A new access to the synthesis of optically pure β-aminosulfides

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Phosphorus, Sulfur, and Silicon
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A New Access to the
Synthesis of Optically Pure β-
Aminosulfides
Y. Arroyo a , A. Meana a , J. F. Rodríguez a , M.
Santos a , M. A. Sanz-Tejedor a & J. L. García Ruano
b
a Departamento de Química Orgánica, E.T.S.I.I.
Universidad de Valladolid , Valladolid, Spain
b Departamento de Química Orgánica, Universidad
Autónoma de Madrid , Cantoblanco, Madrid, Spain
Published online: 16 Aug 2006.
To cite this article: Y. Arroyo , A. Meana , J. F. Rodríguez , M. Santos , M. A. Sanz-
Tejedor & J. L. García Ruano (2005) A New Access to the Synthesis of Optically Pure
β-Aminosulfides, Phosphorus, Sulfur, and Silicon and the Related Elements, 180:5-6,
1491-1492, DOI: 10.1080/10426500590913320
To link to this article: http://dx.doi.org/10.1080/10426500590913320
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Phosphorus, Sulfur, and Silicon, 180:1491–1492, 2005
Copyright © Taylor & Francis Inc.
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500590913320
A New Access to the Synthesis of Optically Pure
β-Aminosulfides
Y. Arroyo
A. Meana
J. F. Rodrıguez
´
M. Santos
M. A. Sanz-Tejedor
Departamento de Qu´ımica Orga´nica, E.T.S.I.I. Universidad de
Valladolid, Valladolid, Spain
´
J. L. Garcıa Ruano
Departamento de Qu´ımica Orga´nica, Universidad Auto´noma de Madrid,
Cantoblanco, Madrid, Spain
Keywords 1,2-Aminosulfides; α-sulfinylbenzyl carbanions
The significance of enantiomerically pure β-aminosulfides as chiral
building blocks1 and their use as effective chiral ligands in enantiose-
lective reactions,2 underlies the importance of developing new methods
for their synthesis as single enantiomers.
We present herein a new route to synthetically useful chi-
ral β-aminosulfides 3, based on the reaction of the lithium
α-sulfenylcarbanion Li-1 (derived from enantiomerically pure (S)-
ortho-2-p-tolylsulfinyl-α-thiomethyltoluene 1) with several (S)-N-p-
toluensulfinylimines 2. As in the case of other previously studied
ortho-sulfinyl benzyl carbanions,3 reactions take place in high yields
Received July 9, 2004; accepted October 5, 2004.
Address correspondence to Y. Arroyo, Departamento de Qu´ımica Orga´nica, E.T.S.I.I.
Universidad de Valladolid, 47011-Valladolid, Spain. E-mail: yarroyo@dali.eis.uva.es
1491

1492
Y. Arroyo et al.
TABLE I Lithiation and Subsequent
Electrophilic Substitution of (S)-1
with (S)-N-sulfinylimines 2a–h
Isolated
Products
R
yield (%) de (%)
3a
3b
3c
3d
3e
3f
Ph
85
78
72
60
70
55
50
70
>98
>98
>98
>98
>98
>98
>98
>98
o-BrC6H4
p-MeOC6H4
p-CNC6H4
2-Naphthyl
i-Pr
3g
3h
n-Pr
n-Bu
and in a completely stereoselective way (only the anti β-aminosulfides
1
are formed in <98% de, measured by H-NMR). It is remarkable that
only using clear solutions of n-BuLi to prepare LDA, one diastereoiso-
mer was formed in reactions from 3g and 3h (Table I).
The α-sulfenyl carbanion Li-1 is configurationally unstable according
to the Hoffmann rule.4 Thus, the high level of stereoselectivity achieved
in these processes should arise through a dynamic kinetic resolution.
Chemical manipulation of compounds 3 have allowed us to obtain a
wide variety of enantiomerically pure anti-1,2-diaryl (or 1-alkyl-2-aryl)
2-(methylthio)ethylamines and derivatives.
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