Metal-catalyzed electrochemical diazidation of alkenes

Article abstract of DOI:10.1126/science.aan6206

Vicinal diamines are a common structural motif in bioactive natural products, therapeutic agents, and molecular catalysts, motivating the continuing development of efficient, selective, and sustainable technologies for their preparation. We report an operationally simple and environmentally friendly protocol that converts alkenes and sodium azide—both readily available feedstocks—to 1,2-diazides. Powered by electricity and catalyzed by Earth-abundant manganese, this transformation proceeds under mild conditions and exhibits exceptional substrate generality and functional group compatibility. Using standard protocols, the resultant 1,2-diazides can be smoothly reduced to vicinal diamines in a single step, with high chemoselectivity. Mechanistic studies are consistent with metal-mediated azidyl radical transfer as the predominant pathway, enabling dual carbon-nitrogen bond formation.

Full text of DOI:10.1126/science.aan6206

RESEARCH
◥
matography analysis of the reaction headspace—
and sodium acetate are the only by-products.
Our catalytic system shows an unusual combina-
tion of high reactivity and excellent chemose-
lectivity. As such, it is applicable to the diazidation
of a substantially greater variety of alkenes
than existing methods, specifically with respect
to substitution pattern and functional group
compatibility.
REPORT
ORGANIC CHEMISTRY
Metal-catalyzed electrochemical
diazidation of alkenes
Our early efforts demonstrated that electro-
chemically generated azidyl radical could induce
the homolysis of C=C p-bonds. To establish proof
of concept, we carried out electrolysis experiments
using 4-(tert-butyl)styrene (1a) as the archetypal
substrate, oxidatively robust graphite as the anode
(working electrode), and platinum (Pt), with its
low overpotential for proton reduction, as the cath-
ode (counter electrode). We chose NaN3 as the
azide source, because it is readily available and
exhibits markedly lower toxicity and volatility
compared with other azide derivatives. With
(2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO)
as a radical scavenger to trap carbon radical in-
termediate I, azidooxygenated product 1c formed
in high yield and with complete regioselectivity
(Fig. 2). However, efforts to trigger diazidation by
directly trapping I with another equivalent of
azidyl radical proved unsuccessful; only traces of
1,2-diazide 1b were detected, despite full con-
sumption of 1a. Owing to their high reactivity,
radicals can undergo a variety of transforma-
tions, including dimerization, polymerization,
oxidation or reduction to ionic species, and re-
action with the electrode surface, many of which
remain diffusion-controlled and virtually barrier-
less. Direct sequestration of I by azidyl radical
proved too sluggish to outpace competing side
reactions, and the majority of the mass balance
came from an array of by-products resulting
from radical homocoupling (1d) (37) and over-
oxidation followed by water addition (1e).
To overcome this challenge and accelerate for-
mation of the elusive second C–N bond, we sought
to introduce a redox-active catalyst to impart se-
lectivity through kinetic control (38). Such a catalyst
could complex with N3– and undergo anodic oxi-
dation to form active metal azidyl (M–N3) adducts,
which could subsequently react with the in situ–
generated carbon radical I via either direct group
transfer or oxidative addition followed by reduc-
tive elimination to complete diazidation. As such,
we envisioned that electrochemistry and redox-
active metal catalysis could act in synergy to
harness radical-mediated reactivities. Drawing
inspiration from recent work on C–H and alkene
azido-functionalization methods catalyzed by
transition metals such as copper complexes
(8, 39, 40), iron-bisoxazoline (13, 41, 42), manganese-
porphyrin (43), and cobalt–Schiff base (44), we
surveyed a series of redox-active metal catalysts
and ultimately discovered that a catalytic amount
of MnII greatly enhanced the propensity of our
system to diazidate. After multiple iterations of
optimization, we developed a highly efficient
diazidation protocol using manganese(II) bro-
mide (MnBr2) as the catalyst, acetic acid (HOAc)
as the proton source, and reticulated vitreous
Niankai Fu, Gregory S. Sauer, Ambarneil Saha, Aaron Loo, Song Lin*
Vicinal diamines are a common structural motif in bioactive natural products, therapeutic
agents, and molecular catalysts, motivating the continuing development of efficient,
selective, and sustainable technologies for their preparation. We report an operationally
simple and environmentally friendly protocol that converts alkenes and sodium azide—
both readily available feedstocks—to 1,2-diazides. Powered by electricity and catalyzed by
Earth-abundant manganese, this transformation proceeds under mild conditions and
exhibits exceptional substrate generality and functional group compatibility. Using
standard protocols, the resultant 1,2-diazides can be smoothly reduced to vicinal diamines
in a single step, with high chemoselectivity. Mechanistic studies are consistent with metal-
mediated azidyl radical transfer as the predominant pathway, enabling dual carbon-
nitrogen bond formation.
icinal diamines are frequently found in
pharmaceuticals and medicinally relevant
natural products, as well as in privileged
molecular catalysts for stereoselective syn-
thesis (1). Despite substantial advances, a
these oxidants produce environmentally delete-
rious by-products and present an explosion hazard
when used alongside an azide source. An elegant
catalytic protocol was recently developed to ad-
dress these conventional issues with reaction se-
lectivity and substrate generality (13). Nonetheless,
both azidotrimethylsilane (TMSN3, a toxic andvola-
tile reagent) and hypervalent iodine derivatives—
compounds that are difficult to handle on a
practical scale—remain necessary to drive the
diazidation reactivity.
V
broadly applicable methodological approach to
their synthesis remains elusive (2). The direct ad-
dition of two nitrogen-based functional groups to
alkenes—a family of abundant, readily accessible,
and structurally diverse feedstocks—is a particu-
larly powerful approach to 1,2-diamine synthesis.
Although several methods are available for the
oxidative transformation of alkenes into 1,2-diols
(3), the analogous extension of this synthetic logic
to vicinal diamines remains underdeveloped. Exist-
ing methods frequently require stoichiometric
heavy metals (e.g., osmium or palladium) or eso-
teric nitrogenous reagents (e.g., nitrogen oxides,
diaziridinones, or N-activated sulfamides) and gen-
erally exhibit limited substrate scope (Fig. 1A) (4–10).
In this context, alkene diazidation is an attract-
ive alternative route to vicinal diamine synthesis
(11–13), because the resulting 1,2-diazides can readily
be reduced to the corresponding diamines (Fig. 1B).
Furthermore, organic azides can participate in 1,3-
dipolar cycloaddition (14), the aza-Wittig reaction
(15), Staudinger ligation (16), and C–H bond ami-
nation (17), making them highly versatile inter-
mediates for synthetic, materials, and biological
applications (18). However, existing protocols
uniformly require stoichiometric quantities of
reagents including peroxydisulfates (11), high-
valent metal salts (11, 12), or hypervalent iodines
(13). The use of strong and indiscriminate oxidiz-
ing agents precludes the use of substrates with
oxidatively labile functionalities, such as alcohol,
aldehyde, sulfide, and amine groups. In addition,
Electrochemistry offers a mild and efficient al-
ternative to conventional chemical approaches for
redox transformations (19–21). With sufficient po-
tential bias, common organic starting materials
can lose or gain electrons at the electrode surface,
readily producing highly reactive intermediates.
Electrochemistry allows for precise, external
control of chemoselectivity and the flux of re-
active intermediates by regulating the applied
potential. Such control also maximizes energy
efficiency, making electrosynthesis one of the
most sustainable approaches for the prepa-
ration of complex organic molecules (21). More-
over, because the driving force derives solely from
electricity, electrosynthesis can be easily coupled
with renewable energy sources such as solar
light (22, 23). Recent studies have demonstrated
electrochemistry’s distinctive capability to engen-
der bond-forming reactions that challenge or-
thodox methods (24–36). Here we present an
electrochemical protocol for the diazidation of
alkenesasa general, efficient, andatom-economical
approach to vicinal diamine synthesis (Fig. 1C).
Anodic generation of azidyl radical (N3·) from
sodium azide (NaN3), followed by successive
additions of N3· to the alkene C=C bond and
the incipient carbon radical adduct (I), forms
two new C–N bonds, furnishing a vicinal diazide.
Hydrogen gas (H2) generated from cathodic
proton reduction—as evidenced by gas chro-
Department of Chemistry and Chemical Biology, Cornell
University, Ithaca, NY 14853, USA.
*Corresponding author. Email: songlin@cornell.edu
Fu et al., Science 357, 575–579 (2017)
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RESEARCH
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carbon (RVC) as the anode, all in 0.10 M lithium
perchlorate (LiClO4)/acetonitrile (MeCN; Me,
methyl) solution under a nitrogen (N2) atmo-
sphere with an applied cell potential (Ecell) of
2.3 V (corresponding to an initial anodic poten-
tial, Eanode, of ~0.62 V versus the ferrocenium
ion/ferrocene redox couple). 1,2-Diazide 1b was
isolated in 92% yield in 2.5 hours with an initial
current of 10 to 12 mA (33 to 40 mA per cubic
centimeter of RVC). Simply passing the reaction
mixture through a short silica plug removed polar
impurities and furnished spectroscopically pure
product.
Previous work: examples of alkene diamination and diamidation (refs. 4, 6, 9)
tBuN
NtBu
tBu
N
Os
NtBu
NHtBu
R1
R1
R2
O
O
1) LiAlH4
2) NaOH
(1 equiv)
R1
Os
R2
R2
tBuN
N
NHtBu
tBu
O O
S
BocHN
NH2
O O
S
PhI(OAc)2 (1.1 equiv)
pyridine
NHBoc
NH2
Boc
N
NH
R
[Rh] (cat.), then NaI
R
R
O
O
We also tested the diazidation protocol under
conditions of constant current or constant elec-
trode potential. At a controlled current of 8 mA,
we observed 90% yield of 1b within 1.5 hours,
with Ecell increasing from 2.1 to 2.4 V. At a con-
trolled Eanode of 0.72 V, the reaction reached com-
pletion within 1.2 hours with an initial current of
~18 mA, furnishing 1b in 86% yield. Thus, Mn-
catalyzed diazidation proceeded readily at a
voltage close to the oxidation potential of azide
S
N N
O
S
N
tBu
tBu
tBu
Ar
1) conc. HCl
BaCO3
NH2
O
(1.5 equiv)
N
NH2
Ar
tBu
Ar
2) NaOH
CuCl-PBu3 (cat.)
Previous work: examples of alkene diazidation (refs. 11, 13)
NaN3
[Fe] (0.8 equiv)
N3
NH2
reduction
–
N3
[E(N3·/N3 ) = 0.71 V] and well below the oxidation
NH2
R
R
R
R
(NH4)2S2O8 (2 equiv)
OH
potential of styrene [E(styrene radical cation/styrene) =
1.55 V]. The Faradaic efficiencies of reaction for
these two operations were 87 and 66%, respectively.
This finding indicates that most of the electricity
passing through the cell was consumed produc-
tively, with the remainder likely engaged in ni-
trogen evolution via azidyl dimerization (45). These
key results demonstrate that addition of the Mn
catalyst played a pivotal role in inhibiting com-
peting side reactions, thus enhancing chemo-
selectivity and energy efficiency. As expected, no
reaction occurred in the absence of externally
applied potential. The reaction system could be
further streamlined by replacement of the Pt
cathode and DC power supply with graphite and
AA batteries, respectively (table S1). Tetraphenyl-
porphinatomanganate(III) chloride also catalyzed
alkene diazidation, albeit in lower yield (64%). A
number of other transition metal catalysts were
surveyed, but none performed as efficiently as
Mn (table S1). The identity of the electrolyte did
not appreciably affect the diazidation reactivity;
using tetrabutylammonium hexafluorophosphate
(TBAPF6) in lieu of LiClO4 resulted in nearly
quantitative yield (97%). Our attempts to mini-
mize NaN3 loading initially proved unsuccessful,
primarily as a result of the low solubility and
I
O
(1.2 equiv)
O
NH2
N3
PPh3, H2O
NH2
N3
R
R
TMSN3, [Fe] (cat.)
This work: metal-catalyzed electrochemical alkene diazidation
N3
NH2
catalyst
reduction
-
2H+
(oxidant)
2N3
+
+
N3
R
NH2
R
R
electricity
+ H2
Mechanistic design principle:
catalyst-controlled radical group transfer
N3
electrochemical radical generation
- e-
M N3
N3
NaN3
N3
R
N3
R
by-products (from dimerization,
over-oxidation, polymerization,
etc.)
I
R
Fig. 1. Pathways to 1,2-diamine synthesis. (A and B) Representative examples of existing 1,2-diamine
syntheses compared with (C) the proposed electrocatalytic approach. R represents an alkyl, aryl, or similar
substituent; Ar, aryl; tBu, tert-butyl; Boc, tert-butyloxycarbonyl; Ph, phenyl; equiv, equivalent; cat., catalyst;
conc., concentrated; e–, electron.
–
sluggish dissolution of N3 in the reaction me-
dium with an excess of alkali metal ions (Na+ and
Li+). Changing the electrolyte to TBAPF6, how-
ever, allowed the diazidation to proceed effi-
ciently with as few as 3 equivalents of NaN3 (1.5
equivalents per C–N bond). No diazide 1b was
produced when RVC recovered from a previous
experiment was used as the anode without catalyst
addition, suggesting that the diazidation reactivity
originated from the dissolved Mn rather than any
nanostructured metal oxide deposited on the anode
during electrolysis (table S1). In the absence of any
catalyst, <10% 1b was observed on full conversion
of the styrene. This result again highlights the
critical role of the catalyst in modulating radical
reactivity.
Me
Me
with TEMPO
N
O
Method A
NaN3
Me Me
(100% conv.)
Ar
1c (70%)
TEMPO (0 or 1.5 equiv)
N3
Ar
LiClO4, MeCN/H2O
C(+)/Pt(-), Ecell = 2.6 V
22 1 °C, 2 h
observed by-products:
1a (Ar =
4-t-butylphenyl)
N3
without TEMPO
(100% conv.)
Ar
Ar
OH
N3
N3
N3
N3
Ar
Ar
1b (<5%)
1d
1e
Fig. 2. Proof-of-concept experiments. Generation and sequestration of the carbon radical intermediate
en route to alkene diazidation are illustrated. h, hour; conv., conversion.
Fu et al., Science 357, 575–579 (2017)
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Fig. 3. Substrate scope for the electrocatalytic alkene diazidation.
All yields are of isolated products. (A) Alkene substitution patterns and
electronic properties. (B) Functional group compatibility. (C) Reduction of
diazide to diamine. *Unless otherwise noted, reaction conditions were
as follows: 0.2 mmol alkene, 0.01 mmol MnBr2·4H2O, 1.0 mmol NaN3,
400 ml of HOAc, 3.5 ml of LiClO4 solution in MeCN (0.1 M, 1.75 equiv
LiClO4), RVC as the anode, Pt as the cathode, under N2, at 22 1°C, in a
one-compartment cell, at 2.3 V cell potential, for 2 to 6 hours. †Yield
of reaction is reported on a 3-mmol scale. ‡With 0.6 mmol NaN3.
§With TBAPF6 instead of LiClO4. ||With 10 mol% MnBr2·4H2O.
¶With 300 ml of HOAc. #Reaction at 40°C. **See the supplementary
materials for detailed reaction conditions. ††Yield of product is reported
with respect to alkene a. dr, diastereomeric ratio; OBn, benzyloxy; Ts,
p-toluenesulfonyl; Et, ethyl.
Fu et al., Science 357, 575–579 (2017)
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Fig. 4. Mechanistic investigation of the electrocatalytic alkene diazidation. (A) Radical clock experiments. (B) Proposed catalytic cycle. V, power supply.
We then explored the substrate scope of our
optimized electrocatalytic diazidation protocol
(Fig. 3A). Aryl-substituted acyclic alkenes underwent
smooth conversion to the corresponding 1,2-
diazides in high yields (1b to 8b). The efficacy of
our protocol showed little dependence on the elec-
tronic properties of the aryl substituent. The scope
of this methodology was then extended to classes
of activated and unactivated substrates beyond
styrenes. The reaction exhibited extraordinary in-
sensitivity to substitution pattern. Terminal (9b
to 12b), 1,1- and 1,2-disubstituted (13b to 18b),
trisubstituted (19b), and tetrasubstituted (20b
and 21b) alkenes underwent radical diazidation
smoothly to produce the corresponding 1,2-diazides
in high yields. Because of steric hindrance, tetra-
substituted alkenes remain notoriously challeng-
ing to functionalize, and no methods are available
for the direct diazidation or diamidation of this
class of substrates. In comparison, our electro-
chemical protocol provides convenient access to
1,1,2,2-tetrasubstituted vicinal diamines in excel-
lent yields (20b and 21b). In particular, product
21b constitutes a masked a,b-diamino acid with
two contiguous, fully substituted carbons. We hy-
pothesize that the unusual substrate generality of
this protocol arose from the high reactivity of the
electrochemically generated group transfer agent,
MnIII–N3, in addition to its small steric profile.
Cyclopropyl-substituted alkene 13a did not yield
an appreciable amount of the ring-opened product;
this selectivity arises from the substantial differ-
ence in stability between the benzylic and primary
alkyl radicals en route to 13b and the acyclic
product, respectively. Diazidation was nonstereo-
specific: trans-b-Methylstyrene and trans-stilbene
afforded diastereomers 16b (3:1 mixture) and
17b (2:1 mixture), respectively. This stereo-
chemical infidelity was consistent with the inter-
mediacy of radical adduct I. Cyclic alkenes
with all substitution patterns also proved to
be suitable substrates, producing predominant-
ly the trans-1,2-diazides in robust yields and
with good to excellent diastereoselectivity (22b
to 27b). Electron-rich heterocycles—including
benzofuran and N-tosyl indole—dearomatized
to form diazides with high diastereomeric ratios
(28b and 29b). The stereoselectivity was imparted
through a catalyst-controlled process, because in
the absence of Mn, reaction with 22a yielded
traces of 22b in a substantially lower diastereo-
meric ratio (2:1).
chloride, and alkyl bromide (43b to 46b), were
also tolerated, likely as a result of the moderately
acidic reaction medium, which attenuates the
nucleophilicity of the azide anion. A representative
set of 11 alkene substrates was also examined
under constant-current conditions and exhibited
high Faradaic efficiencies (62 to 99%; fig. S1). Many
synthetic methods have been established for the
reduction of aliphatic azides to their correspond-
ing amines with high functional group tolerance
(table S1). Accordingly, we demonstrated that a
number of 1,2-diazides, including those bearing
reductively labile groups (31b, 33b, 39b, 40b,
and 46b), could be chemoselectively converted
to 1,2-diamines (Fig. 3C). The diazidation and
reduction procedures could be carried out con-
secutively without elaborate isolation of the inter-
mediate, thereby constituting a general, safe, and
operationally simple method for vicinal diamine
synthesis.
The unusually broad substrate scope of the
alkene diazidation piqued our interest in elucidat-
ing its mechanism, particularly the roles of the
anode and Mn catalyst in regulating the gener-
ation and reactivity of radical intermediates.
Radical clock experiments confirmed the in-
termediacy of radical adduct I (Fig. 4A): (i)
trans-Stilbene and cis-stilbene were converted
to a pair of diastereomeric 1,2-diazides with
identical diastereomeric ratios, (ii) diene 47a
reacted through both diazidation and cyclization
to form pyrrolidine 47b, and (iii) cyclopropyl-
substituted alkenes 48a and 49a underwent
ring opening after the first azidyl addition, fur-
nishing 48b and 49b, respectively, as the major
products. The highly electron-deficient, dicarbonyl-
substituted radical intermediate originating from
substrate 49a was trapped by MnIII–N3, the
The ability to dial in oxidizing potential at the
minimum level required for the desired redox
transformation makes electrochemistry an ideal
means of functionalizing complex synthetic inter-
mediates (21). For instance, the electrochemical
diazidation was conducted at the oxidation po-
tential of the catalyst-azide adduct (~0.62 V; fig.
S3), which is below that of many oxidation-sensitive
functionalities. As such, substrates containing al-
cohol, aldehyde, enolizable ketone, carboxylic acid,
amine, sulfide, and alkyne groups all proved com-
patible with the reaction system (30b to 41b;
Fig. 3B), showing little evidence of undesired side
reactions involving the additional vulnerable func-
tionalities. Ferrocene, a thermodynamically more
reducing group (E = 0) than MnII–N3, was also
tolerated (42b), indicating that the observed high
chemoselectivity may also be attributed to catalyst-
induced kinetic control. In comparison, no pre-
viously reported vicinal diamine syntheses using
conventional oxidants have proven compatible
with a majority of the aforementioned functional
groups. Substituents susceptible to nucleophilic
–
displacement by N3 , such as epoxide, ester, alkyl
Fu et al., Science 357, 575–579 (2017)
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RESEARCH
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putative active catalyst, to form the diazide in
synthetically useful yield, with no evidence of
side reactions involving the electrophilic carbon
radical (e.g, electroreduction, addition to alkene
49a, or hydrogen-atom abstraction from a labile
C–H bond in the reaction system).
ality and high functional group compatibility of
our system.
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We anticipate that this synthetic protocol
will enhance chemists’ access to a diverse array
of 1,2-diamines. From a broader perspective,
we envision that this catalytic electrochemical
strategy and the radical transformations that
it enables will prove widely applicable in both
modern synthetic chemistry and pharmaceutical
research.
We propose two plausible mechanisms for the
diazidation. In the first scenario (Fig. 1C), direct
oxidation of N3– to N3·, followed by its addition
to the alkene and subsequent azidyl transfer from
MnIII–N3, leads to the final product. Alternatively,
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the olefin (Fig. 4B) completes diazidation. In either
case, we propose that the key group transfer agent,
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–
catalytic cycle shown in Fig. 4B. In MeCN, N3
exhibited an irreversible oxidative wave at ~0.5 V,
which shifted positively to 0.84 V on the addition
of HOAc, owing to protonation. MnII alone dis-
played no redox features between 0 and 1.5 V, but
–
on the addition of N3 and HOAc, a series of ir-
reversible anodic events appeared with an onset
potential of ~0.5 V. We assigned these waves to
the oxidation of azide-bound MnII, because this
anionic ligand is known to stabilize the MnIII oxi-
dation state (46). Preliminary ultraviolet-visible
spectroscopy data (figs. S4 to S5) also suggested
that MnII–N3 formed when N3– and MnII were
mixed and was subsequently oxidized to MnIII–N3
at a cell potential of 2.3 V, with a characteristic
ligand-to-metal charge-transfer transition at
422 nm (46). Taken together, the data favor
predominance of Mn-assisted dual radical group
transfer over direct addition of anodically
generated N3· to the alkene. The unusual com-
bination of exceptional reactivity and excellent
chemoselectivity observed in this catalytic sys-
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transfer agent, MnIII–N3. In a manner reminis-
cent of metal-oxo radical chemistry (47), the
redox-active metal catalyst enabled the gen-
eration of an azidyl equivalent in a controlled
fashion as a Mn-bound complex, preserving
the radical character needed to induce C=C
p-bond homolysis while diminishing the high
propensity of N3· to undergo dimerization,
C–H or electron abstraction, and other side re-
actions. This feature, together with the granular
control of oxidizing potential granted by elec-
trochemistry, led to the broad substrate gener-
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ACKNOWLEDGMENTS
The authors declare no competing financial interests. Complete
experimental and characterization data are provided in the
supplementary materials. Financial support was provided by
Cornell University. This study made use of the Cornell Center for
Materials Research Shared Facilities, supported by the NSF
MRSEC (Materials Research Science and Engineering Centers)
program (grant DMR-1120296), and a nuclear magnetic
resonance facility supported by the NSF (grant CHE-1531632).
G.S.S. is grateful for an NSF Graduate Fellowship (DGE-
1650441). We thank K. L. Carpenter and W. Hao for providing
substrates 19a and 43a, respectively; K. M. Lancaster for access
to an ultraviolet-visible spectrometer; and D. B. Collum and
B. Ganem for assistance with manuscript preparation. S.L., N.F.,
and G.S.S. are inventors on U.S. patent application 62/513,646
submitted by Cornell University that covers the electrochemical
alkene diazidation.
SUPPLEMENTARY MATERIALS
www.sciencemag.org/content/357/6351/575/suppl/DC1
Materials and Methods
Figs. S1 to S6
Tables S1 and S2
Spectral Data
References (48–63)
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13 May 2017; accepted 11 July 2017
10.1126/science.aan6206
Fu et al., Science 357, 575–579 (2017)
11 August 2017
5 of 5

Metal-catalyzed electrochemical diazidation of alkenes
Niankai Fu, Gregory S. Sauer, Ambarneil Saha, Aaron Loo and Song Lin
Science 357 (6351), 575-579.
DOI: 10.1126/science.aan6206
A charged approach to forming C−N bonds
Adjacent carbon-nitrogen bonds often appear in chemical compounds of pharmaceutical interest. Fu et al.
developed a versatile method to form these bonds by pairing manganese catalysis with electrochemical azide oxidation
in the presence of olefins. A major advantage of the electrochemical approach is the tunable precision of its oxidizing
power, which leaves other sensitive substituents such as alcohols and aldehydes intact. The reaction proceeded over
several hours at room temperature, forming hydrogen at the counter electrode as a benign by-product.
Science, this issue p. 575
ARTICLE TOOLS
http://science.sciencemag.org/content/357/6351/575
SUPPLEMENTARY
MATERIALS
http://science.sciencemag.org/content/suppl/2017/08/09/357.6351.575.DC1
REFERENCES
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