A polar cycloaddition of 2-thianaphthylium ions with 1,3-dienes and some properties of the cycloadducts

Article abstract of DOI:10.1016/0040-4039(91)80086-L

2-Thianaphthylium ions (1) underwent a polar cycloaddition with 1,3-dienes to afford benzo-fused bicyclic sulfonium salts (2) bearing sulfur atom at bridge-head in excellent yields. The cycloadducts underwent retro-addition reaction to generate the cation

Full text of DOI:10.1016/0040-4039(91)80086-L

Tetrah%dron Letters. Vol.32, No 40, pp 5571-5574, 1991
Printed m Great Britain
0040-4039191 $3.00 +
Pergamon Press pie
A
Polar Cycloaddition of 2-Thianaphthylium Ions with 1,3-Dienes and Some Properties of
the Cycloadducts
H l r o s h l Shimizu, S h o J i r o Miyazaki, Tadashi Kataoka, and Mikio Hori ~
Gifu P h a r m a c e u t i c a l U n i v e r s i t y , 6-1, Mltahora-hlgashi 5-chome, Gifu 502, Japan
Key Words: Polar Cycloaddltion; 2-Thlanaphthylium Ion; Bicyclic Sulfonium Salt; 1,3-
Dienes; Heterodlenophiles
A b s t r a c t : 2-Thianaphthylium ions (1) underwent
a f f o r d benzo-fused b i c y c l l c sulfonium s a l t s (2) b e a r i n g s u l f u r atom at b r i d g e - h e a d in
e x c e l l e n t y i e l d s . The c y c l o a d d u c t s underwent r e t r o - a d d i t i o n r e a c t i o n to g e n e r a t e the
c a t i o n (1), which was e a s i l y t r a p p e d with o t h e r d i e n e . R e a c t i o n of the a d d u e t (2d) with
a p o l a r c y c l o a d d l t i o n with 1 , 3 - d i e n e s to
s e v e r a l n u c l e o p h i l e s c a u s e d t h e r i n g - o p e n i n g of (2d) to a f f o r d 1 - a l l y l (6) and 1-
homoallyl s u b s t i t u t e d 2-thiochromenes (7) in good y i e l d s .
Hetero Diels-Alder reaction is
a
potentially powerful synthetic tool for the
a-Thlocarbocatlons (A) were used as sulfur-
construction of heterocyclic compounds. 1
containing heterodienophiles to conjugated dienes to provide [2*÷ 4] type polar
cycloaddition products (B). 2 We have examined the reaction of quasi-aromatic ring
compounds, thiopyrylium ion derivatives with 1,3-dienes in the hope that
addition might occur, because these cations have the e-thiocarbocation structure as one
of cannonical structures. In this communication, we wish to describe our findings that
2-thianaphthyllum ions underwent readily polar cycloaddition with several types of 1,3-
dienes to afford benzo-fused bicycllc sulfonium salts as isolable compounds.
a [2÷+ 4]cyclo-
a
(A)
(B)
The addition of 2-thlanaphthyllum tetrafluoroborate (la) 3 to two equivalents of 2,3-
dimethyl-l,3-butadiene, isoprene, and 1,3-butadlene in dry 1,2-dlchloroethane at room
temperature and stirring for 10-60 min afforded clear solution, from which the
a
cycloadducts (2) were precipitated in fairly good yields by adding dry ether (Scheme i).
Cycloadditlon of isoprene proceeded regiospeclflcally to give only single adduct (2b).
The structures of these cycloadducts were determined on the basis of several
spectroscopic data. 4 The reaction conditions, yields and physical data are summarized in
Table i.
Prolonged reaction time caused the yield decrease of the cycloadduct, forming
undetermined complex mixture probably because of some decomposition of the product {Run
5571

72
R I
R2
r
Scheme
1
s o l v e n t ,
t
BF 4
(1)
Q
R:H
(2)
b. R:COPh
T a b l e 1. Pota r C y c l o a d d l t J o n of 2 - T h l a n a p h t h y t t u m S a l t s (1) w~th 1 , 3 - O l e n e s
p r o d u c t
run
R
R I
R2
s o l v e n t 1)
t l m e ( m r n )
X
Y i e l d
mP (°C)
1
2
3
4
5
8
7
8
g
H
H
H
H
COPh
COPh
COPh
COPh
COPh
COPh
He
He
He
H
He
He
He
He
H
He
He
H
A
A
A
A
A
B
A
8
10
40
10
60
t5
15
15
15
30
30
2a
2a
2b
2c
2d
2d
2e
2e
2f
7g
41
80
7g
98
87
g6
82
88
82
88
109
102
148
H
He
He
H
H
H
166
A
B
1 4 8 ( d e c )
10
H
H
2f
1) A=CLCH2CH2CI,B=HeCN
2).
However, the r e a c t i o n with butadiene was r a t h e r slow and needed the r e a c t i o n time of
As far as we know, this is the f i r s t
about one hour to get s a t i s f a c t o r y y i e l d (Run 4).
example of cycloaddition of thlopyryllum ion d e r i v a t i v e s with 1, 3-dienes.
In order to r a i s e the y i e l d s of cycloadducts, we next i n v e s t i g a t e d the r e a c t i o n of
3-benzoyl-2-thianaphthyllum t e t r a f l u o r o b o r a t e (lb) 5 b e a r i n g electron-wlthdrawing group at
3 - p o s i t i o n which is e x p e c t e d to a c t i v a t e the 2 - t h i a n a p h t h y l i u m ion.
r e a c t i o n of (lb) with above 1, 3-dlenes proceeded more smoothly to give the corresponding
cycloadducts (2d)-(2f) in more e x c e l l e n t y i e l d s (Table 1). When the above r e a c t i o n s
I n d e e d . the
were conducted in a e e t o n i t r i l e as s o l v e n t , the product y i e l d s decreased by ca. 10~ (Runs
6, 8, and 10).
Scheme
2
©
COPh
+
~
o
C
O
P
h
( l b )
CICH2CH2CL
r - t
~
CLCH2CH2CI, r . t .
(3)
~COPh
( 4 )
He
(5)

5573
When furan was allowed to react as
obtained, but furan rlng-substituted 2-thiochromenes (3) 4 and (4) were obtained in 16%
and 60.6% yields, respectively (Scheme 2). 2,S-Dimethylfuran reacted at 3-position with
a diene with (lb), simllar cycloadduct was not
the cation (lb) to give the furan rlng substituted 2-thiochromene (5) in 31% yield.
These results might be ratlonarized In terms of electrophllic substitution reaction of 2-
thianaphthylium ion to furan ring rather than cycloadditlon reaction.
The above cycloadducts were found to undergo retro-additlon reaction, upon heating
in 1,2-dichloroethane, to generate the thianaphthylium Ion and dlene. For example,
cycloadduct (2f) was heated with reflux in 1,2-dlchloroethane for 10 min in the presence
of two equlvalents of 2,3-dlmethyl-1,3-butadlene to afford
Scheme 3.
a cycloadduct (2d) as shown in
S c h e m e
3
He
He
C
O P h _
>
~
~
+
O
P
h _
~~__
B F
4
BF 4-
( l b )
( 2 f )
+
He
(2d)
The cycloadducts also underwent easy cleavage of the C-S bond by the a t t a c k of
s e v e r a l types of nueleophlles to give two t y p e s of the ring-opened products (6) and (7),
via SN2 and SN2' processes, r e s p e c t i v e l y (Scheme 4 and Table 2).
S c h e m e
4
,
+
COPh
:Nu
(2d)
e
He
( 6 )
( 7 )
a: X=OH
a: X=OH
b: X=OHe
c: X = S e P h
d: X=CN
b: X=OHe
T a b t e 2. R e a c t i o n s of Cyctoadduct (2d) w i t h N u c t e o p h l t e s
p r o d u c t s
run
reagent
s o t v e n t
t e m p .
X
6
x
y i e t d
7
X y l e t d
( d i a s t e r e o m e r r a t i o )
1
2
3
4
H20
HeOH
P h S e L I
THSCN~
acetone
-
T H F - e t h e r
r e f t u x
r e f t u x
- 4 0 ° C ~ r . t .
OH
6a
6b
6c
6d
74
87
80
53
?a
?b
-
25 ( 1 : 4 . 3 )
12 ( 1 : 1 . 7 )
-
-
OHe
SePh
CN
CtCHzCH2Ct
- 3 0 ° C ~ r - t .
-
N
In the p r e s e n c e of n - B u 4 N F
We are currently investigating on the scope and stereochemlstry of this novel[2++4]
cycloaddltlon and on its appllcatlon to other thlopyryllum ion derivatives such as

5574
1 - t h i a n a p h t h y l i u m , 9 - t h i a p h e n a n t h r e n y l l u m , or t h l o x a n t h y l l u m ion and also on the
c o n v e r s i o n of the e y c l o a d d u c t s to novel h e t e r o c y c l e s . We hope to r e p o r t at l a t e r time
a
on the r e s u l t s .
REFERENCES AND NOTES
i.
S . M . Weinreb and R. R. Stalb, Tetrahedron, 1982, 38, 3087; D. L. Boger and S. M.
Weinreb, Hetero Diels-Alder Methodology in Organic Synthesis, Academic Press. San
Diego, 1987.
2.
E. J. Corey and S. W. Walinsky, J. Am. Chem. Soc., 1972, 94, 8932; H. Ishibashl, M.
Okada, H. Nakatani, M. Ikeda, and Y. Tamura, J. Chem. Soc., Perkin Trans. 1, 1986,
1763; K. Fuji, S.
P
Khanapure, M. Node, T. Kawabata, A. itoh, and Y. Masaki,
Tetrahedron, 1990, 46, 7393.
3.
4.
K. NakasuJi, K. Kawamura, T. I s h i h a r a , and I. Murata, Angew. Chem., Int. Ed. E n g l . ,
1976, 15, 611.
S a t i s f a c t o r y a n a l y t i c a l data were o b t a i n e d for a l l new compounds.
( 2 a ) : IR (KBr):
1020-1100 cm-1 (BF4-); 1H-NMR (CDC13) 1.75 and 1.79 (each 3H, each s, Me), 2.80
6
:
(1H, brd, J = l S . 1 Uz, CHCH2), 3.01 (1R, dd, J = 1 8 . 1 , 5.9 Hz, CHCH2), 3.66 and 3.89
(each 3H, each d, J = 1 6 . 1 Hz, S+CH2 ), 4.85 (1H, t, J = 5 . 9 ttz, CHC|t~), 6.34 (1H~ d,
J = 9 . 3 Hz, o l e f i n i c H), 7 . 4 4 - 7 . 5 7 (5H, m, ArR and o l e f l n i c H); T3C:NMR (CD3CN)
6 :
19.6 (q), 20.2 (q), 32.8 ( t ) , 37.9 ( t ) , 43.4 (s), 107.8 (d), 120.1 (s), 128.5 (d),
128.9 (s), 129.1 (s), 130.6 (s), 130.9 (d), 132.0 (d), 133.2 (d), 141.1 (d). (2b):
IR (KBr): 1030-1100 cm -1 (BF4-); 1H-NMR (CD3CN)
6
:
1.87 (31|, s, Me), 2.80 (1H,
brd, J = 1 9 . 0 flz, CHCH2), 2.99 (1H, dd, J = 1 9 . 0 , 5.9 Hz, CRCH~), 3.66 and 4.00 (each
111, each brd, J = 1 5 . 6 Hz, S÷CH2), 4.85 (1H, t, J = 5 . 9 ttz, CHCH2), 5.63 (iLl, brs,
o l e f l n i c H), 6.36 (1H, d, J = 9 . 3 Hz, o l e f i n i c H), 7 . 4 8 - 7 . 5 7 (5H, m, ArU and o l e f i n i c
It); 13C-NMR (CD3CN)
6
:
24.7 (q), 30.1 ( t ) , 33.8 ( t ) , 43.3 (d), 108.4 (d), 113.2
(d), 128.4 (d), 1 2 8 . 7 (s), 129.6 (s), 131.2 (d), 132.1 (d), 133.3 (d), 138.1 (s),
141.6 (d). ( 2 d ) : IR (KBr): 1640 (CO), 1030-1090 cm-1 (BF4-); llt-NMR (CD3CN)6 : 1.68
and 1.89 (each 3H, each s, Me), 3.11 and 3.22 (each 1H, each brs, J=18.1 Hz,
CHC_H2), 3.52 and 3.86 (each 1H, each d, J=15.1 Hz, S÷CH2), 5.17 (1n, brs, CHCH2),
7 . 5 8 - 7 . 8 2 (7H, m, ArH), 7 . 9 1 - 7 . 9 4 (2fl, m, ArH), 8.19 (1H, s, o l e f i n i e H). ( 2 e ) : IR
(KBr): 1640 (CO), 1030-1080 cm-1 (BF4-); 1H-NMR (CD3CN)
6 : 1.95 (3H, s, Me), 3.13
and 3.34 (each 1H, each brd, J=19.5 Hz, CHCH2), 3.48 (1H, brd, J=16.1 nz, S+CH2),
3.97 (1H, dd, J = 1 6 . 1 , 5.4 Hz, S÷CR2), 5.23 (1H, brs, CHCH2), 5.60 (1H, brd, J = 5 . 4
Hz, o l e f i n i c H), 7 . 5 8 - 7 . 8 2 (TH, m, ArH), 7 . 9 2 - 7 . 9 5 (2H, m, ArH), 8.20 (1H, s,
o l e f i n i c H). (3): IR ( n e a t ) : 1640 cm-1 (CO);1H-NMR (CDC13) 6 : 5 . 3 3 (1H, s, methine
H), 5.83 (1H, brd, J = 2 . 9 Hz, f u r a n H), 6.24 (1H, brs, f u r a n H), 7 . 2 2 - 7 . 4 8 (8R, m,
ArH, o l e f i n i c H and f u r a n H), 7 . 5 4 - 7 . 5 9 (1H, m, ArH), 7 . 6 8 - 7 . 7 0 (2H, m, ArH); 13C-
NMR (CDC13) 6 : 40.4 (d), 108.6 (d), 110.3 (d), 127.6 (d), 128.3 (d), 129.3 (d),
130.0 (s), 131.0 (d), 131.8 (s), 132.3 (d), 134.5 (s), 134.8 (d), 136.8 (s), 142.6
(d), 152.5 (s), 1 9 3 . 9 (s); MS m/z: 318 (M+), 105 ( b a s e ) .
5.
6.
3-Benzoyl-2-thianaphthylium t e t r a f l u o r o b o r a t e (lb) was p r e p a r e d from the r e a c t i o n
of 3-benzoyl-2-thiochromene, which was s y n t h e s i z e d from 3-benzoyl-2-thiochroman6
by two s t e p s , with t r l t y l t e t r a f l u o r o b o r a t e in dry n i t r o m e t h a n e , p a l e g r e e n
n e e d l e s (AcOH-Ac20); mp. 128-129 °C ( d e c ) ; IR (KBr): 1100 cm-1 (BE4-); 1H-NMR
(CF3CO2H) 6 : 7 . 5 0 - 8 . 1 6 (5H, m, ArH and C(4)-H), 8 . 3 4 - 8 . 8 8 (41t, m, ArH), 9.51 (1R,
s, C(1)H).
J . J . Zhang and G. B. S c h u s t e r , J. Am. Chem. S o t . , 1989, 111, 7149.
(Recexved m Japan 26 June 1991)