has been determined. Stereochemical results are analysed in terms of competition between two reaction routes involving respectively preliminary reduction of the oxo group and the imino group. The influence of polar and steric factors of the nitrogen substituent is discussed as is also that of solvent polarity. The reduction of some monoimines with sodium borohydride has also been studied. An interpretation of the ratios RR,SS:RS,SR is provided.

A new synthesis of 1,1-diphenyl-3-arylisoquinolin-4-ones by the novel cyclization of 2-azabuta-1,3-dienes.

Abstract The facile synthesis of novel 1,1-diphenyl 3-arylisoquinolin-4-ones by the cyclization of protonated 2-azabuta-1,3-dienes is reported.

The reaction of benzil and 2-aminopyridine: a correction

Abstract On the basis of X-ray crystallographic analysis, it is shown that the reaction of benzil and 2-aminopyridine affords, in agreement with Sokovs previous work, 2,2-diphenylimidazo-[1,2-a]-pyridin-3-one and not N-(2-pyridyl)-benzilmonoimine as we have previously proposed.

Reduction of Chiral Acyclic Ketones with Hydride-transfer Agents. Semiempirical Analysis of the Observed Stereoselectivity

(±)-2,2,6,6-Tetramethyl-5-phenylheptan-3-one (1), (±)-4,4-dimethyl-1,3-diphenylpentan-1-one (2), (±)-2-methyl-1,3-diphenylpropan-1-one (3), and (±)-2,3,3-trimethyl-1-phenylbutan-1-one (4) have been reduced with lithium tetrahydridoaluminate (LAH), sodium tetrahydridoaluminate (NAH), lithium tri-t-butoxyhydridoaluminate (LTBHA), lithium tetrahydridoborate (LBH), lithium tri-s-butylhydridoborate (LS = lithium selectride) and potassium tri-s-butylhydridoborate (KS = potassium selectride) using different solvents and reaction conditions. For ketones (1) and (2) some correlations with the observed stereoselectivity have been found. The applicability of a semiempirical scale for the effective size of reagent to the stereochemical analysis of the observed asymmetric induction has been tested.