Organocatalytic Trapping of Elusive Carbon Dioxide Based Heterocycles by a Kinetically Controlled Cascade Process

Article abstract of DOI:10.1002/anie.202007350

A conceptually novel approach is described for the synthesis of six-membered cyclic carbonates derived from carbon dioxide. The approach utilizes homoallylic precursors that are converted into five-membered cyclic carbonates having a β-positioned alcohol group in one of the ring substituents. The activation of the pendent alcohol group through an N-heterocyclic base allows equilibration towards a thermodynamically disfavored six-membered carbonate analogue that can be trapped by an acylating agent. Various control experiments and computational analysis of this manifold are in line with a process that is primarily dictated by a kinetically controlled acylation step. This cascade process delivers an ample diversity of six-membered cyclic carbonates in excellent yields and chemoselectivities under mild reaction conditions.

Full text of DOI:10.1002/anie.202007350

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Accepted Article
Title: Organocatalytic Trapping of Elusive Carbon Dioxide based
Heterocycles through a Kinetically Controlled Cascade Process
Authors: Chang Qiao, Alba Villar-Yanez, Josefine Sprachmann, Bart
Limburg, Carles Bo, and Arjan Willem Kleij
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To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.202007350
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Organocatalytic Trapping of Elusive Carbon Dioxide based
Heterocycles through a Kinetically Controlled Cascade Process
Chang Qiao,[a] Alba Villar-Yanez,[a] Josefine Sprachmann,[a] Bart Limburg[a] Carles Bo[a][b] and Arjan W.
Kleij*[a][c]
Dedicated to the memory of Prof. Kilian Muñiz
[a]
C. Qiao, A. Villar-Yanez, J. Sprachmann, Dr. B. Limburg, Prof. C. Bo and Prof. A. W. Kleij
Institute of Chemical Research of Catalonia (ICIQ), the Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007 - Tarragona, Spain.
E-mail: akleij@iciq.es
[b]
[c]
Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, Marcel·lí Domingo s/n, 43007 Tarragona, Spain
Prof. A. W. Kleij
Catalan Institute of Research and Advanced Studies (ICREA), Pg. Lluís Companys 23, 08010 Barcelona, Spain
Supporting information for this article is given via a link at the end of the document.
Abstract: A conceptually novel approach is described for the
synthesis of six-membered cyclic carbonates derived from carbon
dioxide. The approach utilizes homoallylic precursors that are
converted into five-membered cyclic carbonates having a -positioned
alcohol group in one of the ring substituents. The activation of the
pendent alcohol group through an N-heterocyclic base allows for
equilibration towards a thermodynamically disfavored six-membered
carbonate analogue that can be conveniently trapped by an acylation
agent. Various control experiments and computational analysis of this
manifold are in line with a process that is primarily dictated by a
kinetically controlled acylation step. This cascade process delivers an
ample diversity of novel six-membered cyclic carbonates in excellent
yields and chemoselectivities under remarkably mild reaction
conditions. This newly developed protocol helps to expand the
repertoire of CO2-based heterocycles that are otherwise difficult to
generate by conventional approaches.
widen their prospective as synthetic intermediates[12] and
polymerizable monomers.[13] With this challenge in mind, we set
out to design a new conceptual route towards the synthesis of six-
membered cyclic carbonates from simple and accessible building
blocks (Scheme 1). Homoallylic alcohols of type A are ubiquitous
precursors and play a significant role in organic synthesis.[14] Their
epoxidation directly affords substrates of type B that should be
easily converted into intermediate 5-membered cyclic carbonate
products 1. Inspired by our previous work on substrate-controlled
synthesis of organic carbonates,[15] we envisioned that the
presence of a suitable organocatalyst (base) should be able to
induce isomerization between carbonates 1 and 1´ with the latter
being thermodynamically less stable. Selective acylation of the
primary alcohol in 1´ offers then a tangible route to isolate the
more elusive cyclic carbonate product 2. Herein, we illustrate this
successful, new and generally high-yielding route towards highly
substituted six-membered carbonates of type 2 creating a
superior diversity of such valuable heterocycles.
The last decade has witnessed a spectacular development of a
plethora of new catalytic processes that focus on the valorization
of carbon dioxide (CO2)[1] affording organic molecules of use as
precursors in fine chemical,[2] pharmaceutical[3] and polymer
chemistry.[4] One of the most widely applied valorization routes is
undoubtedly the non-reductive transformation of CO2. Catalyst
engineering in this area has been mainly focusing on using both
metal-[5] and organo-catalysts[6] for the activation of the requisite
co-reactant (often cyclic ethers such as epoxides) to produce a
nucleophilic intermediate species that activates CO2 followed by
the formation of the desired product. The preparation of
heterocyclic targets such as cyclic carbonates,[7] carbamates[8]
and ureas[9] has greatly advanced as testified by the growing
complexity of these CO2-based products.
Larger-ring, typically difficult to prepare CO2 based
heterocycles remain challenging targets (Scheme 1, top). In the
area of organic carbonate synthesis, methods to generate six-
membered heterocycles are scarce and often rely on
stoichiometric approaches.[10] An exception is presented by the
coupling reaction between oxetanes and CO2, although to date
very few catalysts have been shown to be effective for these
substrates,[11] and oxetanes are much less ubiquitous than
epoxides. Therefore, new concepts are required to empower the
potential of such novel, functionalized heterocyclic scaffolds and
Scheme 1. Top: larger-ring, naturally occurring cyclic organic carbonates.
Bottom: new conceptual approach towards six-membered cyclic carbonates. B
stands for a base.
1
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We first prepared a series of 5-membered cyclic carbonates
of type 1 by employing various homoallylic alcohols (A1‒A17) as
precursors that are conveniently prepared from readily available
ketones and allyl magnesium bromide. Epoxidation of these
homoallylic compounds using m-CPBA at room temperature (rt)
afforded the oxiranes B1‒B17 with a -hydroxy group (see the
Supporting Information, SI, for details). The oxiranes B1‒B17
(Scheme 2) were then used as reagents to furnish the cyclic
carbonates 1a-1q typically in good yields (with some exceptions)
in the presence of CO2 and suitable binary catalysts derived from
conversion of a 5- into a 6-membered cyclic carbonate is rather
unique as the latter type of product is typically difficult to prepare
under such mild conditions.
Table 1. Screening conditions for the conversion of cyclic carbonate 1a into its
6-membered congener 2a under various conditions.[a]
Al-aminotriphenolate complexes AlCl and AlMe [16]
In some cases,
.
significant byproduct formation occurred, and these products
were identified as substituted tetrahydrofuran derivatives (see the
SI for analysis details). The observed dr values for some of the 5-
membered cyclic carbonates are similar to the ones of their
respective precursors B, and hence supports the view that the
formation of these five-membered carbonates is diastereospecific.
Entry
Base
[mol%]
Solvent
Conv. of 1a
Yield of 2a
[%][b]
[%][c]
1
2
3
TBD (20)
DBU (20)
KOH (20)
CH3CN
CH3CN
CH3CN
64
49
64
49
0[d]
100
4
5
DMAP (20)
DBN (20)
DABCO (20)
TEA (20)
K2CO3 (20)
TBD (20)
TBD (20)
TBD (20)
TBD (20)
TBD (20)
TBD (20)
TBD (30)
TBD (50)
TBD (100)
‒
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
THF
8
43
6
2
18
6
0
7
6
0
8
16
31
46
63
15
21
53
94
97
>99
<1
0
9
31
10[e]
11
12
13
14
15
16
17[g]
18
Et2O
32
Toluene
DMF
59
15
EtOH
3
DCM
53
CH3CN
CH3CN
CH3CN
CH3CN
93 (91)[f]
97 (96)[f]
14[h]
0
[a] Reaction conditions: substrate 1a (0.10 mmol), solvent (0.20 mL), 2 h, under
Ar or N2. [b] Conversions measured by 1H NMR (CDCl3). [c] Determined by 1
H
NMR using mesitylene as internal standard. [d] An unidentified byproduct was
formed. [e] Heterogeneous mixture; two duplicate experiments gave 21 (10) and
42 (32)% substrate conversion (yield of 2a). [f] In brackets the isolated yield of
2a. [g] In the absence of acetyl imidazole. [g] Note that 5,5-diphenyl-
tetrahydrofuran-3-ol (3a) was isolated in 14% yield, see the SI for analysis
Scheme 2. Preparation of 5-membered carbonates 1a‒1q from precursors B1‒
B17 that are prepared from homoallylic alkenes A1‒A17 using either AlCl or
details. Abbreviations: TBD
diazabicyclo[5.4.0]-undec-7-ene, DBN
DABCO = 1,4-diazabicyclo[2.2.2]octane, TEA = triethyl amine.
=
triazabicyclodecene, DBU
=
1,8-
=
1,5-diazabicyclo[4.3.0]non-5-ene,
AlMe
.
We then investigated the scope of this novel approach
towards the formation of a wider diversity of 6-membered cyclic
carbonate products (Scheme 3) by varying the R1 and R2
substituents. The presence of substituted aryl groups in the
carbonate substrates 1a-1e was well tolerated and provided
smooth access to six-membered cyclic carbonates 2a-2e in good
to excellent yields (65-91%; gram-scale synthesis of 2a: 1.24 g).
The introduction of alkyl groups such as those present in the
carbonate products 2f-2i also did not pose any significant issue.
Apart from the combination of two equal groups, carbonate
substrates with distinct R1 and R2 substituents (1j-1n) were also
probed. Whereas six-membered cyclic carbonates 2j, 2k, 2m and
2n were synthesized in good yields, the presence of a strongly
electron-withdrawing CF3 group (cf., attempted preparation of 2l)
changed the chemo-selectivity in favour of the decarboxylated, O-
acetyl protected tetrahydrofuran product 3l-Ac which was isolated
For the screening studies focusing on the preparation of six-
membered cyclic carbonate 2a (Table 1), we chose carbonate 1a
as a benchmark substrate. Various N-heterocyclic and standard
bases were examined and acetyl imidazole (AcIm) was used as
acylation reagent.[15c] The nature of the base had a significant
effect on both the yield of 2a and the overall chemo-selectivity.
Among the eight bases tested, the N-heterocyclic ones (Table 1,
entries 1, 2 and 4‒6) gave the best results, with TBD (entry 1,
64%) providing comparatively the best yield of 2a. By further
variation of the solvent and the amount of TBD (entries 9‒17), the
best considered conditions (entry 15; 30 mol% TBD) offered an
easy access to 2a in high yield. In the absence of AcIm and by
using a high loading of TBD, only tetrahydrofuran derivative 3a
could be identified (entry 17). In the absence of TBD (entry 18),
no conversion of 1a could be observed. This rt catalytic
2
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in 89% (see SI for analysis details). Finally, the spiro-derivative
2p (95%) and biphenyl-based carbonate 2q (80%) were prepared
in good yields, and the identity of 2p was further substantiated by
X-ray analysis (see the inset in Scheme 3).[17]
Deprotection of 2h therefore leads to equilibration to 5-membered
cyclic carbonate 1h reinforcing the view that the free alcohol cyclic
carbonate equilibrium is under thermodynamic control.To further
probe the role of the alcohol group, 5-membered cyclic carbonate
1o comprising a secondary (instead of tertiary) OH was examined.
By following the optimized conditions (Table 1, entry 15),
acetylated 1o-Ac (50%) was isolated as the major carbonate
product and only a trace amount of the 6-membered carbonate
was noted. This result can be anticipated as secondary alcohols
should be much more susceptible towards protection largely
precluding competitive carbonate equilibration to the unprotected
6-membered carbonate (cf., Scheme 1: 11´) and subsequent
acylation. Finally, we used other protecting agents (compounds 4
and 5, Scheme 4e) to illustrate that also variations in the ester
group are feasible.
Scheme 3. Scope of six-membered cyclic carbonates 2a-2q using 1a-1q as
precursors and the reaction conditions of entry 15 in Table 1. [a] Gram-scale
synthesis of 2a using 5 mmol 1a: yield 1.24 g, 76%. [b] The desired six-
membered cyclic carbonate 2l was not formed.
Scheme 4. Various control experiments.
Next, a series of control experiments were conducted to
investigate the proposed role of the pendent alcohol group in
substrate 1a and the relative stability of the free alcohol
carbonates (Scheme 4). In the presence of TBD only, there is no
observable conversion of the 5-membered carbonate 1a into a 6-
membered one suggesting indeed that 1a is thermodynamically
significantly more stable (Scheme 4a). We separately prepared
acylated 1h-Ac and subjected this compound to the conditions
that are present at the end of the cascade process (Scheme 4b).
No conversion was observed pointing at the crucial role of a free
alcohol group in carbonate 1h prior to equilibration of the 5- to a
6-membered cyclic carbonate.
To further shed light on the mechanism, density functional
theory (DFT) calculations were carried out (Figure 1).[19] DFT
calculations were performed using ωB97X-D functional and the 6-
311G** basis set. All structures in this study were calculated with
the Gaussian16 program. To obtain results as close as possible
to reality, all calculations were performed at 298 K (room
temperature) and an acetonitrile solvent model SMD was used.
Further details are provided in the supporting information. The
conversion of 1a into 2a was examined as a representative case.
The overall cascade process (Figure 1) can be best described
as two consecutive reactions. The first one is the conversion of
the five-membered carbonate 5MCC-OH (1a) into the six-
membered one named 6MCC-OH, while the second step involves
the protection of the alcohol of 6MCC-OH using acetyl
Whereas 6-membered cyclic carbonate 2h is stable at lower
temperatures, at elevated ones deprotection of the O-Ac group
occurs giving the free alcohol, 5-membered cyclic carbonate 1h
as the sole carbonate product in 40% isolated yield.[18]
3
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Figure 1. Relative Gibbs free energy profile in kcal·mol-1 for the formation of acylated six-membered cyclic carbonate 2a from five-membered 1a using TBD as
catalyst and acetyl imidazole as acylating agent.
imidazole (AcIm) leading to the final product 2a. The first part of
the mechanism only involves 1a and TBD with AcIm as spectator.
First, the tertiary alcohol in 5MCC-OH is deprotonated by TBD
through TS1 obtaining 5MCC-O and TBD-H+. The alkoxide group
in 5MCC-O subsequently approaches the carbonate carbon
center and generates intermediate 5MCC-Int. From here, an
isomerisation of 5MCC-Int to 6MCC-Int1 takes place via TS2.
This second step needs the presence of TBD-H+ as to induce a
closer interaction between the alkoxide and the carbonyl in
5MCC-Int thus enabling the opening of the five-membered ring
generating six-membered 6MCC-Int1. This transformation has an
energetic span of 17.6 kcal·mol-1 and supports the feasibility of all
steps at room temperature. Then, the latter intermediate is
converted into 6MCC-OH through proton transfer from TBD-H+
(TS3) and produces the six-membered carbonate which contains
facilitated by TBD-H+ allows the nucleophilic alkoxide to attack the
carbonyl fragment in AcIm through TS5 and furnishes
intermediate 6MCC-Int2. As a consequence, the carbonyl carbon
of AcIm undergoes a change from sp2 to sp3 hybridization. Finally,
TBD-H+ transfers a proton to the outer nitrogen atom of the
imidazole group (TS6) thus provoking an electronic
rearrangement that allows for the generation of the final product
6MCC-OAc (2a) and Im-H as by-product while regenerating TBD.
The highest barrier (TS6) of the acylation process is located at
14.6 kcal·mol-1 and is substantially lower than the energetic
requirement for the isomerization of 5MCC-OH to 6MCC-OH. This
isomerization appears to be rate-limiting, and the final product
6MCC-OAc (2a) is thermodynamically more stable than 1a by
10.2 kcal·mol-1.
Since all intermediates are in dynamic equilibrium, O-
protection seems to make the overall cascade process
irreversible at ambient temperature. To substantiate that
hypothesis, we also computed the acylation of the starting
carbonate 5MCC-OH (1a) through the same pathway that leads
to 6MCC-OAc (2a). Interestingly, the acetylated carbonate
5MCC-OAc has a substantially higher free energy than 6MCC-
OAc (1.8 and ‒10.2 kcal·mol-1, respectively) but the difference in
activation barrier (G‡) of both acylation processes is markedly
different (see Figure S1). At rt, the O-protection in 5MCC-OH
(having a tertiary alcohol) is energetically not competitive with the
5-to-6 carbonate isomerization/acylation cascade with a G‡ of
7.2 kcal·mol-1. Therefore, key to formation of the protected
product 6MCC-OAc is a kinetic differentiation between both
alcohol protection pathways allowing to selectively trap the
acylated six-membered carbonate 2a in high isolated yield.
In summary, we here present a unique organocatalytic
manifold for the formation of elusive 6-membered heterocycles at
room temperature. The six-membered cyclic carbonates that are
attained this way are highly versatile and allow for the presence
of several alkyl and aryl ring substituents. Computational analysis
a
primary alcohol. This is an important step since the
conformational change while forming TS3 positions the alkoxide
group away from the carbonate carbon avoiding (to some extent)
a
back-reaction to 5MCC-Int1. Importantly, 6MCC-OH is
computed to be thermodynamically significantly less stable than
5MCC-OH (nearly 3 kcal·mol-1, Keq = 7.5 × 10–3) and corroborates
with the observation that an NMR mixture of 2a and TBD (cf.,
Scheme 4a+c) did not show any sign of 6MCC-OH. In order to be
able to isolate the six-membered carbonate, O-protection by AcIm
is thus crucial.
The second part of the cascade process describes the
acylation of the primary alcohol in 6MCC-OH (Figure 1). This O-
protection using AcIm is catalyzed by TBD affording 6MCC-OAc
(2a) as a thermodynamically and kinetically stable product. The
acylation process occurs in three steps. The first one is the
deprotonation of the primary alcohol in 6MCC-OH by TBD (via
TS4) generating intermediate 6MCC-O-1 and TBD-H+. Notably,
6MCC-Int1 is different from 6MCC-O-1 in that the alkoxide group
is located nearer the carbonate carbon center of 6MCC-Int1. This
larger separation present in ternary intermediate 6MCC-O-2 and
4
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[10] a) T. M. McGuire, E. M. López-Vidal, G. L. Gregory, A. Buchard, J. CO2
Util. 2018, 27, 283-288; b) G. L. Gregory, M. Ulmann, A. Buchard, RSC
Adv. 2015, 5, 39404-39408; c) M. Honda, M. Tamura, K. Nakao, K.
Suzuki, Y. Nakagawa, K. Tomishige, ACS Catal. 2014, 4, 1893-1896; d)
T. Hirose, S. Shimizu, S. Qu, H. Shitara, K. Kodama, L. Wang, RSC Adv.
2016, 6, 69040-69044; using a stoichiometric iodine source: e) B. A. Vara,
T. J. Struble, W. Wang, M. C. Dobish, J. N. Johnston, J. Am. Chem. Soc.
complemented by control experiments emphasize the importance
of kinetic differentiation in pendent alcohol protection as a way to
isolate otherwise difficult to prepare CO2 based heterocycles
through a unique cascade process.
2015, 137, 7302-7305. See also: f) A. Hosseinian,
S. Farshbaf, R.
Acknowledgements
Mohammadi, A. Monfaredc, E. Vessally, RSC Adv. 2018, 8, 17976-
17988.
We thank the CERCA Program/Generalitat de Catalunya, ICREA,
the Spanish MINECO (CTQ2017-88920-P and CTQ2017-88777-
R) and AGAUR (2017-SGR-232 and 2017-SGR-290) for financial
support. C. Q. acknowledges the Chinese Research Council for a
predoctoral fellowship (2018-06200078) and B. L. thanks the
Marie Curie COFUND/ProBIST postdoctoral fellowship program
(grant agreement 754510). A.V. thanks MINECO for an FPI
predoctoral fellowship.
[11] a) C. J. Whiteoak, E. Martin, M. Martínez Belmonte, J. Benet-Buchholz,
A. W. Kleij, Adv. Synth. Catal. 2012, 354, 469-476; b) J. Rintjema, W.
Guo, E. Martin, E. C. Escudero-Adán, A. W. Kleij, Chem. Eur. J. 2015,
21, 10754-10762; c) B. R. Buckley, A. P. Patel, K. G. Upul Wijayantha,
Eur. J. Org. Chem. 2014, 474-478; d) D. J. Darensbourg, A. Horn, Jr; A.
I. Moncada, Green Chem. 2010, 12, 1376-1379.
[12] a) J. Vaitla, Y. Guttormsen, J. K. Mannisto, A. Nova, T. Repo, A. Bayer,
K. H. Hopmann, ACS Catal. 2017, 7, 7231-7244; b) B. D. W. Allen, C. P.
Lakeland, J. P. A. Harrity, Chem. Eur. J. 2017, 23, 13830-13857. See
also ref. 2b.
[13] For selected examples: a) G. L. Gregory, G. Kociok-Köhn, A. Buchard,
Polym. Chem. 2017, 8, 2093-2104; b) G. L. Gregory, L. M. Jenisch, B.
Charles, G. Kociok-Köhn, A. Buchard, Macromolecules 2016, 49, 7165-
7169; c) P. Brignou, J.-F. Carpentier, S. M. Guillaume, Macromolecules
2011, 44, 5127-5135; d) D. J. Darensbourg, A. I. Moncada, S.-H. Wei,
Macromolecules 2011, 44, 2568–2576; e) D. J. Darensbourg, A. I.
Moncada, Macromolecules 2010, 43, 5996-6003.
Keywords: carbon dioxide • cyclic carbonates • heterocycles •
homogeneous catalysis • organocatalysis
[1]
a) J. Artz, T. E. Müller, K. Thenert, J. Kleinekorte, R. Meys, A. Sternberg,
A. Bardow, W. Leitner, Chem. Rev. 2018, 118, 434-504; b) S. Liu, L. R.
Winter, J. G. Chen, ACS Catal. 2020, 10, 2855-2871; c) M. B. Ross, P.
de Luna, Y. Li, C.-T. Dinh, D. Kim, P. Yang, E. H. Sargent, Nat. Catal.
2019, 2, 648-658; d) A. Goeppert, M. Czaun, J.-P. Jones, G. K. Surya
Prakash, G. A. Olah, Chem. Soc. Rev. 2014, 43, 7995-8048.
[14] For some recently developed procedures: a) M. Wadamoto, H.
Yamamoto, J. Am. Chem. Soc. 2005, 127, 14556-14557; b) G.-L. Chai,
B. Zhu, J. Chang, J. Org. Chem. 2019, 84, 120-127; d) Y. Zhang, N. Li,
N. Goyal, G. Li, H. Lee, B. Z. Lu, C. H. Senanayake, J. Org. Chem. 2013,
78, 5775-5781.
[2]
[3]
[4]
a) Q. Liu, L. Wu, R. Jackstell, M. Beller, Nat. Commun. 2015, 6, 5933; b)
W. Guo, J. E. Gómez, À. Cristòfol, J. Xie, A. W. Kleij, Angew. Chem. Int.
Ed. 2018, 57, 13735-13747; c) L. Song, Y.-X. Jiang, Z. Zhang, Y.-Y. Gui,
[15] a) J. Rintjema, R. Epping, G. Fiorani, E. Martín, E. C. Escudero-Adán, A.
W. Kleij, Angew. Chem. Int. Ed. 2016, 55, 3972-3976; b) V. Laserna, E.
Martin, E. C. Escudero-Adán, A. W. Kleij, ACS Catal. 2017, 7, 5478-
5482; c) S. Sopeña, M. Cozzolino, C. Maquilón, E. C. Escudero-Adán,
M. Martínez Belmonte, A. W. Kleij, Angew Chem Int Ed. 2018, 57, 11203-
11207; d) R. Huang, J. Rintjema, J. González-Fabra, E. Martín, E. C.
Escudero-Adán, C. Bo, A. Urakawa, A. W. Kleij, Nat. Catal. 2019, 2, 62-
70; e) C. Maquilón, B. Limburg, V. Laserna, D. Garay-Ruiz, J. González-
Fabra, C. Bo, M. Martínez Belmonte, E. C. Escudero-Adán, A. W. Kleij,
Organometallics 2020, 39, 1642-1651.
X.-Y.
Zhou,
D.-G.
Yu,
Chem.
Commun.
2020,
DOI:
10.1039/D0CC00547A.
a) A. Tortajada, F. Juliá-Hernández, M. Börjesson, T. Moragas, R. Martin,
Angew. Chem. Int. Ed. 2018, 57, 15948-15982; b) W. Guo, V. Laserna,
J. Rintjema, A. W. Kleij, Adv. Synth. Catal. 2016, 358, 1602-1607; c) D.
U. Nielsen, X.-M. Hu, K. Daasbjerg, T. Skrydstrup, Nat. Catal. 2018, 1,
244-254.
For some selected examples: a) A. J. Kamphuis, F. Picchioni, P. P.
Pescarmona, Green Chem. 2019, 21, 406-448; b) B. Grignard, S.
Gennen, C. Jérôme, A. W. Kleij, C. Detrembleur, Chem. Soc. Rev. 2019,
48, 4466-4514; c) S. J. Poland, D. J. Darensbourg, Green Chem. 2017,
19, 4990–5011; d) S. Paul, Y. Zhu, C. Romain, R. Brooks, P. K. Saini, C.
K. Williams, Chem. Commun. 2015, 51, 6459-6479.
[16] For the first use of the Al-complexes in cyclic carbonate synthesis: a) C.
J. Whiteoak, N. Kielland, V. Laserna, E. C. Escudero-Adán, E. Martin, A.
W. Kleij, J. Am. Chem. Soc. 2013, 135, 1228-1231; b) C. J. Whiteoak, N.
Kielland, V. Laserna, F. Castro-Gómez, E. Martin, E. C. Escudero-Adán,
C. Bo, A. W. Kleij, Chem. Eur. J. 2014, 20, 2264-2275.
[5]
[6]
a) R. Rajjak Shaikh, S. Pornpraprom, V. D’Elia, ACS Catal. 2018, 8, 419-
450; b) J. W. Comerford, I. D. V. Ingram, M. North, X. Wu, Green Chem.
2015, 17, 1966-1987; c) C. Martín, G. Fiorani, A. W. Kleij, ACS Catal.
2015, 5, 1353-1370.
[17] For details of the structure of 2p, see CCDC-1997736.
[18] Note that beside the 5-membered carbonate product 1h also substantial
amounts of a tetrahydrofuran byproduct (cf., Scheme 2) was noted. At
110 ºC, the ratio ( 4:1) between these products further changed in
favour of the latter.
a) G. Fiorani, W. Guo, A. W. Kleij, Green Chem. 2015, 17, 1375-1389; b)
M. Alves, B. Grignard, R. Mereau, C. Jerome, T. Tassaing, C.
Detrembleur, Catal. Sci. Technol. 2017, 7, 2651-2684; for recent original
work: c) N. Liu, Y.-F. Xie, C. Wang, S.-J. Li, D. Wei, M. Li, B. Dai, ACS
Catal. 2018, 8, 9945-9957.
[19] For fast scans in the potential energy surface the xTB program
developed by Grimme was used, see ref. 20. This program allows the
scanning of one or more distances, angles and dihedral angles at the
same time or sequentially, giving a general idea of each structure.
Furthermore, it performs meta-dynamics simulations using the root-
mean-square deviation (RMSD) in Cartesian space as a collective
variable. Full access to the computational data is provided through:
http://dx.doi.org/10.19061/iochem-bd-1-171.
[7]
For some illustrative, recent examples: a) G. Fiorani, M. Stuck, C. Martín,
M. Martínez-Belmonte, E. Martin, E. C. Escudero-Adán, A. W. Kleij,
ChemSusChem 2016, 9, 1304-1311; b) H. Zhou, H. Zhang, S. Mu, W.-Z.
Zhang, W.-M. Ren, X.-B. Lu, Green Chem. 2019, 21, 6335-6341; c) L.
Longwitz, J. Steinbauer, A. Spannenberg, T. Werner, ACS Catal. 2018,
8, 665-672.
[20] a) S. Grimme, C. Bannwarth, P. Shushkov, J. Chem. Theory Comput.
2017, 13, 1989-2009. See also: b) J.-D. Chai, M. Head-Gordon, Phys.
Chem. Chem. Phys. 2008, 10, 6615-6620.
[8]
[9]
a) B. Yu, L.-N. He, ChemSusChem 2015, 8, 52-62; for some recent
original examples: b) R. Yousefi, R. Yousefi, T. J. Struble, J. L. Payne,
M. Vishe, N. D. Schley, J. N. Johnston, J. Am. Chem. Soc. 2019, 141,
618-625; c) J. K. Mannisto, A. Sahari, K. Lagerblom, T. Niemi, M. Nieger,
G. Sztanó, T. Repo, Chem. Eur. J. 2019, 25, 10284-10289.
a) M. Tamura, K. Noro, M. Honda, Y. Nakagawa, K. Tomishige, Green
Chem. 2013, 15, 1567-1577; b) J. Hwang, D. Han, J. J. Oh, M. Cheong,
H.-J. Koo, J. S. Lee, H. S. Kim, Adv. Synth. Catal. 2019, 361, 297-306.
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10.1002/anie.202007350
Angewandte Chemie International Edition
COMMUNICATION
Entry for the Table of Contents
Mastering rings: A new organocatalytic cascade process
converts alcohol-functionalized 5-membered cyclic carbonates
into 6-membered analogues using organocatalysis at room
temperature. This methodology delivers a wide range of elusive,
substituted CO2-based heterocycles in good yields. Various
control reactions and DFT studies demonstrate that the chemo-
selectivity is kinetically controlled, offering a unique manifold to
forge larger-ring cyclic organic carbonates.
Chang Qiao, Alba Villar-Yanez, Josefine Sprachmann,
Bart Limburg, Carles Bo and Arjan W. Kleij*
Page No. – Page No.
Organocatalytic Trapping of Elusive Carbon
Dioxide based Heterocycles through a Kinetically
Controlled Cascade Process
Institute and/or researcher Twitter usernames:
@ICIQchem
@awkleij
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This article is protected by copyright. All rights reserved.