Catalytic intermolecular alkene oxyamination with nitrenes

Article abstract of DOI:10.1002/chem.201400301

The Rh^II-catalyzed intermolecular addition of nitrenes to aromatic and aliphatic alkenes provides vicinal amino alcohols with yields of up to 95 % and complete regioselectivity. This 1,2-oxyamination reaction involves the formation of an aziridine intermediate that undergoes in situ ring opening. The latter is induced by the Rh-bound nitrene that behaves as a Lewis acid. Rhodium drive: The Rh^II-catalyzed intermolecular addition of nitrenes to alkenes allows the formation of vicinal amino alcohols with complete regioselectivity. The oxyamination reaction occurs with yields of up to 95 %. The mechanism involves the formation of an aziridine intermediate that undergoes a nucleophilic ring opening after activation by the Lewis acidic rhodium-bound nitrene (see scheme; esp=α,α,α',α'-tetramethyl-1,3- benzenedipropionate, Tces=trichloraethylsulfamyl).

Full text of DOI:10.1002/chem.201400301

DOI: 10.1002/chem.201400301
Communication
&
Synthetic Methods
Catalytic Intermolecular Alkene Oxyamination with Nitrenes
Geoffroy Dequirez, Jennifer Ciesielski, Pascal Retailleau, and Philippe Dauban*[a]
Abstract: The RhII-catalyzed intermolecular addition of ni-
trenes to aromatic and aliphatic alkenes provides vicinal
amino alcohols with yields of up to 95% and complete re-
gioselectivity. This 1,2-oxyamination reaction involves the
formation of an aziridine intermediate that undergoes in
situ ring opening. The latter is induced by the Rh-bound
nitrene that behaves as a Lewis acid.
The 1,2-amino alcohol motif is of the utmost importance in or-
ganic chemistry. It is found in several natural products and syn-
thetic compounds. The latter include drugs, exemplified by the
recently approved antibacterial oxazolidinones, as well as the
chiral ligands ubiquitous in asymmetric catalysis.[1] The preva-
lence of vicinal amino alcohols has been a source of inspiration
for synthetic organic chemists who have designed numerous
methods for their preparation.[1,2] Alkene aminohydroxylation,
in this context, provides the most direct access to 1,2-amino al-
Scheme 1. Background for the development of the reaction.
in synthesis.[15] In the course of our studies, we have recently
demonstrated that intermolecular oxyamination can also be
performed with complete regiocontrol starting from indoles
and enamides (Scheme 1b). The regioselectivity, in this case, is
secured by the presence of the vicinal nitrogen functionality.[16]
Importantly, the mechanism of all these nitrene additions re-
mains a matter of debate, particularly regarding the involve-
ment of an aziridine intermediate. In order to enhance the
scope of the reaction, we decided to turn our attention to the
case of simple olefins that have, so far, not been investigated
under these reaction conditions. In this communication, there-
fore, we wish to report the regioselective intermolecular oxy-
amination of alkenes that have brought to light an unexpected
role for the metallanitrene species in the reaction (Scheme 1c).
Initial experiments were aimed at screening the conditions
for the catalytic oxyamination of styrene (Table 1). The combi-
nation of trichloroethylsulfamate (TcesNH2) with [Rh2(esp)2]
(esp=a,a,a’,a’-tetramethyl-1,3-benzenedipropionic acid), both
developed by Du Bois for catalytic alkene aziridination and
CÀH amination,[17] in the presence of PhI(OAc)2 and acetic acid,
was found appropriate to induce the oxyamination of 1a. A
longer reaction time, when compared to that previously re-
ported in the case of indoles and enamides,[16] was necessary
to obtain a yield of 90% (entries 1 and 2). Importantly, the oxy-
aminated product 2a was isolated as a single regioisomer,
with the acetoxy group being introduced at the benzylic posi-
tion.[18] The screening of various rhodium and copper com-
plexes clearly confirmed the superior performance of
[Rh2(esp)2] in alkene oxyamination (entries 2–7), whereas, in
cohols. This transformation has received
a considerable
amount of attention since the pioneering investigations of
Sharpless.[3,4] Particularly, recent studies have focused on devel-
oping conditions that preclude the use of osmium and address
the issue of regioselectivity.[5] Efficient alkene oxyaminations
have been developed in the presence of various metal com-
plexes[6–9] or under metal-free conditions.[10] However, these
processes, with notable exceptions,[6b–d,8a,b] involve the intra-
molecular introduction of one of the functional groups that se-
cures the regioselectivity of the addition. Accordingly, the in-
termolecular alkene aminohydroxylation still remains a chal-
lenge that needs to be addressed.
In parallel to these developments, catalytic nitrene transfer
has been reported as an alternative for the development of re-
gioselective oxyamination reactions. Pioneering studies from
the groups of Rojas[11] and Padwa[12] have shown that dirhod-
ium(II) complexes are the catalysts of choice to perform the
oxyamination of glycal- and indolylcarbamates (Scheme 1a).
Liu et al. have found that sulfamates are also competent ni-
trene precursors for this transformation.[13,14] The relevance of
these reactions, which all rely on the intramolecular addition
of a tethered nitrene, has been highlighted by their application
[a] Dr. G. Dequirez, Dr. J. Ciesielski, Dr. P. Retailleau, Dr. P. Dauban
Centre de Recherche de Gif-sur-Yvette
Institut de Chimie des Substances Naturelles, UPR 2301 CNRS
Avenue de la Terrasse, 91198 Gif-sur-Yvette (France)
E-mail: philippe.dauban@cnrs.fr
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/chem.201400301.
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tries 14–17). The latter are isolated as single regioisomers
though the yields are lower than those recorded with aromatic
alkenes. The same regioselectivity was also observed in the re-
action with 2,5-dimethylhexa-2,4-diene 1s, however, the ex-
pected oxyaminated compound was accompanied by the
product resulting from 1,4-addition (entry 18).
Table 1. Catalytic oxyamination of styrene.[a]
Entry
Catalyst ([mol%])
Solvent
Yield [%][b]
Additional experiments were carried out in the presence of
different carboxylic acids (Scheme 2). These required the initial
preparation of appropriate oxidizing reagents to secure the
presence of a single carboxylic acid in the mixture. Thus, the
expected products 4a–c were isolated in good yields using
pivalic acid, benzoic acid and phenylacetic acid, respectively. In
addition, the oxyamination of styrene with 2 equivalents of
PhI(OCOtBu)2 and 12 equivalents of methanol produced the
methoxy analogue 4d in 74% yield.
1
2
3
4
5
6
7
8
[Rh2(esp)2] (2)
[Rh2(esp)2] (2)
[Rh2(CF3CONH)4] (2)
[Rh2(OAc)4] (2)
[Rh2(CF3CO2)4] (2)
CuOTf (5)
benzene
benzene
benzene
benzene
benzene
benzene
benzene
toluene
70[c]
90
mixture
51
no reaction
degradation
degradation
54
82
66
mixture[d]
mixture[d]
Cu(OTf)2 (5)
[Rh2(esp)2] (2)
[Rh2(esp)2] (2)
[Rh2(esp)2] (2)
[Rh2(esp)2] (2)
[Rh2(esp)2] (2)
9
CH2Cl2
trifluorotoluene
AcOiPr
10
11
12
We then investigated the mechanism of this reaction, and
1
CH3CN
we began by monitoring the course of the reaction by H NMR
spectroscopy. Although previous studies in the catalytic oxy-
amination of glucals, indoles and enamides[11–13,16] revealed
that the aziridine intermediate could not be observed by stan-
dard spectroscopic methods, our investigations with styrene
1a were successful. The oxyamination proceeded through the
postulated N-(Tces)-2-phenylaziridine 5, which gradually trans-
formed to the oxyaminated product 2a (see the Supporting In-
formation). Compound 5 was then prepared according to the
procedure reported by Du Bois,[17a] to elucidate the step of the
aziridine ring opening. Surprisingly, the formation of the oxy-
aminated product 2a from 5 occurred solely under the reac-
tion conditions for oxyamination, that is in the presence of
acetic acid, TcesNH2, the iodine(III) oxidant and the rhodium
complex, [Rh2(esp)2]. Very low conversions were obtained in
the absence of one of these reagents (see the Supporting In-
formation).[22] These observations strongly suggest the involve-
ment of the metallanitrene in the second step of the oxyami-
nation. The second rhodium site may act as Lewis acid that
could activate the aziridine towards the ring opening. Interest-
ingly, a test experiment involving a “catalytic” quantity of the
metallanitrene, generated from 0.2 equivalents of the sulfa-
mate and the iodine oxidant, gave the expected product in
79% yield (Scheme 3).
[a] Reaction conditions: styrene (0.6 mmol), TcesNH2 (1.5 equiv), PhI(OAc)2
(2 equiv), catalyst (2 mol%), acetic acid (12 equiv), solvent (1.7 mL), RT.
[b] Isolated yields. [c] After 3 h reaction. [d] A mixture of 2a and the aziri-
dine was obtained after 60 h of reaction at RT or at 408C.
terms of solvent, the best yield was observed for the reaction
carried out in benzene (entries 2, 8, and 10–12). It should be
mentioned that dichloromethane provided compound 2a in
82% yield, which is a safe alternative to benzene (entry 9).
The best conditions reported in Table 1 (entry 2) were then
used to study the scope of the reaction with respect to the
alkene substitution (Table 2). The reactivity of aromatic alkenes
was first investigated. We found that these substrates are effi-
ciently converted to the expected 1,2-oxyaminated products.
Except the NO2 group, the reaction tolerates the presence of
electron-withdrawing and -donating substituents. Compared
to the p-MeO-substituted styrene 1b (entry 1), the p-bromo
and the o-chloro derivatives, 1c and 1d, required longer reac-
tion times (48 h; entries 2 and 3). In the case of the p-NO2-sty-
rene 1e, the corresponding aziridine 3 (entry 4) was obtained
as the sole product of the reaction, which suggests its involve-
ment in the mechanism of the oxyamination (vide infra).[19,20]
The a- and b-methyl styrenes 1h and 1i were also relevant
substrates for this transformation (entries 7 and 8). Substrate
1i generated a mixture of cis- and trans-oxyaminated products,
a result that was also obtained starting from indene 1j and di-
hydronaphthalene 1k (entries 9 and 10).[21]
Interestingly, the reaction of 1-phenylbutadiene 1l takes
place with complete chemoselectivity at the terminal olefin
(entry 11), an observation in line with that reported by Yoon
et al.[8b] It is worth mentioning the conversion of trans-styryl-
acetic acid 1m to the trans-3,4-disubstituted lactone 2m that
underscores the possibility to perform the reaction in an intra-
molecular manner with complete diastereocontrol as indicated
by the X-ray crystallographic structure (entry 12; see the Sup-
porting Information). The corresponding trans-tetrahydrofur-
ane 2n derivative was also obtained in 55% yield from trans-
styrylethanol 1n (entry 13). Finally, aliphatic alkenes could also
be converted to the corresponding vicinal aminoalcohols (en-
The nature of the aziridine ring opening was also investigat-
ed. The mixture of cis/trans products isolated from b-methyl
styrene 1i, indene 1j, and dihydronaphthalene 1k, as well as
the product 2r formed from allyltrimethylsilane, suggests the
involvement of intermediates with significant cationic charac-
ter. This hypothesis is also in line with the complete regioselec-
tivities observed for aromatic and aliphatic alkenes. We sought
to validate this postulation by preparing substrates, such as 1t,
that could trap the carbocation intermediate, however, these
experiments were unsuccessful. Based on these results, we
have proposed the following hypothetical mechanism for the
intermolecular alkene oxyamination (Scheme 4). A metalla-
nitrene I is generated from the reaction between TcesNH2, PhI-
(OAc)2 and the [Rh2(esp)2] complex. One equivalent of I would
first add to olefin II according to a classical process of aziridina-
tion to provide intermediate III (cycle A). A substoichiometric
quantity of the rhodium-bound nitrene I, could then act as
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Table 2. Catalytic oxyamination of aromatic and aliphatic alkenes.
Entry
Substrate
Product
Yield
[%][a]
Entry
Substrate
Product
Yield
[%][a]
1
2
95
11
12
65
77[b]
89[f]
3
4
60[b]
80[b]
13
14
55[f]
58
5
94
15
27
6
7
8
71
16
17
18
33[b]
56
84
82[c]
38[g]
9
70[d]
19
78
10
52[b,e]
[a] Isolated yields; [b] after 48 h; [c] 2:1 mixture of isomers; [d] 2:1 mixture of cis/trans isomers; [e] 1.4:1 mixture of trans/cis isomers; [f] reaction with PhI-
(OCOtBu)2 in the absence of AcOH; [g] the 1,4-aminoalcohol was also isolated in 48% yield.
Scheme 3. Metallanitrene-mediated aziridine ring-opening.
a Lewis acid and facilitate the aziridine ring opening to gener-
ate the presumed cationic species IV, which is then rapidly
trapped by the acetate to afford the oxyaminated product V
(cycle B).[23]
In conclusion, the catalytic oxidative nitrene addition to ole-
Scheme 2. Reaction of styrene in the presence of various carboxylic acids
and methanol.
fins can provide a solution to address the issue of regioselec-
tivity in intermolecular alkene oxyamination. Application of the
reaction conditions allows isolating the corresponding vicinal
amino alcohols with complete regioselectivity. The study of the
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Keywords: alkenes · aminohydroxylation · nitrenes · rhodium ·
synthetic methods
[1] a) S. C. Bergmeier, Tetrahedron 2000, 56, 2561–2576; b) D. J. Ager, I. Pra-
kash, D. R. Schaad, Chem. Rev. 1996, 96, 835–876.
[2] O. K. Karjalainen, A. M. P. Koskinen, Org. Biomol. Chem. 2012, 10, 4311–
4326.
[3] a) K. B. Sharpless, A. O. Chong, K. Oshima, J. Org. Chem. 1976, 41, 177–
179; b) G. Li, H.-T. Chang, K. B. Sharpless, Angew. Chem. 1996, 108, 449–
452; Angew. Chem. Int. Ed. 1996, 35, 451–454. For reviews, see: c) P.
O’Brien, Angew. Chem. 1999, 111, 339–342; Angew. Chem. Int. Ed. 1999,
38, 326–329; d) J. A. Bodkin, M. D. McLeod, J. Chem. Soc. Perkin Trans.
1 2002, 2733–2746.
[4] Recent studies on the tethered Sharpless aminohydroxylation: a) T. J.
Donohoe, P. D. Johnson, M. Helliwell, M. Keenan, Chem. Commun. 2001,
2078–2079; b) T. J. Donohoe, P. D. Johnson, A. Cowley, M. Keenan, J.
Am. Chem. Soc. 2002, 124, 12934–12935; c) T. J. Donohoe, M. J. Chught-
ai, D. J. Klauber, D. Griffin, A. D. Campbell, J. Am. Chem. Soc. 2006, 128,
2514–2515; d) T. J. Donohoe, C. J. R. Bataille, W. Gattrell, J. Kloesges, E.
Rossignol, Org. Lett. 2007, 9, 1725–1728; e) T. J. Donohoe, C. K. A. Call-
ens, A. R. Lacy, C. Winter, Eur. J. Org. Chem. 2012, 655–663.
Scheme 4. Proposed mechanism for the oxyamination of alkene.
[5] a) P. Dauban, B. Darses, A. G. Jarvis, Addition Reactions with Formation of
CarbonÀNitrogen Bonds, in Comprehensive Organic Synthesis, Vol. 7: Oxi-
dation, 2nd ed. (Eds.: G. Molander, P. Knochel), Elsevier, Oxford, 2014,
pp. 538–604; b) T. J. Donohoe, C. K. A. Callens, A. Flores, A. R. Lacy, A. H.
Rathi, Chem. Eur. J. 2011, 17, 58–76; c) C. E. I. Knappke, A. J. von Wange-
lin, ChemCatChem 2010, 2, 1381–1383.
mechanism has revealed an unexpected role for the rhodium-
bound nitrogen species that can behave as a Lewis acid. This
confirms that this species has the capacity to catalyze the nu-
cleophilic ring opening of the aziridine. Further studies are un-
derway to investigate this new role for metallanitrenes.[24] Fi-
nally, given the ubiquity of amino alcohols in nature and
drugs, this reaction enhances the synthetic value of nitrenes as
reagents in organic synthesis.[25]
[6] Copper: a) M. Noack, R. Gçttlich, Chem. Commun. 2002, 536–537;
b) D. J. Michaelis, C. J. Schaffer, T. P. Yoon, J. Am. Chem. Soc. 2007, 129,
1866–1867; c) D. J. Michaelis, M. A. Ischay, T. P. Yoon, J. Am. Chem. Soc.
2008, 130, 6610–6615; d) T. Benkovics, J. Du, I. A. Guzei, T. P. Yoon, J.
Org. Chem. 2009, 74, 5545–5552; e) T. Benkovics, I. A. Guzei, T. P. Yoon,
Angew. Chem. 2010, 122, 9339–9343; Angew. Chem. Int. Ed. 2010, 49,
9153–9157; f) P. H. Fuller, J. W. Kim, S. R. Chemler, J. Am. Chem. Soc.
2008, 130, 17638–17639; g) E. S. Sherman, S. R. Chemler, Adv. Synth.
Catal. 2009, 351, 467–471; h) F. C. Sequeira, S. R. Chemler, Org. Lett.
2012, 14, 4482–4485; i) D. E. Mancheno, A. R. Thornton, A. H. Stoll, A.
Kong, S. B. Blakey, Org. Lett. 2010, 12, 4110–4113; j) M. Nakanishi, C.
Minard, P. Retailleau, K. Cariou, R. Dodd, Org. Lett. 2011, 13, 5792–5795.
[7] Palladium: a) E. J. Alexanian, C. Lee, E. J. Sorensen, J. Am. Chem. Soc.
2005, 127, 7690–7691; b) G. Liu, S. S. Stahl, J. Am. Chem. Soc. 2006, 128,
7179–7181; c) L. V. Desai, M. S. Sanford, Angew. Chem. 2007, 119, 5839–
5842; Angew. Chem. Int. Ed. 2007, 46, 5737–5740; d) C. Martinez, Y. Wu,
A. B. Weinstein, S. S. Stahl, G. Liu, K. Muniz, J. Org. Chem. 2013, 78,
6309–6315.
[8] Iron: a) K. S. Williamson, T. P. Yoon, J. Am. Chem. Soc. 2010, 132, 4570–
4571; b) K. S. Williamson, T. P. Yoon, J. Am. Chem. Soc. 2012, 134, 12370–
12373; c) G.-S. Liu, Y.-Q. Zhang, Y.-A. Yuan, H. Xu, J. Am. Chem. Soc.
2013, 135, 3343–3346; d) Y.-Q. Zhang, Y.-A. Yuan, G.-S. Liu, H. Xu, Org.
Lett. 2013, 15, 3910–3913.
[9] Various metals: a) A. Muniz, A. Iglesias, Y. W. Fang, Chem. Commun.
2009, 5591–5593; b) T. de Haro, C. Nevado, Angew. Chem. 2011, 123,
936–940; Angew. Chem. Int. Ed. 2011, 50, 906–910; c) J. An, Y.-Q. Zou,
Q.-Q. Yang, Q. Wang, W.-J. Xiao, Adv. Synth. Catal. 2013, 355, 1483–
1489.
Experimental Section
General procedure for the rhodium-catalyzed oxyamination
of alkenes
A flask containing a solution of TcesNH2 (206 mg, 0.90 mmol,
1.5 equiv) in benzene (1.7 mL) was charged with [Rh2(esp)2] (9 mg,
12 mmol, 0.02 equiv), the substrate (0.60 mmol, 1.0 equiv) and
acetic acid (411 mL, 7.20 mmol, 12 equiv). PhI(OAc)2 (387 mg,
1.20 mmol, 2.0 equiv) was added to this mixture. During the addi-
tion of PhI(OAc)2 a color change from green to brown was general-
ly observed. The reaction mixture was stirred at room temperature
(258C) for 16 h. A saturated aqueous NaHCO3 solution (3 mL) was
then added. The aqueous layer was extracted with CH2Cl2 (2ꢁ
10 mL) and the combined organic extracts were stirred 30 min
with a saturated aqueous thiourea solution (5 mL). After separa-
tion, the organic phase was washed with brine (10 mL), dried over
MgSO4, filtered, and concentrated under reduced pressure. The iso-
lated material was purified by flash chromatography on silica gel
to afford the oxyamination product.
[10] a) D. J. Wardrop, E. G. Bowen, R. E. Forslund, A. D. Sussman, S. L. Weera-
sekera, J. Am. Chem. Soc. 2010, 132, 1188–1189; b) H. M. Lovick, F. E. Mi-
chael, J. Am. Chem. Soc. 2010, 132, 1249–1251; c) H. C. Xu, K. D. Moeller,
J. Am. Chem. Soc. 2010, 132, 2839–2844; d) V. A. Schmidt, E. J. Alexani-
an, J. Am. Chem. Soc. 2011, 133, 11402–11405; e) U. Farid, T. Wirth,
Angew. Chem. 2012, 124, 3518–3522; Angew. Chem. Int. Ed. 2012, 51,
3462–3465; f) B. Zhang, A. Studer, Org. Lett. 2013, 15, 4548–4551.
[11] a) E. Levites-Agababa, E. Menhaji, L. N. Perlson, C. M. Rojas, Org. Lett.
2002, 4, 863–865; b) R. Bodner, B. K. Marcellino, A. Severino, A. L. Smen-
ton, C. M. Rojas, J. Org. Chem. 2005, 70, 3988–3996; c) R. Gupta, K. M.
Sogi, S. E. Bernard, J. D. Decatur, C. M. Rojas, Org. Lett. 2009, 11, 1527–
1530.
Acknowledgements
We wish to thank the Institut de Chimie des Substances Na-
turelles for financial support and fellowships (G.D.). This work
is supported by a public grant overseen by the French Nation-
al Research Agency (ANR) (program no. ANR-11-IDEX-0003-02
and CHARMMMAT ANR-11-LABX-0039). Support and sponsor-
ship from the EC (IEF to J.C.; PIEF-GA-2013-623255) are kindly
acknowledged.
[12] a) A. Padwa, T. Stengel, Org. Lett. 2002, 4, 2137–2139; b) A. Padwa, A. C.
Flick, C. A. Leverett, T. Stengel, J. Org. Chem. 2004, 69, 6377–6386.
Chem. Eur. J. 2014, 20, 8929 – 8933
www.chemeurj.org
8932
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Communication
[13] a) R. Lorpitthaya, Z.-Z. Xie, J.-L. Kuo, X.-W. Liu, Chem. Eur. J. 2008, 14,
1561–1570; b) R. Lorpitthaya, K. B. Sophy, J.-L. Kuo, X.-W. Liu, Org.
Biomol. Chem. 2009, 7, 1284–1287; c) R. Lorpitthaya, Z.-Z. Xie, K. B.
Sophy, J.-L. Kuo, X.-W. Liu, Chem. Eur. J. 2010, 16, 588–594.
[20] Under the typical reaction conditions, cis-stilbene afforded the corre-
sponding aziridine in 64% yield.
[21] A 1.4:1 mixture of trans/cis isomers was also isolated when the starting
material was the dihydronaphthalene-derived aziridine.
[14] For isolated examples of intramolecular oxyamination reactions, see for
example: a) A. R. Thornton, V. I. Martin, S. B. Blakey, J. Am. Chem. Soc.
2009, 131, 2434–2435; b) G. C. Feast, L. W. Page, J. Robertson, Chem.
Commun. 2010, 46, 2835–2837; c) L. A. Boralsky, D. Marston, R. D. Grigg,
J. C. Hershberger, J. M. Schomaker, Org. Lett. 2011, 13, 1924–1927.
[15] a) R. Lorpitthaya, S. B. Suryawanshi, S. Wang, K. K. Pasunooti, S. Cai, J.
Ma, X.-W. Liu, Angew. Chem. 2011, 123, 12260–12263; Angew. Chem. Int.
Ed. 2011, 50, 12054–12057; b) S. Sato, M. Shibuya, N. Kanoh, Y. Iwabu-
chi, J. Org. Chem. 2009, 74, 7522–7524.
[16] a) S. Beaumont, V. Pons, P. Retailleau, R. Dodd, P. Dauban, Angew. Chem.
2010, 122, 1678–1681; Angew. Chem. Int. Ed. 2010, 49, 1634–1637;
b) N. Gigant, G. Dequirez, P. Retailleau, I. Gillaizeau, P. Dauban, Chem.
Eur. J. 2012, 18, 90–94. For a single example of intermolecular oxyami-
nation of glycals, see: c) K. Guthikonda, P. M. When, B. J. Caliando, J.
Du Bois, Tetrahedron 2006, 62, 11331–11342.
[22] For examples of aziridine ring opening with O-nucleophiles, see: a) X. E.
Hu, Tetrahedron 2004, 60, 2701–2743; b) B. M. Trost, T. Zhang, Angew.
Chem. 2008, 120, 3819–3821; Angew. Chem. Int. Ed. 2008, 47, 3759–
3761; c) A. M. Taylor, S. L. Schreiber, Tetrahedron Lett. 2009, 50, 3230–
3233; d) H. Lebel, M. Parmentier, O. Leogane, K. Ross, C. Spitz, Tetrahe-
dron 2012, 68, 3396–3406. See also refs. [14b,c].
[23] Alternatively, based on recent studies from the groups of Berry, Zare
and Du Bois, the mixed-valent RhII-RhIII-NHTces dimer that is generated
slowly through proton-coupled electron transfer under these reaction
conditions, may also be competent to mediate the aziridine ring-open-
ing. See: a) K. P. Kornecki, J. F. Berry, Chem. Eur. J. 2011, 17, 5827–5832;
b) K. P. Kornecki, J. F. Berry, Eur. J. Inorg. Chem. 2012, 562–568; c) K. P.
Kornecki, J. F. Berry, Chem. Commun. 2012, 48, 12097–12099; d) R. H.
Perry, T. J. Cahill III, J. L. Roizen, J. Du Bois, R. N. Zare, Proc. Natl. Acad.
Sci. USA 2012, 109, 18295–18299.
[17] a) K. Guthikonda, J. Du Bois, J. Am. Chem. Soc. 2002, 124, 13672–13673;
b) C. G. Espino, K. W. Fiori, M. Kim, J. Du Bois, J. Am. Chem. Soc. 2004,
126, 15378–15379.
[24] A test experiment has shown that the metallanitrene can also induce
the ring opening of styrene oxide to produce the regioisomeric amino
alcohol in 65% yield.
[18] When using a sulfonamide as the nitrene source, (i.e., TsNH2 or NsNH2),
the corresponding oxyaminated product was isolated in low yield. Fur-
thermore, the reaction with iodosylbenzene afforded, only, the corre-
sponding aziridine in 65% yield.
[25] G. Dequirez, V. Pons, P. Dauban, Angew. Chem. 2012, 124, 7498–7510;
Angew. Chem. Int. Ed. 2012, 51, 7384–7395.
[19] Similar results were obtained when heating the reaction mixture at
408C.
Received: January 24, 2014
Published online on June 17, 2014
Chem. Eur. J. 2014, 20, 8929 – 8933
www.chemeurj.org
8933
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