Metal-free tandem oxidative aryl migration and C-C bond cleavage: Synthesis of α-ketoamides and esters from acrylic derivatives

Article abstract of DOI:10.1021/ol502834g

A novel tandem metal-free oxidative aryl migration/C-C bond-cleavage reaction, mediated by hypervalent iodine reagent, has been discovered. The presented transformation provided straightforward access to important α-ketoamide and α-ketoester derivatives from readily available acrylic derivatives via a concerted process of 1,2-aryl shift concomitant with C-C bond cleavage.

Full text of DOI:10.1021/ol502834g

Letter
pubs.acs.org/OrgLett
Metal-Free Tandem Oxidative Aryl Migration and C−C Bond
Cleavage: Synthesis of α‑Ketoamides and Esters from Acrylic
Derivatives
Le Liu,† Liang Du,† Daisy Zhang-Negrerie,† Yunfei Du,*,†,‡ and Kang Zhao*,†
†School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
‡Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China
S
* Supporting Information
ABSTRACT: A novel tandem metal-free oxidative aryl migration/
C−C bond-cleavage reaction, mediated by hypervalent iodine reagent,
has been discovered. The presented transformation provided
straightforward access to important α-ketoamide and α-ketoester
derivatives from readily available acrylic derivatives via a concerted
process of 1,2-aryl shift concomitant with C−C bond cleavage.
Scheme 1. Hypervalent Iodine Reagent Mediated Oxidative
Rearrangement of Alkenes
unctionalization of alkenes represents one of the most
challenging processes and remains a central topic in organic
F
chemistry.1 Oxidative rearrangement, as one of the most
impressive branches of these transformations, permits rapid
and efficient constructions of complex molecules from simple
building blocks.2 Consequently, considerable efforts have been
devoted to the area of oxidative rearrangement.3 Most of the
existing methods are attractive in their effectiveness and efficiency
but are unfortunately associated with the limitation of the
involvement of transition metals such as Cr,3a Pt,3b Rh,3c−f
Cu,3g−i and Pd.3j−l Despite the progress in developing mild and
metal-free procedures4 in recent decades, examples of environ-
mentally green methods are still limited in number.
Hypervalent iodine reagents,5 readily available, nontoxic, and
environmental benign, have been reported to act as electrophiles
to activate the double bonds in alkenes,6 which initiate oxidative
rearrangement through ring expansion,7 ring contraction,8 or aryl
migration.6b−d,m Koser’s group6f reported the first hydroxytosy-
loxy iodobenzene (HTIB)-mediated oxidative rearrangement of
1,1-diphenylethylene, which later expanded to a versatile type of
arylalkenes and cyclic arylalkenes.6g Purohit and co-workers6h
demonstrated an efficient catalytic use of iodine compounds
which generated I(III) in situ to furnish the oxidative 1,2-aryl shift
of 1,1-disubstituted olefins (Scheme 1, a). Wirth and co-workers
reported the first stereoselective rearrangements of alkenes with
high enantioselectivities by chiral hypervalent iodine reagents
(Scheme 1, b).6c A short while ago, we also disclosed a novel
access to 3-arylquinolinones from N-phenylcinnamamide via
oxidative aryl migration and cyclization (Scheme 1, c).6m
Hypervalent iodine reagents are also known to be used as potent
oxidants to realize the cleavage of alkene CC to form carbonyl
compounds.9 Nevertheless, a carful survey of the literature shows
no report on oxidative rearrangement involving C−C double-
bond cleavage under metal-free conditions. We herein report, as a
continuous part of our work on hypervalent iodine chemistry,10
the discovery of a novel I(III)-mediated tandem oxidative
rearrangement and C−C bond cleavage reaction of acrylic
derivatives. To our knowledge, this is an unprecedented metal-
free protocol for the synthesis of α-ketoamide and esters from
acrylic derivatives featuring a cascade oxidative rearrangement
and C−C bond-cleavage process.
In an effort to systematically investigate and gain insight of the
transformations for the synthesis of 3-arylquinolinones,6m we
designed and synthesized N,N-diethylcinnamamide (1a), which
replaced the aniline moiety on the substrate (N-methyl-N-
phenylcinnamamide) with an alkylamine. However, much to our
delight, we found that when 1a was subjected to the conditions
we developed for the synthesis of 3-arylquinolinones, an
unexpected N,N-diethyl-2-oxo-2-phenylacetamide was obtained
in 25% yield (Table 1, entry 1). We were then sidetracked to
explore this novel transformation, a worthwhile pursuit in our
opinion, as not only was the product generated a useful skeleton
in many natural products, pharmaceuticals, and intermediates in
organic synthesis11 but also the concerted nature of the process
Received: September 25, 2014
Published: October 24, 2014
© 2014 American Chemical Society
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Organic Letters
Letter
a
Table 1. Optimization of the Reaction Conditions
Scheme 2. PIDA-Mediated Oxidative Rearrangement and C−
a
C Bond Cleavage of Acrylic Amides
b
oxidant
(equiv)
time
(h)
yield
entry
solvent
additive (equiv)
(%)
1
DCE
DCE
DCE
DCE
DCE
DCE
EA
PIFA (2.0)
PIFA (3.0)
PIFA (3.0)
PIFA (3.0)
PIFA (3.0)
PIFA (3.0)
PIFA (3.0)
PIFA (3.0)
PIFA (3.0)
PIFA (3.0)
PIFA (3.0)
PhIO (3.0)
PIDA (3.0)
PIDA (3.0)
BF3·Et2O/TFA
BF3·Et2O/TFA
24
20
24
15
12
1
25
43
2
3
NR
49
4
NaHSO4 (1.0)
NH4HSO4 (1.0)
H2SO4 (1.0)
H2SO4 (1.0)
H2SO4 (1.0)
H2SO4 (1.0)
H2SO4 (1.0)
H2SO4 (1.0)
H2SO4 (1.0)
H2SO4 (1.0)
H2SO4 (1.0)
5
64
6
73
7
5
82
8
MeOH
CH3CN
DMF
TFE
10
24
24
10
24
10
7
NR
55
9
10
11
12
13
NR
70
EA
20
EA
88
c
14
DCM
90
a
All reactions were carried out with 1a (0.4 mmol) and oxidant in
solvent (c = 0.05 M) under air, and the H2SO4 used is 98% (m/m).
Isolated yields. BF3·Et2O (1.0 equiv) was added. NR = no reaction
a
Conditions A: 1 (0.4 mmol), PIDA (1.2 mmol), concd H2SO4 (0.4
b
c
mmol) refluxing in ethyl acetate under air; isolated yields are given.
b
occurred.
Conditions B: 1 (0.4 mmol), PIDA (1.2 mmol), concd H2SO4 (0.4
mmol), BF3·Et2O (0.4 mmol) in DCM at rt under air; isolated yields
c
d
are given. BF3·Et2O (0.4 mmol) was added to the reaction. TFE was
e
used as the solvent under reflux. Reaction temperature was between
involving an oxidative rearrangement and C−C bond cleavage
appeared fascinating to us.
−20 °C and rt.
We began by optimizing the reaction conditions, the results of
which are shown in Table 1. Increasing the loading of PIFA to 3.0
equiv led to a complete consumption of the starting material and
an overall yield of 43% (Table 1, entry 2). Further screening
indicated that acidic additive was essential to this reaction since
the use of H2SO4 as an additive had dramatically facilitated the
transformation leading to a significantly improved yield of 73%
(Table 1, entries 1−6). Subsequently, the effect of solvent on the
reaction was evaluated. Among the solvents tested, ethyl acetate
was found to be superior to all the other solvents such as DCE,
MeOH, CH3CN, DMF, and TFE, resulting in an 82% yield of the
desired product (Table 1, entries 7−11). Among alternative
hypervalent iodine reagents investigated, iodosobenzene (PhIO)
was less effective with only 20% of the product isolated, while
PIDA provided a slightly higher yield of 88% (Table 1, entries 12
and 13). In addition, a similar high yield was obtained when PIDA
was used as the oxidant in the presence of H2SO4 and BF3·Et2O in
DCM at room temperature (Table 1, entry 14).
With the optimized conditions in hand, a series of acrylic
amides were synthesized to investigate the scope and generality of
the method. The established parameters of reaction conditions
were proven to be generally effective for a wide range of
substrates. A variety of amines, specifically those with the
diethylamine replaced by dibenzylamine, piperidine, or morpho-
line, all reacted under the optimal reaction conditions (Scheme
2). The corresponding 2-oxo-2-phenylacetamides were afforded
in satisfactory yields (2a−d). Moreover, the method was to
extend to phenyl groups bearing both electron-donating (methyl
and methoxyl) and -withdrawing (halogens) substituents, and
the resulting products were obtained in 40−70% yields (2e−g, i−
l). It should be mentioned that the para-substituted substrates,
with either an electron-donating or -withdrawing group,
underwent the oxidative migration/C−C double-bond cleavage
process more smoothly and efficiently than the meta-substituted
substrates and much more so than the ortho-substituted
substrates, which not only required longer reaction time but
suffered decreased yield (2f−k). These observations indicate that
steric hindrance probably plays a role in the transformation
process. The reactivity of 3-(naphthalen-2-yl)acrylic amide was
also demonstrated, and the corresponding product was obtained
in 45% yield (2l). Moreover, the monosubstituted NH free
cinnamamides were also shown to be tolerable under the optimal
conditions, and the corresponding NH free α-ketoamides were
delivered in fair to good yields (2m−s). We also attempted to
extend this protocol to alkyl-substituted acrylic amide.
Disappointingly, compound 1t was proven to be inert to the
standard conditions, yielding no desired product 2t.
Then, the reactivity of a variety of substituted acrylates was
tested for the protocol. To our delight, when the readily available
methyl cinnamate 3a was subjected to slightly modified reaction
conditions employing TFE as the solvent, the reaction proceeded
smoothly and produced the corresponding ester in 75% yield
(Scheme 3, 4a). Moreover, both benzyl and isopropyl cinnamates
were tolerated and the desired α-ketoesters were isolated in 52%
and 65% yields, respectively (Scheme 3, 4b and 4c). Methyl
cinnamates bearing both electron-donating and -withdrawing
groups, even 3-(naphthalen-2-yl)acrylate, were all tolerated,
affording the corresponding aryl migrated and C−C double bond
cleaved products in acceptable yields (Scheme 3, 4d−g). On the
other hand, the low yield of the products could be attributed to
the transeterification reactions between the desired product and
the solvent. The corresponding 2,2,2-trifluoroethyl-α-ketoesters
were detected by crude 19F NMR, and the transesterificated
product derived from 4f and TFE was isolated in 15% yield.
On the basis of the experimental results and literature
overview, a plausible mechanism was proposed (Scheme 4). It
is well-known that hypervalent iodine reagent could be activated
by Lewis acid or Bronsted acid.6e,12 Thus, we assumed that PIDA
was first activated by protonation with H2SO4, which increased
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Organic Letters
Letter
Scheme 3. PIDA-Mediated Aryl Migration and C−C Bond
Scheme 5. Some Experimental Evidence of the Mechanism
a
Cleavage of Acrylates
a
All reactions were carried out with 3 (0.4 mmol), PIDA (1.2 mmol),
concd H2SO4 (0.4 mmol) with refluxing in TFE under air; isolated
yields are given.
the electrophilicity of the iodine center. Then the nucleophilic
attack on the iodine center by the carbonyl oxygen of the amide
moiety in 1a afforded iminium salt A, the resonance structure of
which, namely, the benzyl cation B, was subsequently trapped by
acetate acid to give intermediate C. Assisted by the oxygen lone
pair conjugation, the phenyl group migrated with the release of
phenyl iodide to generate oxonium D, which was attacked by
another acetate to give intermediate E. Oxidation of E by
activated PIDA in a similar fashion generated iminium salt F
which lost one proton to afford G. Nucleophilic attack of the
alkene by water, along with the elimination of iodobenzene and
acetic acid, gave the oxidized alcohol H, which was further
oxidized by a third equivalent of PIDA to furnish intermediate I.
Acetic acid attacked the electrophilic carbonyl carbon in the ester
part of I afforded hemiketal J. Finally, fragmentation of J led to the
cleavage of C−C bond and C−I bond, resulting in the formation
of 2a and acetic formic anhydride.13
In allusion to the proposed mechanism, additional experiments
were conducted, the results of which were all supportive of the
mechanism, even though some of them yielded unexpected
products at first sight. When isopropyl cinnamate 3c was treated
with PIDA in the presence of H2SO4 under refluxing in TFE for
24 h, the reaction proceeded smoothly and gave the expected α-
ketoester 4c in moderate 65% yield. However, 7 h after the
reaction was set, an intermediate product, isopropyl 2-phenyl-
3,3-bis(2,2,2-trifluoroethoxy)propanoate E4 was successfully
isolated in 75% yield. Taking pure E4 as the starting material
and subjecting it to the standard conditions, 4c was obtained in an
expected yield of 81% (65%/75% is roughly 87%) (Scheme 5, eq
1). This observation of E4 gives unambiguous evidence of the
existence of E as suggested by the mechanism. The subtly
structural difference between E4 and E can be attributed to
competition for trapping the generated cation intermediate D
between the nucleophilic solvent TFE and the released acetic
acid. Such competition is absent in cases where ethyl acetate or
DCE was employed as the solvent. More evidence came from fact
that when p-OMe cinnamate 7 was treated with PIDA in the
presence of H2SO4 in DCE an unexpected product, aldehyde 6,
was isolated in moderate 53% yield (Scheme 5, eq 2). We
reasoned that cinnamate 5 underwent the same mechanistic
pathway and formed a G-like intermediate G7. At this point,
instead of being nucleophilically attacked by a water molecule, it
was attacked by acetic acid, a normally weaker nucleophile but
facilitated in this case by the intermediate oxonium K generated
due to the electron-donating methoxy group, in exchange for a
stronger C−O bond and therefore thermodynamically more
stable molecule. Hydrolysis of the diacetate L led to the formation
of the isolated aldehyde 6.
In conclusion, we have developed a novel metal-free oxidative
protocol for the synthesis of α-ketoamides and esters from readily
available acrylic derivatives. The procedure, mediated by the mild
hypervalent iodine reagent, features a tandem oxidative aryl
migration and C−C double bond cleavage process. To our
knowledge, this is the first example of a concerted process
involving both oxidative aryl migration and C−C bond cleavage.
The detailed mechanistic insight for the transformation is under
investigation in our research group.
ASSOCIATED CONTENT
■
S
* Supporting Information
Experimental procedure, new compound characterization data,
and NMR spectra. This material is available free of charge via the
Internet at http://pubs.acs.org.
Scheme 4. Proposed Mechanism
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Organic Letters
Letter
(c) Farid, U.; Malmedy, F.; Claveau, R.; Albers, L.; Wirth, T. Angew.
Chem., Int. Ed. 2013, 52, 7018. (d) Boye, A. C.; Meyer, D. C.; Ingison, K.;
French, A. N.; Wirth, T. Org. Lett. 2003, 5, 2157. (e) Wirth, T. Top. Curr.
Chem. 2003, 224, 185. (f) Rebrovic, L.; Koser, G. F. J. Org. Chem. 1984,
49, 2462. (g) Justik, M. W.; Koser, G. F. Tetrahedron Lett. 2004, 45, 6159.
(h) Purohit, V. C.; Allwein, S. P.; Bakale, R. P. Org. Lett. 2013, 15, 1650.
(i) Shibuya, M.; Ito, S.; Takahashi, M.; Iwabuchi, Y. Org. Lett. 2004, 6,
AUTHOR INFORMATION
Corresponding Authors
■
*E-mail: duyunfeier@tju.edu.cn.
*E-mail: kangzhao@tju.edu.cn.
Notes
The authors declare no competing financial interest.
́ ́ ́
4303. (j) Guerard, K. C.; Guerinot, A.; Bouchard-Aubin, C.; Menard, M.;
Lepage, M.; Beaulieu, M. A.; Canesi, S. J. Org. Chem. 2012, 77, 2121.
(k) Ahmad, A.; Scarassati, P.; Jalaian, N.; Olofsson, B.; Silva, L. F., Jr.
Tetrahedron Lett. 2013, 54, 5818. (l) Singh, O. V.; Garg, C. P.; Kapoor, R.
P. Synthesis 1990, 1025. (m) Liu, L.; Lu, H.; Wang, H.; Yang, C.; Zhang,
X.; Zhang-Negrerie, D.; Du, Y.; Zhao, K. Org. Lett. 2013, 15, 2906.
(n) Shang, S.; Zhang-Negrerie, D.; Du, Y.; Zhao, K. Angew. Chem., Int.
Ed. 2014, 53, 6216. (o) Desjardins, S.; Maertens, G.; Canesi, S. Org. Lett.
ACKNOWLEDGMENTS
Y.D. acknowledges the National Natural Science Foundation of
China (No. 21072148) for financial support.
■
REFERENCES
■
(1) Selected reviews for functionalization of alkenes: (a) McDonald, R.;
Liu, G.; Stahl, S. S. Chem. Rev. 2011, 111, 12981. (b) Muller, T. E.;
́
2014, 16, 4828. (p) Beaulieu, M.; Guerard, K. C.; Maertens, G.; Sabot,
C.; Canesi, S. J. Org. Chem. 2011, 76, 9460.
̈
Hultzsch, K. C.; Yus, M.; Foubelo, F.; Tada, M. Chem. Rev. 2008, 108,
3795. (c) Willis, M. C. Chem. Rev. 2010, 110, 725. (d) Ballini, R.; Bosica,
G.; Fiorini, D.; Palmier, A.; Petrini, M. Chem. Rev. 2005, 105, 933.
(e) Shi, Z.; Zhang, C.; Zhang, C.; Jiao, N. Chem. Soc. Rev. 2012, 41, 3381.
(f) Landelle, G.; Bergeron, M.; Turcotte-Savard, M.; Paquin, J. Chem.
Soc. Rev. 2011, 40, 2867. (g) Minatti, A.; Muniz, K. Chem. Soc. Rev. 2007,
36, 1142. (h) Hahn, C. Chem.Eur. J. 2004, 10, 5888. (i) Beller, M.;
Seayad, J.; Tillack, A.; Jiao, H. Angew. Chem., Int. Ed. 2004, 43, 3368.
(j) Schultz, D. M.; Wolfe, J. P. Synthesis 2012, 44, 351.
(7) (a) Silva, L. F., Jr.; Vasconcelos, R. S.; Nogueira, M. A. Org. Lett.
2008, 10, 1017. (b) Justik, M. W.; Koser, G. F. Molecules 2005, 10, 217.
(c) Abo, T.; Sawaguchi, M.; Senboku, H.; Hara, S. Molecules 2005, 10,
183.
(8) (a) Silva, L. F., Jr.; Siqueira, F. A.; Pedrozo, E. C.; Vieira, F. Y. M.;
Dorigutto, A. C. Org. Lett. 2007, 9, 1433. (b) Yusubov, M. S.; Zholobova,
G. A.; Filimonova, I. L.; Chi, K. Russ. Chem. Bull., Int. Ed. 2004, 53, 1735.
(c) Kameyama, M.; Siqueira, F. A.; Gracia-Mijares, M.; Silva, L. F., Jr;
Silva, M. T. A. Molecules 2011, 16, 9421.
(2) Selected references for oxidative rearrangement of alkenes:
(a) Jones, A. C.; May, J. A.; Sarpong, R.; Stoltz, B. M. Angew. Chem.,
Int. Ed. 2014, 53, 2556. (b) Bach, T.; Hejn, J. P. Angew. Chem., Int. Ed.
2011, 50, 1000. (c) Reddel, J. C. T.; Lutz, K. E.; Diagne, A. B.;
Thomoson, R. J. Angew. Chem., Int. Ed. 2014, 53, 1395. (d) Strick, B. F.;
Mudal, D. A.; Thomson, R. J. J. Am. Chem. Soc. 2011, 133, 14252.
(e) Liang, H.; Ciufolini, M. A. Org. Lett. 2010, 12, 1760. (f) Behenna, D.
C.; Corey, E. J. J. Am. Chem. Soc. 2008, 130, 6720.
(3) Selected references for metal-catalyzed oxidative rearrangement:
(a) Haines, A. H. Methods for the Oxidative of Organic Compounds:
Alkanes, Alkenes, Alkyens, and Arenes; Academic Press: London, 1985.
(b)Kim, S. Y.; Park, Y.; Chung, Y. K. Angew. Chem., Int. Ed. 2010, 49, 415.
(c) May, J. A.; Stoltz, B. M. J. Am. Chem. Soc. 2002, 124, 12426.
(d) Wood, J.; Moniz, G. A. Org. Lett. 1999, 1, 371. (e) Tanaka, K.;
Okazaki, E.; Shibata, Y. J. Am. Chem. Soc. 2009, 131, 10822.
(f) Boyarshikh, V.; Nyong, A.; Rainier, J. D. Angew. Chem., Int. Ed.
2008, 47, 5374. (g) Nordmann, G.; Buchwald, S. L. J. Am. Soc. Chem.
2003, 125, 4978. (h) Zhang, Z.; Ren, Z.; Wang, Y.; Guan, Z. Org. Lett.
2013, 15, 4822. (i) Adrio, L. A.; Hii, K. K. Chem. Commun. 2008, 44,
2325. (j) Coscia, R. W.; Lambert, T. H. J. Am. Soc. Chem. 2009, 131,
2496. (k) Trost, B. M.; Zhang, T. Org. Lett. 2006, 8, 6007. (l) Rosa, D.;
Orellana, A. Org. Lett. 2011, 13, 3648. (m) Overman, L. E.; Owen, C. E.;
Pavan, M. M.; Richard, C. J. Org. Lett. 2003, 5, 1809.
(9) (a) Miyamoto, K.; Tada, N.; Ochiai, M. J. Am. Chem. Soc. 2007, 129,
2772. (b) Niclaou, K. C.; Adsool, V. A.; Hale, C. R. H. Org. Lett. 2010, 12,
1552. (c) Havare, N.; Plattner, D. A. Org. Lett. 2012, 14, 5078.
(d) Thottumkara, P. P.; Vinod, T. K. Org. Lett. 2010, 12, 5640.
(10) For selected examples of our previous work on hypervalent iodine
chemistry, see: (a) Du, Y.; Liu, R.; Linn, G.; Zhao, K. Org. Lett. 2006, 8,
5919. (b) Yu, W.; Zhang, Y.; Wang, S.; Zhao, K. Org. Lett. 2009, 11, 2417.
(c) Li, X.; Du, Y.; Liang, Z.; Li, X.; Pan, Y.; Zhao, K. Org. Lett. 2009, 11,
2643. (d) Zhao, F.; Liu, X.; Qi, R.; Zhang-Negrerie, D.; Huang, J.; Du, Y.;
Zhao, K. J. Org. Chem. 2011, 76, 10338. (e) Ban, X.; Pan, Y.; Lin, Y.;
Wang, S.; Du, Y.; Zhao, K. Org. Biomol. Chem. 2012, 10, 3606. (f) Wang,
J.; Yuan, Y.; Xiong, R.; Zhang-Negrerie, D.; Du, Y.; Zhao, K. Org. Lett.
2012, 14, 2210. (g) Liu, X.; Cheng, R.; Zhao, F.; Zhang-Negrerie, D.; Du,
Y.; Zhao, K. Org. Lett. 2012, 14, 5480. (h) Zheng, Y.; Li, X.; Ren, C.;
Zhang-Negrerie, D.; Du, Y.; Zhao, K. J. Org. Chem. 2012, 77, 10353.
(i) Liu, L.; Zhang-Negrerie, D.; Du, Y.; Zhao, K. Org. Lett. 2014, 16, 436.
(11) For selected examples, see: (a) Zhang, C.; Feng, P.; Jiao, N. J. Am.
Chem. Soc. 2013, 135, 15257. (b) Zhang, C.; Jiao, N. J. Am. Chem. Soc.
2010, 132, 28. (c) Zhang, C.; Zong, X.; Zhang, L.; Jiao, N. Org. Lett.
2012, 14, 3280. (d) Du, F.; Ji, J. Chem. Sci. 2012, 3, 460. (e) Mai, W.;
Wang, H.; Li, Z.; Yuan, J.; Xiao, Y.; Yang, L.; Mao, P.; Qu, L. Chem.
Commun. 2012, 48, 10117. (f) Zhang, X.; Wang, L. Green Chem. 2012,
14, 2141. (g) Li, D.; Wang, M.; Liu, J.; Zhao, Q.; Wang, L. Chem.
Commun. 2013, 49, 3640. (h) Zhang, Z.; Su, J.; Zha, Z.; Wang, Z.
Chem.Eur. J. 2013, 17, 17711.
(4) Selected references for metal-free oxidative rearrangement:
́
(a) Fananas
́
, F. J.; Alvarez-per
́
ez, M.; Rodríguez, F. Chem.Eur. J.
̃
2005, 11, 5938. (b) Kumar, M. A.; Swamy, P.; Naresh, M.; Reddy, M. M.;
Rohitha, C. N.; Prabhakar, S.; Sarma, A. V. S.; Kumar, J. R. P.; Narender,
N. Chem. Commun. 2013, 49, 1711. (c) Redon, S.; Pannecoucke, X.;
Franck, X.; Outurquin, F. Org. Biomol. Chem. 2008, 6, 1260. (d) Shibuya,
M.; Tomizawa, M.; Iwabuchi, Y. J. Org. Chem. 2008, 73, 4750.
(e) Uyanik, M.; Fukatsu, R.; Ishihara, K. Org. Lett. 2009, 11, 3470.
(5) Selected reviews on hypervalent iodine reagents: (a) Zhdankin, V.
V.; Stang, P. J. Chem. Rev. 2008, 108, 5299. (b) Zhdankin, V. V.; Stang, P.
J. Chem. Rev. 2002, 102, 2523. (c) Wirth, T. Angew. Chem., Int. Ed. 2005,
44, 3656. (d) Richardson, R. D.; Wirth, T. Angew. Chem., Int. Ed. 2006,
45, 4402. (e) Dohi, T.; Kita, Y. Chem. Commun. 2009, 16, 2073.
(f) Zhdankin, V. V. Hypervalent Iodine Chemistry; Wiley: Chichester,
2014;. (g) Ding, Q.; Ye, Y.; Fan, R. Synthesis 2013, 45, 1. (h) Zheng, Z.;
Zhang-Negrerie, D.; Du, Y.; Zhao, K. Sci. China, Ser. B 2014, 57, 189.
(i) Samanta, R.; Matcha, K.; Antonchick, A. P. Eur. J. Org. Chem. 2013,
5769.
(12) For selected examples, see: (a) Dohi, T.; Morimoto, K.; Kiyono,
Y.; Maruyama, A.; Tohma, H.; Kita, Y. Chem. Commun. 2005, 41, 2930.
(b) Dohi, T.; Morimoto, K.; Maruyama, A.; Kita, Y. Org. Lett. 2006, 8,
2007. (c) Orrea, A.; Tellitu, I.; Domínguez, E.; SanMartin, R. J. Org.
Chem. 2006, 71, 3501. (d) Romero, A. G.; Darlington, W. H.; McMillan,
M. W. J. Org. Chem. 1997, 62, 6582. (e) Dohi, T.; Ito, M.; Itani, I.;
Yamaoka, N.; Morimoto, K.; Fujioka, H.; Kita, Y. Org. Lett. 2011, 13,
6208. (f) Morimoto, K.; Nakae, T.; Yamaoka, N.; Dohi, T.; Kita, Y. Eur. J.
Org. Chem. 2011, 6326. (g) Matcha, K.; Antonchick, A. P. Angew. Chem.,
Int. Ed. 2013, 125, 2136.
(13) Acetic formic anhydride is moisture sensitive and will decompose
to acetic acid and carbon monoxide under the standard conditions. For
previous literature describing this, see: Krimen, L. I.; Savage, J.; Yates, P.
Org. Synth. 1970, 50, 1.
(6) References for hypervalent iodine reagents mediated oxidative
rearrangement: (a) Singh, F. V.; Wirth, T. Synthesis 2013, 45, 2499.
(b) Singh, F. V.; Rehbein, J.; Wirth, T. ChemistryOpen 2012, 245.
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