Interesting nickel-catalyzed 1,2-addition to α, β-unsaturated aldehydes with arylborates

Article abstract of DOI:10.1248/cpb.57.511

Ni-Et-Duphos-catalyzed 1,2-addition of potassium aryltrifluoroborates to α, β-unsaturated aldehydes is described.

Full text of DOI:10.1248/cpb.57.511

May 2009
Notes
Chem. Pharm. Bull. 57(5) 511—512 (2009)
511
a b
Interesting Nickel-Catalyzed 1,2-Addition to , -Unsaturated Aldehydes
with Arylborates
Fumie SAKURAI, Kazuhiro KONDO,* and Toyohiko AOYAMA*
Graduate School of Pharmaceutical Sciences, Nagoya City University; 3–1 Tanabe-dori, Mizuho-ku, Nagoya 467–8603,
Japan. Received November 25, 2008; accepted February 6, 2009; published online February 9, 2009
Ni-Et-Duphos-catalyzed 1,2-addition of potassium aryltrifluoroborates to a,b-unsaturated aldehydes is de-
scribed.
Key words nickel; arylation; 1,2-addition; borate; a,b-unsaturated aldehyde; Duphos
units, parts per million (ppm) downfield from tetramethylsilane (dꢀ0). EI-
and FAB-MS spectra were measured on a JEOL JMS-SX-102A instrument.
The ee was determined by HPLC analysis (Daicel chiralcel OD-H, eluent:
hexane/i-PrOH).
All aldehydes, reagents, and solvents were available from commercial
sources and used without further purification. In general, all reactions were
performed under an argon atmosphere. Silica gel column chromatography
was performed on Fuji Silysia BW200.
Representative Procedure for the Synthesis of (E)-1,3-Diphenyl-2-
propen-1-ol (Entry 1) To a stirred solution of (R,R)-Et-Duphos (8.6 mg,
0.0238 mmol) in dioxane/H2O (5 : 1, 0.60 ml) were added Ni(cod)2 (6.6 mg,
0.0238 mmol), PhBF3K (87.6 mg, 0.476 mmol) and cinnamaldehyde (1)
(30 ml, 31.5 mg, 0.238 mmol). The reaction mixture was stirred for 6 h at
80 °C, allowed to cool, diluted with water, and extracted with EtOAc. The
organic extracts were successively washed with 10% HCl, water, saturated
aq. NaHCO3, water and brine, dried (Na2SO4) and concentrated. Purification
by silica gel column (hexane : EtOAcꢀ10 : 1) afforded (E)-1,3-diphenyl-2-
propen-1-ol (40.2 mg, 82%, 39% ee) as a colorless oil. The physical data
were comparable to those reported.10)
Arylboron reagents, in particular potassium aryltrifluoro-
borates (ArBF3K), are useful reagents for safe and sustain-
able C–C bond formations, because their reagents are less
toxic, air-stable, and easy to handle.1) Many examples for Rh
catalyzed 1,4-addition to a,b-unsaturated aldehydes with
arylboron reagents have been reported.2) On the other hand,
in relation to 1,2-addition, only one example of Rh(I)-t-Bu3P
catalyzed addition to cinnamaldehyde with phenylboronic
acid has been reported by Ueda and Miyaura.3) Later, less at-
tention has been focuced on metal catalyzed 1,2-addition of
arylboron reagents to a,b-unsaturated aldehydes, although
the control of 1,2-addition vs. 1,4-addition in this reaction is
an important concern.4) Recently, the corresponding authors
of this paper have reported the use of a cheaper metal than
Rh, Ni catalyst, for 1,2-addition of aromatic aldehydes with
arylboron reagents5,6): from the viewpoint of cost and practi-
cal convenience, the use of a much more cheaper and natu-
rally abundant Ni is considered to be desirable. In order to
expand our above arylation, we decided to challenge the Ni-
Et-Duphos-catalyzed 1,2-addition of ArBF3K to a,b-unsatu-
rated aldehydes,7) although it has been known that the combi-
nation of a Ni-catalyst and organometallic reagents promotes
1,4-addition to a,b-unsaturated carbonyl compounds.8)
We examined the addition of ArBF3K to a,b-unsaturated
aldehydes, and the reaction in only the 1,2-mode was found
to proceed at 80—100 °C as shown in Table 1. As shown in
entries 1—7, the reaction of cinnamaldehyde (1) with various
ArBF3K proceeded with moderate to good yields, except for
entry 6. The poor results of entry 6 was due to the decompo-
sition of the product in purifying the crude product by silica
gel column chromatography, although the reaction was pro-
ceeded. The a-substituted a,b-unsaturated aldehydes 2, and
the b,b-disubstituted 3 and 5 were also arylated in the 1,2-
mode (entries 8, 9, 11). Unfortunately, the yield of b-
aliphatic substituted a,b-unsaturated aldehydes 4 was quite
low as shown in entry 10: this low yield might be due to the
decomposition of the starting aldehyde 4 under this reaction
conditions.
(E)-1-(4-Fluorophenyl)-3-phenyl-2-propen-1-ol (Entries 2, 3) IR
(neat): 3306 cmꢁ1 1H-NMR (CDCl3) d: 2.05 (s, 1H), 5.37 (d, Jꢀ6.4 Hz,
.
1H), 6.34 (dd, Jꢀ6.4, 15.8 Hz, 1H), 6.67 (d, Jꢀ15.8 Hz, 1H), 6.95—7.09
Table 1. Ni-Catalyzed 1,2-Addition of ArBF3K to a,b-Unsaturated Alde-
hydesa)
a,b-Unsaturated
ArBF3K
(Arꢀ)
Temp.
(°C)
Time
(h)
Yield
(%)
Entry
1
aldehyde
Ph
80
6
82b)
2
3
4
5
6
7
1
1
1
1
1
1
4-F-C6H4
4-F-C6H4
4-Cl-C6H4
4-Me-C6H4
4-MeO-C6H4
2-Me-C6H4
80
100
100
100
100
100
5
5
3
6
12
12
61c)
66c)
85b)
68c)
ꢂ40
80
8
Ph
100
12
60c)
9
4-t-Bu-C6H4
100
4
100
In summary, Ni-Et-Duphos catalyst was found to promote
1,2-addtion of ArBF3K9) to a,b-unsaturated aldehyde. Devel-
opment of synthetically useful enantioselective version is in
progress.
10
11
4-t-Bu-C6H4
100
100
12
3
27
67
Ph
Experimental
IR spectra were measured on a SHIMADZU FTIR-8100 diffraction grat-
ing IR spectrophotometer. 1H- and 13C-NMR spectra were measured on a
JEOL JNM-EX-270 NMR spectrometer, operating at 270 MHz for 1H-NMR
a) Other ligands such as dppe, dppp, dppb, dppf, BINAP, Segphos, and DIOP re-
sulted in no reaction. b) The ees were as follows: entry 1 (39% ee), enrty 4 (36% ee).
c) Major remainder, which was observed by TLC, was the starting aldehyde.
1
and at 68 MHz for 13C-NMR. H- and 13C-NMR spectra were reported in d
∗ To whom correspondence should be addressed. e-mail: kazu@gakushikai.jp; aoyama@phar.nagoya-cu.ac.jp
© 2009 Pharmaceutical Society of Japan

512
Vol. 57, No. 5
(m, 2H), 7.21—7.42 (m, 7H). 13C-NMR (CDCl3) d: 74.48, 115.19, 115.50,
Acknowledgements We thank Mr. Hiroaki Matsuoka (Nagoya City
126.51, 127.82, 127.89, 128.00, 128.51, 128.57, 130.69, 131.20, 136.23, University) and Mr. Hiroki Ozasa (Nagoya City University) for experimental
138.35, 138.40, 160.37, 163.98. EI-MS m/z: 228 (Mꢃ), 123 (base peak).
HR-MS (EI) Calcd for C15H13OF [Mꢃ]: 228.0951. Found: 228.0946.
(E)-1-(4-Chlorophenyl)-3-phenyl-2-propen-1-ol (Entry 4) IR (neat):
assistant.
References and Notes
1
3470 cmꢁ1. H-NMR (CDCl3) d: 2.00 (br d, Jꢀ3.4 Hz, 1H), 5.37 (br dd, Jꢀ
1) Miyaura N., Suzuki A., Chem. Rev., 95, 2457—2483 (1995).
2) Hayashi T., Yamasaki K., Chem. Rev., 103, 2457—2483 (2003).
3) Ueda M., Miyaura N., J. Org. Chem., 65, 4450—4452 (2000).
4) For a leading reference for 1,2-addition with organometallic reagents:
Imamoto T., “Comprehensive Organic Synthesis,” Vol. 1, ed. by Trost
B. M., Fleming I., Ley S. V., Pergamon Press, Oxford, 1991, pp. 231—
250.
5) Arao T., Kondo K., Aoyama, T., Tetrahedron Lett., 48, 4115—4117
(2007).
6) Yamamoto K., Tsurumi K., Sakurai F., Kondo K., Aoyama, T., Synthe-
sis, 2008, 3585—3590 (2008).
7) Cu-catalyzed asymmetric 1,2-addition of boron reagents to a,b-unsat-
urated aldehydes: Tomita D., Kanai M., Shibasaki M., Chem. Asian J.,
1—2, 161—166 (2006).
8) Schwartz J., Loots M. J., Kosugi H., J. Am. Chem. Soc., 102, 1333—
1340 (1980).
9) For a recent review of ArBF3K, see: Darses S., Genet, J. P., Chem.
Rev., 108, 288—325 (2008).
10) Moriuchi-Kawakami T., Matsuda H., Shibata I., Miyatake M., Suwa
T., Baba A., Bull. Chem. Soc. Jpn., 72, 465—470 (1999).
3.4, 6.6 Hz, 1H), 6.33 (dd, Jꢀ6.6, 15.8 Hz, 1H), 6.68 (d, Jꢀ15.8 Hz, 1H),
7.22—7.40 (m, 9H). 13C-NMR (CDCl3) d: 74.43, 126.51, 127.58, 127.85,
128.50, 128.58, 130.90, 130.93, 133.33, 136.12, 141.02. MS(EI) m/z: 246
(Mꢃ), 244 (Mꢃ), 139 (base peak). HR-MS (EI) Calcd for C15H1335ClO [Mꢃ]:
244.0655. Found: 244.0654, C15H1337ClO [Mꢃ]: 246.0626. Found: 246.0624.
(E)-1-(4-Methylphenyl)-3-phenyl-2-propen-1-ol (Entry 5) The physi-
cal data were comparable to those reported.11)
(E)-1-(2-Methylphenyl)-3-phenyl-2-propen-1-ol (Entry 7) The physi-
cal data were comparable to those reported.12)
(E)-1,3-Diphenyl-2-methyl-2-propen-1-ol (Entry 8) The physical data
were comparable to those reported.13)
(E)-3,3-Diphenyl-1-(4-t-butylphenyl)-2-propen-1-ol (Entry 9) A white
solid. IR (nujol): 3371 cmꢁ1 1H-NMR (CDCl3) d: 1.32 (s, 3Hꢄ3), 1.85
.
(br d, Jꢀ3.7 Hz, 1H), 5.24 (br dd, Jꢀ3.7, 9.6 Hz, 1H), 6.32 (d, Jꢀ9.6 Hz,
1H), 7.23—7.40 (m, 14H). 13C-NMR (CDCl3) d: 31.40, 34.57, 71.39,
125.39, 125.82, 127.44, 127.48, 127.52, 128.02, 128.17, 129.76, 130.13,
139.04, 140.33, 141.50, 143.11, 150.39. MS(EI) m/z: 342 (Mꢃ), 324 (base
peak). HR-MS (EI) Calcd for C25H26O [Mꢃ]: 342.1984. Found: 342.1996.
(E)-1-(4-t-butylphenyl)-2-hexen-1-ol (Entry 10) A white solid. IR
(neat): 3371 cmꢁ1 1H-NMR (CDCl3) d: 0.95 (br t, Jꢀ6.9 Hz, 3H), 1.26— 11) von Matt P., Lloyd-Jones G. C., Minidis A. B. E., Pfaltz A., Macko L.,
.
1.47 (m, 2H), 1.31 (s, 9H), 1.55—1.67 (m, 3H), 4.27 (br d, Jꢀ6.4 Hz, 1H),
6.18 (br dd, Jꢀ6.9 Hz, Jꢀ15.8 Hz, 1H), 6.54 (br d, Jꢀ15.7 Hz, 1H), 7.25—
Neuburger M., Zehnder M., Rüegger H., Pregosin P. S., Helv. Chim.
Acta, 78, 265—284 (1995).
7.33 (m, 4H). 13C-NMR (CDCl3) d: 14.10, 18.76, 31.35, 34.63, 39.56, 12) Nonosita K., Maruoka K., Yamamoto H., Bull. Chem. Soc. Jpn., 61,
72.96, 125.39, 126.07, 129.93, 131.73, 139.30, 150.62. MS(EI) m/z: 232
(Mꢃ), 217 (base peak). HR-MS (EI) Calcd for C16H24O, [Mꢃ]: 232.1827. 13) Takai K., Kimura K., Kuroda T., Hiyama T., Nozaki H., Tetrahedron
Found: 232.1834. Lett., 47, 5281—5284 (1983).
(E)-3-Methyl-1-phenyl-2-buten-1-ol (Entry 11) The physical data 14) Gau A.-H., Lin G.-L., Uang B.-J., Liao F.-L., Wang S.-L., J. Org.
were comparable to those reported.14)
Chem., 64, 2194—2201 (1999).
2241—2243 (1988).