Synthesis of 1,1′-binaphthyl-2,2′-diyl phosphoroselenoic ammonium salts and their conversion to optically active dialkyl diselenides

Article abstract of DOI:10.1246/cl.2007.852

Optically pure phosphoroselenoyl chloride reacted with Et₃N in the presence of H₂O to give a phosphoroselenoic tertiary ammonium salt. Formation of the salt was confirmed by X-ray molecular structure analysis. The quaternary ammonium salt was prepared by reacting phosphoroselenoic acid O-2-silylethyl ester with Bu₄NF. The alkylation of tertiary ammonium salt with racemic alkyl halides gave phosphoroselenoic acid Se-esters as diastereomeric mixtures. The cleavage of Se-esters with Bu₄NF gave optically active dialkyl diselenides. Copyright

Full text of DOI:10.1246/cl.2007.852

852
Chemistry Letters Vol.36, No.7 (2007)
Synthesis of 1,10-Binaphthyl-2,20-diyl Phosphoroselenoic Ammonium Salts
and Their Conversion to Optically Active Dialkyl Diselenides
Toshiaki Murai,ꢀ Masaki Monzaki, and Fumitoshi Shibahara
Department of Chemistry, Faculty of Engineering, Gifu University, Yanagido, Gifu 501-1193
(Received April 24, 2007; CL-070448; E-mail: mtoshi@gifu-u.ac.jp)
E =Se
+
Optically pure phosphoroselenoyl chloride reacted with
Se
P
NBu
4
E' = O
O
O
Et3N in the presence of H2O to give a phosphoroselenoic tertiary
ammonium salt. Formation of the salt was confirmed by X-ray
molecular structure analysis. The quaternary ammonium salt
was prepared by reacting phosphoroselenoic acid O-2-silylethyl
ester with Bu4NF. The alkylation of tertiary ammonium salt with
racemic alkyl halides gave phosphoroselenoic acid Se-esters as
diastereomeric mixtures. The cleavage of Se-esters with Bu4NF
gave optically active dialkyl diselenides.
–
O
75%
4
E
P
Bu NF
4
O
O
E'R
THF
E =O
E' = Se
OH
OH
3a E = Se, E' = O
3b E = O, E' = Se
+
(Me SiCH CH Se)
2
3
2
2
5
83%
R = CH CH SiMe
3
2
2
Scheme 2.
as a byproduct. Initially, a similar reaction of 3b and Bu4NF
leading to 4 was expected. However, in the latter case, diselenide
5 was exclusively obtained along with 1,10-binaphthyl-2,20-diol.
The selective cleavage of P–Se and P–O bonds takes place rather
than desilylation. To the best of our knowledge, this is the first
example of fluoride anion-mediated hydrolysis of phosphoro-
selenoic acid Se-esters, although precedents regarding the substi-
tution reaction of esters with fluoride ions have been reported.10
These critical differences in the reaction course may be due to
the subtle differences in the dissociation energies of these bonds
(P–O: 599.1 ꢁ 12.6 kJ/mol, P–Se: 363 ꢁ 10.0 kJ/mol, P–F:
439 ꢁ 96 kJ/mol, Si–F: 552.7 ꢁ 2.1 kJ/mol).11
Intensive studies on optically active phosphoric acids bear-
ing a 1,10-binaphthyl-2,20-diyl group have recently been per-
formed, and particularly on their use as organocatalysts.1 Sulfur
isologues of phosphoric acids have also been prepared by react-
ing 1,10-binaphthyl-2,20-diol with thiophosphoryl chloride2 or
phosphorus pentasulfide.3 The acids obtained are used to prepare
optically active organosulfur compounds.2,4 In contrast, no ex-
amples of the selenium isologues of phosphoric acids and salts
have been reported, although several types of phosphoroselenoic
acid salts bearing alkyl or phenyl groups on the oxygen atom
have been prepared, and their reactivity has been elucidated.5
During the course of our studies on the compounds bearing
P=Se bonds,6 we recently found that phosphoroselenoyl chlo-
ride 1 could be used as a new molecular tool to discriminate rac-
emic alcohols and to obtain optically active alcohols, amines,
and phosphoramidites.7 We report here the synthesis of optically
pure phosphoroselenoic acid salts from 1 and their reactions
with racemic alkyl halides. A new method for preparing optical-
ly active dialkyl diselenides is also described.
The signals due to the phosphorus atoms in 2 and 4 were
observed at ꢀ 62.1 and 58.4, respectively, in 31P NMR spectra,
whereas 77Se NMR spectra showed signals at ꢀ ꢂ234:95 and
ꢂ217:9. The coupling constants between the phosphorus and
selenium atoms in 2 and 4 were 878.4 and 854.0 Hz; i.e. larger
than the value of the Se-ester 3b (572.4 Hz), and smaller
than that of O-ester 3a (1012.5 Hz). These results suggest that
the phosphorus–selenium bonds in salts 2 and 4 possess
double-bond character to some extent.
Alkylation of the salt 2 was carried out and the results
are shown in Table 1. In all cases, alkylation took place at the
selenium atom of the salt 2. The formation of Se-esters 7 was
confirmed by 31P and 77Se NMR spectra and by the coupling
constants between phosphorus and selenium atoms. The 2-bu-
tenylation of 2 with 6a was complete within 4 h at rt (Entry 1),
whereas the reaction of 2 with cyclohexenyl bromide (6b)
required reflux temperature in CH2Cl2. Similarly, the reaction
of 2 with 1-phenethyl bromide (6c), 2-naphthylethyl bromide
(6d), 2-bromobutane (6e), and ꢁ-bromopropionic acid ester 6f
was carried out under reflux in CH2Cl2 or toluene. The reaction
of racemic alkyl halides 6b–6f gave the diastereomeric mixtures
of 7b–7f in almost equal ratios. These diastereomers were discri-
minated by 31P and 77Se NMR spectra. Some of the diastereom-
ers were separated by the fractional recrystallization. For 7c,
diastereomers were separated by HPLC.
+
Se
P
Se
P
Et N, H O
HNEt
O
O
3
2
3
O
O
O
O
O
O
–
=
O
Cl
THF
reflux, 2 h
2
98%
(S )-1
ax
Scheme 1.
The reaction of chloride 1 with Et3N (3 equiv.) and H2O (2
equiv.) went to completion within 2 h under reflux in THF to
give tertiary salt 2 in 98% yield as a white solid (Scheme 1).8
Formation of the salt 2 was confirmed by X-ray structure analy-
sis.9 The salt 2 was highly soluble in CH2Cl2, but less soluble
in THF and toluene.
Alternatively, the quarternary ammonium salt 4 was synthe-
sized by reacting phosphoroselenoic O-2-(trimethylsilyl)ethyl
ester 3a8 with Bu4NF. Elimination of a silyl group and ethylene
from 3a proceeded smoothly to give the corresponding salt 4
in 75% yield (Scheme 2).
Finally, the cleavage of phosphoroselenoic acid Se-esters 7
was carried out with Bu4NF, as found in Scheme 2. Diastereo-
merically pure ester 7c was treated with Bu4NF (1.5 equiv.) in
During the synthesis of 3a, Se-ester 3b8 was also formed
Copyright Ó 2007 The Chemical Society of Japan

Chemistry Letters Vol.36, No.7 (2007)
853
Table 1. Reaction of phosphoroselenoic acid salt 2 with alkyl
halidesa
This paper is dedicated to the memory of Professor
Yoshihiko Ito.
+
O
P
7
Se
P
HNEt
3
O
O
References and Notes
1
O
O
–
+
RX
6
SeR
O
For recent examples: a) M. Terada, K. Machioka, K. Sorimachi,
Angew. Chem., Int. Ed. 2006, 45, 2254. b) M. Rueping, A. P.
Antonchick, T. Theissmann, Angew. Chem., Int. Ed. 2006, 45,
3683. c) J. Itoh, K. Fuchibe, T. Akiyama, Angew. Chem., Int.
Ed. 2006, 45, 4796. d) T. Akiyama, H. Morita, K. Fuchibe,
J. Am. Chem. Soc. 2006, 128, 13070. e) S. Hoffmann, M.
Nicoletti, B. List, J. Am. Chem. Soc. 2006, 128, 13074. f)
X.-H. Chen, X.-Y. Xu, H. Liu, L.-F. Cun, L.-Z. Gong, J. Am.
Chem. Soc. 2006, 128, 14802. g) M. Rueping, A. P. Antonchik,
T. Theissmann, Angew. Chem., Int. Ed. 2006, 45, 6751. h) H.
Liu, L.-F. Cun, A.-Q. Mi, Y.-Z. Jiang, L.-Z. Gong, Org. Lett.
2006, 8, 6023. i) M. Rueping, C. Azap, Angew. Chem., Int.
Ed. 2006, 45, 7832. j) I. D. Gridnev, M. Kouchi, K. Sorimachi,
M. Terada, Tetrahedron Lett. 2007, 48, 497. k) M. Terada, K.
Sorimachi, J. Am. Chem. Soc. 2007, 129, 292.
2
6c R' = Ph
6d
6e
6f
2-naphthyl
Et
Br
6b
Br
R'
Br
6a
RX Temp
C(O)OEt
31
77
1
J
/Hz
Product
Yield/%
P NMR Se NMR
P−Se
Entry
b
6
Time/h
δ
δ
O
c
rt
4
6a
1
31.4
200.1 561.5
O
O
P
Se
7a 63%
O
O
d
262.3 579.5
269.9 573.4
reflux
2
32.2
6b
6c
6d
6e
6f
2
P
Se
O
7b 93%
2
3
D. Fabbri, G. Delogu, O. D. Lucchi, Tetrahedron: Asymmetry
1993, 4, 1591.
a) B.-Q. Gong, W.-Y. Chen, B.-F. Hu, Phosphorus, Sulfur
Silicon 1991, 57, 87. b) W. Perlikowska, M. Gouygou, M.
Mikolajczyk, J.-C. Daran, Tetrahedron: Asymmetry 2004, 15,
3519.
O
O
d
reflux
12
31.3
31.4
337.1 567.2
343.9 555.1
P
Se
O
3
Ph
7c 73%
O
d
O
O
reflux
12
4
5
P. Biscarini, J. Drabowicz, J. Luczak, M. Mikolajczyk, Phos-
phorus, Sulfur Silicon 1999, 153–154, 365.
31.3
31.4
336.8 567.6
341.1 555.4
4
P
Se
7d 77%
For recent examples: a) G. Mielniczak, A. Lopusinski,
Heteroat. Chem. 2003, 14, 121. b) Q. Xiao, J. Yong, Y. Zhao,
Synth. Commun. 2003, 33, 4157. c) L. A. Wozniak, J. Organo-
met. Chem. 2004, 689, 2745. d) J. Rachon, G. Cholewinski, D.
Witt, Chem. Commun. 2005, 2692. e) P. Guga, A. Maciaszek,
W. J. Stec, Org. Lett. 2005, 7, 3901. f) G. A. Savin, O. M.
Kutsemako, Russ. J. Bioorg. Chem. 2005, 31, 372. g) G. A.
Savin, E. A. Kamneva, Russ. J. Org. Chem. 2005, 41, 962.
h) M. Kullberg, J. Stawinski, Nucleosides, Nucleotides &
Nucleic Acids 2005, 24, 659.
For a review: T. Murai, T. Kimura, Curr. Org. Chem. 2006, 10,
1963.
a) T. Murai, D. Matsuoka, K. Morishita, J. Am. Chem.
Soc. 2006, 128, 4584. b) T. Murai, S. Inaji, K. Morishita, F.
Shibahara, M. Tokunaga, Y. Obora, Y. Tsuji, Chem. Lett.
2006, 35, 1424.
O
O
e
reflux
10
32.1
32.2
249.1 561.2
252.3 561.2
5
P
O
Se
7e 80%
O
O
e
reflux
4
29.7
29.9
289.1 524.6
296.5 530.7
6
P
OEt
O
Se
7f 81%
O
aThe salt 2 was reacted with alkyl halide 6 (1–5 equiv.) in an
apporpriate solvent unless otherwise noted. bIsolated yield.
6
7
cTHF was used as a solvent. CH2Cl2 was used as a solvent.
d
eToluene was used as a solvent.
O
O
O
Bu NF
4
*
*
*
P
Se
Ph
Ph
Se Se Ph
8
9
For spectroscopic properties of the new compounds, see the
Supporting Information.12
For the detail of X-ray molecular structure analysis, see
Supporting Information.12
THF
0 °C – rt, 1.5 h
7c
>99%de
8
81%
20
20
D
[ ]
α
D
= +85 (c = 1, CHCl )
[ ]
α
= -207 (c = 0.75, CHCl )
3
3
10 K. Misiura, D. Szymanowicz, H. Kusnierczyk, Bioorg. Med.
Chem. 2001, 9, 1525.
Scheme 3.
11 CRC Handbook of Chemistry and Physics, ed. by D. R. Lide,
CRC Press, Boca Raton, 2001–2002.
THF for 1.5 h to give optically active diselenide 8 in 81%
yield,12 although the absolute configuration of 8 has not yet been
determined (Scheme 3).
In summary, we have demonstrated the synthesis and alkyl-
ation of the phosphoroselenoic acid salt bearing a 1,10-binaph-
thyl-2,20-diyl group. The separation and cleavage of the resulting
esters have provided a new route to optically active dialkyl dis-
elenides, which are not readily accessible by known methods.13
12 Supporting Information is available electronically on the CSJ
Journal web site: http://www.csj.jp/journals/chem-lett/.
13 For recent examples of dialkyl diselenides bearing chiral
centers adjacent to the selenium atoms: a) M. Tiecco, L.
Testaferri, L. Bagnoli, C. Scarponi, V. Purgatorio, A.
Temperini, F. Marini, C. Santi, Tetrahedron: Asymmetry
2005, 16, 2429. b) N. Chakka, B. D. Johnston, B. M. Pinto,
´
´
Can. J. Chem. 2005, 83, 929. c) J. Scianowski, Z. Rafinski,
A. Wojtczak, Eur. J. Org. Chem. 2006, 3216. d) P. Skowronek,
J. Scianowski, J. Gawronski, Tetrahedron: Asymmetry 2006,
17, 2408. e) M. Tiecco, L. Testaferri, L. Bagnoli, C. Scarponi,
A. Temperini, F. Marini, C. Santi, Tetrahedron: Asymmetry
2006, 17, 2768.
This work was supported in part by Grant-in-Aid for Scien-
tific Research on Priority Area (No. 19027021, ‘‘Synergy of
Elements’’) from the Ministry of Education, Culture, Sports,
Science and Technology, Japan. AIR WATER INC. kindly
provided the optically active 1,10-binaphtyl-2,20-diol.
Published on the web (Advance View) June 2, 2007; doi:10.1246/cl.2007.852