No abstract

The spectrum of the 3-cyclopentenyl Grignard compound (2) also supports this concept : The CL proton gives a clear quintet at r=10.2 (J=IO Hz) in ether and in THF. Thus, unlike the alcohol and the bromide, there is only one coupling constant to all four neighbors. This again suggests rapid inversion, although conclusive proof has not yet been obtained because the Grignard compound (2) is precipitated below -20 "C before the coalescence temperature has been reachedc4]. However, it is quite reasonable to suppose that the five-membered ring Grignard compound (2) should invert more rapidly than the sixmembered ring compound ( I ) , since in the former case the -I effect of the double bonds can act from both sides via only two single bonds. It is therefore understandable that the coalescence point has still not been reached at as low a temperature as -20°C. It is unlikely that homoallyl resonance plays a very important role in comparison with the inductive effects, particularly since the anion of ( 2 ) , even if (T overlapping with the TC electrons of the double bond were permitted by the stereochemistry, would be a "bishomoantiaromatic" system[". In this connection it is interesting to note that primary, open-chain homoallyl Grignard compounds d o not invert significantly more rapidly than the corresponding saturated compounds[61.

No abstract

Die Reaktion der Sulfonylaldehyde (I) bzw. (IV) mit dem Sulfonylazid (II) in Gegenwart eines großen Überschusses NH3 liefert die Sulfonyldiazomethane (III) bzw. (V).

( 5 ) und ( 6 ) , und der Vergleich der chemischen Verschiebungen von (7) und (8) mit denen von 2,4,6-Cycloheptatrien-i,i-dicarbonsaure-dimethylester ( 9 a ) und Norcaradien-7.7-dicarbonsaure-dimethylester (9 b) 19] zeigen, daR weder Cycloheptatriene ( 7 a ) und ( 8 a ) noch Norcaradiene (7b) und (8b) vorliegen. Diese Werte sind jedoch zu