Alkylation of unsaturated aldehyde and allylic bisacetate with organomanganese reagents in presence of tetrakis acetonitrile copper(I) tetrafluroborate

Article abstract of DOI:10.1080/00397910500278461

The conjugate addition of organomanganese reagents to α,β- unsaturated aldehydes and allylic bisacetate in presence of Me₃Si-Cl and tetrakis acetonitrile copper(I) tetrafluroborate is described. Copyright Taylor & Francis, Inc.

Full text of DOI:10.1080/00397910500278461

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Synthetic Communications , 35: 2967–2971, 2005
Copyright # Taylor & Francis, Inc.
ISSN 0039-7911 print/1532-2432 online
DOI: 10.1080/00397910500278461
Alkylation of Unsaturated Aldehyde and
Allylic Bisacetate With Organomanganese
Reagents in Presence of Tetrakis
Acetonitrile Copper(I) Tetrafluroborate
M. B. Deshmukh
Department of Chemistry, Shivaji University, Kolhapur,
Vidyanagar, India
S. D. Jadhav, A. R. Mali, A. W. Suryawanshi, P. V. Anbhule,
S. S. Jagtap, and S. A. Deshmukh
Department of Chemistry, Annasaheb Awate College, Manchar, India
and Department of Chemistry, Shivaji University, Kolhapur,
Vidyanagar, India
Abstract: The conjugate addition of organomanganese reagents to a,b-unsaturated
3
aldehydes and allylic bisacetate in presence of Me Si-Cl and tetrakis acetonitrile
copper(I) tetrafluroborate is described.
Keywords: Organomanganese reagents, allylic bisacetate, conjugate addition
Recently, it has been shown that carbonyl compounds can be. easily prepared
[1]
in high yields by alkylation of organomanganese halide reagent. These
[2]
reagents react quantitatively with geminal diacetate derived from a,b-
unsaturated aldehydes. The alkylation of allylic acetates with Grignard
reagents containing 1–10 mol% cuprous salt is accompanied by carbonyl
[3–6]
attack.
Received in India June 14, 2005
Address correspondence to M. B. Deshmukh, Department of Chemistry, Shivaji
University, Kolhapur, Vidyanagar 416 004, India. E-mail: m_deshmukh1@
rediffmail.com
2
967

2968
M. B. Deshmukh et al.
The reaction of butyl manganese chloride with 3.3-diacetoxy-1t-phenyl-
propene-(1) in the presence of Cu(NCMe) [BF ] and Me Si-Cl gave the
4
4
3
conjugated product in moderate yield (entries 1–8). The low conjugation
may be due to the steric effect of the butyl group. However, when the alkylation
reaction is carried out with cupric bromide and Me Si-Cl at 2788C, the
3
conjugate addition product was isolated in high yield (entry 5). The phenyl
manganese chloride on treatment with allylic diacetate gave 1,2-addition
product in high yield (entry 9) whereas with Li CuCl both products resulted
2
4
(entry 4). In the presence of two equivalents of Me Si-Cl and
Cu(NCMe) [BF ], the conjugated product (entry 3) was predominant
3
4
4
(Scheme 1).
These results prompted us to undertake conjugate addition with a,b-
unsaturated aldehyde. The reaction of trans-cinnamaldehyde with butyl
manganese chloride at 2788C, gave a conjugated addition product (entry 2)
(
Scheme 2). However, with 2 equivalents of Me Si-Cl, at 2158C, a higher
3
percentage of conjugated product resulted (entry 1). The catalytic activity of
Li CuCl was also explored, which resulted in a conjugated product in
2
4
moderate yield as compared with 3,3-diacetoxy-1t-phenyl-propene-(1). The
,2-addition product was obtained without the use of Me Si-Cl (entry 4).
Five equivalents of Me Si-Cl gave a high degree of conjugation product in
1
3
3
presence of Li CuCl (entry 5) (Tables 1 and 2).
2
4
CONCLUSION
This article describes a useful 1,4-conjugated addition versus 1,2-addition
studies. The use of tetrakis acetonitrile copper(I) tetrafluroborate as a
catalyst gives better results.
EXPERIMENTAL
All reactions were carried out under an atmosphere of nitrogen. THF
was freshly distilled from sodium benzophenone ketyl under a nitrogen
Scheme 1. Reaction of 3,3-diacetoxy-1t-phenyl-propene-(1) with butyl manganese
chloride.

Unsaturated Aldehyde and Allylic Bisacetate
2969
Scheme 2. Reaction of trans-cinnamaldehyde with organomanganese reagents.
atmosphere. Manganese chloride, 98%, and lithium chloride were purchased
from Merck Chemical Company, Germany. It must be finely pulverized,
then dried by heating at 120–1408C for 3 h prior to use. A 1 M solution
of MnCl , and 2 LiCl in dry THF is made. Tetrakis acetonitrile copper(I)
tetrafloroborate, Cu(NCMe) [BF ], is readily prepared by protonation of
2
4
4
Cu O with aqueous HBF in acetonitrile. The solution of butyl and
2
4
[7]
phenyl manganese bromide was freshly prepared and standardized,
immediately before use according to the charge-transfer titration method
described. Me SiCl was used without distillation. Yields are based on
3
starting geminal diacetate and are actually calculated analytically.
Reactions were monitored by thin-layer chromatography (TLC), using E.
Merck silica gel 60. Components were visualized by exposure to iodine
vapor. The proton spectra were recorded on a JEOL 400-MHz instrument
in CDCl with Me Si as internal standard.
3
4
Table 1. Reaction of 3,3-diacetoxy-1t-phenyl-propene-(1) with butyl manganese
a
chloride
Additives
(equiv.)
Temp.
(8C)
1:4 1:2
Addition Addition
Entry
[Cu]
1
2
3
4
5
6
7
8
9
CuBr
CuBr
Cu(NCMe )[BF ] Me SiCl (2)
—
215
210
216
210
278
210
210
215
0
22
38
61
17
58
19
25
33
84
29
60
23
27
13
8
3
Me SiCl (1.5)
4
4
3
CuCN þ 2 LiCl
—
CuBr
Cu(NCMe )[BF ]
2
Me
3
SiCl (1.5)
—
4
4
Li
2
CuCl
4
—
SiCl (1)
13
11
8
Cu(NCMe
Cu(NCMe )[BF ] Me SiCl (3)
4
)[BF
4
]
Me
3
b
4
4
3
a
All reactions were carried out on a 1-mmol scale in dry THF. Mass balance is
starting material.
b
Reaction was carried out with PhMnCl.

2970
M. B. Deshmukh et al.
Table 2. Reaction of trans-cinnamaldehyde wih organomanganese reagents
Additives
(equiv.)
Temp.
(8C)
1:4
Addition
1:2
Addition
Entry
[Cu]
1
2
3
4
5
Cu(NCMe
Cu(NCMe
4
4
) [BF
) [BF
4
]
]
Me
Me
3
SiCl (2)
SiCl (2)
215
278
215
210
215
63
78
38
04
44
27
11
12
31
06
4
3
Cu(NCMe ) [BF ]
4
Me SiCl (1)
3
4
Cu(NCMe ) [BF ]
4
—
4
Li
2
CuCl
4
3
Me SiCl (5)
All reactions were carried out on a 1-mmol scale. Mass balance is starting material.
Typical Procedure: Conjugate Addition Reaction of Butyl
Manganese Bromide to trans-Cinnamaldehyde
A solution of butyl magnesium bromide (12 mmol) in tetrahydrofuran was added
to a solution of the “ate” complex of Li MnCl (10 mmol) at 2108C. After
2
4
stirring for 30min, Cu(NCMe) [BF ] (10 mol%), 3,3-diacetoxy-1t-phenyl-
4
4
propene-(1) (10 mmol), and Me SiCl (2 equiv.) were added successively. After
3
l h at 2108C and 30 min at rt, the reaction mixture was quenched with
10 mL of 1 M HCl and worked up. The crude product was chromatographed
on silica gel to get pure products.
Data
1
3
,3-Diacetoxy-1t-phenyl-propene-(1): H NMR (400 MHz, CDCl ) data.
3
d 7.1–7.6 (m, 6H), 6.87 (d, J ¼ 16 Hz, 1H), 5.93 (dd, J ¼ 16.7 Hz, 1H), 2.1
(
s, 6H). IR (KBr) data. 1755, 1660, 1615, 1490, 1470, 1245, 1195, 1120,
2
1
1
1
060, 1005, 940, 758, 690 cm . MS m/e (relative intensity) 234.1 (P, 4),
90.4 (1), 175.1 (2), 133 (59), 131 (100), 115 (3), 104 (19), 77 (11), 63
(
25), 43 (89).
(
1
2E)-1-(Acetyloxy)-3-phenylprop-2-enyl acetate: H NMR (400 MHz,
CDCl ) data. d 7.1 (m, 6H), 6.87 (d, J ¼ 16 Hz, 1H), 5.93 (dd, J ¼ 16.
3
7
Hz, 1H), 2.1 (s, 6H) ppm.
3
1
-Phenylheptanal: H NMR (400 MHz, CDCl ) data. d 0.8–1 (s, 3H),
3
1
.2–1.4 (m, 2H), 2 ꢀ CH ), 1.65 (m, 2H, CH ), 3.2 (m, CH), 6.15 (d, 1H,
2
2
1
3
J ¼ 16.7 Hz), 7.1–7.35 (m, 5 Ar H), 9.8 (1H, CHO) ppm. C NMR
(300 MHz, CDCl ) data. d ppm (13.80, 22.44, 22.54, 29.35, 35.80, 117.30,
3
1
1
26.69, 127.43, 129.00, 130.42, 146.69, 152.79, 193.67). IR (KBr) data.
1
2
676, 1629, 1578, 1495, 1451, 1415, 1216, 1126, 972, 756, 701 cm
1
.
1E)-1-Phenylhept-1-en-3-ol: H NMR (400 MHz, CDCl ) data. d 0.8–1
(
t, 3H), 1.2 (m, 4H), 1.7 (m, 2H), 2.15 (m, 2H), 3.1 (m, 1H), 7.3–7.6
3
(
(
1
m, 5H), 9.75 (s, 1H) ppm. C NMR (300 MHz, CDCl ) data. d ppm
3
3

Unsaturated Aldehyde and Allylic Bisacetate
2971
(
14.08, 20.89, 22.45, 29.37, 60.36, 126.48, 127.60, 128.85, 128.42, 130.40,
1
1
30.56, 134.07, 171.37). IR (KBr) data. 3200, 2930, 1744, 1634, 1494,
2
1
452, 1375, 1239, 1047, 846, 758, 669, 668 cm
1
.
2E)-1,3-Diphenylprop-2-en-1-ol: H NMR (400 MHz, CDCl ) data.
(
d 4.2 (s, 1H), 3.4 (d, 1H), 6.15 (d, 1H), 7.2–7.5 (m, 10H), 7.65 (d, 1H) ppm.
(
d 5.1 (t, 1H), 6.3–6.5 (dd, 1H), 6.7–6.8 (d, 1H), 7.2–7.5 (m, 10H) ppm.
3
1
1E)-3,3-Diphenylprop-1-en-1-ol: H NMR (400 MHz, CDCl ) data.
3
ACKNOWLEDGMENT
We gratefully acknowledge use of spectral facility given by Simon Woodward
from Hull University, U.K.
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1
2
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1
765–1767.
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4
5
6
7
. Chung, C. T.; Paisley, S. D.; Goering, H. L. J. Org. Chem. 1986, 51, 2884–2891.
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4–55.