Lajos Gera

Transformation of compounds containing C-N bonds on heterogeneous catalysts: Part V. Hydrogenolysis of C-N bonds in substituted azacycloalkanones: preparation of sterically hindered amines and amino derivatives

Abstract On various transition metal catalysts (Raney nickel, Pd/C, Pd black, RuO2, Rh/C), the N-C(2) bond in N-benzoyl-2,2,4,4-tetraMe-azetidin-3-one (1) undergoes hydrogenolysis with 100% selectivity, as does that in the corresponding azetidine derivative 2 on Raney nickel; in the process, the oxo group in the ring in 1 is converted to a hydroxy group. In the analogues with higher numbers of ring atoms, only the latter hydrogenation proceeds; under identical reaction conditions, C-N hydrogenolysis does not occur. The rate of hydrogenolysis is increased by the carbonyl group at position 3 in azetidinone, as compared to that of azetidine, which does not possess the carbonyl function. A proposal is made concerning the reaction mechanism.

Stereochemical studies. Part 30. Synthesis and conformational analysis of deca- and dodeca-hydropyrido[2,1-b]quinazolin-11-ones

cis- and trans- Decahydro- and dodecahydro-pyrido[2,1-b]quinazolin-11-ones have been synthesized and their preferred conformations established by 1H n.m.r. spectroscopy. At room temperature the A and B rings of the cis-decahydro derivatives are conformationally mobile, while the t-butyl derivatives have fixed conformations. The predominant conformation of the cis-dodecahydro-derivatives is that in which the CO group is equatorial, the N atom is axial, and the configuration of the nitrogen bridgehead B/C fusion is trans.

Homogeneous and heterogeneous catalytic asymmetric reactions: II. Asymmetric hydrogenation of steroid ketones

Abstract The asymmetric reduction of steroid 17- and 20-ketones with chiral hydrosilanerhodium-(+)- and (−)-diop-complex catalysts allows different stereoselectivities in the formation of 17-alchols, but not of 20-alcohols. The degree of this stereoselectivity is higher than that attained with other methods. The stereoselectivity can be explained in terms of the most preferred conformation of the α-siloxysteroid-rhodium intermediate complexes.

Transformation of compounds containing C-N bonds on heterogeneous catalysis: Part IV1. Hydrogenolysis of β lactams on raney ni: a new method for the preparation of 1,3-aminoalcohols

Abstract The transformations of the condensed-skeleton β-lactams (azetidin-2-ones) 1 – 4 were studied under various reductive conditions. On the action of a complex metal hydride, selective formation of azetidines occurs. A new heterogeneous catalytic method is reported, which is suitable for the preparation of cyclic 1,3-aminoalcohols in the presence of Raney Ni in liquid-phase hydrogenation. On a Ni on Cab-O-Sil ® catalyst in a flow reactor, 1 is converted to the carboxylic acid amide 9 with high selectivity.

2-Substituted hexahydroacylanthranils: Synthesis and selective reactions with amines

SummaryIn contrast to their aromatic analogues, the corresponding saturated diamides5–9 are formed exclusively when hexahydro-3,1,4-benzoxazinones (3,4) are reacted with amines. The cyclodehydration reaction of the diamides5–9 cannot be carried out at arbitrarily high temperatures.ZusammenfassungIm Gegensatz zu den aromatischen Analoga bilden sich bei der Reaktion von Hexahydro-3,1,4-benzoxazinonen (3,4) mit Amien ausschließlich die entsprechenden gesättigten Diamide5–9. Die Cyclodehydrierungsreaktion der Diamide5–9 kann nicht bei beliebig hoher Temperatur durchgeführt werden.

Crystal structure of (Z)-3,4-methylenedioxybenzaldehyde oximium 4-toluenesulfonate at 110 K

C 15 H 15 NSO 6 cristallise dans P2 1/n avec affinement jusqua 0,053. Le noyau benzenique du cation et de lanion sont quasiment plans. Anions et cations forment des chaines dans la direction b grâce a des liaisons hydrogenes

Differential geometry and organic chemistry; The Bonnet transformation applied to the racemization of tri-o-thymotide and isomerization of cyclophenes

Application des concepts empruntes a la geometrie differentielle, des surfaces minimales et de la transformation de Bonnet a la reorganisation moleculaire. Interpretation de la racemisation et de lisomerisation E/Z des doubles liaisons en termes de transformation de surface