Erratum: A general synthesis of alkenyl-substituted benzofurans, indoles, and isoquinolones by cascade palladium-catalyzed heterocyclization/oxidative heck coupling (Chemistry - A European Journal)

Full text of DOI:10.1002/chem.201201973

CORRIGENDUM
DOI: 10.1002/chem.201201973
A General Synthesis of Alkenyl-Substituted Benzofurans, Indoles, and
Isoquinolones by Cascade Palladium-Catalyzed Heterocyclization/Oxidative
Heck Coupling
Rosana ꢀlvarez,*[a] Claudio Martꢁnez,[a] Youssef Madich,[b] J. Gabriel Denis,[a]
Josꢂ M. Aurrecoechea,*[b] and ꢀngel R. de Lera*[a]
originally reported. However, the conclusions of the paper
do not change. The authors apologize for this oversight.
As a result, corrected versions of Schemes 2, 3, 5, 7, and
the schemes of Tables 2–4 are provided here, and the follow-
ing amendments are needed in the main text of the paper:
1) Page 12747, left column, lines 23–24: “…The synthesis of
3-(3-oxoprop-2-enyl)benzofurans…” replaces “…The
synthesis of 3-(3-oxoprop-2-enyl)benzofurans and corre-
sponding 4-alkenylisoquinolones…”.
2) References [7c,d] and [8] in the original manuscript are
no longer applicable.
3) The term “1H-isochromen-1-imine” replaces the term
“isoquinolone” throughout the rest of the paper.
4) Page 12750, right column, line 48: The term “5-exo-trig-
derived” replaces the term “isoindolone-type”.
5) Page 12752, left column, line 24 and Scheme 7 legend:
The term “carboximidate” replaces the term “amide”.
6) For the legend of Scheme 2 “Strategy for the preparation
Figure 1. ORTEP diagram of 11a with thermal ellipsoids at 50% proba-
bility.
of heterocyclic derivatives 9–12” replaces “Strategy for
In the Full Paper by A. R. de Lera[1a] et al. the structures
of the products derived from benzamides 7 are incorrectly
displayed in Schemes 3, 5, 7, and the schemes of Tables 2–4.
The authors have now determined with X-ray diffraction
analysis data (Figure 1)[1b] that those reactions proceed by
O-cyclization and not through the N-cyclization pathway
[a] Dr. R. ꢀlvarez, C. Martꢁnez, J. G. Denis, Prof. ꢀ. R. de Lera
Departamento de Quꢁmica Orgꢂnica
Facultad de Quꢁmica, Universidade de Vigo
Lagoas Marcosende, 36310 Vigo (Spain)
Fax : (+34) 986-811940
Scheme 2. Strategy for the preparation of heterocyclic derivatives 9–12.
E-mail: rar@uvigo.es
qolera@uvigo.es
[b] Y. Madich, Dr. J. M. Aurrecoechea
Departamento de Quꢁmica Orgꢂnica II
Facultad de Ciencia y Tecnologꢁa
Universidad del Paꢁs Vasco
Apartado 644, 48080 Bilbao (Spain)
Fax : (+34) 946-013500
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201201973.
Scheme 3. Preparation of 1H-pyranoACTHNUGTRNEUNG[4,3-c]pyridin-1-imine 11h.
Chem. Eur. J. 2012, 00, 0 – 0
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Table 3. General preparation of 3-alkenylbenzofurans, 3-alkenylindoles,
and 4-alkenyl-1H-isochromen-1-imines from alkynyl substrates 5–7 and
n-butyl (8a) or ethyl acrylate (8b).[a]
Scheme 5. Olefins 8c–n used in the oxidative Heck coupling reactions
and side-products 17–19 obtained in the cyclization/coupling reactions
(Table 4).
Table 4. General preparation of 3-alkenylbenzofurans, 3-alkenylindoles,
and 4-alkenyl-1H-isochromen-1-imines from alkynyl substrates 5–7 and
alkenes 8c–n (Scheme 5).[a]
Scheme 7. Formation of lactone 23e from carboximidate 11e.
Table 2. Test of the standard reaction conditions for aniline and benza-
mide substrates.[a]
Entry
8
5–7 Conditions[a] 9–11 R1
R2 R3 Yield [%][b]
1
2
3
4
5
6
7
8
8c 5b
8e 5b
8 f 5b
A
A
A
9g
9h
9i
9j
9k
9l
9m
9n
9o
9p
9q
CO2Me Me
COMe
COMe Me
(CH2)3CO
(CH2)2CO
CONH2
CONH2 Me
H
H
H
H
H
H
H
H
H
H
H
H
70[c]
91
56
31
36
H
8g 5b A[d]
N
8h 5b A[d]
8i
5b A[d]
H
50
8j 5b A[d]
8k 5b A[f]
43[e]
60[g]
57[h]
57
CN
H
9
8l
5b
A
CN
SO2Me
Ph
Me
H
H
10
11
12
13
14
15
16
17
18
8m 5b A[d]
8n 5b
A
60
51
the preparation of benzofurans 9, indoles 10, and isoqui-
nolones 11”. Scheme 2 is reproduced here for clarity.
7) For the legend of Scheme 3 “Preparation of 1H-pyrano-
8c 6a B[i,j]
10h CO2Me Me
10i
10j
10k CONH2
10l CN
10m SO2Me
11i COMe
8d 6a B[k,l]
CO2Me
COMe
H
H
H
H
H
H
Me 67
8e 6a
8i 6a
B
B
H
H
H
H
H
79
95
ACHTUNGTRENNUNG[4,3-c]pyridin-1-imine 11h” replaces “Preparation of 6-
8k 6a B[f,i]
8m 6a B[k]
8e 7b C[j]
77[m]
87
azaisoquinolone (a 2,6-naphthyridine-1-one) 11h”.
8) Footnote [o] in Table 4 is corrected. The whole table is
reproduced here for clarity.
71[n]
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Corrigendum
CORRIGENDUM
s.[5a,d] The same isochromen-1-imine core structure is also
generated in analogous reactions where the Heck-type cou-
pling is performed intramolecularly.[6a] In the manuscript in
ref. [6a], the structures were also incorrectly displayed,
therefore this paper is corrected by another Addendum/Cor-
rection.[6b] In any event, in common with the processes lead-
ing to iminoisobenzofurans mentioned above,[3,4] the Pd-cat-
alyzed formation of 11 from 2-alkynylbenzamides 7 also fol-
lows an initial O-cyclization pathway, albeit of the 6-endo-
dig type, therefore giving rise to a regiochemically different
family of products. An even more fundamental difference
arises in the nature of the catalytic cycle, which is shared by
all products 9–11, and incorporates a coupling with an exter-
nal alkene, thus providing a new strategic element in the
synthesis of various heterocyclic motifs.
Table 4. (Continued)
Entry
8
5–7 Conditions[a] 9–11 R1
7b 11j CONH2
11k Ph
R2 R3 Yield [%][b]
19
20
8i
C
H
H
H
H
78
8n 7b C[d]
39[o]
[a] Unless otherwise indicated, reactions were conducted with PdII com-
plex (5 mol%), KI (0.5 equiv), and alkene (6 equiv) in DMF under an air
atmosphere for the indicated time. Conditions A: PdCl2, 808C, 20 h. Con-
ditions B: PdCl2, 1008C, 20 h. Conditions C: [PdCl2ACTHNUGTRNEUG(N PPh3)2], 808C, 21–
23 h. [b] Isolated yield. [c] A 1:1 mixture of 9g and 17a (Scheme 5) was
obtained. [d] Reaction conducted at 1008C. [e] A 1:1.5 mixture of 9m
and 17b (Scheme 5) was obtained. [f] Reaction conducted in a sealed
tube. [g] A 3:1 E/Z mixture was obtained. [h] A 1.2:1 E/Z mixture was
obtained. [i] Reaction conducted with 12 equiv of olefin. [j] Reaction
time: 8 h. [k] [PdCl2ACHTUNGTRENNUNG(PPh3)2] was used as catalyst. [l] Reaction conducted
at 608C. [m] A 13:1 E/Z mixture was obtained. [n] The conjugate addi-
tion product 18 (20%) was also obtained (Scheme 5). [o] A 5:1 mixture
of regioisomers tentatively assigned as 11k and 19 (Scheme 5) was ob-
tained.
[1] a) R. ꢀlvarez, C. Martꢁnez, Y. Madich, J. G. Denis, J. M. Aurrecoe-
chea, ꢀ. R. de Lera, Chem. Eur. J. 2010, 16, 12746–12753; b) CCDC-
884748 contains the supplementary crystallographic data for this
paper. These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_
request/cif.
Accordingly, revised names and structures for all products
derived from benzamides 7 are also provided in the new
Supporting Information file.
[2] a) H. Sashida, A. Kawamukai, Synthesis 1999, 1145–1148; b) N. G.
Kundu, M. W. Khan, Tetrahedron 2000, 56, 4777–4792; c) H. Cao, L.
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Additional Discussion
Palladium-catalyzed cycloisomerization reactions of 2-alky-
nylbenzamides 7 have been shown in various instances to
proceed with formation of isoindolone or isoquinolone
products through 5-exo- or 6-endo-dig-N-cyclizations, re-
spectively.[2] Recently, the alternative 5-exo-dig-O-cycliza-
tion mode has also been observed, resulting in the regiose-
lective formation of iminoisobenzofuran derivatives by Pd0-
catalyzed cyclization/coupling with aryl halides[3] or cycliza-
tive dimerization using CuII as both stoichiometric oxidant
and co-catalyst.[4] In the present case, the initial heterocycli-
zation from 7 is followed by an oxidative intermolecular
Heck-type coupling (Scheme 6 in the original manuscript, in
À
which Y= CONR) leading to 1H-isochromen-1-imine de-
rivatives (11). These are interesting compounds[5] not only
for being the nitrogen analogues of the biologically impor-
tant isocoumarins but also because of their own propertie-
Chem. Eur. J. 2012, 00, 0 – 0
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