6 – c5h6–c5h10

Wasserstoff-Verschiebungen, III. Thermische Isomerisierung von cis-Hexadien-(1.4)†

Pyrolysis of alkenylidenecyclopropane and bis-cyclopropylidene systems

(S)-cis,trans-3-Methyl-7-deutero-octadien-(4.6) (5) lagert sich bei 250° in einer nichtkatalysierten Reaktion erster Ordnung in ein Gemisch aus (R)-trans,cis-3-Methyl-7-deutero-octadien-(3.5) (3) und (S)-cis,cis-3-Methyl-7-deutero-octadien-(3.5) (4) um. In diesem System durchlauft die sigmatrope 1.5-Wasserstoffverschiebung damit bevorzugt einen suprafacialen Ubergangszustand, der um mindestens 8 kcal/Mol gegenuber dem antarafacialen Ubergangszustand begunstigt ist.



The Stereochemistry of Sigmatropic 1,5-Hydrogen Shifts



At 250° (S)-cis,trans-3-methyl-7-deutero-octa-4,6-diene (5) rearranges by a non-catalysed first order reaction to a mixture of (R)-trans,cis-3-methyl-7-deutero-octa-3,5-diene (3) and (S)-cis,cis-3-methyl-7-deutero-octa-3,5-diene (4). Therefore the sigmatropic 1,5-hydrogen shift proceeds in this system preferentially by way of a suprafacial transition state, which is at least 8 kcal/mol lower in energy than the antarafacial one.

Die Stereochemie sigmatroper 1.5‐Wasserstoffverschiebungen

Evidence for a dominant suprafacial-inversion pathway in the thermal unimolecular vinylcyclopropane to cyclopentene 1,3-sigmatropic shift

Continuous diradical as transition state. II. Internal rotational preference in the cyclopentene rearrangement of the vinylcyclopropanes, (1S,2R)-(+)-cis- and (1R,2R)-(-)-trans-1-cyano-2-isopropenylcyclopropane

6 – c5h6–c5h10

References

Wasserstoff-Verschiebungen, III. Thermische Isomerisierung von cis-Hexadien-(1.4)†

Pyrolysis of alkenylidenecyclopropane and bis-cyclopropylidene systems

Die Stereochemie sigmatroper 1.5‐Wasserstoffverschiebungen

Evidence for a dominant suprafacial-inversion pathway in the thermal unimolecular vinylcyclopropane to cyclopentene 1,3-sigmatropic shift

Continuous diradical as transition state. II. Internal rotational preference in the cyclopentene rearrangement of the vinylcyclopropanes, (1S,2R)-(+)-cis- and (1R,2R)-(-)-trans-1-cyano-2-isopropenylcyclopropane