Photoredox Ni-Catalyzed Branch-Selective Reductive Coupling of Aldehydes with 1,3-Dienes

Article abstract of DOI:10.1021/acscatal.9b05137

We report here a Ni-catalyzed reductive coupling of aldehydes with widely available 1,3-dienes under visible-light photoredox dual catalysis. The homoallyic alcohols are obtained in broad scope with complete branched regioselectivity. Hantzsch ester is used as the hydrogen radical source to oxidize low-valent nickel salt affording Ni-H species. Preliminary mechanistic studies indicate a successive single-electron transfer (SET) pathway and the generation of a key π-allylnickel intermediate via Ni-H insertion of 1,3-diene in this synergistic catalytic process.

Full text of DOI:10.1021/acscatal.9b05137

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Letter
Photoredox Ni-catalyzed Branch-Selective
Reductive Coupling of Aldehydes with 1,3-Dienes
Yan-Lin Li, Wen-Duo Li, Zheng-Yang Gu, Jie Chen, and Ji-Bao Xia
ACS Catal., Just Accepted Manuscript • DOI: 10.1021/acscatal.9b05137 • Publication Date (Web): 31 Dec 2019
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ACS Catalysis
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Photoredox Ni-catalyzed Branch-Selective Reductive Coupling of
Aldehydes with 1,3-Dienes
Yan-Lin Li,†,‡ Wen-Duo Li,†,‡ Zheng-Yang Gu,† Jie Chen,† and Ji-Bao Xia*,†
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†State Key Laboratory for Oxo Synthesis and Selective Oxidation, Suzhou Research Institute of LICP, Lanzhou Institute of
Chemical Physics (LICP), University of Chinese Academy of Sciences, Chinese Academy of Sciences, Lanzhou 730000,
China
‡University of Chinese Academy of Sciences, Beijing, 100049, China
KEYWORDS: synergistic catalysis, photoredox catalysis, nickel, reductive coupling, 1,3-diene
ABSTRACT: We report here a Ni-catalyzed reductive coupling of aldehydes with widely available 1,3-dienes under visible light
photoredox dual catalysis. The homoallyic alcohols are obtained in broad scope with complete branched regioselectivity. Hantzsch
ester is used as the hydrogen radical source to oxidize low-valent nickel salt affording Ni−H species. Preliminary mechanistic
studies indicate a successive single-electron transfer (SET) pathway and the generation of a key π-allylnickel intermediate via Ni−H
insertion of 1,3-diene in this synergistic catalytic process.
Allylation of aldehydes is one of the most important and
reliable C−C bond-forming reactions for the production of
homoallylic alcohols in synthetic chemistry. Traditionally,
these valuable compounds are synthesized via addition of
aldehydes with premetalated C-nucleophiles (from
organometallic reagents or organic halides).1 These methods
often pose issues of safety, cost, and multi-step pre-synthesis.
Alternatively, 1,3-butadiene, an abundant petrochemical
feedstock, has been applied to the reductive coupling with
aldehydes producing homoallylic alcohols under various
transition-metal catalysts.2 Remarkably, Ru or Ir-catalyzed
borrowing hydrogen strategy with alcohol as reductant (or as
both reductant and aldehyde precursor) reported by Krische
and others is a tremendous improvement in the diene-aldehyde
reductive coupling reactions.3-5
enable branched selectivity, and this would highly broaden the
synthetic utility of this diene-aldehyde coupling further.
Scheme 1. Ni-catalyzed Reductive Coupling of Aldehydes with
1,3-Dienes
a) Known works: Mori, Sato, Tamaru, Ogoshi, Zhou, Krische, Breit et al.
OH
O
Ni catalyst
H
Et2Zn, Et3B, R3SiH, or (CH2O)n
linear selectivity
b) Research hypothesis: -allylNi intermediate from Ni–H insertion of 1,3-diene

OH
NiLn
Path a
OH
h Ni
ketyl radical
H
O
H
H
H
CH3
LnNi
O
Ni–H
As a base metal catalyst, nickel has also been applied in
reductive coupling reactions, as well as diene-aldehyde
couplings (Scheme 1a).6 In 1994, Mori, Sato and colleagues
reported the seminal Ni-catalyzed intramolecular coupling of
1,3-dienes with carbonyl groups in the presence of silanes
giving homoallylic or bishomoallylic alcohols.7 Shortly after
that Tamaru et al. disclosed intermolecular reductive coupling
reactions of 1,3-dienes with aldehydes by using BEt3 as
reducing reagents to produce bishomoallylic alcohols.8 Elegant
enantioselective reactions were also reported independently by
the groups of Zhou and Sato.9 Recently, Breit and Krische
realized that Ni-catalyzed reductive coupling of 1,3-dienes and
formaldehyde afforded linear bishomoallylic alcohols with
formaldehyde as both coupling partner and reductant.10 To the
best of our knowledge, all of these reactions produce allylation
or homoallylation products with linear regioselectivity. In
addition, most of these reactions require toxic and flammable
organometallic reagents (Et2Zn/Et3B) or silanes as reductants.
The origin of the linear selectivity has been recognized to be
Ni(0)-mediated oxidative coupling of diene with aldehyde
generating an isolable π-allyloxanickelacycle intermediate.11
Therefore, exploring new nickel based catalytic systems may
H
Path b
c) This work: Branch selectivity by Photoredox nickel synergistic catalysis
PC Ni
OH
O
H
Hantzsch ester (HE)
CH3
branch selectivity
Recently, the photocatalytic reductive coupling of aldehyde
with electron-deficient olefins, such as acrylic ester and vinyl
pyridine, generating alcohols via ketyl radicals has been
disclosed by Chen, Ngai, and others using Hantzsch ester (HE)
as reducing reagents.12 In addition, König and co-workers
reported a photoredox Ni-catalyzed hydrocarboxylation of
styrenes via nickel hydride intermediate using HE as the
hydrogen source.13 Inspired by these elegant works, we aimed
to develop a base metal catalyzed reductive allylation of
aldehydes with 1,3-dienes to deliver the branched products.
We hypothesized that merging visible light photoredox and
nickel catalysis14 may achieve this goal. A key Ni−H species
could be generated by oxidation of low valent nickel catalyst
with hydrogen radical under photoredox catalysis.15 Then,
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branch-selective allylation may be realized via addition of
Page 2 of 7
bipyridine (L1) as a ligand, and Ir(ppy)3 as a photocatalyst
(Table 1, entry 1). Further examination of photocatalysts
showed that product 3 was obtained in 50% yield with 1.9:1
d.r. ratio with Ir[dF(CF3)ppy]2(dtbbpy)PF6 (I) (Table 1, entry
2). Subsequent screening of the nickel catalysts demonstrated
that NiCl2·6H2O gave better result with improved yield (Table
1, entry 6, also see Table S2 in Supporting Information). The
ligand played an important role in the reaction (Table 1,
entries 7-12, and Table S3 in Supporting Information).
Electron-rich 5,5'-dimethyl-2,2'-bipyridine (L2) gave better
yield and similar d.r. ratio (Table 1, entry 8). No reaction
occurred with ortho-disubstituted 6,6'-dimethyl-2,2'-bipyridine
(L4) (Table 1, entry 10). Lower yields of 3 were obtained with
1
2
3
4
5
6
7
8
ketyl radical to π-allylnickel intermediate generated via Ni−H
insertion of 1,3-diene followed by reductive elimination
(Scheme 1b, path a). Alternatively, allylation of aldehyde with
π-allylnickel intermediate through Zimmerman-Traxler
transition state16 may also lead to branched homoallylic
alcohols (Scheme 1b, path b). Herein, we report our
preliminary results on the branch-selective reductive coupling
of aldehyde with 1,3-dienes under visible light photoredox
nickel dual catalysis (Scheme 1c).
9
We began the research by studying allylation of
benzaldehyde 1 with 1,3-butadiene (2) under visible light
photoredox Ni dual catalysis. With Hantzsch ester (HE) as a
reductant, initial investigation found that homoallylic alcohol
3 was obtained in moderate yield with complete branch
regioselectivity using NiCl2 as a catalyst, 4,4'-di(t-Bu)-2,2'-
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11
12
13
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1,10-phenanthroline
(L5)
and
2-(pyridin-2-yl)-4,5-
dihydrooxazole (L6) (Table 1, entries 11 and 12). Further
inspection of the solvents indicated that easily handled THF
was a better choice with similar yield as DMF but improved
d.r. ratio (Table 1, entry 15). When reducing the catalyst
loading of nickel and ligand from 10 mol % to 5 mol %, the
catalytic efficiency can also be maintained (Table 1, entry 18).
Finally, we were glad to find that the reaction ran smoothly
with a catalytic amount of Hünig’s base (iPr2NEt, 12 mol %)
(standard conditions, Table 1, entry 19).
Table 1. Reaction Developmenta
2 mol % photocatalyst
O
OH
5 or 10 mol % Ni catalyst
5 or 10 mol % Ligand
H
1.5 equiv Hantzsch ester
12 mol % or 2 equiv iPr2NEt
CH3
1
2
3
(0.2 mmol)
(2 equiv) solvent, blue LED, rt, 16 h
Entry
1
Photocatalyst
Ni catalyst Ligand Solvent Yieldb (%) d.r.b
With the optimal reaction conditions in hand, we then
examined the generality of this transformation (Table 2). Both
aromatic and aliphatic aldehydes were found efficient
coupling components affording the syn-homoallylic alcohols
as the major products (up to 99% yield). The mild reaction
conditions are compatible with a wide range of functional
groups including OMe (5), SMe (6), OCF3 (7), ether (10, 27),
phenol (11), CF3 (16), and ester (17, 18, 28). It is noteworthy
that the ortho, meta, and para-substituents on aromatic
aldehydes show little influence on the reaction yield (4, 5, 8,
Ir(ppy)3
NiCl2
L1
L1
L1
L1
L1
L1
BiPy
L2
L3
L4
L5
L6
L2
L2
L2
L2
L2
L2
L2
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMSO
MeOH
THF
39
50
54
39
33
67
78
88
72
0
1.1:1
1.9:1
1.2:1
1.4:1
0.8:1
1.7:1
1.5:1
1.6:1
1.6:1
-
2
I
II
III
I
NiCl2
3
NiCl2
4
NiCl2
5
NiBr2
6
I
NiCl2·6H2O
NiCl2·6H2O
NiCl2·6H2O
NiCl2·6H2O
NiCl2·6H2O
NiCl2·6H2O
NiCl2·6H2O
NiCl2·6H2O
NiCl2·6H2O
NiCl2·6H2O
NiCl2·6H2O
NiCl2·6H2O
NiCl2·6H2O
NiCl2·6H2O
7
I
8
I
9
I
10
11
12
13
14
15
16
17
18c
19c,d
I
and
9).
Moreover,
sterically
hindered
2,4,6-
I
8
1:1
trimethylbenzaldehyde also gave the corresponding product 12
in moderate yield. In addition, the halogen functionalities
remain intact after the coupling, furnishing additional reaction
cite for further synthetic elaborations (13, 14, 15, 26).
Considering the wide presence of heterocyclic structures in the
biologically important molecules, heteroaryl aldehydes (20, 21)
and alkyl aldehyde bearing heteroarene group (furan, 24) are
found suitable substrates in this reductive coupling reaction.
Next, isoprene, another important industrial raw material
with annual production scale of about 1 milllion tons,17 was
tested in this transformation. Benzaldehyde coupled with
isoprene to furnish 29 and 30 at C2 and C3 position in
moderate yield with branch selectivity. Notably, allylic
alcohol 30 was obtained in excellent d.r. ratio. Furthermore,
coupling of 2,3-dimethyl-1,3-butadiene with benzaldehyde
occurred smoothly producing 31 in 66% yield. Unfortunately,
no reaction occurred with 1-phenyl substituted 1,3-butadiene
and cyclohexa-1,3-diene.
I
23
71
58
85
0
1.8:1
1.5:1
2.1:1
1.9:1
-
I
I
I
I
Toluene
Et2O
I
0
-
I
THF
81
86
1.6:1
1.9:1
I
THF
Photocatalyst
R1
Ligand
tBu
tBu
R2
PF6
tBu
N
Ir
N
N
N
N
N
N
R1
R1
L1
L4
L5
L2
L3
(R = Me)
R
R
(R = OMe)
N
N
N
N
N
tBu
R1
R2
O
Ir[dF(CF3)ppy]2(dtbbpy)PF6 ()
N
N
Me
Me
R1 = F, R2 = CF3
L6
To further demonstrate the synthetic utility of the reaction,
we tested the natural products and complex molecules
containing aldehyde functionality. For example, coupling of
1,3-butadiene with natural citronellal or myrac aldehyde
afforded the desired product 32 and 33 as diastereomeric
mixtures in moderate to good yields. The sugar group,
diacetone-D-glucose, could also be tolerated in this reductive
coupling reaction (34).
Hantzsch ester (HE)
O
Ir[dF(CH3)ppy]2(dtbbpy)PF6 ()
R1 = F, R2 = CH3
O
EtO
OEt
Me
Ir(ppy)2(dtbbpy)PF6 ()
R1
=
R2 = H
Me
N
H
aAll reaction were performed with 2 mol % photocatalyst, 10 mol % Ni catalyst,
i
10 mol % Ligand, 1.5 equiv Hantzsch ester, 2 equiv Pr2NEt, and 5 W blue
LEDs if otherwise noted. bDetermined by crude 1H NMR with 1,1,2,2-
tetrachloroethane as an internal standard. cWith 5 mol % NiCl2·6H2O and 5 mol %
L2. dWith 12 mol % iPr2NEt.
We next explored the mechanism of this reductive diene-
aldehyde coupling reaction. First, control experiments showed
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Table 2. Scope of Photoredox Ni-catalyzed Branch-Selective Reductive Coupling of Aldehydes with 1,3-Dienesa
1
2
Ni catalyst & photocatalyst (PC)
CF3
PF6
F
3
4
5
6
tBu
N
Ir
N
N
Me
Me
F
F
OH
Ni
PC
O
N
N
Hantzsch ester
Ni
H
N
7
Cl
Cl
tBu
8
F
:
aryl, alkyl
homoallylic alcohol
CF3
9
L2
NiCl2
[Ir(dFCF3ppy)2(dtbbpy)]PF6 ()
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
scope of aldehydes with 1,3-butadiene 2
OH OH
aromatic aldehydes
OH
OH
OH
Me OH
MeO
CH3
CH3
, 92%, 2.4:1 dr
OH OH
CH3
CH3
CH3
CH3
Me
MeO
MeS
F3CO
4
5
6
7
8
9
, 91%, 2:1 dr
OH
, 54%, 2.2:1 dr
Me OH
, 92%, 1.7:1 dr
OH
, 92%, 1.7:1 dr
OH
, 91%, 2.4:1 dr
OH
O
O
Cl
CH3
CH3
CH3
Me
CH3
CH3
CH3
Me
F
Cl
10
16
11
17
12
13
14
20
15
, 50%, 1.7:1 dr
, 96%, 1.7:1 dr
OH
, 89%, 0.6:1 dr
OH
, 59%, 0.72:1 dr
, 89%, 2:1 dr
OH
, 88%, 1.3:1 dr
OH
OH
Ts OH
N
MeO2C
MeO2C
MeO
O
CH3
CH3
CH3
CH3
CH3
CH3
21
, 70%, 4.5:1 dr
F3C
18
19
, 34%, 1.5:1 dr
, 79%, 1.4:1 dr
, 99%, 2.3:1 dr
, 87%, 1.3:1 dr
, 55%, 1.3:1 dr
alkyl aldehydes
OH
OH
OH
Cl
OH
OBn
OH
CO2Me
OH
Ph
n
O
H3C
Me
7
CH3
CH3
CH3
CH3
CH3
CH3
28
, 93%, 1:1 dr
22
24
25
26
27
n = 1, , 73%, 1.2:1 dr
, 78%, 1.3:1 dr
, 81%, 1:1 dr
, 80%, 1:1 dr
, 85%, 1.3:1 dr
23
n = 2, , 70%, 1.2:1 dr
scope of dienes with benzaldehyde 1
OH
OH CH3
CH3
OH CH3
H3C CH3
CH3
+
CH3
H3C CH3
CH3
2,3-dimethyl-1,3-butadiene
isoprene
29
30, >20:1 dr
= 1.9/1)
31
, 66%
29 30
57% (
/
allylation of natural products or complex molecules
H3C
H3C
O
O
OH
OH
O
CH3
H3C
CH3 OH
O
O
CH3
CH3
CH3
CH3
O
O
H3C
CH3
CH3
from (R)-citronellal
32
from myrac aldehyde
34
33
, 64%, 1.4:1 dr
, 88%, 1:1:1.2:1 dr
, 53%, 1:1:1:1 dr
aAll reactions performed with 0.2 mmol of aldehyde and 0.4 mmol 1,3-dienes. Isolated yield was provided. The d.r. value (syn:anti) was
determined by 1H NMR analysis. For standard conditions, see Table 1, entry 19. For details, see Supporting Information.
Scheme 2. Control Experiments
2 mol % photocatalyst 
O
OH
O
O
OH
L2
 mol % NiCl2
"standard conditions"
without iPr2NEt
(eq 1)
(eq 2)
(eq 3)
(eq 4)
H
H
H
iPr2NEt / HE
CH3
CH3
THF, blue LED, rt, 16 h
1
2
2
3
1
2
2
3
, 88%, 1.9:1 dr
, <5%
CH3
OH
"standard conditions"
"standard conditions"
O
Ph
Ph
5 equiv iPr2NEt
without HE
H
OH
CH3
3
, 40%, 1.9:1 dr
35
36
1
, 55%
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Page 4 of 7
Scheme 3. Proposed Catalytic Pathway
1
2
PyH
3
4
5
6
LnNiII
H
diene
LnNiII
INT1
HE
CH3
LnNiII
INT1'
syn--allyl
N
LnNiI
HE
CH3
*IrIII
IrIII
7
iPr2NEt
anti--allyl
8
9
LnNiII
LnNiII
CH3
SET
SET
SET
e
Ir
Ni
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
CH3
INT2'
(E)--allyl
INT2
O
(Z)--allyl
H
aldehyde
LnNiII
HP
LnNiII
HE
LnNiII
O
IrII
N
CH3
O
ONiIILn
[iPr2NEt]
CH3
INT3
INT3'
CH3
INT4
OH
OH
PyH
CH3
CH3
anti product
syn product
EtO2C
Me
CO2Et
Me
EtO2C
Me
CO2Et
EtO2C
Me
CO2Et
Me
EtO2C
Me
CO2Et
Me
N
H
N
H
Me
N
N
H
HE
HP
HE
PyH
(LnNiII) by IrII (E1/2red[IrIII/IrII] = −1.37 V vs. SCE in
CH3CN)20 affords active NiI species (E1/2red[NiII/NiI] = -0.68
V vs. SCE in DMSO)23 and IrIII to close the iridium
photoredox catalytic cycle. The following capture of the
hydrogen radical from HE•+ with NiI species would yield
pivotal nickel hydride (Ni−H) species and pyridinium ion
PyH+. The kinetically preferred hydrometalation of the s-cis
conformer of 1,3-diene with the nickel hydride generates the
key anti-π-allyl-nickel intermediate INT1,24 which can
isomerize to syn-π-allyl-nickel intermediate INT1' rapidly.
The corresponding (Z)- and (E)-σ-crotyl nickel intermediate
INT2 and INT2' would be formed subsequently. In our
reaction, the unusual syn-diastereoselectivity is observed in
most of the cases. The syn-product may be achieved via
Zimmerman-Traxler transition state INT3, generating syn-
homoallylic nickel alkoxide INT4 through C−C bond
formation. Finally, protonation of INT4 by PyH+ affords
homoallylic alcohol product. The corresponding pyridine
compound (HP) has been isolated as a byproduct. The crotyl
methyl group placed pseudoaxially in transition state INT3
may minimize gauche interactions between this group and
the substituent of the aldehyde, which has been observed in
certain reactions.25 This may account for INT3 more
favorable than INT3' in this reaction, and the latter TS
model results in anti-diastereoselectivity.
that no reaction occurred without ligand L2. The reaction ran
smoothly affording 2 in excellent yield with L2NiCl2 as the
catalyst, indicating that the ligand coordinated Ni complex is
an active catalyst (Scheme 2, eq 1). Next, addition of radical
scavengers into the reaction did not inhibit the reaction, such
as 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) or ethene-
1,1-diyldibenzene
(See
Supporting
Information).
Furthermore, the radical clock experiment18 was conducted
with cyclopropane-substituted aldehyde 35 as a substrate
under standard conditions. The direct coupling product 36
was formed, but no ring opening product was observed
(Scheme 2, eq 2). This result demonstrates that the reaction
may not occur via ketyl radical intermediate generated
through single electron transfer between photoexcited
Hantzsch ester and aldehyde. Moreover, a trace amount of
product was observed in the absence of Hünig’s base
(iPr2NEt) (Scheme 2, eq 3). In addition, moderate yield of
product was obtained in the presence of stoichiometric
iPr2NEt without Hantzsch ester as the reducing reagent
i
(Scheme 2, eq 4). These results indicate that Pr2NEt can
function as a reductant albeit with low efficiency comparing
with Hantzsch ester in this transformation. The Pr2NEt is
i
considered to be an electron shuttle between Hantzsch ester
and photocatalyst.19
Our proposed catalytic cycle for this transformation is
described in Scheme 3. Initial excitation of IrIII photocatalyst
Ir[dF(CF3)ppy]2(dtbbpy)PF6 (I) generates the photoexcited
In summary, the first Ni-catalyzed branch-selective
reductive coupling of aldehydes with 1,3-dienes has been
developed under visible light photoredox catalysis. A novel
strategy was realized to achieve the branch selectivity
through the key π-allylnickel intermediate which was
*IrIII intermediate. The *IrIII catalyst (E1/2 [*IrIII/IrII] =
red
+1.21 V vs. saturated calomel electrode (SCE) in CH3CN)20
is reduced by iPr2NEt (Eox (iPr2NEt) = +0.65 V)21 via SET to
produce a highly reducing IrII species and [iPr2NEt]•+, which
accepts one electron from Hantzsch ester (HE) to regenerate
iPr2NEt and the corresponding Hantzsch ester radical cation
(HE•+).22 Reduction of ligand coordinated NiII complex
obtained via insertion of 1,3-dienes with
a Ni−H
intermediate derived from oxdative addition of low valent Ni
salt with hydrogen radical. Coupling of widely available 1,3-
dienes with (hetero)aryl, and alkyl aldehydes afforded
homoallylic alcohols with broad scope and good
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ACS Catalysis
Hydrogenation: Carbonyl Allylation from the Alcohol or Aldehyde
functionality tolerance under the synergistic catalysis.
Development of an enantioselective version of this novel
transformation is currently ongoing in our laboratory.
Oxidation Level Employing Acyclic 1,3-Dienes as Surrogates to
Preformed Allyl Metal Reagents J. Am. Chem. Soc. 2008, 130, 6338.
(b) Smejkal, T.; Han, H.; Breit, B.; Krische, M. J. All-carbon
quaternary centers via ruthenium-catalyzed hydroxymethylation of
2-substituted butadienes mediated by formaldehyde: beyond
hydroformylation. J. Am. Chem. Soc. 2009, 131, 10366. (c) Zbieg, J.
R.; Moran, J.; Krische, M. J. Diastereo- and enantioselective
ruthenium-catalyzed hydrohydroxyalkylation of 2-silyl-butadienes:
carbonyl syn-crotylation from the alcohol oxidation level J. Am.
Chem. Soc. 2011, 133, 10582. (d) Zbieg, J. R.; Yamaguchi, E.;
McInturff, E. L.; Krische, M. J. Enantioselective C-H Crotylation of
Primary Alcohols via Hydrohydroxyalkylation of Butadiene Science
2012, 336, 324. (e) McInturff, E. L.; Yamaguchi, E.; Krische, M. J.
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ASSOCIATED CONTENT
Supporting Information
Experimental procedures and characterization data. This
material is available free of charge via the Internet at
http://pubs.acs.org.
9
AUTHOR INFORMATION
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Corresponding Author
Chiral-anion-dependent
inversion
of
diastereo-and
enantioselectivity in carbonyl crotylation via ruthenium-catalyzed
butadiene hydrohydroxyalkylation. J. Am. Chem. Soc. 2012, 134,
20628.
(4) For Ir catalyst, see: (a) Bower, J. F.; Krische, M. J. Iridium-
Catalyzed C-C Coupling via Transfer Hydrogenation: Carbonyl
Addition from the Alcohol or Aldehyde Oxidation Level Employing
1,3-Cyclohexadiene Org. Lett. 2008, 10, 1033. (b) Zbieg, J. R.;
Ji-Bao Xia: jibaoxia@licp.cas.cn
ORCID
Ji-Bao Xia: 0000-0002-2262-5488
Notes
The authors declare no competing financial interest.
Fukuzumi,
T.;
Krische,
M.
J.
Iridium-catalyzed
hydrohydroxyalkylation of butadiene: carbonyl crotylation Adv.
Synth. Catal. 2010, 352, 2416. (c) Nguyen, K. D.; Herkommer, D.;
Krische, M. J. Enantioselective Formation of All-Carbon
Quaternary Centers via C-H Functionalization of Methanol:
Iridium-Catalyzed Diene Hydrohydroxymethylation. J. Am. Chem.
Soc. 2016, 138, 14210. (d) Xiang, M.; Luo, G.; Wang, Y.; Krische,
M. J. Enantioselective iridium-catalyzed carbonyl isoprenylation via
alcohol-mediated hydrogen transfer. Chem. Commun. 2019, 55, 981.
(5) For selected reviews, see: (a) Kim, S. W.; Zhang, W.; Krische,
M. J. Catalytic Enantioselective Carbonyl Allylation and
Propargylation via Alcohol-Mediated Hydrogen Transfer: Merging
the Chemistry of Grignard and Sabatier Acc. Chem. Res. 2017, 50,
2371. (b) Nguyen, K. D.; Park, B. Y.; Luong, T.; Sato, H.; Garza, V.
J.; Krische, M. J. Metal-catalyzed reductive coupling of olefin-
derived nucleophiles: Reinventing carbonyl addition Science 2016,
354, aah5133. (c) Bower, J. F.; Kim, I. S.; Krische, M. J. Catalytic
carbonyl addition through transfer hydrogenation: a departure from
preformed organometallic reagents Angew. Chem. Int. Ed. 2009, 48,
34.
(6) (a) Standley, E. A.; Tasker, S. Z.; Jensen, K. L.; Jamison, T. F.
Nickel Catalysis: Synergy between Method Development and Total
Synthesis Acc. Chem. Res. 2015, 48, 1503. (b) Jackson, E. P.; Malik,
H. A.; Sormunen, G. J.; Baxter, R. D.; Liu, P.; Wang, H.; Shareef, A.-
R.; Montgomery, J. Mechanistic Basis for Regioselection and
Regiodivergence in Nickel-Catalyzed Reductive Couplings Acc.
Chem. Res. 2015, 48, 1736 (c) Weix, D. J. Methods and
Mechanisms for Cross-Electrophile Coupling of Csp2 Halides with
Alkyl Electrophiles Acc. Chem. Res. 2015, 48, 1767. (d) Gu, J.;
Wang, X.; Xue, W.; Gong, H. Nickel-catalyzed reductive coupling
of alkyl halides with other electrophiles: concept and mechanistic
considerations Org. Chem. Front. 2015, 2, 1411. (e) Moragas, T.;
Correa, A.; Martin, R. Metal-Catalyzed Reductive Coupling
Reactions of Organic Halides with Carbonyl-Type Compounds
Chem. Eur. J. 2014, 20, 8242.
ACKNOWLEDGMENT
We thank OSSO, NSFC (21772208 for J.-B. Xia, 21702212 for
J. Chen) and NSF of Jiangsu Province (BK20170404) for
funding. We thank one of the reviewers for suggestion on the
stereochemical outcome of the products.
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ACS Catalysis
and 3e. (a) Lam, Y. H.; Houk, K. N.; Scheffler, U.; Mahrwald, R.
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Asymmetric
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OH
Ni
O
H
Ni
H
H
Ni
:
Branch Selectivity
aryl, alkyl
H
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