Photoredox Catalytic Phosphite-Mediated Deoxygenation of α-Diketones Enables Wolff Rearrangement and Staudinger Synthesis of β-Lactams

Article abstract of DOI:10.1002/anie.202107080

A novel visible-light-driven catalytic activation of C=O bonds by exploiting the photoredox chemistry of 1,3,2-dioxaphospholes, readily accessible from α-diketones and trialkyl phosphites, is reported. This mild and environmentally friendly strategy provides an unprecedented and efficient access to the Wolff rearrangement reaction which traditionally entails α-diazoketones as precursors. The resulting ketenes could be precisely trapped by alcohols/thiols to give α-aryl (thio)acetates and by imines to afford the valuable β-lactams in up to 99 % yields.

Full text of DOI:10.1002/anie.202107080

Angewandte
Communications
Chemie
How to cite:
International Edition: doi.org/10.1002/anie.202107080
German Edition: doi.org/10.1002/ange.202107080
Photoredox Catalysis
Photoredox Catalytic Phosphite-Mediated Deoxygenation of a-
Diketones Enables Wolff Rearrangement and Staudinger Synthesis of
b-Lactams
Hui Yang+, Haijun Li+, Guo Wei,* and Zhiyong Jiang*
À
Abstract: A novel visible-light-driven catalytic activation of
a novel activation platform for C O bonds of carboxylic acids,
yielding a green procedure for the synthesis of ketones
directly from the abundant acids and alkenes (Scheme 1a).[7c]
Doyle and co-workers disclosed their work for the photo-
catalytic hydrodeoxygenation of not only carboxylic acids but
also alcohols adopting essentially the same strategy.[7d] How-
ever, to the best of our knowledge, the direct deoxygenation
=
C O bonds by exploiting the photoredox chemistry of 1,3,2-
dioxaphospholes, readily accessible from a-diketones and
trialkyl phosphites, is reported. This mild and environmentally
friendly strategy provides an unprecedented and efficient
access to the Wolff rearrangement reaction which traditionally
entails a-diazoketones as precursors. The resulting ketenes
could be precisely trapped by alcohols/thiols to give a-aryl
(thio)acetates and by imines to afford the valuable b-lactams in
up to 99% yields.
=
of C O bonds has never been achieved with photoredox
catalysis.
C
hemoselective deoxgenation of carbon–oxygen bonds
represents one of the fundamental transformations in organic
chemistry.[1] In particular, the reductive deoxygenation of
ketones has attracted increasing attention of researchers
owing to its wide application in the synthesis of bioactive
natural products[2] and in processes for the transformation of
petroleum and biomass feedstocks.[1,3] However, the direct
=
activation of C O bonds is particularly difficult due to their
strong bond strength and high redox potentials. Modern
hydrodeoxygenation transformations both in the laboratory
and on industrial scales are still highly dependent on the
classical Clemmensen (Zn/Hg, HCl)[4] and Wolff–Kishner
methods,[5] demanding fierce conditions which lead to func-
tional group compatibility problems.
À
Scheme 1. Photocatalytic C O bond activation.
Our group has a lasting interest in developing innovative
photocatalytic methodologies, among which we paid special
attention to the transformations of ketones.[8] By drawing
Visible-light-driven photoredox catalysis is a powerful
tool revitalized in recent years for the activation of covalent
bonds, featuring intrinsic mildness and unparalleled reactivity
that is usually difficult or impossible to access by other
À
inspiration from the phosphine-mediated C O bond activa-
tion strategy, we imagined that photoredox-catalyzed frag-
mentation of 1,3,2-dioxaphospholes, the penta-coordinated
oxyphosphoranes readily accessible from the reaction of a-
diketones with phosphites,[9] would be a possible way of direct
reductive deoxygenation of ketones (Scheme 1b). We present
herein our work along this line, which yielded a photoredox
catalytic manifold for the direct synthesis of ketenes from
activated ketones via formal Wolff rearrangement.[10] The
strategy was further adapted for the direct preparation of b-
lactams[11] (Staudinger reaction),[12] important core structures
of antibiotic drugs and natural bioactive molecules.[13]
We began our investigation with benzil and triethyl
phosphite as the model substrate and the deoxygenation
reagent, respectively. With the irradiation of a 3 W blue LED
(450 nm) and the catalysis of a dicyanopyrazine derived
chromophore (DPZ) photosensitizer,[8,14] benzil underwent
swift deoxygenation and Wolff rearrangement, affording
means.[6] Direct photoredox cleavage of C O single bonds has
À
already been realized by exploring the b-fission chemistry of
phosphoranyl radicals.[7] In 2018, the Zhu group reported
[*] H. Li,[+] Dr. G. Wei, Prof. Dr. Z. Jiang
Key Laboratory of Natural Medicine and Immune Engineering of
Henan Province, Henan University
Jinming Campus, Kaifeng, Henan, 475004 (P. R. China)
E-mail: weiguo0325@henu.edu.cn
chmjzy@henu.edu.cn
Prof. Dr. Z. Jiang
School of Chemistry and Chemical Engineering, Henan Normal
University
Xinxiang, Henan, 453007 (P. R. China)
Dr. H. Yang[+]
School of Pharmacy, Henan University
Jinming Campus, Kaifeng, Henan, 475004 (P. R. China)
[+] These authors contributed equally to this work.
a
ketene intermediate which was trapped by ethanol
(Table 1). Under optimized conditions, a,a-diphenylacetate
2a was obtained in excellent yield (90%, entry 6). When polar
solvents such as THF or DMF were used, the yields dropped
Supporting information and the ORCID identification number(s) for
the author(s) of this article can be found under:
https://doi.org/10.1002/anie.202107080.
Angew. Chem. Int. Ed. 2021, 60, 1 – 6
ꢀ 2021 Wiley-VCH GmbH
1
These are not the final page numbers!

Angewandte
Communications
Chemie
Table 1: Optimization of the reaction conditions.[a]
(95%) possibly due to the added nucleophilicity of ethane-
thiol. Both electron-donating (2 f–2h, 2l, 2m, 2w, 2x) and
electron-withdrawing (2i–2k, 2n–2s, 2u, 2v) substituents on
the phenyl rings could be well tolerated regardless of whether
the ketone substrates are symmetrical or not. Electron-
donating groups promoted Wolff rearrangement efficiently,
while substrates with electron-withdrawing groups on the
phenyl ring usually gave slightly lower yields, reflecting their
different substituent effect on the migratory aptitude of the
phenyl ring. When two phenyl groups of benzil were replaced
by 2-naphthyl, reaction also worked effectively, furnishing
product 2t [U1] in 50% yield. Less successful or failed
substrates for this transformation afforded a substantial
amount of a-alkoxy ketones and a-benzyl ketones, originat-
Entry
Photocatalyst [x mol%]
Solvent
Yield [%][b]
1
2
DPZ [0.1 mol%]
DPZ [0.1 mol%]
toluene
THF
22
15
N.D.
70
53
3
4
5
DPZ [0.1 mol%]
DPZ [0.1 mol%]
DPZ [0.1 mol%]
DPZ [0.1 mol%]
DPZ [0.1 mol%]
–
DMF
MeCN
DCE
DCE
DCE
6[c]
7[d]
8
90
N.D.
N.D.
34
38
12
DCE
9
[Ru(bpy)3][PF6]2 [1.0 mol%]
[Ir(dtbbpy)(ppy)2][PF6] [1.0 mol%]
Methylene Blue [1.0 mol%]
Eosin Y [1.0 mol%]
DCE
DCE
DCE
DCE
À
ing from the O H bond insertion and H abstraction of the
10
11
12
carbene intermediates, respectively, as has already been well
documented.[10]
5
The Staudinger synthesis of b-lactams[11] from ketenes by
[2+2] cycloaddition with imines represents one of the most
practical strategies to date. To our delight, under slightly
modified conditions, our phosphite-mediated generation of
ketenes could be efficiently merged with the Staudinger
reaction (Table 3). When N-phenyl imine 3, instead of
alcohol, was added to the stirred solution of benzil and
triethyl phosphite, the cycloaddition product b-lactam 4a was
[a] Reaction conditions: benzil 1a (0.1 mmol), P(OEt)3 (0.2 mmol),
EtOH (0.2 mmol), DPZ (0.1 mol%), solvent (1.0 mL), under argon
protection, 3 W blue LED, 24 h, rt. [b] Determined by crude NMR with
mesitylene as the internal standard. [c] Reaction time was extended to
48 h. [d] In the dark. DCE=dichloroethane. DMF=N,N-dimethylfor-
mamide. N.D.=not detected.
dramatically (entries 2 and 3). Other transition-metal or
organic photosensitizers turned out to be less effective, even
with a tenfold increase of the catalyst loading (entries 9–12).
It is noteworthy that when the reaction was performed in the
absence of photocatalyst or in the dark, 2a could not be
observed, thus underlining a photocatalyzed transformation.
With the optimal reaction conditions in hand, we explored
the substrate scope for this Wolff rearrangement-enabled
synthesis of 2-aryl acetates. As can be seen from Table 2, this
method could be readily applied to the preparation of
different alkyl esters by using the corresponding alcohols
(2a–2d). Thioester 2e could be obtained in even better yield
Table 3: Visible-light-promoted Staudinger synthesis of b-lactams from
a-diketones.[a]
Table 2: Substrate scope for the synthesis of 2-aryl (thio)acetates.[a]
[a] Reaction conditions: a-diketone 1 (0.2 mmol), imine 3 (0.1 mmol),
P(OEt)3 (0.24 mmol), DPZ (0.1 mol%), DCE (1.0 mL), degassed with
argon by three freeze–pump–thaw cycles, 3 W blue LED, 48 h, rt.
[b] 0.3 mmol of 1 and 0.36 mmol of P(OEt)3 used.
[a] Reaction conditions: a-diketone 1 (0.1 mmol), ROH (0.2 mmol),
P(OEt)3 (0.2 mmol), DPZ (0.1 mol%), DCE (1.0 mL), degassed with
argon by three freeze–pump–thaw cycles, 3 W blue LED, 48 h, rt.
2
www.angewandte.org
ꢀ 2021 Wiley-VCH GmbH
Angew. Chem. Int. Ed. 2021, 60, 1 – 6
These are not the final page numbers!

Angewandte
Communications
Chemie
obtained in 98% yield. The substituents on the N-aryl ring can
be varied, with product yields mostly ranging from good to
excellent (4a–4g). N-Benzyl protection (4q) is another good
option, giving b-lactam in very good yield too. The substitu-
tions on the aryl rings of a-diketone 1, electron-donating or
-withdrawing, can also be largely tolerated, affording cyclo-
addition products smoothly (4h–4n). It is worth mentioning
that two monocyclic b-lactam molecules with potent anti-
[15]
bacterial and antifungal activities
(4o, 4p) were synthe-
sized in good yields by our concise strategy, comparing
favorably with the originally reported method.[15] The Ar1
group of the aldimine 3 could be tuned with different
substitutions on the phenyl ring (4r–4u) or other aromatic
systems (4y) to give the desired cycloadducts in up to 99%
yields. Cyclic imines incorporated in fused ring systems (4v,
4w) are also viable substrates for our strategy. In addition to
aldimines, ketimines derived from aromatic ketones are also
compatible substrates for the [2+2] cycloaddition, as exem-
plified by 4x, thus greatly extending the imine scope of our
method.
Mechanistic studies were carried out to gain insights into
the reaction mechanism (Scheme 2). Firstly, control experi-
ments showed that 1,3,2-dioxaphosphole INT1 prepared in
advance could be converted to diphenylacetate 2a directly
under the same conditions (Scheme 2a), suggesting that INT1
might be the key intermediate to undergo the photoredox
cycle. Then, when ethanol was applied as the solvent for the
model Wolff rearrangement reaction, in addition to 2a, two
new products, that is, 5 and 6, which could be generated
Figure 1. Free energy profiles of the photoredox Wolff rearrangement
from benzil and triethyl phosphite. [a] Free energy with one mole of
triethyl phosphate included.
To help further elucidate the detailed process of ketene
generation, DFT computation at the M06-2X/def2-TZVPP/
SMD(DCE)// B3LYP-D4/def2-TZVP level of theory[16] was
conducted (Figure 1). As can be seen from the free energy
À
profile of this transformation, the fission of the P O bond in
radical cation INT2 is very fast, with an energy barrier of only
6.2 kcalmolÀ1. Reduction of the radical cation INT3 is highly
exothermic (À63.4 kcalmolÀ1), affording diradical INT4,
which could undergo straightforward decomposition (energy
barrier: 2.0 kcalmolÀ1) to release the crucial a-keto carbene
intermediate. Triplet carbene INT5B, only 4.2 kcalmolÀ1
more stable, is in fast equilibrium with the singlet state
structure INT5A. However, Wolff rearrangement from
INT5B to ketene INT6 has a remarkably higher energy
barrier than that from INT5A (18.8 vs. 9.1 kcalmolÀ1),
indicating that the rearrangement proceeds mainly from the
singlet carbene intermediate at room temperature. This is
consistent with the fact that halogenated solvents (such as
DCE), which can selectively stablize singlet carbenes via
halogen–carbene complexation,[17] greatly promote the Wolff
rearrangement (Table 1, entry 6). The overall transformation
from benzil and triethyl phosphite to ketene INT6 is energeti-
cally favorable by À12.3 kcalmolÀ1.
À
through trapping a-keto carbene by HAT and H O bond
insertion reactions,[10] were obtained in 20% and 14% yield,
respectively (Scheme 2b), serving as solid evidence for a step-
wise Wolff rearrangement process. A cyclic voltammetry
study showed that 1,3,2-dioxaphosphole INT1 had a half-
wave oxidation potential of + 0.696 V (vs. SCE in CH3CN,
Scheme 2c, see Supporting Information for details), well
below the reduction potential of excited state DPZ (Et(S*/
SCÀ) =+ 1.42 V vs. SCE in CH3CN).[14] Fluorescence quench-
ing experiments (Scheme 2d) finally concluded that INT1 was
an active reductive quencher of the excited DPZ (*DPZ).
Based on mechanistic study results and our DFT compu-
tation study above, a photoredox catalytic Wolff rearrange-
ment from a-diketones and phosphites is proposed herein
(Figure 2). 1,3,2-Dioxaphosphole INT1, formed in situ at the
initial stage, undergoes photoredox decomposition with the
catalysis of the excited sensitizer DPZ*, to give a-keto
carbene INT5B, which is in fast equilibrium with the singlet
state INT5A. The Wolff rearrangement from the singlet state
is the dominant process at room temperature, affording
ketene INT6 exothermically. Trapping the ketenes with
alcohols yields diphenyl acetates 2, while [2+2] cycloaddition
with imines gives valuable b-lactams 4. The intermediate
À
carbene could also be trapped by alcohol via HAT or O H
bond insertion reaction to yield single-carbonyl reduced
product 5 and a-alkoxy ketone 6.
To demonstrate the application potential of this method,
the Staudinger synthesis of b-lactams 4q was scaled up to
1.0 mmol without noticeable decrease in yield, proving its
Scheme 2. Mechanistic studies.
Angew. Chem. Int. Ed. 2021, 60, 1 – 6
ꢀ 2021 Wiley-VCH GmbH
www.angewandte.org
3
These are not the final page numbers!

Angewandte
Communications
Chemie
Acknowledgements
Grants from the NSFC (21925103) and Henan Normal
University are gratefully acknowledged.
Conflict of Interest
The authors declare no conflict of interest.
Keywords: photoredox catalysis · Staudinger reaction ·
Wolff rearrangement · a-diketones · b-lactams
[1] a) C. H. Zhou, J. N. Beltramini, Y. X. Fan, G. Q. Lu, Chem. Soc.
Rev. 2008, 37, 527; b) J. J. Bozell, G. R. Petersen, Green Chem.
2010, 12, 539; c) P. N. R. Vennestrøm, C. M. Osmundsen, C. H.
Christensen, E. Taarning, Angew. Chem. Int. Ed. 2011, 50, 10502;
Angew. Chem. 2011, 123, 10686; d) A. M. Ruppert, K. Weinberg,
R. Palkovits, Angew. Chem. Int. Ed. 2012, 51, 2564; Angew.
Chem. 2012, 124, 2614; e) D. M. Alonso, S. G. Wettstein, J. A.
Dumesic, Chem. Soc. Rev. 2012, 41, 8075; f) R. A. Sheldon,
Green Chem. 2014, 16, 950.
Figure 2. Proposed mechanism.
[2] a) F. E. Chen, Z. R. Guo, Method of Organic Pharmaceutical
Synthesis, Chinese Medicine Science and Technology Press,
Beijing, 1998, p. 56; b) M. V. Kumudhavalli, C. Margret, D.
Sripriya, B. Jayakar, Int. J. Pharm. Biol. Sci. 2010, 1, 1.
[3] a) E. Furimsky, Appl. Catal. A 2000, 199, 147.
[4] a) E. Clemmensen, Ber. Dtsch. Chem. Ges. 1914, 47, 681; b) E.
Vedejs, Org. React. 1975, 22, 401.
Scheme 3. Scale up and further transformation.
[5] L. Wolff, Justus Liebigs Ann. Chem. 1912, 394, 86.
[6] For selected reviews, see: a) M. C. Andrew, K. Prier, D. W. C.
MacMillan, Science 2011, 334, 1114; b) C. K. Prier, D. A. Rankic,
D. W. C. MacMillan, Chem. Rev. 2013, 113, 5322; c) D. M.
Schultz, T. P. Yoon, Science 2014, 343, 1239176; d) J. W. Beatty,
C. R. J. Stephenson, Acc. Chem. Res. 2015, 48, 1474; e) M. H.
Shaw, J. Twilton, D. W. C. MacMillan, J. Org. Chem. 2016, 81,
6898; f) N. A. Romero, D. A. Nicewicz, Chem. Rev. 2016, 116,
10075; g) J. Twilton, C. C. Le, P. Zhang, M. H. Shaw, R. W.
Evans, D. W. C. MacMillan, Nat. Rev. Chem. 2017, 1, 0052.
[7] a) R. Ruzi, J. Ma, X.-A. Yuan, W. Wang, S. Wang, M. Zhang, J.
Dai, J. Xie, C. Zhu, Chem. Eur. J. 2019, 25, 12724; b) M. Zhang,
X.-A. Yuan, C. Zhu, J. Xie, Angew. Chem. Int. Ed. 2019, 58, 312;
Angew. Chem. 2019, 131, 318; c) M. Zhang, J. Xie, C. Zhu, Nat.
Commun. 2018, 9, 3517; d) E. E. Stache, A. B. Ertel, T. Rovis,
A. G. Doyle, ACS Catal. 2018, 8, 11134; e) P.-J. Xia, Z.-P. Ye, Y.-
Z. Hu, D. Song, H.-Y. Xiang, X.-Q. Chen, H. Yang, Org. Lett.
2019, 21, 2658.
[8] a) K. Cao, S. M. Tan, R. Lee, S. Yang, H. Jia, X. Zhao, B. Qiao, Z.
Jiang, J. Am. Chem. Soc. 2019, 141, 5437; b) B. Qiao, C. Li, X.
Zhao, Y. Yin, Z. Jiang, Chem. Commun. 2019, 55, 7534; c) Y. Liu,
X. Liu, J. Li, X. Zhao, B. Qiao, Z. Jiang, Chem. Sci. 2018, 9, 8094;
d) L. Lin, X. Bai, X. Ye, X. Zhao, C.-H. Tan, Z. Jiang, Angew.
Chem. Int. Ed. 2017, 56, 13842; Angew. Chem. 2017, 129, 14030.
[9] a) F. Ramirez, Pure Appl. Chem. 1964, 9, 337; b) W. C. Hamilton,
S. J. La Placa, F. Ramirez, C. P. Smith, J. Am. Chem. Soc. 1967,
89, 2268; c) D. B. Denney, H. M. Relles, J. Am. Chem. Soc. 1964,
86, 3897; d) D. B. Denney, L. Saferstein, J. Am. Chem. Soc. 1966,
88, 1839; e) L. L. Chang, D. B. Denney, D. Z. Denney, R. J.
Kazior, J. Am. Chem. Soc. 1977, 99, 2293; f) F. Ramirez, J. F.
Marecek, Tetrahedron 1984, 40, 2837.
value in a practical synthetic context (Scheme 3). The lactam
was reduced efficiently by lithium aluminium hydride in
refluxing ether to give, in good yield, azetidine 7, the core
structure of many natural and non-natural bioactive mole-
cules,[18] thus providing an attractive alternative strategy for
its preparation.
In summary, by exploring the photoredox chemistry of
1,3,2-dioxaphospholes readily accessible from a-diketones
=
and trialkyl phosphites, we developed a direct C O bond
deoxygenation strategy that provides novel access to the
Wolff rearrangement which demands traditionally a-diazo-
ketones as the precursors. The resulting ketenes can be
trapped by nucleophilic alcohols/thiols to give a-aryl (thio)-
acetates, or imines to afford, through [2+2] cycloaddition,
valuable b-lactams which are the core structure of important
antibiotic drugs and natural bioactive molecules. This strat-
egy, notable for its high efficiency, environmental benignancy
and operational simplicity, represents an unprecedented
example of photoredox catalytic Wolff rearrangement from
in situ formed 1,3,2-dioxaphospholes, and the first successful
synthesis of b-lactams via photoredox Staudinger reaction
from a-diketones. Furthermore, the reaction can be safely
scaled up and the b-lactam core is able to be readily
transformed to azetidine, underscoring the application poten-
tial of our strategy in not only the chemical preparation of b-
lactam-containing bioactive molecules, but also other struc-
turally related compounds.
[10] For selected reviews on Wolff rearrangement, see: a) Y.
Coquerel, J. Rodriguez, The Wolff Rearrangement: Tactics,
Strategies and Recent Applications in Organic Synthesis, Wiley,
Hoboken, 2015; b) N. R. Candeias, A. F. Trindade, P. M. P. Gois,
C. A. M. Afonso, Comprehensive Organic Synthesis II, Elsevier,
4
www.angewandte.org
ꢀ 2021 Wiley-VCH GmbH
Angew. Chem. Int. Ed. 2021, 60, 1 – 6
These are not the final page numbers!

Angewandte
Communications
Chemie
Amsterdam, 2014, p. 944; c) W. Kirmse, Eur. J. Org. Chem. 2002,
theory: b) F. Weigend, R. Ahlrichs, Phys. Chem. Chem. Phys.
2193.
2005, 7, 3297; The SMD level of theory: c) A. V. Marenich, C. J.
Cramer, D. G. Truhlar, J. Phys. Chem. B 2009, 113, 6378; the
B3LYP level of theory: d) P. J. Stephens, F. J. Devlin, C. F.
Chabalowski, M. J. Frisch, J. Phys. Chem. 1994, 98, 11623; the
atom-pairwise dispersion correction based on tight binding
partial charges (D4): e) E. Caldeweyher, S. Ehlert, A. Hansen,
H. Neugebauer, S. Spicher, C. Bannwarth, S. Grimme, J. Chem.
Phys. 2019, 150, 154122; f) E. Caldeweyher, C. Bannwarth, S.
Grimme, J. Chem. Phys. 2017, 147, 034112.
[11] For recent reviews on the chemical synthesis of b-lactams, see:
a) C. R. Pitts, T. Lectka, Chem. Rev. 2014, 114, 7930; b) N. Fu,
T. T. Tidwell, Tetrahedron 2008, 64, 10465; c) A. Brandi, S.
Cicchi, F. M. Cordero, Chem. Rev. 2008, 108, 3988.
[12] H. Staudinger, Justus Liebigs Ann. Chem. 1907, 356, 51.
[13] a) L. Decuyper, M. Jukic, I. Sosic, A. Zula, M. D’hooghe, S.
Gobec, Med. Res. Rev. 2018, 38, 426; b) P. Galletti, D. Giacomini,
Curr. Med. Chem. 2011, 18, 4265.
ˇ
ˇ
ˇ
[14] a) Y. Yin, Y. Li, T. P. GonÅalves, Q. Zhan, G. Wang, X. Zhao, B.
Qiao, K.-W. Huang, Z. Jiang, J. Am. Chem. Soc. 2020, 142, 19451;
b) H. Yang, G. Wei, Z. Jiang, ACS Catal. 2019, 9, 9599; c) T.
Shao, Y. Li, N. Ma, C. Li, G. Chai, X. Zhao, B. Qiao, Z. Jiang,
iScience 2019, 16, 410; d) X. Liu, Y. Liu, G. Chai, B. Qiao, X.
Zhao, Z. Jiang, Org. Lett. 2018, 20, 6298; e) J. Li, M. Kong, B.
Qiao, R. Lee, X. Zhao, Z. Jiang, Nat. Commun. 2018, 9, 2445;
f) Y. Yin, Y. Dai, H. Jia, J. Li, L. Bu, B. Qiao, X. Zhao, Z. Jiang, J.
Am. Chem. Soc. 2018, 140, 6083.
[17] J. Wang, J. Kubicki, H. Peng, M. S. Platz, J. Am. Chem. Soc. 2008,
130, 6604.
[18] a) J. P. Milton, J. S. Fossey, Tetrahedron 2021, 77, 131767; b) V.
Mehra, I. Lumb, A. Anand, V. Kumar, RSC Adv. 2017, 7, 45763;
c) D. Ferraris, S. Belyakov, W. Li, E. Oliver, Y.-S. Ko, D. Calvin,
S. Lautar, B. Thomas, C. Rojas, Curr. Top. Med. Chem. 2007, 7,
597.
[15] G. S. Singh, E. Mbukwa, T. Pheko, ARKIVOC 2007, 80.
[16] The M06 level of theory: a) Y. Zhao, D. G. Truhlar, Theor. Chem.
Acc. 2008, 120, 215; The def2-TZVP and def2-TZVPP level of
Manuscript received: May 27, 2021
Accepted manuscript online: June 17, 2021
Version of record online: && &&, &&&&
Angew. Chem. Int. Ed. 2021, 60, 1 – 6
ꢀ 2021 Wiley-VCH GmbH
www.angewandte.org
5
These are not the final page numbers!

Angewandte
Communications
Chemie
Communications
Photoredox Catalysis
H. Yang, H. Li, G. Wei,*
Z. Jiang*
&&&& — &&&&
Photoredox Catalytic Phosphite-Mediated
Deoxygenation of a-Diketones Enables
Wolff Rearrangement and Staudinger
Synthesis of b-Lactams
=
Photocatalytic C O bond activation is
a novel diazo-free access to the Wolff
rearrangement. The strategy was suc-
cessfully applied to the efficient synthesis
of a-aryl (thio)acetates and valuable b-
lactams.
enabled by exploring the unprecedented
photoredox chemistry of 1,3,2-dioxa-
phospholes formed from a-diketones and
trialkyl phosphites, which provides
6
www.angewandte.org
ꢀ 2021 Wiley-VCH GmbH
Angew. Chem. Int. Ed. 2021, 60, 1 – 6
These are not the final page numbers!