Michel Rouillard

Ouverture par hf-pyridine des aziridines bicycliques. I. effet configurationnel en serie saturee

Abstract Cis and trans epimino cyclohexanes containing no groups exerting any marked polar or conjugative effects produce, with HF-pyridine, 2-fluoro amines. The structures of the diastereoisomeric amines established by 1 H and 19 F NMR show that Furst and Plattner rule applies to the stereochemical course of HF-pyridine ring opening of those aziridines. In every case, the opening involves F trans addition to NH 2 .

Conformational analysis using torsion angle notation : attempted prediction and interpretation of the steric course of the cleavage reaction between bicyclic aziridines and hydrogen fluoride in pyridine solution

Abstract Dynamic conformational analysis of the cleavage of methyl-substituted 7-aza bicyclo [4.1.0] heptanes by Olahs reagent (30 wt % of pyridine in hydrogen fluoride), using the torsion angle notation, allows structural and conformational prediction of the 2-fluoro cyclohexylamine products. Consequently, a mechanism for the cleavage is proposed.

Ouverture par HF-pyridine d'aziridines tricycliques. III. Comparaison entre la reactivite des aziridines et celle des oxiranes

Abstract The ring opening of 3-aza 1,8,8-trimethyl tricyclo [5.2.1.0 2,4 ]octane isomers by HF-pyridine has been studied. A series of γ-fluoroamines and non fluorinated amines, isomers of the starting aziridines, was obtained. No β-fluoroamines were isolated. The structures of diastereoisomeric amines, established by 1 H and 19 F NMR, show product structure dependence upon the exo-endo aziridine configuration. A comparison between aziridine reactivity and oxirane one is done.

Ouverture par HF-pyridine des aziridines bicycliques. II. Derives α,β-ethyleniques diversement substitues

Abstract The ring opening of three isomeric α,β-ethylenic aziridines by HF-pyridine has been studied. The reaction proceeds, depending on temperature, solvent or structure, either to expected 2-fluoro amines and 4-fluoro allylic amines or to elimination products. A type of Wagner-Meerwein rearrangement was observed and benzene as solvent gave a type of Friedel-Crafts reaction. The steric constraints may explain the differences in the yields of cis and trans addition products. Also, the rigid structures allow the detection of vicinal couplings and the study of configuration and conformation.

Reaction de wittig-horner entre phosphonates et cyclohexenones β-substituees.

Abstract Various procedures were attempted in order to prepare α,β,γ,δ-unsaturated nitriles via the Wittig-Horner reaction of β-substituted cyclohex-2-en-1-ones with diethyl cyanomethyl phosphonate. Among them, the one using NaH as base in refluxing THF gives only the products resulting from carbonyl attack, in good yields. The stereochemistry of the reaction is discussed.

Basicity of the carbonyl group. Part 13. 4-Substituted camphors as models for transmission of polar effects. A calorimetric, infra-red and 1H NMR study

In a series of 4-substituted camphors, in which the substituent, X, varies from ethyl through hydrogen to nitro, we have shown that the enthalpies of complexation, with BF3 in dichloromethane, which cover a range of 14.5 kJ mol–1 correlate well with r > 0.99 with polar substituent constants with the sensitivity ρ*ca. 8.IR spectroscopy of the free ketones and the more polar BF3 complexes indicates that the latter are ca. 1.44 times more sensitive to substituent variation.Complexation occurs at both sites when X = OAc and only at the ketone when X = CO2Me.We rationalise the smaller sensitivity of the protons to substituent-induced 1H shift displacement when in the E-complexed form to the electron-attracting effect of complexation that leads to diminished electronic screening. The 4JH3exo–H5exo coupling is diminished by complexation which enhances hyperconjugation between the C(3)–Hσ and the carbonyl p orbitals to the detriment of back lobe C(3)–H3exo–C(5)–H5exoσ–σ overlap. A number of chemical shift and coupling correlations are reported.