Jean-Marie Conia

‘Paddle-wheel’ hydrocarbons. Intracyclic C–C bond length shortening in rotanes. X-Ray crystal structures of [3]- and [4]-rotane

Single crystal X-ray determinations of the structures of [3]- and [4]-rotane reveal that bond-length shortening occurs in the inner central cyclopropane or cyclobutane ring; this may be attributed to a π bond order enhancement resulting from the disposition of the adjacent (paddle-like) peripheral cyclopropane rings.

Interaction of walsh orbitals in rotanes. Photoelectron spectroscopic investigation

He I photoelectron spectroscopic investigations of bicyclopropylidene (4), [3]rotane (5), and [4]rotane (6) reveal considerably larger resonance integrals for (4) and (5) compared with values reported for bicyclopropyl and tricyclopropyl derivatives.

X-Ray molecular structure of a highly symmetrical triketone: [3.3.3]propellane-2,8,9-trione

X-Ray analysis of a single crystal of [3.3.3]propellane-2,8,9-trione (3) reveals unexpected attractive interactions between the carbonyl groups.

REACTION OF SILYL ENOL ETHERS WITH CARBENES AND CARBENOIDS. NEW SYNTHESES OF VARIOUS CARBONYL COMPOUNDS

Abstract The reaction of carbenes or carbenoid species (CH 2 ,CBr 2 ,CClMe) with silyl enol ethers leads to silyloxycyclopropanes and easy ring opening of these products yields various interesting carbonyl compounds. An account of the recent literature in the field is given and the main results obtained in the Laboratoire des Carbocycles at Orsay are reported. The halocarbenes CBr 2 and CClMe lead to unsaturated carbonyl compounds because ring opening always occurs with the elimination of XSiMe 3 . Ring enlargement of cycloalkanones into higher 2-methyl-cycloalkenones and the direct preparation of E and (or) Z αβ-ethylenic ketones and aldehydes from the appropriate halo-silyloxycyclopropane isomers, without Z → E isomerisation, are discussed in greater detail.