Corrigendum: Up the Hill: Selective Double-Bond Isomerization of Terminal 1,3-Dienes towards Z-1,3-Dienes or 2Z,4E-Dienes (Angewandte Chemie International Edition, (2012), 51, 5, (1270-1273), 10.1002/anie.201107512)

Article abstract of DOI:10.1002/anie.201902504

Several years ago the authors reported an isomerisation of E-1,3-dienes by a cobalt catalyst into Z-1,3-dienes in this Communication (Scheme —original scheme). Scheme (Figure presented.) Double bond isomerisation for the stereoselective generation of Z-4

Full text of DOI:10.1002/anie.201902504

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Chemie
.
Angewandte
Corrigendum
Several years ago the authors reported an isomerisation of E-1,3-dienes by a cobalt
catalyst into Z-1,3-dienes in this Communication (Scheme 1—original scheme).
Up the Hill: Selective Double-Bond
Isomerization of Terminal 1,3-Dienes
towards Z-1,3-Dienes or 2Z,4E-Dienes
F. Pꢀnner, A. Schmidt,
G. Hilt*
1270–1273
Angew. Chem. Int. Ed. 2012, 51
DOI: 10.1002/anie.201107512
Scheme 1. Double bond isomerisation for the stereoselective genera-
tion of Z-4a.
The result was of high interest, as the reaction led to the thermodynamically less stable
isomer Z–4a. Some time later, Prof. T. V. RajanBabu reported similar results with
a somewhat different ligand system consisting of CoCl2·(bidentate phosphine ligands)
and AlMe3.[1] The group of RajanBabu realised in a detailed investigation that the cobalt-
catalysed reaction is not an isomerisation process but rather a kinetic resolution of the
E/Z-isomers.[2] Subsequently, Dr. Felicia Weber tried to reproduce the original isomer-
isation reaction and observed essentially the same behaviour of a kinetic resolution of
the E/Z-isomers by the catalyst system (Scheme 2). Also, when pure E-isomer was
submitted to the reaction only traces of the Z-isomer could be detected by GCMS
analysis. The formation of the Z-isomer was attributed to a thermodynamic equilibra-
tion of the pure E-isomer by a process other than the proposed cobalt isomerisation.
Scheme 2. Reaction of double bond isomers with the cobalt catalyst.
Whereas the E-isomers are converted mostly into a polymer of unknown constitution,
the Z-isomer is relatively unreactive and in NMR spectra and GC analysis it could be
shown that the signals for the E-isomer disappeared for many substrates while the
signals for the Z-isomer remained unchanged. In fact, the previously mistakenly
reported isomerisation towards the Z-isomer could not be observed. Accordingly, the
results presented in Table 1 of the original Communication have to be corrected. The
results of the kinetic resolution of E- and Z-1,3-dienes according to Scheme 2 are now
presented in Table 1. Interestingly, for substrate 4c the E-isomer remained while the Z-
isomer disappeared over time, while 4g remained essentially unchanged. The other Z-
1,3-dienes could be isolated in moderate yields, and with E/Z ratios <5:>95 in most
cases.
The kinetic resolution of the E/Z mixture is surely an interesting process on its own, but
the authors regret the misinterpretation of the results reported and apologise for all
inconvenience caused by the original Communication.
Angew. Chem. Int. Ed. 2019, 58, 17087 – 17104
ꢀ 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org 17103

Angewandte
Contents
Chemie
Table 1: Results of the cobalt-catalysed transformation of E/Z-1,3-dienes.[a]
Entry
SM[b]
Ratio E:Z
Product
Yield (Z-4)
(Ratio E:Z)
24%
(2:98)
1
2
3
4
5
49:51
49:51
50:50
48:52
50:50
~10%[c]
(3:97)
41%
(91:9)
27%
(8:92)
38%
(13:87)
40%[d]
(<1:99)
6
40:60
51%
(69:31)
7
8
9
67:33
56:44
58:42
14%
(20:80)
41%
(<1:99)
25%
(<1:99)
10
57:43
[a] CoBr2(py-imine 5) (5–15 mol%), zinc powder (10–30 mol%), zinc iodide (10–30 mol%), 5–
120 h, CH2Cl2, ambient temperature. [b] SM = starting material. [c] Due to its high volatility,
product with acceptable purity was obtained in low yield. [d] The 1H NMR spectrum shows another
isomerisation product with chemical shifts that do not match those of the E-isomer.
The authors thank Stanley Jing, Prof. T. V. RajanBabu, and Dr. Felicia Weber for their
efforts to shed light on the process of kinetic resolution of E/Z-isomers. Special thanks
go to M.Sc. Luomo Li and M.Sc. Sebastian M. Weber who obtained the results shown in
Table 1.
[1] Y. N. Timsina, S. Biswas, T. V. RajanBabu, J. Am. Chem. Soc. 2014, 136, 6215.
[2] Y. N. Timsina, S. Biswas, T. V. RajanBabu, J. Am. Chem. Soc. 2018, 140, 2700.
17104 www.angewandte.org
ꢀ 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2019, 58, 17087 – 17104