A novel preparation of allylic trichlorotins from α,α-diisopropylhomoallylic alcohols and its application to carbonyl allylations

Article abstract of DOI:10.1055/s-2001-18102

α,α-Diisopropylhomoallylic alcohols react with tin(II) chloride and NCS in CH₂Cl₂ at -40 °C to -60 °C to produce allylic tins and diisopropyl ketone, and the allylic tins in situ cause nucleophilic addition to aldehydes to afford α-s

Full text of DOI:10.1055/s-2001-18102

1
802
LETTER
A Novel Preparation of Allylic Trichlorotins from , -Diisopropylhomoallylic
Alcohols and Its Application to Carbonyl Allylations
A
Y
N
ovel Preparatio
o
n
of
A
llylic
s
Trichloro
h
tins iro Masuyama,* Keisuke Saeki, Sachiko Horiguchi, Yasuhiko Kurusu
Department of Chemistry, Faculty of Science and Technology, Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo 102-8554, Japan
Fax +81(3)32383361; E-mail: y-masuya@sophia.ac.jp
Received 3 September 2001
SnCl2
NCS
Abstract: , -Diisopropylhomoallylic alcohols react with tin(II)
R
R
OH
R1
1
chloride and NCS in CH Cl at –40 °C to –60 ºC to produce allylic
+
R CHO
2
2
OH
1, R=i-Pr
CH2Cl2
tins and diisopropyl ketone, and the allylic tins in situ cause nucleo-
philic addition to aldehydes to afford -substituted homoallylic al-
cohols.
2
Scheme 1
Key words: nucleophilic additions, allylations, organometallic re-
agents, allylic tins, homoallylic alcohols
The reaction of , -diisopropylhomoallyl alcohol (1)9
with aldehydes was carried out by the following two
methods (Scheme 1). Method A: To the solution of 1, ar-
omatic aldehydes and tin(II) chloride in dichloromethane
was added NCS at –40 °C or –60 ºC, and Method B: to the
solution of 1 and tin(II) chloride in dichloromethane at –
Barbier-type carbonyl allylation with tin(II) halides is one
of the most convenient methods for introduction of allylic
1
functions, because of ease of operation and the availabil-
ity and tractability of starting allylic substrates, such as al-
lylic halides, esters, and alcohols, from which allylic tin
intermediates are usually prepared in situ. The regioselec-
tivity ( - and -addition) for producing homoallylic alco-
hols in palladium-catalyzed carbonyl allylation by 2-
buten-1-ol with tin(II) chloride correlates with the dielec-
tric constant values of solvents; the lower the polarity of
4
0 ºC was added NCS and aliphatic aldehydes were added
after 12–20 h. The results are summarized in Table 1.
Both of the methods need more than two equimolar
amounts of tin(II) chloride and NCS each to 1, and have
to be carried out at temperatures of –20 °C to –60 ºC. The
allylation of benzaldehyde (Method A) or heptanal (Meth-
od B) scarcely proceeds at all with one equimolar amount
of tin(II) chloride and NCS each to 1. Method A is not
available for aliphatic aldehydes, in contrast to aromatic
2
the solvents, the higher is the -regioselectivity. Polar
solvents, such as THF, MeOH, DMF, and 1,3-dimeth-
ylimidazolidin-2-one, are needed for the high yields in the
carbonyl allylations with tin(II) halides. The carbonyl al-
lylations are hopelessly slow in nonpolar solvents such as
CH Cl and Et O because of the insolubility of tin(II) ha-
aldehydes.10 CHCl and 1,2-dichloroethane can be em-
3
ployed as well as CH Cl . Tin(II) chloride-NCS is the best
2
2
combination of reagents [tin(II) halides-N-halosuccinim-
ides] for the allylation of benzaldehyde with 1. No carbo-
nyl allylation with 1 took place with tin(II) iodide-NBS or
tin(II) fluoride-NCS.
2
2
2
lides. Therefore, the allylations in nonpolar solvents under
usual conditions are not a practical method for the -regi-
3
–5
oselection. Another new method of preparing -substi-
tuted allyltins in nonpolar solvents is needed for the - Regiochemistry in the carbonyl allylations by , -diiso-
9
regioselection. Knochel has developed a novel method of propyl- -methylhomoallyl alcohol (3) with tin(II) chlo-
preparing allylic zincs; retro-allylation of sterically hin- ride and NCS was investigated under the same conditions
dered tertiary homoallylic alcohols, bearing two bulky as those of the allylations by 1 (Scheme 2). The results are
groups on -position, with BuLi and then with zinc ha- summarized in Table 2. The allylations of aromatic alde-
lides generates allylic zinc compounds that react with hydes such as benzaldehyde and 4-chlorobenzaldehyde or
6
electrophiles. We have found that tin(II) chloride and aliphatic aldehydes such as heptanal and cyclohexanecar-
NCS can be utilized for preparing trichlorotin alkoxides baldehyde by 3 selectively occurred at a nonsubstituted al-
from the corresponding alcohols without using strong lylic position ( -regioselection) to produce 4 (Entries 1,
7
bases. We thus hoped that trichlorotin homoallyloxides, 2, 8 and 9). 4-Cyanobenzaldehyde, 4-methoxycarbonyl-
derived from sterically hindered tertiary homoallylic alco- benzaldehyde and 3-phenylpropanal underwent the carbo-
hols with tin(II) chloride and NCS in CH Cl , would cause nyl allylation by 3 at a more substituted allylic position ( -
2
2
the retro-allylation to allylic trichlorotins followed by the regioselection) to produce 4 (Entries 3–7). The -regi-
allylation of aldehydes with the allylic trichlorotins.8
oselectivity was enhanced by the use of three equimolar
amounts each of SnCl and NCS to 3 (Entries 4, 6 and 7).
2
1H NMR observation confirmed that 2-propenyltin could
be prepared from , -diisopropylhomoallyl alcohol (1)
11
Synlett 2001, No. 11, 26 10 2001. Article Identifier:
with tin(II) chloride and NCS in CD Cl at –40 ºC. Thus,
2
2
1
437-2096,E;2001,0,11,1802,1804,ftx,en;Y16401ST.pdf.
Georg Thieme Verlag Stuttgart · New York
ISSN 0936-5214
the actual allylating agents in the carbonyl allylations by
and 3 are probably allylic tin analogues. A plausible
©
1

LETTER
A Novel Preparation of Allylic Trichlorotins
1803
Table 1 Carbonyl Allylation with 1, Tin(II) Chloride, and NCSa
Table 2 Carbonyl Allylation with 3, Tin(II) Chloride, and NCSa
R1
Ph
Ph
Ph
Ph
Ph
Ph
Method Temp (ºC) Time (h) 2, Yield (%)b
Entry R1
Time 4; Yield / c
;syn/antic
( ; Z/E )
c
(
h)
(%)
49
69
78
52
68
59
54
39
23
A
A
B
A
A
A
A
A
A
A
A
A
A
B
B
B
A
B
A
B
0
–20
–20
–40
–60
–70
–40
–60
–40
–60
–40
–40
–40
–20
–40
–60
–40
–40
–40
–40
13
13
29
49
47
58
74
61
58
72
56
62
69
36
12
53
59
49
10
57
5
1
Ph
37
25
24
20
20
22
67/33
91/9
(72/28)
(85/15)
79/21
2d
4-ClC H
6
4
2c
3d
4-NCC H
17/83
6
4
4
20
39
4d,e
5d
4-NCC H
1/99 73/27
20/80 89/11
6
4-MeOOCC H
6
4
4
111
17
6d,e
7e,f
8f
4-MeOOCC H
1/99 70/30
1/99 62/38
6
4
4
4
4
4
4
-ClC H4
6
PhCH CH
2g
2
2
-ClC H4
33
6
C H
2g
2g
99/1
84/16
(58/42)
(53/47)
6
13
-NCC H4
21
6
9e,f
c-C H
6 11
-NCC H4
62
6
a
The allylation of aldehydes (1 mmol) by , -diisopropyl- -meth-
-MeOOCC H4
17
ylhomoallyl alcohol (3, 2 mmol) was carried out with SnCl (4
mmol) and NCS (4 mmol) in CH Cl (3 mL).
6
2
2
2
20
b
c
d
e
f
6
-MeC H4
Isolated yields.
1
The ratios were determined by 500 MHz H NMR (JEOL -500).
Method A.
Each 6 mmol of SnCl and NCS were used.
Method B.
After addition of aldehydes.
19
2
PhCH CH2
PhCH CH2
2c
2
2
2c
2c
g
PhCH CH2
2
PhCH CH2
2
C H
36
+
6
13
13
act with another SnCl , derived from excess SnCl and
NCS, to form a 2-butenyl( -chloro)ditin cationic interme-
diate (B) that actually causes -regioselective carbonyl al-
lylation via
3
2
3c
C H
6
c-C H
29
6
11
11
a chair-formed six-membered cyclic
5
2c
transition state (C) containing -chloroditin. -Regiose-
c-C H
30
6
a
The allylation of aldehydes (1.0 mmol) by 1 (2.0 mmol) was carried
out with SnCl (4.0 mmol) and NCS (4.0 mmol) in CH Cl (3 mL).
Isolated yields.
After addition of aldehydes.
2
2
2
SnCl2 + NCS
O
b
c
N
SnCl3
R
R
R R
O
OH
OSnCl3
OH
CH Cl
2
2
R1
O
3, R=i-Pr
SnCl2
NCS
R
R
4α
-
NH
R
R
1
+
R CHO
+
OH
-
CH2Cl2
OH
R1
O
O
3
, R=i-Pr
Cl
Sn
SnCl2/NCS
4γ
Cl
+
SnCl3
SnCl
3
Cl
Scheme 2
A
B
1
R CHO
mechanism that explains the -regioselection, namely the
allylations of aldehydes bearing no coordinating groups at
a nonsubstituted allylic -position of 2-butenyltin derived
from 3, is shown in Scheme 3. Trichlorotin alkoxide, de-
Cl
OH
R1
+
Cl
H
Cl
Sn
SnCl3
R1
O
4α
rived from 3 with SnCl and NCS, can cause retro-allyla-
2
C
tion to produce 2-butenyltrichlorotin (A)12 and
diisopropyl ketone. The 2-butenyltrichlorotin (A) may re- Scheme 3
Synlett 2001, No. 11, 1802–1804 ISSN 0936-5214 © Thieme Stuttgart · New York

1
804
Y. Masuyama et al.
LETTER
(6) Jones, P.; Knochel, P. J. Org. Chem. 1999, 64, 186; and
lection in the allylations of benzaldehydes, bearing a cy-
ano or methoxycarbonyl group on the p-position to
carbonyl group, and 3-phenylpropanal, bearing a phenyl
group on the -position to carbonyl group, may be in-
duced by the strong coordination of those substituents to
the second cationic tin of B, in contrast to the coordination
of aldehyde carbonyl to the second tin in the -regioselec-
tion. That is to say, the coordination of those substituents
probably favors the approach of those aldehyde carbonyls
to the -carbon of B rather than to the -carbon of B.
references cited therein.
(
7) (a) Masuyama, Y.; Kobayashi, Y.; Yanagi, R.; Kurusu, Y.
Chem. Lett. 1992, 2039. (b) Masuyama, Y.; Kobayashi, Y.;
Kurusu, Y. J. Chem. Soc., Chem. Commun. 1994, 1123.
1
3
(c) Masuyama, Y.; Goto, S.; Kurusu, Y. Synth. Commun.
1995, 25, 1989.
(8) Tagliavini, G. Rev. Si Ge Sn Pb 1985, 8, 237.
(9) , -Diisopropylhomoallylic alcohols 1 and 3 were prepared
by the reaction of 2-propenylmagnesium bromide and 2-
butenylmagnesium chloride respectively with diisopropyl
1
ketone in ether on ice-bath. 1: H NMR (JEOL -500) 0.94,
0
.97 (2d, J = 7.0 Hz, 12 H), 1.22 (br, 1 H), 1.94 (hept, J = 7.0
Hz, 2 H), 2.32 (d, J = 7.0 Hz, 2 H), 5.07 (d, J = 9.7 Hz, 1 H),
.10 (d, J = 17.8 Hz, 1 H), 5.88 (ddt, J = 17.8, 9.7, 7.0 Hz, 1
H). 3: H NMR (JEOL -500) 0.97, 0.98 (2d, J = 7.0 Hz,
12 H), 1.08 (d, J = 7.0 Hz, 3 H), 1.42 (s, 1 H), 2.05, 2.06
(2hept, J = 7.0 Hz, 2 H), 2.66 (quintet, J = 7.0 Hz, 1 H), 5.05
Acknowledgement
5
1
This work was supported by a Grant-in-Aid for Scientific Research
(No. 12640573) from the Japan Society for the Promotion of Sci-
ence (JSPS).
(
d, J = 17.1 Hz, 1 H), 5.06 (d, J = 10.6 Hz, 1 H), 5.97 (ddd,
J = 17.1, 10.6, 7.0 Hz, 1 H).
References
(
(
10) TLC observation has confirmed that a large quantity of the
starting homoallyl alcohol 1 is present after the corres-
ponding reaction times in method A with aliphatic alde-
hydes.
(
1) (a) Masuyama, Y. J. Synth. Org. Chem. Jpn. 1992, 50, 202.
b) Masuyama, Y. Advances in Metal-Organic Chemistry,
Vol. 3; Liebeskind, L. S., Ed.; JAI Press: Greenwich, CT,
994, 255. (c) Masuyama, Y. Recent Research
(
11) After 7 days at –40 °C, homoallyl alcohol 1 disappeared and
1
2
-propenyltin and diisopropyl ketone were prepared [2-
Developments in Organic Chemistry, Vol. 4; Transworld
Research Network: Trivandrum, India, 2000, 373; and
references cited therein..
1
propenyltin: H NMR (JEOL -500) 3.33 (d, J = 8.2 Hz, 2
H), 5.34 (d, J = 10.1 Hz, 1 H), 5.42 (d, J = 16.8 Hz, 1 H), 6.11
1
(
m, 1 H)]. In H NMR experiments of 3, no spectral change
(2) Takahara, J. P.; Masuyama, Y.; Kurusu, Y. J. Am. Chem.
Soc. 1992, 114, 2577.
was observed at –40 °C, and at 0 °C complicated reactions
of 3 was observed and no 2-butenyltins were recognized.
12) In general, 2-butenyltins are in equilibrium with 1-methyl-
(
3) For -regioselective carbonyl allylations with metal reagents
other than tin(II) halides, see: (a) Yamamoto, Y.;
Maruyama, K. J. Org. Chem. 1983, 48, 1564.
(
(
2-propenyltins, and the overall equilibrium lies to the 2-
butenyltins. In this carbonyl allylation, the actual allylating
agent derived from 3 is probably not 1-methyl-2-propenyltin
but 2-butenyltin, because active aldehydes such as 4-
cyanobenzaldehyde and 4-methoxycarbonylbenzaldehyde
undergo -regioselective addition.
(b) Kanagawa, Y.; Nishiyama, Y.; Ishii, Y. J. Org. Chem.
1992, 57, 6988. (c) Yanagisawa, A.; Habaue, S.; Yasue, K.;
Yamamoto, H. J. Am. Chem. Soc. 1994, 116, 6130.
4) For -regioselective carbonyl allylations by an acid-
catalyzed allyl-transfer from -adducts, see: Sumida, S.;
Ohga, M.; Mitani, J.; Nokami, J. J. Am. Chem. Soc. 2000,
(
(
6
13) Since tin -arene complexes [ -ArSn(AlCl ) Ar and -
4
2
ArSnCl(AlCl )] have been prepared, a -coordination of
4
122, 1310.
arenes bearing no electron-withdrawing groups to cationic
tin may occur in dichlorometane solution. See:
5) For -regioselective carbonyl allylations with tin(II) halides,
see: (a) Masuyama, Y.; Hayakawa, A.; Kishida, M.; Kurusu,
Y. Inorg. Chim. Acta 1994, 220, 155. (b) Ito, A.; Kishida,
M.; Kurusu, Y.; Masuyama, Y. J. Org. Chem. 2000, 65, 494.
(
1
a) Rodesiler, P. F.; Auel, T.; Amma, E. L. J. Am. Chem. Soc.
975, 97, 7405. (b) Weininger, M. S.; Rodesiler, P. F.;
Amma, E. L. Inorg. Chem. 1979, 18, 751.
Synlett 2001, No. 11, 1802–1804 ISSN 0936-5214 © Thieme Stuttgart · New York