Redox-neutral α-allylation of amines by combining palladium catalysis and visible-light photoredox catalysis

Article abstract of DOI:10.1002/anie.201409999

An unprecedented α-allylation of amines was achieved by combining palladium catalysis and visible-light photoredox catalysis. In this dual catalysis process, the catalytic generation of allyl radical from the corresponding π-allylpalladium intermediate wa

Full text of DOI:10.1002/anie.201409999

Angewandte
Chemie
DOI: 10.1002/anie.201409999
Synthetic Methods
Redox-Neutral a-Allylation of Amines by Combining Palladium
Catalysis and Visible-Light Photoredox Catalysis**
Jun Xuan, Ting-Ting Zeng, Zhu-Jia Feng, Qiao-Hui Deng, Jia-Rong Chen, Liang-Qiu Lu,* Wen-
Jing Xiao,* and Howard Alper
Abstract: An unprecedented a-allylation of amines was
achieved by combining palladium catalysis and visible-light
photoredox catalysis. In this dual catalysis process, the catalytic
generation of allyl radical from the corresponding p-allylpal-
ladium intermediate was achieved without additional metal
reducing reagents (redox-neutral). Various allylation products
of amines were obtained in high yields through radical cross-
coupling under mild reaction conditions. Moreover, the trans-
formation was applied to the formal synthesis of 8-oxoproto-
berberine derivatives which show potential anticancer proper-
ties.
P
alladium-catalyzed allylation reactions are among the most
important methods for creating new chemical bonds.[1–4]
Critical to the success of this chemistry is the formation of
key p-allylpalladium intermediates from allylic esters or their
analogues (Scheme 1a, path 1), which can be utilized as
efficient electrophilic components to react with diverse
carbon or heteroatom nucleophiles.[1,2] In contrast, reversal
of reactivity of the p-allylpalladium complex can be realized
through two-electron[3] or single-electron reduction[4] (Sche-
me 1a, paths 2 and 3) in the presence of stoichiometric
amounts of reducing reagents (e.g., Et3B, Et2Zn, InI, SmI2, or
Mn powder). The resultant allylic metal complex (h1-type) or
Scheme 1. Palladium-catalyzed allylation reactions. Cp=cyclopenta-
diene.
allylic radical enables the nucleophilic addition to aldehydes,
ketones, and imines,[3] as well as radical homocoupling[4a,d] and
intramolecular radical addition reactions.[4b–d] Despite the
advances, the catalytic generation of an allylic radical from
a p-allylpalladium complex without additional reductants
remains a challenge. Furthermore, developing novel trans-
formations and expending the substrate scope of this chemis-
try is highly desirable.
Recently, visible-light-induced photoredox catalysis has
become an important platform for the design and develop-
ment of a variety of radical reactions under remarkably mild
reaction conditions.[5] More intriguingly, dual catalysis com-
bining photocatalysis with transition-metal catalysis[6,7] can
accomplish many new chemical transformations which are
impossible or not easily accessible for a single catalytic cycle.
For instance, the group of Sanford successfully achieved
[*] J. Xuan, T.-T. Zeng, Z.-J. Feng, Q.-H. Deng, Prof. Dr. J.-R. Chen,
Dr. L.-Q. Lu, Prof. Dr. W.-J. Xiao
CCNU-uOttawa Joint Research Centre, Key Laboratory of
Pesticide & Chemical Biology, Ministry of Education
College of Chemistry, Central China Normal University (CCNU)
152 Luoyu Road, Wuhan, Hubei 430079 (China)
E-mail: luliangqiu@mail.ccnu.edu.cn
wxiao@mail.ccnu.edu.cn
Homepage: http://chem-xiao.ccnu.edu.cn/
À
photoredox Pd/Ru-catalyzed C H arylation reactions using
aryldiazonium and diaryliodonium salts as the radical sour-
ce.[7b,c] The key to these reactions was the oxidation of Ar–
PdIII to Ar–PdIV in with the high-valent RuIII or IrIV species,
which was generated by the oxidative quenching of the
visible-light excited RuII* or IrIII* complex. In contrast, we
questioned whether the p-allylpalladium complex could be
reduced to a neutral p-allyl radical and Pd0 species using the
low-valent species, generated from the excited state of the
photocatalyst, through reductive quenching. As part of our
ongoing efforts to develop novel photocatalytic reactions,[8]
we herein disclose an unprecedented redox-neutral a-allyla-
tion of amines (Scheme 1b)[9] through radical cross-coupling
by combining palladium catalysis (to generate p-allylic radical)
and photoredox catalysis (to generate a-amino radical).
Initially, cinnamyl acetate (1a) and N-phenyltetrahydro-
isoquinoline (2a) were selected as model substrates to
Prof. Dr. W.-J. Xiao
Collaborative Innovation Center of Chemical Science and
Engineering, Tianjin (China)
and
State Key Laboratory of Applied Organic Chemistry
Lanzhou University, Lanzhou, Gansu 730000 (China)
Prof. Dr. H. Alper
Centre for Catalysis Research and Innovation, Department of
Chemistry, University of Ottawa
10 Marie Curie, Ottawa, Ontario, K1N 6N5 (Canada)
[**] We are grateful to the National Science Foundation of China (NO.
21232003, 21202053, and 21272087) and the National Basic
Research Program of China (2011CB808603) for support of this
research. We thank Prof. Ai-Wen Lei and Hong Yi at Wuhan
University for the mechanism discussion and EPR measurement.
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/anie.201409999.
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examine the feasibility of the designed process. Fortunately,
optimization of the reaction conditions showed that the
proposed a-allylation reaction of amines did indeed occur
with an 81% yield in the presence of 5 mol% [Pd(PPh3)4] and
2 mol% [Ir(ppy)2(dtbbpy)]PF6 in degassed CH3CN under
irradiation with a 3 W blue LED for 48 hours (for details of
the optimization, see the Supporting Information). Control
experiments indicated that the photosensitizer, palladium
catalyst, visible-light irradiation, and degassing procedure are
all crucial for this dual catalytic a-allylation reaction of
amines (see Table S7 in the Supporting Information).
Under the optimal reaction conditions, we evaluated the
generality of this photoredox Pd/Ir dual catalytic allylation
reaction. As highlighted in Table 1, a wide range of allylic
compounds were applicable and generally moderate to good
yields were achieved. With cinnamyl alcohol as an example,
not only its acetate (1a) but also tert-butoxy carbonate (1b)
and diethyl phosphate (1c) proved successful for this reaction
(Table 1, entries 1–3). Notably, the direct employment of
allylic alcohol 1d itself as the allyl radical precursor was also
feasible with the assistance of formic acid (entry 4). When
cinnamyl bromide (1e) was used under best reaction con-
ditions, the allylation product 3aa was obtained in 45% yield.
A control experiment revealed that the absence of the
palladium catalyst did not affect the reaction efficiency and
a similar yield of isolated 3aa was obtained (entry 5),
presumably because 1e can directly undergo a visible-light-
induced reductive dehalogenation process to give the key
allylic radical intermediate. Other substituted allylic reagents
were also surveyed to explore the potential of this method-
ology. The results in entries 6–8 revealed that alkyl- (1 f and
1g) and w-vinyl- (1h) substituted substrates were well
tolerated under this dual catalytic system and moderate to
good yields of corresponding products were obtained (3 fa–
3ha: 57-69% yields). Notably, simple allylic esters could be
employed in the reaction. With 2a and its electron-rich
analogue 2l as the example, the Pd/Ir-catalyzed a-allylation of
amines with 1i proceeded well, thus affording desired
products in good yields upon isolation (entries 8 and 9).
The experiments investigating the scope of the amine
component are described in Table 2. The reaction appears to
be general with a variety of N-aryl tetrahydroisoquinolines.
For example, the substitutes on the benzene ring of tetrahy-
droisoquinoline can be varied, thus delivering the allylation
products in satisfactory yields (3cb: 81% yield and 3cc: 62%
yield). Moreover, both electron-withdrawing groups (i.e., F,
Cl, and ester) and electron-donating groups (i.e., Me and
OMe) can be successfully introduced to the para, meta, and
ortho positions of the benzene ring on the nitrogen atom, thus
giving the corresponding allylation products (3cd–3ci) in
good yields. It is important to note that the substrate 2j, with
a sensitive vinyloxy functional group, can participate in this
transformation, thus giving the desired product in 51% yield.
Additionally, the N-alkyl substituted tetrahydroisoquinoline
2k is suitable for this dual catalytic process, albeit with
relatively low yield of the corresponding allylation product
(3ck, 15% yield).
Table 1: Substrate scope of allylic esters.[a]
Entry
1
Substrate
Product
Yield [%][b]
81
2
3
70
83
4[c]
5
42
The success of this dual catalysis system could be also
significantly extended to the allylation reaction of secondary
amines. For instance, the a-amino methyl ester 4a and ethyl
ester derivatives 4b and 4c can facilely react with cinnamyl
diethyl phosphate 1c, and the resulting allylation products
were obtained in moderate yields (Table 3). Additionally, we
45 (41)[d]
6
7
60[e]
57
Table 2: Substrate scope of tetrahydroisoquinolines.[a]
8[f]
9
69[e]
73
10
76
[a] Reaction conditions: 1 (0.3 mmol), 2a or 2l (0.36 mmol), [Pd(PPh3)4]
(5 mol%), [Ir(ppy)2(dtbbpy)]PF6 (2 mol%), and CH3CN (3 mL) at RT for
48 h under irradiation with a 3 W blue LED. [b] Yield of the isolated
product. [c] Adding 1.0 equiv of HCO2H. [d] Without the addition of
[Pd(PPh3)4]. [e] 3:1 E/Z of products. [f] 6:1 E/Z of substrate 1g.
Ac=acetyl, Boc=tert-butoxycarbonyl, dtbbpy=4,4’-di-tert-butyl-2,2’-
bipyridine, ppy=2-phenylpyridine.
[a] Reaction conditions: 1c (0.3 mmol), 2 (0.36 mmol), [Pd(PPh3)4]
(5 mol%), [Ir(ppy)2(dtbbpy)]PF6 (2 mol%), and CH3CN (3 mL) at RT for
48 h under irradiation with a 3 W blue LED. Yield is that of the isolated
product.
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Table 3: Substrate scope of secondary amines.[a]
[a] Reaction conditions: 1b (0.3 mmol), 2 (0.36 mmol), [Pd(PPh3)4]
(5 mol%), [Ir(ppy)2(dtbbpy)]PF6 (2 mol%), and CH3CN (3 mL) at RT for
48 h under irradiation with a 3 W blue LED. Yield is that of the isolated
product.
demonstrated that a-amino ketones, such as aryl- and alkyl-
derived systems, are amenable to this allylation process using
this dual palladium/photoredox catalysis (5 cd: 52% yield and
5ce: 57% yield).
Figure 1. Plausible reaction mechanism.
Moreover, to our delight, 1-phenylpyrrolidin-3-one (6)
was also suitable for this transformation. The allylation
material. It is noteworthy that a higher reaction temperature
is needed for the process, presumably because of the steric
hindrance of the benzoxazole moiety. Subsequently, the
benzoxazole moiety can be easily removed under reductive
conditions with LiAlH4 in refluxing THF.[11] A SN2 substitu-
tion reaction of 8 with 3-bromo-2-iodoprop-1-ene (9) gave
a good yield of the product 10, which is the key synthetic
intermediate to the target molecule 11.[10a]
À
reaction occurred selectively at the C H bond between the
carbonyl group and nitrogen atom, thus delivering the
corresponding product 7 in moderate yield [Eq. (1)]. Other
types of amines (i.e., N-Boc-protected tetrahydroisoquino-
line, N-phenylpyrrolidine, and triethylamine) were also tested
under optimal reaction conditions, and no reaction or only
1,5-diene was obtained as a major product in most cases (see
the Supporting Information for details).
A plausible reaction mechanism was proposed (Figure 1)
based on the several mechanism studies (see Section S7). The
reductive quenching process of the visible-light excited IrIII*
by amine substrates 2 initially generated a low-valent IrII
complex and simultaneously delivered the radical cation A,
the deprotonation of which afforded the a-amino alkyl radical
B.[12] In contrast, the palladium catalytic cycle started from the
formation of the p-allylpalladium complex C, which was
subsequently reduced by IrII to afford the allyl radical D and
regeneration of the Pd0 catalyst as well as ground-state IrIII
photocatalyst to complete both catalytic cycles. The proposed
redox process was consistent with the redox potentials of key
intermediates (i.e., IrII as reductant: E1 = À1.51 V vs
SCE;[3d,13a] C as oxidant: when R2 = R3 = H, E2 = À1.35 V vs
SCE[13b]). Finally, the radical cross-coupling of B and D
delivered the desired allylation product.[14] As evidence, the
homocoupling adducts of D were observed in certain cases. It
is worthy to note that in 2012, the group of Reiser reported an
addition reaction of Michael acceptors with a-amino radical
derived from N-aryltetrahydroisoquinoline.[12a] In this elegant
work, they isolated and confirmed the radical self-coupling
product in the absence of Michael acceptors. The yield of the
reaction is 10% after one week, and indicates that this type of
a-amino radical might be stable and self-coupling does not
proceed easily, probably because it is quite bulky. In contrast,
the allylic radical generated from the reduction reaction of p-
allylic palladium complex was relatively reactive. At low
concentration, this radical tends to react with the a-amino
radical to form the desired cross-coupling product. Another
reaction pathway involving the addition of a-amino radical B
to p-allylpalladium species might be possible and cannot be
totally ruled out at the current stage (see Section S7.5).
However, the fact that no enantioselectivity was observed
Remarkably, this reaction can be further applied to the
formal synthesis of the 8-oxoprotoberberine derivative 11,
a member of natural isoquinoline alkaloids in the proto-
berberine family, which holds potential anticancer properties
(Scheme 2).[10] As shown, the heteroaryl-substituted tetrahy-
droisoquinoline 2m was successfully incorporated into this
dual catalytic allylation reaction, thus giving the correspond-
ing product 3im in good yield based on recovering starting
Scheme 2. Formal synthesis of the 8-oxoprotoberberine derivative 11.
DMSO=dimethylsulfoxide, THF=tetrahydrofuran.
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A. M. Echavarren, J. M. Cuerva, Chem. Eur. J. 2011, 17, 3985 –
3994.
[5] For selected reviews, see: a) J. M. R. Narayanam, C. R. J.
when chiral ligands were used in the reaction, made radical
cross-coupling more favorable.[15]
In conclusion, we have developed the catalytic generation
of an allyl radical from a p-allylpalladium complex by
combining visible-light-induced photoredox catalysis and
palladium catalysis. The a-amino radical derived from the
same catalytic cycle can react with the allyl radical through
a cross-coupling process to afford various a-allylation prod-
ucts of amines in high yields. In contrast to prior reduction
methods using stoichiometric amounts of additional reduc-
tants, this strategy utilized the bifunctional property of the
photoredox catalyst: oxidizing amines to a-amino radical and
reducing p-allylpalladium complex to allyl radical. Notably,
this reaction has been successfully applied to the formal
synthesis of the 8-oxoprotoberberine derivative 11, which has
potential anticancer activities. Moreover, a plausible reaction
mechanism was proposed based on a series of control
experiments and EPR studies.
´
Stephenson, Chem. Soc. Rev. 2011, 40, 102 – 113; b) F. Teply,
Collect. Czech. Chem. Commun. 2011, 76, 859 – 917; c) J. Xuan,
W.-J. Xiao, Angew. Chem. Int. Ed. 2012, 51, 6828 – 6838; Angew.
Chem. 2012, 124, 6934 – 6944; d) C. K. Prier, D. A. Rankic,
D. W. C. MacMillan, Chem. Rev. 2013, 113, 5322 – 5363; e) Y. Xi,
H. Yi, A. Lei, Org. Biomol. Chem. 2013, 11, 2387 – 2403; f) D. M.
Schultz, T. P. Yoon, Science 2014, 343, 985.
[6] For reviews, see: a) B. Kçnig in Chemical Photocatalysis, De
Gruyter, Berlin, 2013, Chap. 9, pp. 151 – 168; b) M. N. Hopkin-
son, B. Sahoo, J. Li, F. Glorius, Chem. Eur. J. 2014, 20, 3874 –
3886.
[7] For selected examples with palladium catalysis, see: a) M.
Osawa, H. Nagai, M. Akita, Dalton Trans. 2007, 827 – 829;
b) D. Kalyani, K. B. McMurtrey, S. R. Neufeldt, M. S. Sanford, J.
Am. Chem. Soc. 2011, 133, 18566 – 18569; c) S. R. Neufeldt, M. S.
Sanford, Adv. Synth. Catal. 2012, 354, 3517 – 3522. With copper
catalysis, see: d) Y. Ye, M. S. Sanford, J. Am. Chem. Soc. 2012,
134, 9034 – 9037; e) Y. Ye, S. A. Kunzi, M. S. Sanford, Org. Lett.
2012, 14, 4979 – 4981. With gold catalysis, see: f) B. Sahoo, M. N.
Hopkinson, F. Glorius, J. Am. Chem. Soc. 2013, 135, 5505 – 5508;
g) X.-Z. Shu, M. Zhang, Y. He, H. Frei, F. D. Toste, J. Am. Chem.
Soc. 2014, 136, 5844 – 5847; h) M. N. Hopkinson, B. Sahoo, F.
Glorius, Adv. Synth. Catal. 2014, 356, 2794 – 2800. With nickel
catalysis, see: i) Z. Zuo, D. T. Ahneman, L. Chu, J. A. Terrett,
A. G. Doyle, D. W. MacMillan, Science 2014, 345, 437 – 440;
j) J. C. Tellis, D. N. Primer, G. A. Molander, Science 2014, 345,
433 – 436.
[8] a) Y.-Q. Zou, L.-Q. Lu, L. Fu, N.-J. Chang, J. Rong, J.-R. Chen,
W.-J. Xiao, Angew. Chem. Int. Ed. 2011, 50, 7171 – 7175; Angew.
Chem. 2011, 123, 7309 – 7313; b) Y.-Q. Zou, J.-R. Chen, X.-P.
Liu, L.-Q. Lu, R. L. Davis, K. A. Jørgensen, W.-J. Xiao, Angew.
Chem. Int. Ed. 2012, 51, 784 – 788; Angew. Chem. 2012, 124, 808 –
812; c) J. Xuan, X.-D. Xia, T.-T. Zeng, Z.-J. Feng, J.-R. Chen, L.-
Q. Lu, W.-J. Xiao, Angew. Chem. Int. Ed. 2014, 53, 5653 – 5656;
Angew. Chem. 2014, 126, 5759 – 5762.
Experimental Section
Representative procedure: 1a (0.3 mmol), 2a (0.36 mmol), [Ir(ppy)2-
(dtbbpy)]PF6 (0.006 mmol), [Pd(PPh3)4] (0.015 mmol) and dry
CH3CN (3.0 mL) were added to a 10 mL Schlenk flask equipped
with a magnetic stir bar was added. The resulting mixture was
degassed by using a freeze–pump–thaw procedure (3 times). The
solution was then stirred at a distance of ca. 5 cm from a 3 W blue
LED at room temperature for 48 h. Then, the solvent was removed by
vacuum and the crude reaction mixture was purified by flash
chromatography on silica gel (silica: 200 to 300; eluent: petroleum
ether/CH2Cl2 (5:1 to 3:1) to provide pure product 3aa as a light yellow
oil in 81% yield.
Received: October 12, 2014
Revised: November 11, 2014
[9] For selected examples on oxidative a-allylation of amines with
allylic silica and tin reagents, see: a) G. Kumaraswamy, A. N.
Murthy, A. Pitchaiah, J. Org. Chem. 2010, 75, 3916 – 3919; b) E.
Boess, D. Su-reshkumar, A. Sud, C. Wirtz, C. Farꢂs, M.
Klussmann, J. Am. Chem. Soc. 2011, 133, 8106 – 8109; c) D. B.
Freeman, L. Furst, A. G. Condie, C. R. J. Stephenson, Org. Lett.
2012, 14, 94 – 97.
[10] a) S. Husinec, V. Savic, M. Simic, V. Tesevic, D. Vidovic,
Tetrahedron Lett. 2011, 52, 2733 – 2736; b) Y. Sun, K. Xun, Y.
Wang, X. Chen, Anti-Cancer Drugs 2009, 20, 757 – 769; c) V.
Kettmann, D. Kostalova, S. Jantova, M. Cernakova, J. Drimal,
Pharmazie 2004, 59, 548 – 551.
Published online: && &&, &&&&
Keywords: allylic compounds · palladium · photochemistry ·
.
radicals · synthetic methods
[1] For selected books, see: a) B. M. Trost, C. Lee, In Catalytic
Asymmetric Synthesis, 2nd ed. (Ed.: I. Ojima), Wiley-VCH, New
York, 2000, Chap. 8, pp. 593 – 649; b) J. Tsuji in Palladium
Reagents and Catalysts: New Perspectives for the 21st Century,
Wiley, Chichester, 2004, Chap. 4, pp. 431 – 518.
[2] For some reviews, see: a) Z. Lu, S.-M. Ma, Angew. Chem. Int.
Ed. 2007, 47, 258 – 297; Angew. Chem. 2007, 120, 264 – 303; b) M.
Bandini, Angew. Chem. Int. Ed. 2011, 50, 994 – 995; Angew.
Chem. 2011, 123, 1026 – 1027; c) B. M. Trost, Org. Process Res.
Dev. 2012, 16, 185 – 194; d) C.-X. Zhuo, C. Zheng, S.-L. You,
Acc. Chem. Res. 2014, 47, 2558 – 2573.
[3] For selected reveiws, see: a) J. A. Marshall, Chem. Rev. 2000,
100, 3163 – 3186; b) G. Zanoni, A. Pontiroli, A. Marchetti, G.
Vidari, Eur. J. Org. Chem. 2007, 3599 – 3611.
[4] a) S.-I. Sasaoka, T. Yamamoto, H. Kinoshita, K. Inomata, H.
Kotake, Chem. Lett. 1985, 315 – 318; b) A. G. CampaÇa, B.
Bazdi, N. Fuentes, R. Robles, J. M. Cuerva, Angew. Chem. Int.
Ed. 2008, 47, 7515 – 7519; Angew. Chem. 2008, 120, 7625 – 7629;
c) A. Millꢀn, A. Martꢁn-Lasanta, D. Miguel, L. A. Cienfuegos,
J. M. Cuerva, Chem. Commun. 2011, 47, 10470 – 10472; d) A.
Millꢀn, A. G. Campana, B. Bazdi, D. Miguel, L. A. Cienfuegos,
[11] G. Lahm, T. Opatz, Org. Lett. 2014, 16, 4201 – 4203.
[12] a) P. Kohls, D. Jadhav, G. Pandey, O. Reiser, Org. Lett. 2012, 14,
672 – 675; b) Y. Miyake, K. Nakajima, Y. Nishibayashi, J. Am.
Chem. Soc. 2012, 134, 3338 – 3341; c) L. R. Espelt, E. M.
Wiensch, T. P. Yoon, J. Org. Chem. 2013, 78, 4107 – 4114.
[13] a) J. D. Slinker, A. A. Gorodetsky, M. S. Lowry, J. Wang, S.
Parker, R. Rohl, S. Bernhard, G. G. Malliaras, J. Am. Chem. Soc.
2004, 126, 2763 – 2767; b) P.-P. Zhang, W.-C. Zhang, T.-F. Zhang,
Z.-Q. Wang, W.-J. Zhou, J. Chem. Soc. Chem. Commun. 1991,
491 – 492.
[14] a) L.-L. Zhou, S. Tang, X.-T. Qi, C.-T. Lin, K. Liu, C. Liu, Y. Lan,
A.-W. Lei, Org. Lett. 2014, 16, 3404 – 3407; b) S. B. Lang, K. M.
OꢃNele, J. A. Tunge, J. Am. Chem. Soc. 2014, 136, 13606 – 13609.
[15] For details on a chiral ligand screening, please see the Support-
ing Information.
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Synthetic Methods
J. Xuan, T.-T. Zeng, Z.-J. Feng, Q.-H. Deng,
J.-R. Chen, L.-Q. Lu,* W.-J. Xiao,*
H. Alper
&&&& — &&&&
Redox-Neutral a-Allylation of Amines by
Combining Palladium Catalysis and
Visible-Light Photoredox Catalysis
Double up: The title reaction was ac-
complished by merging palladium catal-
ysis and visible-light photoredox cataly-
sis. The catalytic generation of an allyl
radical from the corresponding p-allyl-
palladium intermediate was realized
without additional metal reducing
reagents for the first time. Various a-
allylation products of amines were ach-
ieved in high yields by radical cross-
coupling under mild reaction conditions.
SET=single-electron transfer.
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