Polyspiranes, 16. - Cascade Rearrangements, 11. - Synthesis, Structure, Conformation, and Dynamics of Heptacyclo1,5.05,9.09,13.013,17.017,21>tetracosane (Coronane)
Coronane (2) was synthesized by addition of allylmagnesium bromide to ketone 7, rearrangement of the resulting homoallyl alcohol 8a to diene 9, hydrozirconization of 9 followed by bromination to give 11, and finally radical cyclization of 11.A direct cyclization of 9 using tri(n-butyl)tin hydride failed. 2 is all-cis-configurated, adopts a chair conformation in the crystal state and in solution and exhibits an extremely low barrier of inversion (ΔG(excit.)173 /= 8.6 kcal/mol).
Wehle, Detlef,Schormann, Norbert,Fitjer, Lutz
p. 2171 - 2178
(2007/10/02)
FORMATION OF SOME BICYCLIC SYSTEMS BY RADICAL RING-CLOSURE
The rates and stereochemistry of ring closure of the radicals (2), (9), (10), and (16) have been determined and rationalised.
Beckwith, Athelstan L. J.,Phillipou, George,Serelis, Algirdas K.
p. 2811 - 2814
(2007/10/02)
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