Cu(I)-catalyzed intermodular diamination of activated terminal olefins

Article abstract of DOI:10.1021/ol702061s

This paper describes a novel intermolecular diamination process with CuCl as catalyst and di-fert-butylthiadiaziridine 1,1-dioxide as nitrogen source. A variety of activated terminal olefins can be effectively diaminated in good yields under mild reaction

Full text of DOI:10.1021/ol702061s

ORGANIC
LETTERS
2007
Vol. 9, No. 24
4943-4945
Cu(I)-Catalyzed Intermolecular
Diamination of Activated Terminal
Olefins
Baoguo Zhao, Weicheng Yuan, Haifeng Du, and Yian Shi*
Department of Chemistry, Colorado State UniVersity, Fort Collins, Colorado 80523
yian@lamar.colostate.edu
Received August 21, 2007
ABSTRACT
This paper describes a novel intermolecular diamination process with CuCl as catalyst and di-tert-butylthiadiaziridine 1,1-dioxide as nitrogen
source. A variety of activated terminal olefins can be effectively diaminated in good yields under mild reaction conditions.
Vicinal diamines are present in various biologically active
compounds and are widely used as chiral control elements
in asymmetric synthesis.1 Metal-mediated and -catalyzed
diamination of olefins provides an attractive approach to
synthesis of 1,2-diamines and has been actively pursued,1-6
including very recent reports on Pd(II)-catalyzed intermo-
lecular diamination of conjugated dienes4 as well as Cu(II)-
mediated5 and Pd(II)-catalyzed6 intramolecular diamination
of terminal olefins. Recently, we reported a Pd(0)-7,8 and
Cu(I)9-catalyzed regio- and stereoselective diamination of
conjugated dienes and trienes using di-tert-butyldiaziridinone
Scheme 1
(1) For leading reviews, see: (a) Lucet, D.; Gall, T. L.; Mioskowski, C.
Angew. Chem., Int. Ed. 1998, 37, 2580. (b) Mortensen, M. S.; O’Doherty,
G. A. Chemtracts: Org. Chem. 2005, 18, 555. (c) Kotti, S. R. S. S.;
Timmons, C.; Li, G. Chem. Biol. Drug. Des. 2006, 67, 101.
(2) For examples of metal-mediated diaminations, see: Co: (a) Becker,
P. N.; White, M. A.; Bergman, R. G. J. Am. Chem. Soc. 1980, 102, 5676.
Hg: (b) Barluenga, J.; Alonso-Cires, L.; Asensio, G. Synthesis 1979, 962.
Mn: (c) Fristad, W. E.; Brandvold, T. A.; Peterson, J. R.; Thompson, S. R.
J. Org. Chem. 1985, 50, 3647. Os: (d) Chong, A. O.; Oshima, K.; Sharpless,
K. B. J. Am. Chem. Soc. 1977, 99, 3420. (e) Mun˜iz, K.; Nieger, M. Synlett
2003, 211. (f) Mun˜iz, K.; Nieger, M. Chem. Commun. 2005, 2729. Pd: (g)
Ba¨ckvall, J.-E. Tetrahedron Lett. 1978, 163. Tl: (h) Aranda, V. G.;
Barluenga, J.; Aznar, F. Synthesis 1974, 504.
(3) For metal-catalyzed diamination with TsNCl2 or TsNClNa, see: (a)
Li, G.; Wei, H.-X.; Kim, S. H.; Carducci, M. D. Angew. Chem., Int. Ed.
2001, 40, 4277. (b) Wei, H.-X.; Kim, S. H.; Li, G. J. Org. Chem. 2002, 67,
4777. (c) Masuyama, Y.; Ohtsuka, M.; Harima, M.; Kurusu, Y. Heterocycles
2006, 67, 503.
(4) Bar, G. L. J.; Lloyd-Jones, G. C.; Booker-Milburn, K. I. J. Am. Chem.
Soc. 2005, 127, 7308.
(2)10,11 as the nitrogen source (Scheme 1). Generally, catalytic
intermolecular diamination of terminal olefins is still chal-
(7) Du, H.; Zhao, B.; Shi, Y. J. Am. Chem. Soc. 2007, 129, 762.
(8) For a related diamination of terminal olefins at allylic and homoallylic
carbons via C-H activation, see: Du, H.; Yuan, W.; Zhao, B.; Shi, Y. J.
Am. Chem. Soc. 2007, 129, 7496.
(9) Yuan, W.; Du, H.; Zhao, B.; Shi, Y. Org. Lett. 2007, 9, 2589.
(10) Greene, F. D.; Stowell, J. C.; Bergmark, W. R. J. Org. Chem. 1969,
34, 2254.
(11) For a leading review on diaziridinones, see: Heine, H. W. In The
Chemistry of Heterocyclic Compounds; Hassner, A., Ed.; John Wiley &
Sons, Inc.: New York, 1983; p 547.
(5) (a) Zabawa, T. P.; Kasi, D.; Chemler, S. R. J. Am. Chem. Soc.
2005, 127, 11250. (b) Zabawa, T. P.; Chemler, S. R. Org. Lett. 2007, 9,
2035.
(6) Streuff, J.; Ho¨velmann, C. H.; Nieger, M.; Mun˜iz, K. J. Am. Chem.
Soc. 2005, 127, 14586.
10.1021/ol702061s CCC: $37.00
© 2007 American Chemical Society
Published on Web 11/01/2007

lenging. Herein we wish to report our preliminary efforts
on this subject.
Table 1. Catalytic Diamination of Terminal Olefinsa
Initial studies were carried out with styrene as substrate
and di-tert-butyldiaziridinone (2) as nitrogen source. Little
diamination was observed with Pd(PPh3)4 as catalyst, but a
low yield of the diamination product was obtained when the
reaction was carried out with CuCl-P(OPh)3 as catalyst.
After much experimentation, the diamination was further
improved by using di-tert-butylthiadiaziridine 1,1-dioxide
(6)12 as the nitrogen source and CuCl-P(n-Bu)3 as the
catalyst in CDCl3 (Scheme 2). As shown in Table 1, various
Scheme 2
styrenes with different substituents can be diaminated
smoothly in moderate to good yields (Table 1, entries 1-9)
(the X-ray structure of compound 7h is shown in Figure 1).13
It appears that styrenes with electron-donating groups are
better substrates than those with electron-withdrawing groups.
Naphthylethene and various heteroarylethenes are also ef-
fective substrates (Table 1, entries 10-14). Certain enyne
and vinyl enol ether can also be diaminated (Table 1, entries
15 and 16). However, terminal olefins such as 1-octene and
ethyl acrylate are not effective substrates toward diamination.
The deprotection of diamination product 7 is illustrated
in Scheme 3. The tert-butyl groups of compound 7a were
smoothly removed with CF3CO2H at room temperature.
When 7a was treated with concentrated HCl and BaCO3 at
60 °C, both tert-butyl and sulfonyl groups were removed
cleanly.14
When deuterated styrene 10 was subjected to the diami-
nation condition, a mixture of two isomers (11a and 11b)
was obtained (Scheme 4). While a precise reaction mecha-
nism awaits further study, this diamination appears to proceed
via a radical mechanism as proposed previously9 (Scheme
(12) Prepared based on reported procedure: Timberlake, J. W.; Alender,
J.; Garner, A. W.; Hodges, M. L.; O¨ zmeral, C.; Szilagyi, S.; Jacobus, J. O.
J. Org. Chem. 1981, 46, 2082.
(13) A representative diamination procedure (Table 1, entry 1): To
a 1.5 mL vial equipped with a stirrer bar was added CuCl (0.008 g, 0.08
mmol). The sealed vial was evacuated and filled with Ar three times,
followed by addition of CDCl3 (0.1 mL) and tri-n-butylphosphine (0.020
mL, 0.08 mmol). After the mixture was stirred at room temperature for 10
min, styrene (5a) (0.042 g, 0.40 mmol) and di-tert-butylthiadiaziridine 1,1-
dioxide (6) (0.124 g, 0.60 mmol) were added (for solid olefins, they were
added together with CuCl). The reaction mixture was stirred at 50 °C for
24 h and purified by flash chromatography (silica gel, petroleum ether:
ethyl acetate:chloroform ) 15:1:1.5) to give the diamination product 7a as
a white solid (0.080 g, 65%).
(14) The deprotection with BaCO3‚HCl has also been investigated with
additional substrates. For example, both the tert-butyl and sulfonyl groups
of compound 7h were cleanly removed in 91% yield. Compound 7k was
deprotected in 70% yield with a slightly modified procedure (small amount
of ethanol was added to improve solubility of 7k and the reaction time was
extended to 24 h). However, compounds 7l-n decomposed under this
deprotection condition. For a reductive deprotection of sulfamide with
LiAlH4, see ref 5a.
a All reactions were carried out with olefin (0.4 mmol), di-tert-
butylthiadiaziridine 1,1-dioxide (6) (0.6 mmol), CuCl-P(n-Bu)3 (1:1) (0.08
mmol) in CDCl3 (0.1 mL) at 50 °C under argon for 24 h unless otherwise
stated. For entry 2, 7 h; for entry 15, 48 h at rt; for entry 16, 14 h at 65 °C
with olefin (0.6 mmol) and 6 (0.4 mmol) in an NMR tube without stirring.
b With CuCl-P(n-Bu)3 (1:1) (0.04 mmol). c In 0.2 mL of CDCl3. d Isolated
yield based on olefin except entry 16 where the yield is based on 6.
5). The CuCl probably first reduces the N-N bond of di-
tert-butylthiadiaziridine 1,1-dioxide (6) to form radical
4944
Org. Lett., Vol. 9, No. 24, 2007

Scheme 5. A Proposed Catalytic Cycle for Diamination
Figure 1. The X-ray structure of compound 7h.
In summary, diamination for a variety of conjugated
terminal olefins has been effectively achieved with CuCl as
catalyst and di-tert-butylthiadiaziridine 1,1-dioxide (6) as
nitrogen source under mild reaction conditions, providing
various 1,2-diamines that are present in various biologically
active compounds.20 The diamination is likely to proceed
via a nitrogen radical intermediate. Further studies of the
reaction mechanism, investigation of different catalysts and
nitrogen sources, and expansion of the substrate scope as
well as development of an asymmetric process are currently
underway.
species 12.15-18 Addition of 12 to olefin 5 forms radical
intermediate 13, which undergoes C-N bond formation to
Scheme 3
Acknowledgment. We are grateful for the generous
financial support from the Camille and Henry Dreyfus
Foundation and the Monfort Foundation (CSU).
Supporting Information Available: The diamination and
deprotection procedures, the characterization of diamination
products, and the X-ray data of compounds 7h along with
the 1H and 13C NMR spectra of 7, 8, 9, and 11. This material
is available free of charge via the Internet at http://pubs.acs.org.
give diamination product 7 and regenerates the CuCl
catalyst.19 The higher reactivities displayed with electron-
rich olefins (e.g., Table 1, entries 2 and 16) as compared to
OL702061S
(15) For a leading review on metal-promoted radical reactions, see: Iqbal,
J.; Bhatia, B.; Nayyar, N. K. Chem. ReV. 1994, 94, 519.
(16) For leading reviews on CuX-catalyzed atom transfer reactions see:
(a) Patten, T. E.; Matyjaszewski, K. Acc. Chem. Res. 1999, 32, 895. (b)
Clark, A. J. Chem. Soc. ReV. 2002, 31, 1.
Scheme 4
(17) For leading references on nitrogen-centered radicals, see: Stella,
L. In Radicals in Organic Synthesis; Renaud, P., Sibi, P., Eds.; Wiley-
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Lichtenfeld, C.; Grimme, S.; Studer, A. J. Am. Chem. Soc. 2007, 129, 4498.
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Laaman, S. M. Synthesis 2006, 1981.
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D. A. Org. Lett. 2002, 4, 941. (c) Kumar, V.; Guo, D.; Cassel, J. A.; Daubert,
J. D.; DeHaven, R. N.; DeHaven-Hudkins, D. L.; Gauntner, E. K.; Gottshall,
S. L.; Greiner, S. L.; Koblish, M.; Little, P. J.; Mansson, E.; Maycock, A.
L. Bioorg. Med. Chem. Lett. 2005, 15, 1091.
electron-poor olefins are consistent with the electrophilic
nature of nitrogen radical 12.17
Org. Lett., Vol. 9, No. 24, 2007
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