cis-Selective Transfer Semihydrogenation of Alkynes by Merging Visible-Light Catalysis with Cobalt Catalysis

Article abstract of DOI:10.1002/adsc.201901562

Herein, the first example of visible-light-driven, cobalt-catalyzed transfer semihydrogenation of alkynes to alkenes is reported. It is carried out by using Ir[dF(CF₃)ppy]₂(dtbbpy)]PF₆ as photosensitizer, CoBr₂/n-Bu₃P as proton-reducing catalyst, and i-Pr₂NEt/AcOH as the hydrogen source. Under the established catalytic system, the semihydrogenation proceeds with Z as the major selectivity and with inhibition of over-reduction. Under mild reaction conditions, both internal and terminal alkynes, as well as reducible functional groups such as halogen, cyano, and ester, are tolerated. Preliminary mechanistic studies revealed the dual role of the photosensitizer in initiating the reaction via a single-electron transfer process and controlling the stereoselectivity via an energy transfer process. (Figure presented.).

Full text of DOI:10.1002/adsc.201901562

Title: cis-Selective Transfer Semihydrogenation of Alkynes by Merging
Visible-Light Catalysis with Cobalt Catalysis
Authors: Wan-Fa Tian, Yongqin He, Xian-Rong Song, Haixin Ding, Jing
Ye, Wen-Jie Guo, and Qiang Xiao
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Adv. Synth. Catal. 10.1002/adsc.201901562
Link to VoR: http://dx.doi.org/10.1002/adsc.201901562

10.1002/adsc.201901562
Advanced Synthesis & Catalysis
COMMUNICATION
DOI: 10.1002/adsc.201((will be filled in by the editorial staff))
cis-Selective Transfer Semihydrogenation of Alkynes by
Merging Visible-Light Catalysis with Cobalt Catalysis
Wan-Fa Tian,a,† Yong-Qin He b,†, Xian-Rong Song,a Hai-Xin Ding,a Jing Ye,a Wen-Jie
Guo,a and Qiang Xiaoa,*
a
Institute of Organic Chemistry, Jiangxi Science & Technology Normal University, Key Laboratory of Organic
Chemistry, Jiangxi Province, Nanchang, 330013, P. R. of China. E-mail: xiaoqiang@tsinghua.org.cn.
School of Pharmaceutical Science, Nanchang University, Nanchang, 330006, P. R. of China.
These authors contributed equally.
b
†
Received: ((will be filled in by the editorial staff))
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201######.((Please
delete if not appropriate))
Mn,[18] and even Fe.[19] Despite these significant
Abstract. Herein, the first example of visible-light-driven,
cobalt-catalyzed transfer semihydrogenation of alkynes to achievements, many of the above mentioned
alkenes is reported. It is carried out by using
Ir[dF(CF3)ppy]2(dtbbpy)]PF6 as photosensitizer, CoBr2/n-
Bu3P as proton-reducing catalyst, and i-Pr2NEt/AcOH as
the hydrogen source. Under the established catalytic
system, the semihydrogenation proceeds with Z as the
major selectivity and with inhibition of over-reduction.
Under mild reaction conditions, both internal and terminal
alkynes, as well as reducible functional groups such as
halogen, cyano, and ester, are tolerated. Preliminary
mechanistic studies revealed the dual role of the
photosensitizer in initiating the reaction via a single-
procedures face limitations, such as lengthy synthesis
process for catalysts, elevated reaction temperature,
by-product formation due to over-reduction, and
tedious operation of H2 usage. Therefore,
development of a simpler, milder, and safer protocol
for selective semihydrogenation of alkynes is highly
demanded and it remains a challenging task.[9]
In recent years, visible-light-induced photoredox
catalysis has attracted significant research attention
due to the environmentally friendly reaction
procedures and the sustainability of visible light.[20]
Therefore, merging the visible-light catalysis with
transition metal catalysis can provide a new
opportunity to achieve the semihydrogenation of
alkynes with high efficiency and simple procedure.
To the best of our knowledge, this strategy has only
been explored by Wu and co-workers, who developed
a semihydrogenation protocol by employing eosin Y
as the photocatalyst and colloidal Pd nanoparticles as
hydrogenation catalyst.[21]
electron
transfer
process
and
controlling
the
stereoselectivity via an energy transfer process.
Keywords: Photoredox catalysis; Cobalt catalysis;
Semihydrogenation; Alkynes
Olefins are essential structural units in many
biologically active molecules.[1] For example,
resveratrol, an analogue of stilbene, demonstrates
outstanding anti-oxidation, heart protection, and anti-
carcinogenic activities.[2] Moreover, alkenes are
widely used as building blocks in organic synthesis,
which can be further modified into many other
functional groups. Owing to the significant
importance of alkenes, numerous methodologies,
including the Wittig reaction,[3] Horner–Wadsworth–
Emmons reaction,[4] Julia–Kocienski reaction,[5]
Peterson reaction,[6] olefin metathesis,[7] and cross-
coupling reactions,[8] have been developed to
construct olefinic groups. In particular, transition-
metal-catalyzed semihydrogenation of alkynes
represents one of the most efficient and
straightforward approaches for alkene preparation.[9]
To date, several homogeneous catalytic systems have
been developed for semihydrogenation of alkynes.
The transition metals involved in these systems are
Pd,[10] Ru,[11] Rh,[12] Ir,[13] V,[14] Ni,[15] Co,[16] Cu,[17]
Notably, metal hydride plays an important role in
transition
metal-catalyzed
semihydrogenation
reactions of alkynes. Among metal hydride species,
Co–H has gained immense attention because it could
be easily generated via single electron transfer (SET)
process mediated by visible light, which have been
well documented for the reactions such as water
photolysis reactions,[22] photocatalytic hydrogen
evolution reactions,[23] and recently developed
photoredox-mediated coupling reaction.[24] Inspired
by these pioneering studies, we continued our long-
standing interest in photoredox/cobalt (Co) catalytic
system,[25] and we speculated that the photochemical
generated Co–H intermediate could be used for the
semihydrogenation of alkynes, and there is no
literature precedent of using the photoredox/Co
catalytic system for semihydrogenation of alkynes.
We proposed that the reaction followed a
mechanism described in Scheme 1. The excited
1
This article is protected by copyright. All rights reserved.

10.1002/adsc.201901562
Advanced Synthesis & Catalysis
reduction product 4a was also observed. Other
photocatalysts, such as Ir[ppy]2(dtbbpy)PF6 and
Ir[ppy]2(bpy)PF6 showed slight decrease of yield and
selectivity with generation of alkane by-product
(entries 9 and 10). Ir(ppy)3 (E*IrIII/IrII = +0.31 V vs
SCE)[28] showed no catalytic activity, which should
be rationalized to its weaker oxidation ability (entry
11). Next, a survey of common organic solvents
revealed that 1,4-dioxane provided the highest yield
of >99% with the best Z/E ratio; nonetheless, no
reaction occurred with CH2Cl2 (entries 12–17). Other
reductants were also examined (entries 1821).
Among them, i-Pr2NEt still exhibited the best
performance. (Cy3P)2CoBr2 as cobalt catalyst
provided a low yield of 31% (entry 22). Noteworthy,
the over-reduction of alkenes could be completely
inhibited by selecting correct catalytic system and
this phenomenon should be attributed to the rapid β-
hydride elimination after insertion of alkene into Co–
H hydride.[16a,29] Moreover, the control experiments
demonstrated that photocatalyst, Co, ligand, and
visible-light irradiation were essential for the
effective occurrence of the reaction (entries 2326).
Finally, a simple and easily manipulated approach
Scheme 1. Working hypothesis. CoII = (Cy3P)2CoBr2, IrIII
= Ir[dF(CF3)ppy]2(dtbbpy)]PF6.
iridium
catalyst
*Ir[dF(CF3)ppy]2(dtbbpy)]PF6
(E*IrIII/IrII = +1.21 V vs SCE)[26] could be reductively
quenched by sacrificial reagent, such as i-Pr2NEt (Ei-
i
Pr2NEt+/ -Pr2NEt = +0.78 V vs SCE, see SI), to afford IrII
species. The IrII (EIrIII/IrII = 1.37 V vs SCE)[26] is
capable of reducing the high-valent Co catalysts, such
as (Cy3P)2CoBr2 (E1/2CoII/CoI = 1.09 V vs SCE, see SI)
to CoI species under visible-light irradiation.[24a,24d]
The generated CoI species could react with a proton
to form CoIII–H hydride,[22-24] which subsequently
undergoes hydrometalation with alkynes followed by
protonation to form the semihydrogenation product
and CoIII species. The CoIII could further accept an
electron from IrII to form CoII and thus close the Co
Table 1. Optimization of the reaction conditions.[a]
cycle.
Recently,
of
visible-light-induced
alkenes leading to
photoisomerization
stereodefined alkenes via energy transfer (EnT) was
reported.[27] Therefore, we expected that the excited
*IrIII could further catalyze the alkenes via EnT
process to generate the final products in a
stereoselective manner. It was further envisioned that
the key advantage of such a photo-driven reaction
would be milder reaction conditions, readily available
catalyst, easy operations, and good tolerance of
functionalities, including halides and other reducible
groups. More importantly, it would provide a new
route for reduction of other unsaturated compounds.
With these hypotheses in mind, the investigation of
the photoredox/Co catalyzed semihydrogenation was
thus initiated using 1,2-diphenylacetylene 1a as the
model substrate. Herein, Ir[dF(CF3)ppy]2(dtbbpy)PF6
was used as photosensitizer, CoBr2 as cobalt catalyst,
i-Pr2NEt as electron donor, and CH3CN as solvent
with reaction mixture subjected to blue LED
irradiation. First, various ligands were explored. To
our delight, tri-alkyl phosphine ligands, such as Cy3P
and n-Bu3P afforded the mixture of alkene products
containing (Z)-stilbene 2a and (E)-stilbene 3a in 54
and 81% total yield respectively, with moderate
stereoselectivity. Moreover, no over-reduction
product 4a was observed (Table 1, entries 1 and 2).
Other aryl containing phosphine ligands, such as
Ph3P and dppp did not show any desired products
(entries 3 and 4). 4,4'-Di-tert-butyl bipyridine (dtbbpy)
resulted in a slightly decreased yield of 78% with
lower Z/E ratio (entry 5). When examining the
influence of protic additives (entries 68), we found
that AcOH further improved the yield up to 97% and
the Z/E ratio up to 78:22; however, 3% of over-
[a]
Reaction conditions:
1a (0.2 mmol), PS (1 mol%),
CoBr2 (5 mol%), ligand (15 mol%), reductant (3.0 equiv.),
additive (5.0 equiv.), solvent (2.0 mL), irradiation with
blue LEDs for 14 h. After irradiation, the reaction mixture
1
was filtered using a small pad of silica gel and H NMR
yield was reported using Cl2CHCHCl2 as an internal
standard. [b] the Co catalyst is (Cy3P)2CoBr2. [c] no CoBr2. [d]
in dark.
2
This article is protected by copyright. All rights reserved.

10.1002/adsc.201901562
Advanced Synthesis & Catalysis
involving the following reaction conditions: 1 mol%
acetone as solvent with prolonged reaction time.
Ir[dF(CF3)ppy]2(dtbbpy)PF6, 5 mol% CoBr2, 15 mol% Propargyl ether derivative 1p could also react well to
n-Bu3P, 3.0 equiv. i-Pr2Net, and 5.0 equiv. AcOH in
1,4-dioxane solvent under blue LEDs irradiation for
14 h, was successfully established.
provide the corresponding Z-selective product in 72%
yield.
Moreover, this reaction system was also extended
to terminal alkynes (Table 3). Substituted aromatic
terminal alkynes, such as 1q and 1r, smoothly
underwent semihydrogenation and afforded the
corresponding alkenes in 60% and 52% yield,
respectively. Remarkably, this protocol also worked
well on the complex bioactive steroids substrates
such as ethisterone 1s and ethinylestradiol 1t,
affording the desired products quantitatively.
In order to test the generality of the photoredox/Co
catalytic system, various internal alkynes were
investigated (Table 2). Notably, diaryl alkynes
bearing either electron-donating or electron-
withdrawing groups on the phenyl ring (1a–1l),
reacted smoothly under the standard conditions and
provided the desired products in excellent yields with
moderate to good Z/E ratios (86–99% yield;
63/3780/20 Z/E). Importantly, reducible functional
groups such as halogen, cyano, and ester, survived
under the standard conditions. Significantly, substrate
containing thiophenyl (1m), which is believed to be a
difficult substrate for hydrogenation due to its
coordinating ability to metal centers, also exhibited
excellent yields with acceptable chemo-selectivity
(89%, 55/45 Z/E). The aryl–alkyl alkyne featuring a
hydroxyl group 1n was also found to be compatible
with the reaction and afforded the alkenes in 97%
yield with 72/28 Z/E selectivity. Strikingly, 6-
dodecyne 1o, an example of typical dialkyl alkynes,
exhibited an excellent yield of 95% with > 95/5 Z/E
selectivity when dtbbpy was introduced as ligand and
Table 3. Substrate scope of terminal alkynes.[a]
Table 2. Substrate scope of internal alkynes.[a]
[a]
Reaction
conditions:
1
(0.2
mmol),
Ir[dF(CF3)ppy]2(dtbbpy)PF6 (1 mol%), CoBr2 (5 mol.%),
n-Bu3P (15 mol%), i-Pr2NEt (3.0 equiv.), AcOH (5.0
equiv.), dioxane (2.0 mL), irradiation with blue LEDs for
14 h, isolated yield was reported. [b] reaction time = 7 h.
In order to obtain more information about the Z/E
selectivity, several control experiments were further
conducted (Scheme 2). Scheme 2 Eq. 1 illustrates that
when (E)-stilbene 3a was employed as the substrate
under standard conditions, a large proportion of (E)-
stilbene 3a was isomerized to (Z)-stilbene 2a in a
ratio of 78/22. Similar result was also observed in the
absence of Co catalyst (Scheme 2, Eq. 2). Besides,
when only Ir[dF(CF3)ppy]2(dtbbpy)PF6 was present in
the reaction system, (E)-stilbene 3a could be partially
isomerized to (Z)-stilbene 2a in a ratio of 62/38
(Scheme 2, Eq. 3). Noteworthy, almost none of
isomerization occurred in the absence of
photosensitizer. (Scheme 2, Eq. 4). Moreover, when
these experiments were conducted using (Z)-stilbene
2a as the substrate, similar results of (Z)-major
selectivity was obtained (Scheme S1). These
investigations revealed the following conclusions: i)
the Z/E selectivity was mainly determined by
photosensitizer instead of Co catalyst; ii) i-Pr2NEt
and AcOH additives played an important role in
deciding the Z/E selectivity;[27a] and iii) the selectivity
is in fact an equilibrium which is largely shifted to
the Z-isomers. From above mentioned observation
and literature reports,[27] we believed that the triplet–
[a]
Reaction
conditions:
1
(0.2
mmol),
Ir[dF(CF3)ppy]2(dtbbpy)PF6 (1 mol.%), n-Bu3P (15 mol.%),
CoBr2 (5 mol.%), i-Pr2NEt (3.0 equiv.), AcOH (5.0 equiv.),
dioxane (2.0 mL), irradiation with blue LEDs for 14 h,
isolated yield was reported, Z/E ratio was determined by
crude 1H NMR. [b] dtbbpy as ligand, reaction time = 36 h. [c]
acetone as solvent. [d] THF as solvent.
3
This article is protected by copyright. All rights reserved.

10.1002/adsc.201901562
Advanced Synthesis & Catalysis
reaction pathway.
In order to understand the role of AcOH,
deuterium labeling experiment was conducted using
AcOD as the external proton source. According to the
1
crude H NMR analysis, 38% of deuterium and 62%
of hydrogen were contained in the corresponding
alkenes, indicating that AcOH provides partial
hydrogen to the alkynes (Scheme 3, Eq. 2, for details
see SI). When the reaction was conducted without
AcOH, the products were obtained in 60% yield, thus
confirming the dual role of i-Pr2NEt as electron donor
and hydrogen donor for the catalytic transfer
hydrogenation (Scheme 3, Eq. 3). Moreover, when
the reaction was performed in dioxane-d8, D-labeled
products were not obtained, thus excluding the
possibilities of solvent acting as the hydrogen source
(Scheme 3, Eq. 4).
Next, the luminescent quenching experiments were
performed (Figure 1). 1a and CoBr2 showed only
slight quenching phenomena; however, i-Pr2NEt
displayed the most obvious quenching phenomenon,
indicating that i-Pr2NEt underwent an effective SET
with excited *Ir[dF(CF3)ppy]2(dtbbpy)PF6. This result
definitely supported the hypothesized mechanism
depicted in Scheme 1. Moreover, CoBr2(n-Bu3P)2
showed a slightly lower quenching rate with i-Pr2NEt
toward the excited photosensitizer *IrIII, which
indicated the involvement of another plausible
mechanism for the reaction (see Scheme S3). In this
Scheme 2. Photoinduced alkenes isomerization.
triplet EnT process is responsible for the Z-major
selectivity. Ir[dF(CF3)ppy]2(dtbbpy)PF6 possesses a
higher triplet energy (ET = 2.64 eV)[26] than (Z)-
stilbene 2a (ET = 2.5 eV)[30] and (E)-stilbene 3a (ET =
2.2 eV)[30], thus both (Z)- and (E)-stilbene could be
excited to their triplet states, leading to the production
of both isomers. Moreover, the corresponding (E)-
isomer 2a can more easily accept energy from the
photosensitizer due to lower triplet states, and
reversible isomerization shift to (Z)-major selectivity
could occur. Thus, visible-light catalysis not only
initiates the reaction, but also plays a crucial role in
deciding the selectivity.
path,
the
excited
photosensitizer
*Ir[dF(CF3)ppy]2(dtbbpy)PF6 (EIV/*III = −0.89 V vs.
SCE)[26] is oxidatively quenched by (n-Bu3P)2CoBr2
(ECoII/CoI = −0.89 V vs SCE, see SI) via a SET to form
the IrVI and CoI species. The IrIV (EIV/III = +1.69 V vs.
SCE)[26] subsequently abstracts an electron from i-
Further, for the comprehensive understanding of
the reaction mechanism, the reaction was performed
in the presence of the following three radical
scavengers:
2,2,6,6-tetramethylpiperidine-1-oxyl
(TEMPO); 2,6-di-tert-butyl-4-methylphenol (BHT);
and 9,10-dihydroanthracene (DHA) (Scheme 3, Eq.
1). When TEMPO was added to the solution, the
yield of the reaction dropped to 20%; however, when
BHT and DHA were added to the solution,
respectively, the yields of the reaction were not
affected. Considering that TEMPO may not solely act
as a radical scavenger and may inhibit the reaction
through another avenue,[31] these experiments further
demonstrated that free radical was not involved in the
Pr2NEt (Ei-Pr2NEt+/ -Pr2NEt = +0.78 V vs SCE, see SI) to
i
give i-Pr2NEt radical cation and regenerate IrIII to
close the catalytic cycle. Then, CoI follows the
similar process as depicted in Scheme 1 to afford the
final products.
Figure 1. Emission-quenching plots.
Scheme 3. Control experiments.
4
This article is protected by copyright. All rights reserved.

10.1002/adsc.201901562
Advanced Synthesis & Catalysis
In summary, we successfully demonstrated the
[4] a) L. Horner, H. Hoffmann, H. G. Wippel, Chem. Ber.
1958, 91, 61-63; b) W. S. Wadsworth, W. D. Emmons,
J. Am. Chem. Soc. 1961, 83, 1733-1738; c) J. Boutagy,
R. Thomas, Chem. Rev. 1974, 74, 87-99.
efficiency of photoredox/cobalt dual catalytic system
in transfer semihydrogenation reaction of alkynes.
This transformation occurred smoothly under blue
LED irradiation at ambient temperature and tolerated
both internal and external alkynes as well as various
functional groups. i-Pr2NEt and AcOH were proved
to be the hydrogen source for the transfer
hydrogenation. The advantages of the established
protocol may inspire more extensive research on
hydrogenation of alkynes.
[5] P. R. Blakemore, J. Chem. Soc., Perkin Trans. 1, 2002,
2563-2585.
[6] D. J. Peterson, J. Org. Chem. 1968, 33, 780-784.
[7] G. C. Vougioukalakis, R. H. Grubbs, Chem. Rev. 2009,
110, 1746-1787.
[8] A. B. Dounay, L. E. Overman, Chem. Rev. 2003, 103,
2945-2964.
Experimental Section
[9] a) A. M. Kluwer, C. J. Elsevier, in The Handbook of
Homogeneous Hydrogenation, Vol. 2 (Eds.: J. G. de
Vries, C. J. Elsevier), Wiley-VCH, Weinheim, 2007, pp.
374-411; b) K. C. K. Swamy, A. S. Reddy, K. Sandeep,
A. Kalyani, Tetrahedron Lett. 2018, 59, 419-429.
General procedure for the semihydrogenation of
alkynes.
To a Schlenk tube containing a stirring bar was added
Ir[dF(CF3)ppy]2(dtbbpy)PF6 (0.002 mmol, 1 mol%), CoBr2
(0.01 mmol, 5 mol%), alkynes 1 (0.20 mmol, 1.0 equiv.).
Then n-Bu3P (0.03 mmol, 15 mol%), i-Pr2NEt (0.6 mmol,
3.0 equiv), AcOH (1.0 mmol, 5.0 equiv.), and 2.0 mL
anhydrous 1,4-dioxane were added to the reaction tube via
syringe under Ar atmosphere. The reaction mixture was
stirred for 14 h under Blue LED irradiation at ambient
temperature (the temperature range from 38 C to 42 C).
Finally, the solvent was removed in vacuum and the
residue was purified by column chromatography on silica
gel to afford the desired products.
[10] a) J. Li, R. Hua, T. Liu, J. Org. Chem. 2010, 75,
2966-2970; b) R. Maazaoui, R. Abderrahim, F. Chemla,
F. Ferreira, A. Perez-Luna, O. Jackowski, Org. Lett.
2018, 20, 7544-7549; c) S. Rao, K. R. Prabhu, Chem.
Eur. J. 2018, 24, 13954-13962; d) C.-Q. Zhao, Y.-G.
Chen, H. Qiu, L. Wei, P. Fang, T.-S. Mei, Org. Lett.
2019, 21, 1412-1416.
o
o
[11] a) J. Li, R. Hua, Chem. Eur. J. 2011, 17, 8462-8465;
b) K. Radkowski, B. Sundararaju, A. Fürstner, Angew.
Chem. 2013, 125, 373-378; Angew. Chem. Int. Ed.
2013, 52, 355-360; c) K. T. Neumann, S. Klimczyk, M.
N. Burhardt, B. Bang-Andersen, T. Skrydstrup, A. T.
Lindhardt, ACS Catal. 2016, 6, 4710-4714; d) I. D.
Alshakova, B. Gabidullin, G. I. Nikonov,
ChemCatChem. 2018, 10, 4874-4883; e) A. Guthertz,
M. Leutzsch, L. M. Wolf, P. Gupta, S. M. Rummelt, R.
Goddard, C. Farès, W. Thiel, A. Fürstner, J. Am. Chem.
Soc. 2018, 140, 3156-3169.
Acknowledgements
We acknowledge the National Natural Science Foundation of
China (No. 21676131 and No. 21462019), the Science
Foundation of Jiangxi Province (20143ACB20012), Jiangxi
Science& Technology Normal University (2018BSQD024, Doctor
Startup Fund) for financial support.
References
[12] S. A. Jagtap, B. M. Bhanage, ChemistrySelect 2018, 3,
[1] For selected reviews, see: a) A. Cirla, J. Mann, Nat.
Prod. Rep. 2003, 20, 558-564; b) G. C. Tron, T. Pirali,
G. Sorba, F. Pagliai, S. Busacca, A. A. Genazzani, J.
Med. Chem. 2006, 49, 3033-3044; c) C. Oger, L. Balas,
T. Durand, J.-M. Galano, Chem. Rev. 2013, 113, 1313-
1350; for selected examples, see: d) M. Fuchs, A.
Fürstner, Angew. Chem. 2015, 127, 4050-4054; Angew.
Chem. Int. Ed. 2015, 54, 3978-3982; e) H. Ding, Z.
Ruan, P. Kou, X. Dong, J. Bai, Q. Xiao, Marine Drugs
2019, 17, 226; f) R. Li, F. Jin, X.-R. Song, T. Yang, H.
Ding, R. Yang, Q. Xiao, Y.-M. Liang, Tetrahedron Lett.
2019, 60, 331-334.
713-718.
[13] a) K. Tani, A. Iseki, T. Yamagata, Chem. Commun.
1999, 1821-1822; b) J. Yang, C. Wang, Y. Sun, X. Man,
J. Li, F. Sun, Chem. Commun. 2019, 55, 1903-1906.
[14] H. S. La Pierre, J. Arnold, F. D. Toste, Angew. Chem.
2011, 123, 3986-3989; Angew. Chem. Int. Ed. 2011, 50,
3900-3903.
[15] a) R. Barrios-Francisco, J. J. García, Inorg. Chem.
2009, 48, 386-393; b) E. Richmond, J. Moran, J. Org.
Chem. 2015, 80, 6922-6929; c) K. Murugesan, C. B.
Bheeter, P. R. Linnebank, A. Spannenberg, J. N. H.
Reek, R. V. Jagadeesh, M. Beller, ChemSusChem. 2019,
12, 3363-3369.
[2] a) J. A. Baur, D. A. Sinclair, Nat. Rev. Drug. Discov.
2006, 5, 493-506; b) M. Athar, J. H. Back, X. Tang, K.
H. Kim, L. Kopelovich, D. R. Bickers, A. L. Kim,
Toxicol. Appl. Pharmacol. 2007, 224, 274-283; c) D. C.
Ferraz da Costa, E. Fialho, J. L. Silva, Molecules 2017,
22, 1014.
[16] a) S. Fu, N. Y. Chen, X. Liu, Z. Shao, S. P. Luo, Q.
Liu, J. Am. Chem. Soc. 2016, 138, 8588-8594; b) K.
Tokmic, A. R. Fout, J. Am. Chem. Soc. 2016, 138,
13700-13705; c) C. Chen, Y. Huang, Z. Zhang, X. Q.
Dong, X. Zhang, Chem. Commun. 2017, 53, 4612-
4615; d) V. G. Landge, J. Pitchaimani, S. P. Midya, M.
Subaramanian, V. Madhu, E. Balaraman, Catal. Sci.
Technol. 2018, 8, 428-433; e) K. Li, R. Khan, X. Zhang,
[3] a) G. Wittig, W. Haag, Chem. Ber. 1955, 88, 1654-
1666; b) B. E. Maryanoff, A. B. Reitz, Chem. Rev.
1989, 89, 863-927.
5
This article is protected by copyright. All rights reserved.

10.1002/adsc.201901562
Advanced Synthesis & Catalysis
Y. Gao, Y. Zhou, H. Tan, J. Chen, B. Fan, Chem.
Commun. 2019, 55, 5663-5666; f) W. Ai, R. Zhong, X.
Liu, Q. Liu, Chem. Rev. 2019, 119, 2876-2953.
[25] a) W. F. Tian, D. P. Wang, S. F. Wang, K. H. He, X.
P. Cao, Y. Li, Org. Lett. 2018, 20, 1421-1425; b) W.-F.
Tian, C.-H. Hu, K.-H. He, X.-Y. He, Y. Li, Org. Lett.
2019, 21, 6930-6935.
[17] a) K. Semba, R. Kameyama, Y. Nakaoa, Synlett.
2015, 26, 318-322; b) T. Wakamatsu, K. Nagao, H.
Ohmiya, M. Sawamura, Organometallics. 2016, 35,
1354-1357; c) E. Korytiaková, N. O. Thiel, F. Pape, J.
F. Teichert, Chem. Commun. 2017, 53, 732-735; d) J.
W. Hall, D. M. L. Unson, P. Brunel, L. R. Collins, M.
K. Cybulski, M. F. Mahon, M. K. Whittlesey,
Organometallics. 2018, 37, 3102-3110.
[26] M. S. Lowry, J. I. Goldsmith, J. D. Slinker, R. Rohl,
R. A. Pascal, G. G. Malliaras, S. Bernhard, Chem.
Mater. 2005, 17, 5712-5719.
[27] a) K. Singh, S. J. Staig, J. D. Weaver, J. Am. Chem.
Soc. 2014, 136, 5275-5278; b) D. C. Fabry, M. A.
Ronge, M. Rueping, Chem. Eur. J. 2015, 21, 5350-
5354; c) W. Cai, H. Fan, D. Ding, Y. Zhang, W. Wang,
Chem. Commun. 2017, 53, 12918-12921; d) J. B.
Metternich, D. G. Artiukhin, M. C. Holland, M. von
Bremen-Kühne, J. Neugebauer, R. Gilmour, J. Org.
Chem. 2017, 82, 9955-9977; e) J. Lu, B. Pattengale, Q.
Liu, S. Yang, W. Shi, S. Li, J. Huang, J. Zhang, J. Am.
Chem. Soc. 2018, 140, 13719-13725.
[18] a) A. Brzozowska, L. M. Azofra, V. Zubar, I.
Atodiresei, L. Cavallo, M. Rueping, O. El-Sepelgy,
ACS Catal. 2018, 8, 4103-4109; b) Y.-P. Zhou, Z. Mo,
M.-P. Luecke, M. Driess, Chem. Eur. J. 2018, 24,
4780-4784.
[19] a) G. Wienhoefer, F. A. Westerhaus, R. V. Jagadeesh,
K. Junge, H. Junge, M. Beller, Chem. Commun. 2012,
48, 4827-4829; b) D. Srimani, Y. Diskin-Posner, Y.
Ben-David, D. Milstein, Angew. Chem. 2013, 52,
14381-14384; Angew. Chem. Int. Ed. 2013, 52, 14131-
14134; c) C. Johnson, M. Albrecht, Catal. Sci. Technol.
2018, 8, 2779-2783; d) D. Wei, C. Darcel, Chem. Rev.
2018, 119, 2550-2610.
[28] L. Flamigni, A. Barbieri, C. Sabatini, B. Ventura, F.
Barigelletti, in Photochemistry and Photophysics of
Coordination Compounds II (Eds.: V. Balzani, S.
Campagna), Springer, Berlin, Heidelberg, 2007, pp.
143-203.
[29] a) X. Liu, W. Zhang, Y. Wang, Z. X. Zhang, L. Jiao,
Q. Liu, J. Am. Chem. Soc. 2018, 140, 6873-6882; b) Q.
Y. Meng, T. E. Schirmer, K. Katou, B. Konig, Angew.
Chem. 2019, 131, 5779-5784; Angew. Chem. Int. Ed.
2019, 58, 5723-5728.
[20] a) C. K. Prier, D. A. Rankic, D. W. C. MacMillan,
Chem. Rev. 2013, 113, 5322-5363; b) N. A. Romero, D.
A. Nicewicz, Chem. Rev. 2016, 116, 10075-10166; c)
K. L. Skubi, T. R. Blum, T. P. Yoon, Chem. Rev. 2016,
116, 10035-10074; d) X. Q. Hu, J. R. Chen, W. J. Xiao,
Angew. Chem. 2017, 129, 1988-1990; Angew. Chem.
Int. Ed. 2017, 56, 1960-1962; e) B. König, Eur. J. Org.
Chem. 2017, 2017, 1979-1981; f) C.-S. Wang, P. H.
Dixneuf, J.-F. Soulé, Chem. Rev. 2018, 118, 7532-7585.
[30] W. G. Herkstroeter, D. S. McClure, J. Am. Chem. Soc.
1968, 90, 4522-4527.
[31] J. E. Nutting, M. Rafiee, S. S. Stahl, Chem. Rev. 2018,
118, 4834-4885.
[21] J. J. Zhong, Q. Liu, C. J. Wu, Q. Y. Meng, X. W. Gao,
Z. J. Li, B. Chen, C. H. Tung, L. Z. Wu, Chem.
Commun. 2016, 52, 1800-1803.
[22] a) P. Du, K. Knowles, R. Eisenberg, J. Am. Chem.
Soc. 2008, 130, 12576-12577; b) J. L. Dempsey, B. S.
Brunschwig, J. R. Winkler, H. B. Gray, Acc. Chem. Res.
2009, 42, 1995-2004; c) P. Du, J. Schneider, G. Luo, W.
W. Brennessel, R. Eisenberg, Inorg. Chem. 2009, 48,
4952-4962; d) T. Lazarides, T. McCormick, P. Du, G.
Luo, B. Lindley, R. Eisenberg, J. Am. Chem. Soc. 2009,
131, 9192-9194.
[23] a) K.-H. He, Y. Li, ChemSusChem 2014, 7, 2788-
2790; b) B. Chen, L.-Z. Wu, C.-H. Tung, Acc. Chem.
Res. 2018, 51, 2512-2523; c) H. Wang, X. Gao, Z. Lv,
T. Abdelilah, A. Lei, Chem. Rev. 2019, 119, 6769-6787.
[24] a) K. E. Ruhl, T. Rovis, J. Am. Chem. Soc. 2016, 138,
15527-15530; b) S. M. Thullen, T. Rovis, J. Am. Chem.
Soc. 2017, 139, 15504-15508; c) J. Hou, A. Ee, W.
Feng, J. H. Xu, Y. Zhao, J. Wu, J. Am. Chem. Soc.
2018, 140, 5257-5263; d) B. D. Ravetz, K. E. Ruhl, T.
Rovis, ACS. Catal. 2018, 8, 5323-5327; e) P. Rai, K.
Maji, B. Maji, Org. Lett. 2019, 21, 3755-3759.
6
This article is protected by copyright. All rights reserved.

10.1002/adsc.201901562
Advanced Synthesis & Catalysis
COMMUNICATION
cis-Selective Transfer Semihydrogenation of
Alkynes by Merging Visible-Light Catalysis with
Cobalt Catalysis
Adv. Synth. Catal. Year, Volume, Page – Page
Wan-Fa Tian, Yong-Qin He , Xian-Rong Song,
Hai-Xin Ding, Jing Ye, Wen-Jie Guo, and Qiang
Xiao *
7
This article is protected by copyright. All rights reserved.