Synthesen mit aliphatischen Dialdehyden, XLII. (2,4,6‐Cycloheptatrien‐1‐yliden)malonaldehyd (8,8‐Diformylheptafulven) — Herstellung, Struktur und Reaktionen

Abstract

(cycloheptatrieny1) malonaldehydes (2 and 3). In solution, 5 exists in a solventdependent equilibrium with its valence isomer 6. The structure of 5 was determined by means of its 'H and 13C NMR spectrum, dipole moment (5.24 D), and an X-ray analysis; its dipole moment and chemical reactivity were also estimated by MNDO calculations. -Reactions of 5 with electrophiles (4 7) and with nucleophiles (-+ 8-14) are described.Monosubstituierte Malonaldehyde und Malonaldehyd selbst sind wertvolle CjSynthe~ebausteine~.~), die in Losung und im Kristall vollstandig enolisiert vor1iegen6,'); ihre Reaktivitat entspricht der vinyloger Carbonsauren. Dagegen sind 2,2-disubstituierte Malonaldehyde, R'R2C(CH = 0)28), und Aikylidenmalon aldehyde, R'R2C = C(CH = 0)2, wegen fehlender Enolisierungsmoglichkeiten echte C,Dialdehyde mit entsprechend gesteigerter Reaktivitat.

Dipole Moments of Compounds Containing Double Bonds

“…Experimental was first decomposed into the contributions of 60 and 61 (as in equation 4, of 61 was estimated from bond moments), then the strong electron displacement in 60 was revealed 153 . As expected, the sevenmembered ring bears some negative charge.…”