Efficient stereoselective synthesis of nitrocyclopropanes by the oxidative cyclization of Michael adducts of nitroolefins with activated methylene compounds

Article abstract of DOI:10.1002/adsc.200800452

An efficient oxidative cyclopropanation of the Michael adducts of nitroolefins with activated methylene compounds by the combination of iodobenzene diacetate and tetrabutylammonium iodide is reported. Highly functionalized nitrocyclopropanes are synthesiz

Full text of DOI:10.1002/adsc.200800452

COMMUNICATIONS
DOI: 10.1002/adsc.200800452
Efficient Stereoselective Synthesis of Nitrocyclopropanes by the
Oxidative Cyclization of Michael Adducts of Nitroolefins with
Activated Methylene Compounds
Renhua Fan,a,* Yang Ye,a Weixun Li,a and Lingfei Wanga
a
Department of Chemistry, Fudan University, 220 Handan Road, Shanghai 200433, Peopleꢀs Republic of China
Fax : (+86)-216-510-2412; e-mail: rhfan@fudan.edu.cn
Received: July 22, 2008; Published online: October 16, 2008
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/adsc.200800452.
Abstract: An efficient oxidative cyclopropanation
of the Michael adducts of nitroolefins with activat-
ed methylene compounds by the combination of io-
dobenzene diacetate and tetrabutylammonium
iodide is reported. Highly functionalized nitrocyclo-
propanes are synthesized in moderate to good
yields via the Michael addition and cyclopropana-
tion with high diastereoselectivity and enantioselec-
tivity under mild conditions.
Catalytic asymmetric Michael additions of activated
methylene compounds to nitroolefins to afford the
Michael adducts in high enantioselectivity have been
achieved.[13] The development of an expedient and ef-
ficient method for the synthesis of enantiomerically
enriched functionalized nitrocyclopropanes by the
direct cyclization of the corresponding Michael ad-
ducts, if applicable, will be desirable in many applica-
tions (Scheme 1).
Recently, Connon et al. reported the stereoselective
synthesis of nitrocyclopropanes via a one-pot reaction
involving the organocatalytic asymmetric Michael ad-
dition of dimethyl chloromalonate to nitroolefins, fol-
lowed by cyclization in the presence of 1,8-
Keywords: cyclization; cyclopropanes; hypervalent
compounds; Michael addition; oxidation; stereose-
lectivity
diazabicycloACTHUNTGRNEUNG[5.4.0]undec-7-ene (DBU) under carefully
controlled reaction conditions.[14] However, the use of
chloromalonate resulted the low enantioselectivity
Nitrocyclopropanes are versatile intermediates in or- (7–47% ee), and highly toxic hexamethylphosphor-
ganic synthesis.[1] They not only appear as substruc-
AHCTUNGTRENNUNG
tures in a variety of biologically active natural and un- ficient ring closure. On the other hand, although the
natural compounds, for example, peptide-lactone hor- asymmetric Michael addition of dimethyl malonate to
maomycin[2] and nitropyrethroids,[3] but also can un- nitroolefins gave the Michael adduct 1a in high enan-
dergo transformations to other useful synthetic build- tioselectivity,[13a] it could not be converted into the
ing blocks, e.g., the conformationally restricted corresponding cyclopropane via bromination in the
aminocyclopropanecarboxylic acids.[4] Nitrocyclopro- presence of a base.
panes are most often prepared by the intermolecular
As a part of our development of the synthetic ap-
addition of nitrodiazo esters,[5] ylides,[6] diazoalkanes,[7] plications of hypervalent iodine compounds,[15] we
or carbenoids[8] to unsaturated systems, or intramolec- were delighted to find that the oxidative cyclopropa-
ular cyclization of g-nitroalkanols[9] or g-halo nitro nation of 1a occurred in the presence of PhI
ACHTUNGTRENNUNG(OAc)2
compounds.[10] However, compared to the extensive and Bu4NBr, and afforded cyclopropane 2a in 51%
studies on asymmetric cyclopropanations,[11,12] the effi- yield with high diastereoselectivity after 12 h
cient catalytic asymmetric synthesis of functionalized (Scheme 2).
nitrocyclopropanes is underdeveloped.
Scheme 1.
2488
ꢁ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2008, 350, 2488 – 2492

Efficient Stereoselective Synthesis of Nitrocyclopropanes by the Oxidative Cyclization
COMMUNICATIONS
cyclopropanation (Table 1, entries 8 and 9). The reac-
tion proceeded sluggishly at 08C (Table 1, entry 10).
When the reaction mixture was warmed to 508C, the
reaction time was shortened to 2 h, but a lower yield
of 2a was obtained (Table 1, entry 11). It was note-
worthy that, when the reaction was carried out in an
air-open system with untreated toluene as the solvent,
the reaction still proceeded smoothly, and gave rise to
cyclopropane 2a in a slightly lower yield (Table 1,
entry 12).
Scheme 2.
The presence of a strong base was not good for the
Several control experiments were conducted to in-
cyclopropanation (Table 1, entry 1). As a strained-ring vestigate the possible reaction pathway. During the
compound, cyclopropane 2a was sensitive to the basic reaction, the formation of iodine was observed. How-
conditions, and it decomposed when the reaction was ever, no cyclopropanation was detected when I2, the
left for a longer time (Table 1, entry 2). The yield of combination of K2CO3 with I2, or PhIACTHUNTGRNEUNG(OAc)2 with I2
2a increased to 78% using Bu4NI (Table 1, entry 4), was used (Table 1, entries 13–15). The combinations
while no cyclopropane was detected in the presence of H2O2 with Bu4NI, and NIS with AcOH were also
of Bu4NCl (Table 1, entry 3). The best ratio of 1a, not effective to the cyclopropanation (Table 1, en-
PhIACHTUNGTRENNUNG(OAc)2, and Bu4NI was 1:1.5:1.5, with which the tries 16 and 17), while cyclopropane 2a was obtained
yield of 2a increased to 93% (Table 1, entry 6). Cata- in 45% yield using m-CPBA and Bu4NI under the
lytic amounts of Bu4NI were not enough to finish the same conditions (Table 1, entry 18).
A proposed reaction pathway for the oxidative cy-
clopropanation is outlined in Scheme 3. The reaction
Table 1. Optimization of the cyclopropanation of 1a.
Entry Reagent (equivalents)
2a
dr[f]
[%][a]
1
2
PhI
(1)
PhI
(1)
N
>95:5
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
19
PhI
PhI
PhI
PhI
PhI
PhI
PhI
PhI
PhI
PhI
N
0
78
65
93
67
45
21
<5[c]
74[d]
88[e]
0
>95:5
>95:5
>95:5
>95:5
>95:5
>95:5
Scheme 3.
of PhIACHTNUTGRNEUNG(OAc)2 with Bu4NI gives a tetrabutylammoni-
um salt of diacetoxyiodine(I) A,[16] which can be re-
garded as an acetyl hypoiodite equivalent.[17] In the
presence of intermediate A or acetyl hypoiodite, the
enolate of the Michael adduct is converted into the
intermediate B, which undergoes an intramolecular
cyclization to afford the intermediate C. After the
elimination of HI in the presence of Bu4NOAc, the
corresponding highly functionalized nitrocyclopro-
pane is formed.
88:12
>95:5
I2 (1.5)
K2CO3 (1.5), I2 (1.5)
PhI
H2O2 (1.5), Bu4NI (1.5)
NIS (1.5), AcOH (1.5)
m-CPBA (1.5), Bu4NI (1.5)
0
0
0
0
45
83:17
The generality of the present PhIACHTUNGRTENUNG(OAc)2/Bu4NI-in-
[a]
[b]
[c]
[d]
[e]
Isolated yield based on 1a.
duced cyclopropanation of Michael adducts was fur-
ther explored under the optimized conditions
(Table 2). The reactions of substrates with an aromat-
ic or heteroaromatic ring proceeded smoothly, and
gave the corresponding cyclopropanes in moderate to
excellent yields (entries 1–12). Compounds with an
The reaction was stirred at 308C for 24 h.
The reaction was carried out at 08C.
The reaction was carried out at 508C.
The reaction was carried out in an air-open system with
untreated toluene as the solvent.
[f]
1
The ratio was determined by H NMR.
Adv. Synth. Catal. 2008, 350, 2488 – 2492
ꢁ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
2489

Renhua Fan et al.
COMMUNICATIONS
Table 2. PhIACHTUNGTRENNUNG(OAc)2/Bu4NI-induced cyclopropanation of Michael adducts.
Entry
R
E1
E2
2
Yield [%][a]
dr[b]
1
2
3
4
5
6
7
8
C6H5
C6H5
COOMe
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOBu-t
COCH3
COCH3
NO2
COOMe
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOBu-t
COOEt
COCH3
COOEt
COOEt
CN
2a
2b
2c
2d
2e
2f
2g
2h
2i
2j
2k
2l
2m
2n
2o
2p
2q
2r
93
88
64
78
98
80
91
88
87
55
47
88
78
88
38
52
66
0
>95:5
>95:5
>95:5
>95:5
>95:5
>95:5
>95:5
>95:5
>95:5
>95:5
>95:5
91:9
>95:5
>95:5
94:6
>95:5
>95:5
4-CH3O-C6H4
4-CH3-C6H4
4-Cl-C6H4
4-F-C6H4
4-NO2-C6H4
2-Br-C6H4
1-naphthyl
2-furanyl
9
10
11
12
13
14
15
16
17
18
19
20
2-thiophenyl
2-pyridinyl
CH
N
ACHTUNGTRENNUNG
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
CN
CN
2s
2t
0
0
[a]
Isolated yield based on 1.
The ratio was determined by H NMR.
[b]
1
electron-withdrawing substituent were better sub-
b-Aminocyclopropanecarboxylic acids are the con-
strates than those with an electron-donating substitu- formationally most rigid cycloalkyl bridged b-alanine
ent. Compounds derived from aliphatic nitroolefins derivatives and are therefore of special interest.[18]
were also good substrates (entries 13 and 14). The re- The synthetically relevant reduction of 1,1-dicarbon-
action of sterically hindered di-tert-butyl malonate de- yl-2-nitro-cyclopropane 2a to afford the correspond-
rivative required a longer time, and gave a low yield ing b-aminocyclopropane-1,1-dicarboxylate 4a can be
(entry 15). Moreover, the reactions with ethyl aceto- achieved (Scheme 4).[5b]
A
In summary, we report here an efficient oxidative
the corresponding cyclopropanes in moderate yields cyclopropanation of the Michael adducts of nitroole-
(entries 16 and 17). All 1,1-dicarbonyl-2-nitrocyclo- fins with activated methylene compounds by the com-
propanes were formed with high diastereoselectivity. bination of iodobenzene diacetate and tetrabutylam-
The anti relative stereochemistry was confirmed by monium iodide. Highly functionalized nitrocyclopro-
1H NMR and the comparison with known com- panes are synthesized in moderate to good yields with
pounds.[14] No corresponding cyclopropanes were high diastereoselectivity and enantioselectivity. The
formed when ethyl 2-nitroacetate, ethyl 2-cyanoace- potential of this reaction system can be evaluated by
tate, and malononitrile derivatives were employed its mild conditions and simple process. Studies on the
(entries 18–20).
scope, mechanism, and synthetic application are ongo-
Enantiomerically enriched Michael adducts were ing and will be reported in due course.
prepared by the asymmetric addition of 1,3-dicarbon-
yl compounds to nitroolefins catalyzed by the bifunc-
tional thiourea 3,[13b] and then underwent the oxida-
Experimental Section
tive cyclopropanation under the optimized condition
(Table 3). The corresponding functionalized nitrocy-
clopropanes were obtained in moderate to good
yields over two steps with high diastereoselectivity
and enantioselectivity. No racemization was observed
during the cyclopropanation.
Typical Experimental Procedure
The mixture of 1a (56 mg, 0.2 mmol) and PhIACTHNURGTNEUNG(OAc)2 (97 mg,
0.3 mmol) in toluene (1 mL) was treated with Bu4NI
(111 mg, 0.3 mmol). The reaction was allowed to stir at
2490
asc.wiley-vch.de
ꢁ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2008, 350, 2488 – 2492

Efficient Stereoselective Synthesis of Nitrocyclopropanes by the Oxidative Cyclization
COMMUNICATIONS
Table 3. Stereoselective synthesis of enantiomerically enriched functionalized nitrocyclopropanes.
Entry
R
E1
E2
2
Yield [%][a]
ee [%][b]
dr[c]
1
2
3
4
5
6
7
8
9
C6H5
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOMe
COCH3
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOEt
COOMe
COCH3
2b
2c
2e
2f
2h
2i
2k
2a
2q
73
52
87
71
81
80
35
81
60
87
89
90
93
94
93
89
92
86
>95:5
>95:5
>95:5
>95:5
>95:5
>95:5
>95:5
>95:5
>95:5
4-CH3O-C6H4
4-Cl-C6H4
4-F-C6H4
2-Br-C6H4
1-naphthyl
2-thiophenyl
C6H5
C6H5
[a]
Isolated yield based on nitroolefins over two steps.
[b]
[c]
Determined by HPLC (see Supporting Information).
1
The ratio was determined by H NMR.
D. S. Yufit, J. A. K. Howard, V. N. Khrustalev, Y. N. Be-
lokon, A. de Meijere, Eur. J. Org. Chem. 2003, 869–
877; e) J. Zindel, A. Zeeck, W. A. Koenig, A. de Mei-
jere, Tetrahedron Lett. 1993, 34, 1917–1920; f) T. Vet-
tiger, D. Seebach, Liebigs Ann. Chem. 1990, 195–201;
g) P. E. OꢀBannon, W. P. Dailey, J. Org. Chem. 1990, 55,
353–355; h) P. E. OꢀBannon, W. P. Dailey, J. Am.
Chem. Soc. 1989, 111, 9244–9245; i) H. H. Baer, U.
Williams, B. Radatus, Carbohydr. Res. 1988, 174, 291–
303; j) P. A. Wade, W. P. Dailey, P. J. Carroll, J. Am.
Chem. Soc. 1987, 109, 5452–5456; k) J. B. Lambert, J. J.
Napoli, K. K. Johnson, K. N. Taba, J. Org. Chem. 1985,
50, 1291–1295; l) F. G. Bordwell, J. E. Bartmess, J. A.
Hautala, J. Org. Chem. 1978, 43, 3113–3116; m) S.
Ranganathan, C. S. Panda, Tetrahedron Lett. 1971, 12,
3841–3842; n) P. E. Iversen, Chem. Ber. 1971, 104,
2195–2198; o) E. P. Kohler, H. E. Williams, J. Am.
Chem. Soc. 1919, 41, 1644–1655.
Scheme 4.
308C for 12 h. Upon completion as shown by TLC, the reac-
tion mixture was directly purified by flash column chroma-
tography (5–10% ethyl acetate in hexanes) to provide the
corresponding nitrocyclopropane 2a; yield: 93%. The char-
acterization data are available in the Supporting Informa-
tion file.
Acknowledgements
[2] a) B. D. Zlatopolskiy, K. Loscha, P. Alvermann, S. I.
Kozhushkov, S. V. Nikolaev, A. Zeeck, A. de Meijere,
Chem. Eur. J. 2004, 10, 4708–4717; b) J. Zindel, A. de
Meijere, J. Org. Chem. 1995, 60, 2968–2973.
[3] M. K. Chyan, S. J. Norton, J. Agric. Food Chem. 1995,
43, 2286–2290.
Financial support from National Natural Science Foundation
of China (20702006), the Shanghai Rising-Star program
(07QA14007), and Fudan University are gratefully acknowl-
edged.
[4] a) F. Fꢂlçp, Chem. Rev. 2001, 101, 2181–2204; b) J.
Zindel, A. de Meijere, Synthesis 1993, 190–194.
[5] a) B. Moreau, A. B. Charette, J. Am. Chem. Soc. 2005,
127, 18014–18015; b) R. P. Wurz, A. B. Charette, J.
Org. Chem. 2004, 69, 1262–1269.
[6] a) H. T. Bonge, T. Hansen, Synlett 2007, 55–58; b) J.
Hꢂbner, J. Liebscher, M. Pꢃtzel, Tetrahedron 2002, 58,
10485–10500; c) V. K. Aggarwal, H. W. Smith, G.
Hynd, R. V. H. Jones, R. Fieldhouse, S. E. Spey, J.
Chem. Soc. Perkin Trans. 1 2000, 3267–3276; d) G.
Galley, J. Hꢂbner, S. Anklam, P. G. Jones, M. Pꢃtzel,
References
[1] a) E. M. Budynina, O. A. Ivanova, E. B. Averina, T. S.
Kuznetsova, N. S. Zefirov, Tetrahedron Lett. 2006, 47,
647–649; b) R. P. Wurz, A. B. Charette, J. Org. Chem.
2004, 69, 1262–1269; c) P. Rademacher, T. Coskun, K.
Kowski, O. Larionov, A. de Meijere, Chem. Eur. J.
2003, 9, 2953–2962; d) O. V. Larionov, T. F. Savel’eva,
K. A. Kochetkov, N. S. Ikonnokov, S. I. Kozhushkov,
Adv. Synth. Catal. 2008, 350, 2488 – 2492
ꢁ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
2491

Renhua Fan et al.
COMMUNICATIONS
Tetrahedron Lett. 1996, 37, 6307–6310; e) G. Kumaran,
G. H. Kulkarni, Synthesis 1995, 1545–1548; f) C. R.
Johnson, J. P. Lockard, E. R. Kennedy, J. Org. Chem.
1980, 45, 264–271; g) J. Asunskis, H. Shechter, J. Org.
Chem. 1968, 33, 1164–1168.
Adam, H. Baier, G. Frank, G. Dꢂrner, Liebigs Ann.
Chem. 1982, 1999; k) D. E. McClure, B. H. Arison, J. J.
Baldwin, J. Am. Chem. Soc. 1979, 101, 3666.
[13] a) S. H. McCooey, S. J. Connon, Angew. Chem. Int. Ed.
2005, 44, 6367–6370; b) T. Okino, Y. Hoashi, T. Furu-
kawa, X. Xu, Y. Takemoto, J. Am. Chem. Soc. 2005,
127, 119–125; c) M. Watanabe, A. Ikagawa, H. Wang,
K. Murata, T. Ikariya, J. Am. Chem. Soc. 2004, 126,
11148–11149; d) W. Notz, F. Tanaka, C. F. Barbas III,
Acc. Chem. Res. 2004, 37, 580–591; e) H. Li, Y. Wang,
L. Tang, L. Deng, J. Am. Chem. Soc. 2004, 126, 9906–
9907; f) T. Okino, Y. Hoashi, Y. Takemoto, J. Am.
Chem. Soc. 2003, 125, 12672–12673; g) D. M. Barnes, J.
Ji, M. G. Fickes, M. A. Fitzgerald, S. A. King, H. E.
Morton, F. A. Plagge, M. Preskill, S. H. Wagaw, S. J.
Wittenberger, J. Zhang, J. Am. Chem. Soc. 2002, 124,
13097–13105; h) O. M. Berner, L. Tedeschi, D. Enders,
Eur. J. Org. Chem. 2002, 1877–1894; i) N. Krause, A.
Hoffmann-Rçder, Synthesis 2001, 171–196; j) M. P.
Sibi, S. Manyem, Tetrahedron 2000, 56, 8033–8061;
k) J. Ji, D. M. Barnes, J. Zhang, S. A. King, S. J. Witten-
berger, H. E. Morton, J. Am. Chem. Soc. 1999, 121,
10215–10216.
[7] a) P. E. OꢀBannon, W. P. Dailey, Tetrahedron 1990, 46,
7341–7358; b) P. E. OꢀBannon, W. P. Dailey, Tetrahe-
dron Lett. 1988, 29, 987–990; c) W. E. Parham, H. G.
Braxton, C. Serres, J. Org. Chem. 1961, 26, 1831–1834.
[8] P. A. Wade, W. P. Dailey, P. J. Carroll, J. Am. Chem.
Soc. 1987, 109, 5452–5456.
[9] a) J. Yu, J. R. Falck, J. Org. Chem. 1992, 57, 3757; b) B.
Radatus, U. Williams, H. H. Baer, Carbohydr. Res.
1986, 157, 242–250.
[10] a) R. Ballini, D. Fiorini, A. Palmieri, Synlett 2003,
1704–1706; b) G. A. Russell, M. Makosza, J. Hersh-
berger, J. Org. Chem. 1979, 44, 1195–1199.
[11] a) H. Xie, L. Zu, H. Li, J. Wang, W. Wang, J. Am.
Chem. Soc. 2007, 129, 10886–10894; b) H. Kakei, T.
Sone, Y. Sohtome, S. Matsunaga, M. Shibasaki, J. Am.
Chem. Soc. 2007, 129, 13410–13411; c) X. Deng, P. Cai,
S. Ye, X. L. Sun, W. W. Liao, K. Li, Y. Tang, Y. D. Wu,
L. X. Dai, J. Am. Chem. Soc. 2006, 128, 9730; d) V. K.
Aggarwal, E. Grange, Chem. Eur. J. 2006, 12, 568;
e) C. C. C. Johansson, N. Bremeyer, S. V. Ley, D. R.
Owen, S. C. Smith, M. J. Gaunt, Angew. Chem. Int. Ed.
2006, 45, 6024; f) H. Jiang, X. Deng, X. L. Sun, Y.
Tang, L. X. Dai, J. Org. Chem. 2005, 70, 15202; g) J. C.
Zheng, W. W. Liao, Y. Tang, X. L. Sun, L. X. Dai, J.
Am. Chem. Soc. 2005, 127, 12222; h) R. K. Kunz,
D. W. C. MacMillan, J. Am. Chem. Soc. 2005, 127,
3240; i) N. Bremeyer, S. C. Smith, S. V. Ley, M. J.
Gaunt, Angew. Chem. Int. Ed. 2004, 43, 2681; j) C. D.
Papageorgiou, S. V. Ley, M. J. Gaunt, Angew. Chem.
Int. Ed. 2003, 42, 828; k) V. K. Aggarwal, E. Alsono, G.
Fang, M. Ferrara, G. Hynd, M. Porcelloni, Angew.
Chem. Int. Ed. 2001, 40, 1433; l) V. K. Aggarwal, H. W.
Smith, R. V. H. Jones, R. Fieldhouse, Chem. Commun.
1998, 1785; m) A. H. Li, L. X. Dai, V. K. Aggarwal,
Chem. Rev. 1997, 97, 2341; n) Y. Tang, Y. Z. Huang,
L. X. Dai, J. Sun, W. Xia, J. Org. Chem. 1997, 62, 954.
[12] a) H. M. Hansen, D. A. Longbottom, S. V. Ley, Chem.
Commun. 2006, 4838; b) Y. Kazuta, A. Matsuda, S.
Shuto, J. Org. Chem. 2002, 67, 1669; c) P. Langer, I.
Freifeld, Org. Lett. 2001, 3, 3903; d) S. Arai, K. Na-
kayama, T. Ishida, T. Shioiri, Tetrahedron Lett. 1999,
40, 4215; e) D. Moye-Sherman, S. Jin, I. Ham, D. Lim,
J. M. Scholtz, K. Burgess, J. Am. Chem. Soc. 1998, 120,
9435; f) S. Ramaswamy, K. Prasad, O. Repic, J. Org.
Chem. 1992, 57, 6344; g) K. Burgess, K. K. Ho, J. Org.
Chem. 1992, 57, 5931; h) M. C. Pirrung, S. E. Dunlap,
U. P. Trinks, Helv. Chim. Acta 1989, 72, 1301; i) Y. Gao,
K. B. Sharpless, J. Am. Chem. Soc. 1988, 110, 7538;
j) G. Quinkert, U. Schwartz, H. Stark, W. D. Weber, F.
[14] S. H. McCooey, T. McCabe, S. J. Connon, J. Org. Chem.
2006, 71, 7494–7497.
[15] a) R. Fan, Y. Ye, Adv. Synth. Catal. 2008, 350, 1526–
1530; b) R. Fan, W. Li, Y. Ye, L. Wang, Adv. Synth.
Catal. 2008, 350,1531–1536; c) R. Fan, D. Pu, J. Gan, B.
Wang, Tetrahedron Lett. 2008, 49, 4925–4928; d) R.
Fan, D. Pu, F. Wen, J. Org. Chem. 2007, 72, 8994–8997;
e) R. Fan, W. Wang, D. Pu, J. Wu, J. Org. Chem. 2007,
72, 5905–5907; f) R. Fan, F. Wen, L. Qin, D. Pu, B.
Wang, Tetrahedron Lett. 2007, 48, 7444–7447.
[16] a) A. Kirschning, C. Plumeier, L. Rose, Chem.
Commun. 1998, 33–34; b) G. Doleschall, G. Tꢄth, Tet-
rahedron 1980, 36, 1649–1665; c) C. Szꢅntay, G.
Blaskꢄ, M. Bꢅrczai-Beke, P. Pꢆchy, G. Dçrnyei, Tetra-
hedron Lett. 1980, 21, 3509–3512.
[17] For reviews of hypervalent iodine, see: a) R. M. Mor-
iarty, J. Org. Chem. 2005, 70, 2893; b) P. J. Stang, J.
Org. Chem. 2003, 68, 2997; c) V. V. Zhdankin, P. J.
Stang, Chem. Rev. 2002, 102, 2523; d) P. J. Stang, Chem.
Rev. 1996, 96, 1123; e) R. M. Moriarty, R. K. Vaid, Syn-
thesis 1990, 431.
[18] a) S. Yamazaki, T. Inoue, T. Hamada, T. Takada, K. Ya-
mamoto, J. Org. Chem. 1999, 64, 282; b) A. A. Tishkov,
A. V. Kozintsev, I. M. Lyapkalo, S. L. Ioffe, V. V. Ka-
chala, Y. A. Strelenko, V. A. Tartakovsky, Tetrahedron
Lett. 1999, 40, 5075; c) J. Voigt, M. Noltemeyer, O.
Reiser, Synlett 1997, 202; d) R. Csuk, Y. Scholz, Tetra-
hedron 1996, 52, 6383; e) R. Csuk, Y. Scholz, Tetrahe-
dron 1995, 51, 7193; f) J. G. Cannon, J. E. Garst, J. Org.
Chem. 1975, 40, 182; g) C. C. Shroff, W. S. Stewart, S. J.
Uhm, J. W. Wheeler, J. Org. Chem. 1971, 36, 3356.
2492
asc.wiley-vch.de
ꢁ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2008, 350, 2488 – 2492