Synlett 2015; 26(16): 2243-2246
DOI: 10.1055/s-0035-1560092
letter
© Georg Thieme Verlag Stuttgart · New York

Stereospecific Oxidative Demetallation of Highly Functionalized CpCo(1,3-Diene) Complexes: An Experimental and Computational Study

Ryan L. Holland
,
Joseph M. O'Connor*
a   Department of Chemistry and Biochemistry (0358), University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0358, USA   eMail: jmoconnor@ucsd.edu
,
Kevin D. Bunker
a   Department of Chemistry and Biochemistry (0358), University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0358, USA   eMail: jmoconnor@ucsd.edu
,
Pengjin Qin
a   Department of Chemistry and Biochemistry (0358), University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0358, USA   eMail: jmoconnor@ucsd.edu
,
Stephen K. Cope
a   Department of Chemistry and Biochemistry (0358), University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0358, USA   eMail: jmoconnor@ucsd.edu
,
Kim K. Baldridge*
b   Institute of Organic Chemistry, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland   eMail: kimb@oci.uzh.ch
,
Jay S. Siegel*
c   School of Pharmaceutical Science and Technology, Tianjin University, 92 Weijin Road, Nankai District, Tianjin, P. R. of China
a   Department of Chemistry and Biochemistry (0358), University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0358, USA   eMail: jmoconnor@ucsd.edu
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Publikationsverlauf

Received: 03. Mai 2015

Accepted after revision: 13. Juli 2015

Publikationsdatum:
24. August 2015 (online)


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Kudos to Professor K. Peter C. Vollhardt for his 25 years of innovative contributions to SYNLETT

Abstract

Three diastereomers of a highly functionalized tetrasubstituted cyclopentadienylcobalt–diene complex, (Cp)Co[η4-CH(CO2Et)=C(SO2Ph)C(SiMe3)=CH(CO2Et)] (4-ZE, 4-EZ, 4-ZZ; Cp = C5H5), undergo oxidative demetallation by ceric ammonium ­nitrate (CAN) to give the corresponding metal-free dienes, CH(CO2Et)=C(SO2Ph)C(SiMe3)=CH(CO2Et) (5-ZE, 5-EZ, 5-ZZ), with retention of configuration. The oxidation of 4-ZE by iodine occurs with a different stereoselectivity than that observed with CAN, to provide the fourth diastereomer 5-EE in high yield. B97D/Def2-TZVPP(CH2Cl2) calculations predict the diene free-energy ordering as: 5-EE < 5-ZE < 5-EZ < 5-ZZ.

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