10.1002/anie.201710498
Angewandte Chemie International Edition
COMMUNICATION
Cardellicchio, M. A. Capozzi, G. Romanazzi, R. Luisi, Eur. J. Org.
Chem. DOI: 10.1002/ejoc.201700850.
Experimental Section
[8]
For related work, see: a) A. Tota, M. Zenzola, S. J. Chawner, S. St.
John-Campbell, C. Carlucci, G. Romanazzi, L. Degennaro, J. A. Bull, R.
Luisi, Chem. Commun. 2017, 53, 348-351; b) Y. Xie, B. Zhou, S. Zhou,
S. Zhou, W. Wei, J. Liu, Y. Zhan, D. Cheng, M. Chen, Y. Li, B. Wang,
Y.-s. Yue, Z. Li, Chem.Select 2017, 2, 1620-1624; c) J. Lohier, T.
Glachet, H. Marzag, A. Gaumont, V. Reboul, Chem. Commun. 2017,
53, 2064-2067.
General procedure for the sulfoximine synthesis (Scheme 1): Under
argon atmosphere, a 10 mL sealed tube was charged with sulfoxides (0.2
mmol), reagent 2b (166.0 mg, 0.5 mmol), FeSO4 (6.1 mg, 0.04 mmol),
phenanthroline (14.5 mg, 0.08 mmol) and MeCN (0.4 mL). Then, the
reaction mixture was stirred at 30 °C for 48 h. After cooling to room
temperature, the reaction mixture was quenched with
NaHCO3 solution (5 mL). The organic layer was separated from the
aqueous one, which was extracted with CH2Cl2 (5 mL 3). The
a saturated
[9]
a) T. Bach, C. Körber, Tetrahedron Lett. 1998, 39, 5015-5016; b) T.
Bach, C. Körber, Eur. J. Org. Chem. 1999, 1033-1039.
×
combined organic layers were dried over anhydrous MgSO4 and
concentrated in vacuo. The product was purified by column
chromatography using silica gel as stationary phase and mixtures of
pentane/ethyl acetate or ethyl acetate/methanol as eluent.
For the synthesis of heteroaromatic sulfoximines 7 (Scheme 2), the
procedure was identical except that the FeSO4/ligand combination was
substituted by FeIIPc (22.7 mg, 0.04 mmol).
[10] a) O. García Mancheño, C. Bolm, Org. Lett. 2006, 8, 2349-2352; b) O.
García Mancheño, C. Bolm, Chem. Eur. J. 2007, 13, 6674-6681; c) O.
García Mancheño, J. Dallimore, A. Plant, C. Bolm, Org. Lett. 2009, 11,
2429-2432; d) O. García Mancheño, J. Dallimore, A. Plant, C. Bolm,
Adv. Synth. Catal. 2010, 352, 309-316; e) J. Wang, M. Frings, C. Bolm,
Angew. Chem. 2013, 125, 8823-8827; Angew. Chem. Int. Ed. 2013, 52,
8661-8665; f) J. Wang, M. Frings, C. Bolm, Chem. Eur. J. 2014, 20,
966-969. For
a related iron-catalyzed aziridinations, see: g) M.
Nakanishi, A.-F. Salit, C. Bolm, Adv. Synth. Catal. 2008, 350, 1835-
1840; h) A. C. Mayer, A.-F. Salit, C. Bolm, CHem. Commun. 2008,
5975-5977.
Acknowledgements
[11] Lebel and co-workers described an iron-catalyzed sulfur imidation
under flow conditions. For details, see ref. 5b.
H.Y. thanks the China Scholarship Council for pre-doctoral
stipend. Furthermore, we are grateful to Plamena Staleva
(RWTH Aachen University) for HPLC analyses.
[12] a) L. Legnani, B. Morandi, Angew. Chem. 2016, 128, 2288−2292;
Angew. Chem. Int. Ed. 2016, 55, 2248−2251; b) L. Legnani, G. P.
Cerai, B. Morandi, ACS Catal. 2016, 6, 8162−8165.
[13] J. Liu, K. Wu, T. Shen, Y. Liang, M. Zou, Y. Zhu, X. Li, X. Li, N. Jiao,
Chem. Eur. J. 2017, 23, 563-567.
Keywords: imidation • iron catalysis • heterocycles • sulfoxides
• sulfoximines
[14] For the synthesis of the reagent, see: N. Guimond, S. I. Gorelsky, K.
Fagnou, J. Am. Chem. Soc. 2011, 133, 6449-6457.
[1]
For reviews, see: a) C. R. Johnson, Aldrichimica Acta 1985, 18, 3-10;
b) M. Reggelin, C. Zur, Synthesis 2000, 1-64; c) H.-J. Gais, Heteroat.
Chem. 2007, 18, 472-481; d) M. Harmata,. Chemtracts 2003, 16, 660-
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Worch, A. C. Mayer, C. Bolm, in Organosulfur Chemistry in Asymmetric
Synthesis (Eds.: T. Toru, C. Bolm), Wiley-VCH, Weinheim, 2008, pp.
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[15] For syntheses of reagent 2b and 2c, see ref. 13.
[16] Considering that the imidating agents (used in excess) were TfOH salts
with oxidation capability, we also applied Fe(OTf)2 amd Fe(OTf)3 as iron
sources (20 mol %). Under standard conditions (with 2.5 equiv of 2b
and 40 mol % of 1,10-phen), they provided NH sulfoximine 3a in 91%
and 90% (NMR) yield, respectively. Performing the catalysis (under
standard conditions) at 50 °C (instead of 30 °C) had only a minor effect
on the reaction time.
[2]
[3]
For a recent summary, see: K. E. Arndt, D. C. Bland, N. M. Irvine, S. L.
Powers, T. P. Martin, J. R. McConnell, D. E. Podhorez, J. M. Renga, R.
Ross, G. A. Roth, B. D. Scherzer, T. W. Toyzan, Org. Process Res.
Dev. 2015, 19, 454-462 and references therein.
[17] The transformations shown in Scheme
1 started from racemic
sulfoxides. The use of enantioenriched (S)-1a (62% ee) with 2b
provided (S)-3a with retention of configuration showing that the
imidation was stereospecific. Attempts to kinetically resolve racemic 1a
by substituting 1,10-phen by chiral py-Box ligands failed (for details see
Supporting Information).
For overviews and selected recent work, see: a) U. Lücking, Angew.
Chem. 2013, 125, 9570-9580; Angew. Chem. Int. Ed. 2013, 52, 9399-
9408; b) M. Frings, C. Bolm, A. Blum, C. Gnamm, Eur. J. Med. Chem.
2017, 126, 225-245; c) J. A. Sirvent, U. Lücking, ChemMedChem 2017,
12, 487-501; d) F. P. Vendetti, A. Lau, S. Schamus, T. P. Conrads, M.
J. O’Connor, C. J. Bakkenist, Oncotarget 2015, 42, 44289-44305; e) G.
Karpel-Massler, R. E. Kast, M. D. Siegelin, A. Dwucet, E. Schneider,
M.-A. Westhoff, C. R. Wirtz, X. Y. Chen, M.-E. Halatsch, C. Bolm,
Neurochem. Res. DOI 10.1007/s11064-017-2378-6.
[18] Substrates with strongly electron-withdrawing substituents such as nitro
groups proved unsuitable.
[19] Z. Li, H. Yu, C. Bolm, Angew. Chem. 2017, 129, 9660-9663; Angew.
Chem. Int. Ed. 2017, 56, 9532-9535.
[20] For a theoretical investigation of the NR transfer reactivity of an azo
analog of the P450 related high-valent iron-oxo intermediate O-Cpd I,
see: Y. Moreau, H. Chen, E. Derat, H. Hirao, C. Bolm, S. Shaik, J. Phys.
Chem. B 2007, 111, 10288-10299.
[4]
[5]
For a summary of the relevant oxidative sulfur imination reactions, see:
V. Bizet, C. M. M. Hendriks, C. Bolm, Chem. Soc. Rev. 2015, 44, 3378-
3390.
[21] The importance of the acid being present in the reaction mixture was
confirmed by the following experiments: 1. Use of the corresponding
MsOH salt of 2b gave product 3a in 90% yield. 2. Applying the pure
arylhydroxylamine (2b without TfOH led to 3a in only 18% (NMR) yield.
3. In the presence of 2.5 equiv of K2CO3, the (NMR) yield of product 3a
was reduced to 42%.
Recently, those safety concerns have been addressed by applying flow
chemistry. See: a) B. Gutmann, P. Elsner, A. O'Kearney-McMullan, W.
Goundry, D. M. Roberge, C. O. Kappe, Org. Process Res. Dev. 2015,
19, 1062-1067; b) H. Lebel, H. Piras, M. Borduy, ACS Catal. 2016, 6,
1109-1112.
[6]
[7]
J. Miao, N. G. J. Richards, H. Ge, Chem. Commun. 2014, 50, 9687–
9689.
[22] The reaction between the iron(II) salt and 2b might also involve ET
processes as suggested by Jiao and co-workers (ref. 13). Here, the
presence of 2.0 equiv of TEMPO did not inhibit the catalysis but only
reduced the yield of 3a (to 72% as determined by NMR spectroscopy).
a) M. Zenzola, R. Doran, L. Degennaro, R. Luisi, J. A. Bull, Angew.
Chem. 2016, 128, 7319-7323, Angew. Chem. Int. Ed. 2016, 55, 7203-
7207; b) For a recently developed flow strategy providing sulfoximines
by using PhI(OAc)2 and an aqueous solution of ammonia as reagents,
see: L. Degennaro, A. Tota, S. D. Angelis, M. Andresini, C.
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