LETTER
Novel Preparation and Reactivity of Poly[4-hydroxy(tosyloxy)iodo]styrenes
23
Table 2 Oxidative a-Tosyloxylation of Alcohols
droxy(tosyloxy)iodo]styrene (0.53 g). The mixture was
refluxed for 1.5 h under argon atmosphere. A mixture of
hexane (15 ml) and chloroform (15 ml ) was added to the
reaction mixture and the solution was filtered. Here, the
formed poly(4-iodo)styrene was recovered as a solid
quantitatively. The filtrate was evaporated and the residue
was chromatographed on silica gel using a mixture of hex-
ane and ethyl acetate (4 / 1) as an eluent to give 3-tosylox-
ypentane-2,4-dione in 66% yield.
OH
O
I(III) (2.0 eq.)
CHCl3, reflux
R'
R'
OTs
R
R
I(III)
PS
Yields (%)
PMS
PhI(OH)OTs
I(OH)OTs
I(OH)OTs
Product
O
OTs
Typical Procedure 2: To a solution of a-methylbenzylal-
cohol in chloroform (3 ml) was added poly[4-hydroxy(to-
syloxy)iodo]styrene (0.88 g). The mixture was refluxed
for 16 h under argon atmosphere. A mixture of hexane (15
ml) and chloroform (15 ml ) was added to the reaction
mixture and the solution was filtered. The formed poly(4-
iodo)styrene was again recovered as a solid quantitatively.
The filtrate was evaporated and the residue was chromato-
graphed on silica gel using a mixture of hexane and ethyl
acetate (4 / 1) as an eluent to give a-tosyloxyacetophenone
in 80% yield.
35
40
80
94
94
86
O
OTs
Me
O
OTs
0
33
42
Acknowledgement
In these reactions, the reaction mixtures became homoge-
neous solutions at refluxing conditions in acetonitrile and
Financial support from The Research Center of Taiho Pharmaceuti-
cal Co. is gratefully acknowledged. We thank Prof. Choji Kashima
chloroform, respectively. However, after the reactions of Tsukuba University for the elemental analysis.
with poly[4-hydroxy(tosyloxy)iodo]styrene and poly{a-
methyl[4-hydroxy(tosyloxy)iodo]styrene}, the formed
poly(4-iodo)styrene and poly[a-methyl(4-iodo)styrene]
were quantitatively recovered, respectively, by the addi-
tion of a mixture of hexane and chloroform (1 / 1), or
ether. Here, the recovered poly(4-iodo)styrene and
poly[a-methyl(4-iodo)styrene] were again oxidized to
poly[4-(diacetoxy)iodo]styrene and poly{a-methyl[4-(di-
acetoxy)iodo]styrene} with peracetic acid and then con-
verted to poly[4-hydroxy(tosyloxy)iodo]styrene and
References and Notes
(1) Varvoglis A.; Hypervalent Iodine in Organic Synthesis,
Academic Press, San Diego (1997). Recent reviews: Ochiai,
M. Rev. Heteroatom Chem. 1989, 2, 92; Moriarty, R. M.;
Vaid, R. K.; Koser, G. F. Synlett 1990, 365; Moriarty, R. M.;
Vaid, R. K. Synthesis 1990, 431; Stang, P. J.; Angew. Chem.
Int. Ed. Engl. 1992, 31, 274; Prakash, O.; Saini, N.; Sharma,
P. K. Synlett 1994, 221; Kitamura, T. Yuki Gosei Kagaku
Kyokaishi 1995, 53, 893; Stang, P. J.; Zhdankin, V. V. Chem.
Rev. 1996, 96, 1123; Umemoto, T. Chem. Rev. 1996, 96,
1757; Kita, Y.; Takada, T.; Tohma, H. Pure Appl. Chem.
1996, 68, 627; Togo, H.; Hoshina, Y.; Nogami, G.;
Yokoyama, M. Yuki Goesi Kagaku Kyokaishi 1997, 55, 90;
Varvoglis, A. Tetrahedron 1997, 53, 1179; Zhdankin, V. V.
Rev. Heteroatom Chem. 1997, 17, 133; Kitamura, T.;
Fujiwara, Y. Org. Prep. Proced. Int. 1998, 29, 409; Varvoglis,
A.; Spyroudis, S. Synlett 1998, 221; Moriarty, R. M.; Prakash,
O. Adv. Heterocycl. Chem. 1998, 69, 1.
poly{a-methyl[4-hydroxy(tosyloxy)iodo]styrene},
re-
spectively. These regenerated polymer reagents showed
the same reactivity as in the first use with poly[4-hy-
droxy(tosyloxy)iodo]styrene and poly{a-methyl[4-hy-
droxy(tosyloxy)iodo]styrene} in the a-tosyloxylation of
ketones.
Ultrasonic enhancement of a-tosyloxylation of ketones
with the present polymer reagents was not observed,
though a-tosyloxylation of ketones with [hydroxy(tosyl-
oxy)iodo]benzene was accelerated by ultrasonic irradia-
tion.7
(2) Togo, H.; Nogami, G.; Yokoyama, M. Synlett 1998, 534;
Togo, H.; Abe, S.; Nogami, G.; Yokoyama, M. Bull. Chem.
Soc. Jpn. 1999, 72, 2351.
(3) Ley, S. V.; Thomas, A. W.; Finch, H. J. Chem. Soc., Perkin
Trans. 1 1999, 669; Tohma, H.; Takizawa, S.; Maegawa, T.;
Kita, Y. Angew. Chem. Int. Ed. 2000, 39, 1306.
(4) Koser, G. F.; Relenyi, A. G.; Kalos, A. N.; Rebrovic, L.;
Wettach, R. H. J. Org. Chem. 1982, 47, 2487: Rebrovic, L.;
Koser, G. F.; J. Org. Chem. 1984, 49, 2462; Vasudevan, A.;
Koser, G. F.; J. Org. Chem. 1988, 53, 5158; Moriarty, R. M.;
Vaid, R. K.; Koser, G. F. Synlett 1990, 365; Prakash, O.; Saini,
N.; Sharma, P. K. Synlett 1994, 221.
(5) Poly[4-hydroxy(tosyloxy)iodo]styrene (high M.W.) and
poly{a-methyl[4-hydroxy(tosyloxy)iodo]styrene} (low
M.W.) were prepared through the iodination of polystyrenes
[average M.W. = 45,000; IR(KBr) : 700 and 760 cm-1] and
poly(a-methylstyrene) [average M.W. = 6,200; IR(KBr):
In conclusion, poly[4-hydroxy(tosyloxy)iodo]styrene and
poly{a-methyl[4-hydroxy(tosyloxy)iodo]styrene} have
enough reactivity for the a-tosyloxylation of ketones and
oxidative a-tosyloxylation of alcohols; moreover, these
polymer reagents can be regenerated and reused as envi-
ronmentally benign reagents. Study of further elaboration
with poly[4-hydroxy(tosyloxy)iodo]styrene and poly{a-
methyl[4-hydroxy(tosyloxy)iodo]styrene} is now under
way in this laboratory.
Typical Procedure 1: To a solution of acetylacetone (0.5
mmol) and acetonitrile (5 ml) was added poly[4-hy-
Synlett 2001, No. 1, 22–24 ISSN 0936-5214 © Thieme Stuttgart · New York
Abe
