Table 3 Formation of N-substituted quaternary centres
Producta
3 For a review of hydrofunctionalisation of multiple bonds, see
(a) A. S. K. Hashmi and M. Buehrle, Aldrichim. Acta, 2010,
43, 27; for reviews of nucleophilic cyclisation of allenes, see
(b) N. Nishina and Y. Yamamoto, Tetrahedron, 2009, 65, 1799 and
(c) N. Krause and C. Winter, Chem. Rev., 2011, 111, 1994; for a review
of gold-catalysed hydroamination, see (d) R. A. Widenhoefer and
X. Han, Eur. J. Org. Chem., 2006, 20, 4555. For a relevant example,
see (e) N. T. Patil, L. M. Lutete, N. Nishina and Y. Yamamoto,
Tetrahedron Lett., 2006, 47, 4749.
Entry Sulfamate
Yield (%)
92%
1
4 The Rh-nitrene chemistry of such compounds has been investi-
gated and products arising from formation of a metal-stabilised
2-aminoallyl intermediate predominate, in contrast to our work.
See G. C. Feast, L. W. Page and J. Robertson, Chem. Commun.,
2010, 46, 2835.
2
3
68%
37%
5 Allenic alcohols were prepared either by Johnson-Claisen rearran-
gements of the corresponding propargyl alcohols, see (a) S. Ma and
W. Gao, J. Org. Chem., 2002, 67, 6104 or alternatively by Crabbe
´
homologation of homopropargyl alcohols see (b) B. M. Trost,
A. B. Pinkerton and M. Seidel, J. Am. Chem. Soc., 2001,
123, 12466. Sulfamate formation was conducted according to
standard procedures, see (c) C. G. Espino, P. M. Wehn, J. Chow
and J. Du Bois, J. Am. Chem. Soc., 2001, 123, 6935.
6 N. Mezailles, L. Ricard and F. Gagosz, Org. Lett., 2005, 7, 4133.
´
7 A. S. K. Hashmi, Gold Bull., 2004, 37, 51.
8 Reaction times were between 24–120 h, see supporting
information.
9 The 1H NMR signals in the olefinic region of the spectra differ
consistently for the cis and trans 1,3-isomers; see ESIw for details.
10 For lead references and mechanistic studies, see (a) K. Williams Fiori,
C. G. Espino, B. H. Brodsky and J. Du Bois, Tetrahedron, 2009,
65, 3042. For recent work targeted at allylic C–H nitrene insertion
using sulfamidates, see (b) E. Milczek, N. Boudet and S. Blakey,
Angew. Chem., Int. Ed., 2008, 47, 6825; (c) M. E. Harvey,
D. G. Musaev and J. Du Bois, J. Am. Chem. Soc., 2011, 133, 17207
(Ru catalysis) and (d) S. M. Paradine and M. C. White, J. Am. Chem.
Soc., 2012, 134, 2036 (Fe catalysis). Notably, there are no examples of
insertion into tertiary allylic C–H bonds in these reports.
4
90%
5
Traceb
11 For mechanistic studies, see (a) Z. Zhang, C. Liu, R. E. Kinder,
X. Han, H. Qian and R. A. Widenhoefer, J. Am. Chem. Soc., 2006,
128, 9066; (b) Z. Zhang and R. A. Widenhoefer, Org. Lett., 2008,
10, 2079; (c) J. J. Kennedy-Smith, S. T. Staben and F. D. Toste,
J. Am. Chem. Soc., 2004, 126, 4526; (d) J. Zhang, C.-G. Yang and
C. He, J. Am. Chem. Soc., 2006, 128, 1798; (e) A. S. K. Hashmi,
J. P. Weyrauch, W. Frey and J. W. Bats, Org. Lett., 2004, 6, 4391;
(f) Y. Liu, F. Song, Z. Song, M. Liu and B. Yan, Org. Lett., 2005,
7, 5409.
12 Diastereoselectivities for Au-catalysed exo-hydroamination to give
6-membered rings typically vary from 4 : 1 to 7 : 1. See ref. 11a.
13 Fluxionality of an Au(I)-allene complex: T. J. Brown, A. Sugie,
M. G. D. Leed and R. A. Widenhoefer, Chem.–Eur. J., 2012, 18, 6959.
14 There are only a few examples of hydroamination to form
C-tertiary amines; none involves a 6-exo-trig cyclisation, see
(a) R. E. Kinder, Z. Zhang and R. A. Widenhoefer, Org. Lett.,
2008, 10, 3157; (b) C. Winter and N. Krause, Angew. Chem., Int.
Ed., 2009, 48, 6339; (c) R. L. Lalonde, Z. J. Wang, M. Mba,
A. D. Lackner and F. D. Toste, Angew. Chem., Int. Ed., 2010,
49, 598.
a
b
5 mol% Ph3PAuNTf2, DCM, r.t. 24–120 h, see ESI. B3% of 90%
pure product isolated.
Further studies on the scope and limitations of this reaction
will be reported in due course. Development of an asymmetric
version of this process and other metal-catalysed reactions of
sulfamates are also underway in our laboratories.
The authors thank the EPSRC (for a DTA to M.C.M.H.),
the EPSRC National Mass Spectrometry Service for mass
spectra, Dr G. M. Rosair for assistance with X-ray crystallo-
graphy and Dr A.-L. Lee for helpful discussions.
Notes and references
z X-ray crystallographic data for cis-2 (CCDC 871548): C11H19NO3S,
M = 245.33, monoclinic, a = 19.8419(15), b = 5.3049(4), c =
11.5941(9), b = 90.646(4), V = 1220.31(16) A3, T = 100(2)K, space
group P21/c, Z = 4, Mo-Ka radiation (l = 0.71073 A), GOF =
1.049, agreement index R1 = 0.0329, 27 110 reflections measured, 4215
unique(Rint = 0.0325) which were used in all calculations. The final
oR(F2) was 0.890.
15 For relevant reviews, see (a) M. Shibasaki and M. Kanai, Chem.
Rev., 2008, 108, 2853 and (b) J. Clayden, M. Donnard, J. Lefranc
and D. J. Tetlow, Chem. Commun., 2011, 47, 4624.
16 For a review of asymmetric catalysis with gold complexes, see
A. Pradal, P. Y. Toullec and V. Michelet, Synthesis, 2011, 1501.
17 For examples of catalytic asymmetric hydroamination of allenes,
see (a) R. L. Lalonde, B. D. Sherry, E. J. Kang and F. D. Toste,
J. Am. Chem. Soc., 2007, 129, 2452; (b) Z. Zhang, C. F. Bender and
R. A. Widenhoefer, Org. Lett., 2007, 9, 2887; (c) K. L. Butler,
M. Tragni and R. A. Widenhoefer, Angew. Chem., Int. Ed., 2012,
51, 5175. See also ref. 14b and c.
1 For a recent review, see J. F. Bower, J. Rujirawanich and
T. Gallagher, Org. Biomol. Chem., 2010, 8, 1505.
2 For a review of C–H amination, see D. N. Zalatan and J. Du Bois,
Top. Curr. Chem., 2010, 292, 347.
c
This journal is The Royal Society of Chemistry 2012
Chem. Commun., 2012, 48, 7565–7567 7567