Acta Crystallographica Section C

Crystal Structure Communications

Volume 60, Part 5 (May 2004)

fa1050 scheme

Acta Cryst. (2004). C60, o308-o311 [doi:10.1107/S0108270104006067]

(E)- and {(Z)-2-[,-bis(methoxycarbonyl)vinyl]cyclopentadien-1-ylidene}triphenylphosphorane

L. J. Higham, P. G. Kelly, H. Müller-Bunz and D. G. Gilheany

Abstract: The Ramirez ylide undergoes electrophilic substitution with dialkyl acetylenedicarboxylates, yielding a mixture of the Z and E adducts. The crystal structure analyses of the two adducts formed using dimethylacetylene, viz. dimethyl (E)- and (Z)-1-[2-(triphenylphosphoranylidene)cyclopentadien-1-yl]ethylenedicarboxylate, both C₂₉H₂₅O₄P, explain an unusual chemical shift observed for the vinyl H atom of the Z adduct, which had previously precluded a definitive assignment of the isomers. In addition, the structures explain why only one of the isomers reacts further with acetylene esters to produce azulenes with a rare substitution pattern.

Formula: Two isomers of C₂₉H₂₅O₄P

Online 9 April 2004


	Structure factor file (CIF format) (300.0 kbytes) Contains datablock IIIa

	Structure factor file (CIF format) (208.9 kbytes) Contains datablock IIIb

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