Stereoselective crossed aldol reaction via boron enolates generated from α-iodo ketones and 9-borabicyclo[3.3.1]nonane

Article abstract of DOI:10.1246/bcsj.76.813

Boron enolates were in situ-generated reductively by treating various α-iodo ketones such as 2-iodo-1-phenylpropan-1-one, 2-iodo-1-(4-methoxyphenyl)propan-1-one, 2-iodopentan-3-one, 2-iodo-2-methyl-1-phenylpropan-1-one, 3,4-dihydro-2-iodo-1(2H)-naphthalenone, 2-iodo-1-phenylethan-1-one and 1-iodo-4-phenylbutan-2-one with 9-borabicyclo[3.3.1]nonane (9-BBN). Aldols were produced in good yields with good to high diastereoselectivities by subsequent reaction of boron enolates thus formed with various aldehydes. Several boron enolates derived from α-iodo ketones and pinacolatoborane were successfully isolated by distillation, though the yields were rather moderate.

Full text of DOI:10.1246/bcsj.76.813

Ó 2003 The Chemical Society of Japan
Bull. Chem. Soc. Jpn., 76, 813–823 (2003)
813
Stereoselective Crossed Aldol Reaction via Boron Enolates Generated
from ꢀ-Iodo Ketones and 9-Borabicyclo[3.3.1]nonane
Teruaki Mukaiyama, # Tomofumi Takuwa, Keiko Yamane, and Shouhei Imachi
ꢀ;
Center for Basic Research, The Kitasato Institute 6-15-5 (TCI), Toshima, Kita-ku, Tokyo 114-0003
(Received October 30, 2002)
Boron enolates were in situ-generated reductively by treating various ꢀ-iodo ketones such as 2-iodo-1-phenylpropan-1-
one, 2-iodo-1-(4-methoxyphenyl)propan-1-one, 2-iodopentan-3-one, 2-iodo-2-methyl-1-phenylpropan-1-one, 3,4-dihydro-
2-iodo-1(2H)-naphthalenone, 2-iodo-1-phenylethan-1-oneand1-iodo-4-phenylbutan-2-onewith9-borabicyclo[3.3.1]nonane
(9-BBN). Aldols were produced in good yields with good to high diastereoselectivities by subsequent reaction of boron
enolates thus formed with various aldehydes. Several boron enolates derived from ꢀ-iodo ketones and pinacolatoborane were
successfully isolated by distillation, though the yields were rather moderate.
Aldol reaction is one of the most fundamental and frequently
employed tools for C–C bond formation. There have been many
useful methodsdeveloped for the synthesis ofvarious aldolsusing
metal enolates as aldol donors. Since reactions of metal enolates
depend on the nature of the metal atoms, various metal enolates
such as Na, Li, Mg, Zn, Si, B, Sn(b) and Sn(d) enolates1 were
investigated in detail to examine their behavior as aldol donors.
Of these metal enolates, boron atom was noted to have strong
affinity toward carbonyl oxygen atom. The length of the B–O
asymmetric aldol reactions8 and Abiko and co-workers recently
reported9 anti-selective ones.
Boron enolates were generated by treating unsymmetrical
ketones with the dialkylborane triflates in the presence of tertiary
amines under neutralization conditions, because the triflates
behave as a counter anion of a strong acid. Therefore, a new
method for the generation of boron enolates under milder
conditions was still needed. Despite the employment of Et3B as
a reductant for the aldol reaction between ꢀ-iodo ketones with
several aldehydes was reported,10 no satisfactory results were
shown concerning the diastereoselectivities. The regioselective
generation of boron enolates might successfully be performed by
simple and straightforward hydride reduction of ꢀ-halo ketones
with dialkyl- or dialkoxylboranes. Further, the aldol reaction
using boron enolate generated by hydride reduction might be
superior to that using boron triflate, in terms of their applicability
to the total synthesis of complicated natural compounds, since
boron hydrides behave as a milder Lewis acid compared with
boron trifrates. Actually, boron hydride reduced ꢀ-iodo ketone
smoothly to afford boron enolate, and the treatment with
aldehydes that followed afforded various aldols.
ꢀ
bond (1.36–1.47 A) was shorter than other metal–O bonds such as
ꢀ
ꢀ
ꢀ
Ti–O (1.62–1.73 A), Al–O (1.92 A), Mg–O (2.01–2.13 A) and
2
ꢀ
Sn–O (2.70 A). Thus, the aldol reaction of boron enolates with
aldehydes proceeded via rigid chair-like six-membered transition
state to afford the corresponding aldols stereoselectively.
Accordingly, the aldol reactions using boron enolates are
employed frequently as useful tools in many strategies for natural
products’ synthesis.3
Concerning generation of boron enolates, there are several
methods reported: for example, Hoozet al. reportedthat the boron
enolates were generated by treating tributylborane with
diazoketones.4 Koster showed that the enolates were generated
¨
also by treating ketones with Et3B at 130–150 ꢁC.5 Further, the
boron enolates were generated from methyl vinyl ketone and tri-
n-butylborane,6a and subsequent reaction of boron enolates thus
formed with aldehydes,6b,6c effectively affording aldols, which
was the first example of using boron enolate as a useful aldol-
donor. Our laboratory reported that the regioselective generation
of boron enolates was directly carried out from unsymmetrical
ketones by treating them with dialkylborane triflate using tertiary
amines under neutralization conditions (1976).7 This simple
method for the generation of boron enolates has contributed
considerably to the development of aldol chemistry. Also,
stereoselective boron aldol reactions for the synthesis of optically
active compounds were established by using chiral auxiliary
groups. For example, Evans et al. reported syn-selective
Preliminary results on the aldol reaction of boron enolates
generated from ꢀ-iodo ketones and 9-BBN with several alde-
hydes were reported in the previous communication.11 After
screening the reaction conditions of the above reaction, it was
found that the ꢀ-iodo ketones were smoothly reduced to generate
boron enolates when catecholatoborane, pinacolatoborane or 9-
BBN was used in the presence of tertiary amines. The boron
enolates, 9-BBN enolates in particular, afforded aldols in a
diastereoselective manner by successive treatment with
aldehydes. Here, we would like to describe in detail the
diastereoselective aldol reaction of ꢀ-iodo carbonyl compounds
with various aldehydes.
Results and Discussion
Isolation of Boron Enolates and Their Aldol Reactions.
Isolation of boron enolates by reductive treatment of ꢀ-iodo
ketones with pinacolatoborane was first tried; several boron
# Kitasato Institute for Life Sciences, Kitasato University,
5-9-1 Shirokane, Minato-ku, Tokyo 108-8641

814 Bull. Chem. Soc. Jpn., 76, No. 4 (2003)
Crossed Aldol Reaction via Boron Enolates
Scheme 1.
Table 1. Isolations of Boron Enolates following Aldol Reactions with Aldehyde (4a)
Isolated yield
(bp)
Iodo ketone
Aldol adduct/yield/%
2a
2b
3a 43% (106 ꢁC/33 Pa)
3b 40% (60 ꢁC/267 Pa)
5 72%
6 58%
2c
3c 32% (140 ꢁC/53 Pa)
3d 40% (130 ꢁC/93 Pa)
7 61%
8 38%
2d
enolates were obtained in 32–43% yields by distillation
(Scheme 1).12 Next, these isolated boron enolates were allowed
to react with 3-phenylpropionaldehyde, and the desired aldols
were obtained in 38–72% yields (Table 1). The low-yields of the
above boron enolates and aldol adducts were ascribed to the
decomposition of labileboron enolates duringisolating procedure
or to reaction with aldehydes.
precursor, thedesiredaldol adductwasobtainedin92%yieldwith
relatively low diastereoselectivities (entry 2). In cases of using 2-
iodopentan-3-one and 2-iodo-1,2-diphenylethan-1-one in the
present reaction, the corresponding aldols were obtained in 95%
and 81%yields, respectivelyalthoughthe diastereoselectivitiesof
the produced aldols were not yet improved (entries 3 and 4).
Aldol Reaction of Aldehydes with Boron Enolates In Situ
Formed from ꢀ-Iodo Ketones and 9-BBN. Our laboratory
reported thata certain kindofvinyloxyboranewas formedby1,4-
addition of n-dibutyltiophenyllborane to vinyl methyl ketone; the
corresponding aldol was obtained by the subsequent reaction with
benzaldehyde in a highly diastereoselective manner.6b Further, a
highly diasteleoselective aldol reaction was achieved by treating
several aldehydes with Z-boron enolates which were derived
from ꢀ,ꢁ-unsaturated ketones and catecholatoborane.13 These
meant that the present procedure has not generated the boron
enolates stereoselectively (Fig. 1). Then, it was assumed that the
aldol reaction would diastereoselectively proceed when Lewis
Aldol Reaction of Aldehydes with Boron Enolates In Situ
Formed from Several ꢀ-Iodo Ketones and Catecholato-
borane. Boronenolatesweregenerated insitubytreatingꢀ-iodo
ketones with catecholatoborane. The corresponding aldols were
obtained by successive addition of aldehydes in one pot manner:
that is, the generation of enol borate derived from 2-iodo-1-
phenylethan-1-one was tried in the coexistence of K2CO3 using
ꢁ
catecholatoborane as a reducing reagent at ꢂ78 C in CH2Cl2.
The subsequent treatment with benzaldehyde afforded the
corresponding aldol in 95% yield, as shown in Table 2, entry 1.
When 2-iodo-1-phenylpropan-1-one was used as an enolate

T. Mukaiyama et al.
Bull. Chem. Soc. Jpn., 76, No. 4 (2003)
815
Fig. 1.
Table 2. Aldol Reaction Using Catecholatoborane
Table 3. Aldol Reactions Using Several Boranes
Entry
1
ꢀ-Iodo ketone
Aldol adduct/yield/%
syn=antia)
Entry Borane (mol. amt.) Temp./ꢁC Yield/% syn=antib)
9 95
—
1
2
(1.5)
(1.5)
ꢂ78
ꢂ78
92
53=47
2e
N.D.
—
2
3
4
10 92
11 95
12 81
55=45
50=50
72=28
3
4
(1.5) ꢂ78–ꢂ23
21
41
50=50
46=54
2a
2b
(1.5) ꢂ78–ꢂ23
5
6
7
Et2BH
EtBH2
9-BBNa)
(2.1)
(2.1)
(3.0)
ꢂ78
ꢂ78
0
77
79
48
>99=<1
95=5
95=5
2f
a) Determined by 1H NMR.
a) 9-Borabicyclo[3.3.1]nonane. b) Determined by 1H NMR.
acidity and/or bulkiness of the substituents of boron increased.
Several boron hydrides were examined by taking generation
and aldol reaction of boron enolate from 2-iodo-1-phenylpropan-
1-one as models (Table 3). When pinacolatoborane was used, the
desired aldol adduct was not obtained at all because the reduction
of coexisting carbonyl acceptor, benzaldehyde, took place in
preference to that of 2-iodo-1-phenylpropan-1-one (entry 2). In
the cases when boron hydride derived from 2-phenylmalonic acid
wasused,thedesiredaldolwasobtainedonlyin21%yieldwithno
diastereoselection (entry 3). On the other hand, the diastereo-
selectivity was greatly improved by using alkylboranes such as
monoethylborane or diethylborane as a reducing reagent (entries
5 and 6).
single-structured reducing reagent (entry 7). These results
indicated that the most suitable reagent for reducing ꢀ-iodo
ketone was a bulky alkyl group-substituted boron hydride such as
9-BBN.
In order to find appropriate reaction conditions, bases, solvents
andreactiontemperaturewerecarefullyinvestigated. Concerning
bases, the aldol reaction of 2-iodo-1-phenylpropan-1-one with
benzaldehyde using 9-BBN in toluene proceeded smoothly in the
presence of several bases (Table 4). In cases of using solid bases
such as K2CO3 and KF, the yields of the reactions were moderate
and a considerable amount of propiophenone was formed as a by-
product (entries 1 and 2). It was considered that propiophenone
was given either by direct reduction of ꢀ-iodo ketone with boron
hydride or by decomposition of initially formed boron enolate
with HI formed at the same time.
These alkylboranes are known toexist inequilibrium witheach
other and it is difficult to show which one is the key reductant for
thegenerationofenolborate. Thedesiredaldol,ontheotherhand,
was obtained in a moderate yield with high diastereoselectivity
when the above reaction was carried out by using 9-BBN as a
When organic bases such as triethylamine or ethyldiisopropyl-
amine were used (entries 3 and 4), yields of the desired aldols

816 Bull. Chem. Soc. Jpn., 76, No. 4 (2003)
Crossed Aldol Reaction via Boron Enolates
Table 4. Aldol Reaction Using Various Bases under Several Temperature
Entry
Base (mol. amt.)
Temp./ꢁC
Time/h
Yield/%
syn=antia)
1
2
3
4
5
6
7
8
9
10
K2CO3 (3.0) + MS4A
KF (3.0) + MS4A
Et3N (1.1)
rtb)
rt
rt
rt
rt
rt
rt
rt
20
20
20
20
3
20
3
1
62
43
37
38
59
85
98
11
92
39
93=7
69=31
95=5
95=5
85=15
90=10
90=10
46=54
99=1
iPr2NEt (1.1)
DBU (1.1)
2,6-Lutidine (1.1)
Pyridine (1.1)
None
Pyridine (1.1)
Pyridine (1.1)
ꢂ10
ꢂ23
30
60
92=8
a) Determined by 1H NMR and HPLC. b) Room Temperature.
Table 5. Aldol Reactions Using Several Bases or Several Solvents
Entry
Base (mol. amt.)
Solvent
Yield/%
syn=antia)
1
2
3
4
5
6
7
Pyridine (1.5)
Pyridine (3.0)
Toluene
Toluene
Toluene
CH2Cl2
Et2O
18 (68)b)
10 (78)b)
52
trace
trace
NRc)
91
99=1
99=1
99=1
99=1
—
2,6-Lutidine (1.5)
2,6-Lutidine (1.5)
2,6-Lutidine (1.5)
2,6-Lutidine (1.5)
2,6-Lutidine (1.5)
EtCN
THF
—
99=1
a) Determined by HPLC. b) Numbers in parentheses are yields of propiophenone. c) No
Reaction.
extremely decreased even after prolonged reaction times. The
formation of the key six-membered cyclic intermediates formed
from boron enolate and aldehyde. The desired aldol reaction
should proceed smoothly if amines having bulky substituents
were used, as they could not coordinate to the boron enolate.
Actually, the aldol was obtained in moderate yield (entry 3) when
2,6-lutidine was used.
reaction smoothly proceeded, however, to afford ꢁ-hydroxy
ketones in higher yields with good syn-selectivities (entries 6 and
7) when aromatic amines such as pyridine or 2,6-lutidine were
used. Theyieldofthereactionwasrelativelylowintheabsenceof
base and little diastereoselectivity was observed (entry 8).
The reaction proceeded slowlyasthe temperature lowered, and
the yield of the product markedly decreased at ꢂ23 ꢁC (Table 4,
entry 10). The reaction rate of ꢀ-iodo ketone reduction with 9-
BBN somewhat decreased at temperatures below ꢂ10 ꢁC, while
the aldol products were obtained with high diastereoselectivity at
the same temperature. Based on these results, the following
procedure was employed thereafter: generation of boron enolate
was carried out at room temperature, and aldehyde was subse-
Next, the effect of solvents was examined in order to find a
suitablesolvent forthe formation ofenolboratebyreductionofꢀ-
iodo ketone. Of the solvents tested, THF was found to be most
effective for the generation of the corresponding boron enolates
using 9-BBN as a reductant, and the subsequent reaction with
aldehyde afforded the desired aldol in 91% yield with high
diastereoselectivity (entry 7).
The yields and ratios of two aldol isomers produced by using
secondary ꢀ-iodo ketones and several aldehydes are summarized
in Table 6. By adding aldehydes at ꢂ78 ꢁC after the formation of
boron enolates (method A), both aromatic and aliphatic ꢀ-iodo
ketonesreactedsmoothlytogivethecorrespondingaldolproducts
ingoodyieldswithgoodsyn-diastereoselectivities. Further,when
ꢁ
quently added at ꢂ78 C. Investigations on the effect of bases
under the above conditions where enolates were generated in
advance showed that the aldol reaction took place and gave the
adduct in 18% yield in the presence of 1.5 molar amounts of
pyridine. This accompanied the formation of propiophenone in
68% yield after purification procedure (Table 5, entry 1). Also,
the yield of the desired aldol decreased down to 10% in the
presence of 3.0 molar amounts of pyridine (entry 2) and
propiophenone was obtained in 78% yield. Such low-yielding
of the aldol adducts may be attributed to the coordination of
pyridine to Lewis acidic boron enolate which prevented the
ꢁ
aldehydes were added at ꢂ10 C before the addition of 9-BBN
(method B), aromatic ꢀ-iodo ketones reacted with aldehydes to
give aldols also in good yields with good diastereoselectivity
(entries 2, 4, 6, 8 and 10), while diastereoselectivity of the aldol
products of aliphatic ꢀ-iodo ketones decreased (entries 17, 19, 21
and 23). This was probably because the reaction temperatures

T. Mukaiyama et al.
Bull. Chem. Soc. Jpn., 76, No. 4 (2003)
817
Table 6. Aldol Reaction Using Several ꢀ-Iodo Ketones with Several Aldehydes
Aldol adduct
syn=antib)
Yield/%
Entry
ꢀ-Iodo ketone
Aldehyde
Reaction typea)
1
2
A
B
95
99
99=1c)
97=3
98=2c)
98=2
98=2c)
98=2
97=3c)
92=8
4b
10
5
3
4
A
B
97
98
4a
4c
4d
5
6
A
B
94
96
13
14
15
7
8
A
B
95
81
9
10
A
B
96
89
99=1c)
97=3
4e
11
12
13
14
15
4b
4a
4c
4d
4e
A
A
A
A
A
16
17
18
19
20
93
98
90
99
94
>99=<1
>99=<1
>99=<1
>99=<1
>99=<1
16
17
A
B
82
88
95=5c)
93=7
99=1c)
83=17
4b
4a
4d
4e
11
6
18
19
A
B
81
85
20
21
A
B
90
71
88=12
85=15
94=6c)
72=28
21
22
22
23
A
B
94
48d)
24
25
26
27
28
4b
4a
4c
4d
4e
Be)
Be)
Be)
Be)
Be)
23
24
25
26
27
96
99
96
82
77
—
—
—
—
—
a) Type A: Boron enolate were previously generated at room temperature, then aldehydes were added at ꢂ78 ꢁC.
Type B: Boron hydride was added to the mixture of ꢀ-iodo ketone, amine and aldehyde at ꢂ10 ꢁC. b) Determined by
1H NMR. c) Determined by HPLC. d) 49% of cinnamyl alcohol was obtained. e) Reactions were performed at room
temperature.
were too high to control diastereoselectivity of the aldol reaction
of enol borate derived from aliphatic ꢀ-iodo ketones. Further, the
desired products were obtained in good yields (entries 24–28) by
treating 2-iodo-2-methyl-1-phenylpropan-1-one with several
aldehydes at room temperature according to method B. On the
otherhand, thedesiredaldoladductwasobtainedin48%yieldand
cinnamylalcoholwas obtainedin49%yield asa by-productwhen
cinnamaldehyde was used as a carbonyl acceptor under the above
conditions (entry 23).
The boron enolate generated from 3,4-dihydro-2-iodo-1(2H)-
naphthalenone and 9-BBN in THꢁF at room temperature reacted
with several aldehydes at ꢂ78 C to give anti-aldol adducts
(Table 7) as major products because E-enolates were formed
from cyclic ketones.14 On the other hand, it was found that anti-
diastereoselectivity of the products decreased when bulky
aldehyde was used (entry 1 vs 8) since the bulky substituent of
aldehydes prevented the formation of the characteristic rigid six-
membered transition state with the enol borate.
In the cases of using primary ꢀ-iodo ketones, the generated
boron enolates were very labile to be converted to the ketones,
reduced forms, probably because the enolates were decomposed
by HI that formed synchronously. Then, 9-BBN was added to a
mixture of primary ꢀ-iodo ketone, 2,6-lutidine, and aldehyde on
the assumption that the formed boron enolates would react
immediately with the coexisting aldehyde. As shown in Table 8,
aldol reaction of primary ꢀ-iodo ketones with aldehydes gave the
corresponding aldol adducts in good yields, however, the
dehydration of the formed aldols sometimes took place to afford
ꢀ,ꢁ-unsaturated ketones as by-products (entries 5, 6 and 10).
A proposed reaction pathway is shown in Fig. 2: ꢀ-Iodo
ketone was reduced with9-BBN in the coexistence of2,6-lutidine
andthusformedboronenolatesreactedwithaldehydesviathesix-
membered cyclic transition state to form the desired aldols
stereoselectively.

818 Bull. Chem. Soc. Jpn., 76, No. 4 (2003)
Crossed Aldol Reaction via Boron Enolates
Table 7. Aldol Reaction of 3,4-Dihydro-2-iodo-1(2H)-naph-
thalenone with Various Aldehydes
Table 8. Aldol Reactions of Primary ꢀ-Iodo Ketones with
Several Aldehydes
Aldol adduct
Yield/%a)
Entry
ꢀ-Iodo ketone
Aldehyde
Aldol adduct
yield/%
Entry
Aldehyde
syn=antia)
1
2
3
4
5
4b
4a
4c
4d
4e
9
91
91
90
82
16=84
34=66
1
4b
4b
99
87
35
36
37
38
28
2b)
3
4
5
6
4a
4c
4d
4e
29
30
31
32
98
82
98
82
23=77
10=90
20=80
19=81
50 (21)
6
7
8
9
10
4b
4a
4c
4d
4e
39
40
41
42
43
71 (12)
84
88
86
61 (13)
7
33
76
26=74
8
34
84
36=64
a) Numbers in parentheses are yields of ꢀ,ꢁ-unsaturated
ketones formed by dehydration of aldol adducts.
1
a) Determined by H NMR. b) Aldehyde was added at room
temperature.
Fig. 2.
shifts(ꢂ)arereportedinpartspermillionrelativetotetramethylsilane.
Splitting patterns are designed as s, singlet; d, doublet; t, triplet; q,
quartet; m, multiplet; br, broad. 13C NMR spectra were recorded on a
JEOL EX270 (68 MHz) spectrometer with complete proton
decoupling. Chemical shifts are reported in parts per million relative
to tetramethylsilane with the solvent resonance as the internal
standard(CDCl3;ꢂ77.0ppm). Highresolutionmassspectra(HRMS)
were recorded on a JEOL JMS-700T mass spectrometer. Analytical
TLC was performed on Merk precoated TLC plates (silica gel 60
GF254, 0.25mm). Silica gelcolumnchromatography wascarried out
on Merck silica gel 60 (0.063–0.200 mm). Preparative thin-layer
chromatography (PTLC) was carried out on silica gel Wacogel B-5F.
Solvents were freshly distilled when dry solvents were needed.
Aldehydes and 2-iodo-1-phenylethan-1-one were purchased from
Tokyo Kasei Kogyo, Kanto Chemical, Aldrich Chemical, or Merck,
and were used after purification by distillation or recrystallization.
Conclusion
Insummary, a new method for the generation ofboronenolates
was established by simple and straightforward 9-BBN reduction
of ꢀ-iodo ketones in the coexistence of 2,6-lutidine. Thus
generated boron enolates reacted smoothly with various alde-
hydes to afford ꢁ-hydroxy ketones in good to high yields with
good to high diastereoselectivities.
Experimental
General. All melting points were determined on a Yanagimoto
micro melting point apparatus (Yanaco MP-S3) and are uncorrected.
Infrared (IR) spectra were recorded on a Horiba FT300 FT-IR
spectrometer. 1H NMR spectra were recorded on a JEOL 270 (270
MHz) or a JEOL JNM-LA300 (300 MHz) spectrometer; chemical

T. Mukaiyama et al.
Bull. Chem. Soc. Jpn., 76, No. 4 (2003)
819
Other ꢀ-iodo ketones were prepared according to the literature
procedures.10;15{18
1H), 2.88 (d, J ¼ 2:7 Hz, 1H), 3.95 (m, 1H), 7.19–7.29 (m, 5H);
13C NMR (68 MHz, CDCl3) ꢂ 7.67, 10.2, 32.4, 35.1, 35.8, 49.8, 70.2,
125.8, 128.3 (ꢃ2), 128.4 (ꢃ2), 141.7, 216.5.
General Procedure for Isolation of Boron Enolates (Table 1).
Toa solution ofꢀ-iodo ketone (14.1mmol)and pyridine (21.2mmol)
in toluene (100 mL) was added pinacolatoborane (21.2 mmol) under
argon atmosphere at room temperature, and the reaction mixture was
stirred for 1 h. The precipitate was removed by filtration under argon
atmosphere and the filtrate was concentrated in vacuo. The crude
product was purified by distillation under reduced pressure to afford
the corresponding pinacol boron enolate.
4,4,5,5-Tetramethyl-2-(1-phenylprop-1-enyloxy)[1,3,2]diox-
aborolane (3a): Isolated as a colorless oil: bp 106 ꢁC/33 Pa;
1H NMR (270 MHz, C6D6) ꢂ 0.91 (s, 12H), 1.71 (d, J ¼ 6:9 Hz, 3H),
5.40 (q, J ¼ 6:9 Hz, 1H), 7.10 (m, 3H), 7.50 (d, J ¼ 8:1 Hz, 1H);
13C NMR (68 MHz, C6D6) ꢂ 11.4, 24.5, 83.1, 106.5, 124.7, 127.7,
128.5, 137.5, 149.1.
2-(1-Hydroxy-3-phenylpropyl)cyclohexanone (7):19
Syn-
isomer: IR (neat, cmꢂ1) 3574, 1698; 1H NMR (270 MHz, CDCl3) ꢂ
1.76–1.54 (m, 4H), 1.81–2.09 (m, 4H), 2.27–2.41 (m, 3H), 2.60–2.70
(m, 1H), 2.76 (d, J ¼ 3:3 Hz, 1H), 2.84–2.90 (m, 1H), 4.09–4.13 (m,
1H), 7.16–7.25 (m, 3H), 7.27–7.29 (m, 2H); 13C NMR (68 MHz,
CDCl3) ꢂ 24.9, 26.5, 27.6, 32.3, 34.8, 42.6, 55.1, 68.4, 125.7, 128.3
(ꢃ2), 128.4 (ꢃ2), 142.1, 214.9.
5-Ethyl-6-hydroxy-8-phenyloctan-4-one (8): Syn-isomer: IR
(neat, cmꢂ1) 3687, 3602, 1697; 1H NMR (270 MHz, CDCl3) ꢂ 0.85–
0.92 (m, 6H), 1.50–1.85 (m, 6H), 2.37–2.68 (m, 5H), 2.78–2.89 (m,
1H),3.77(t, J ¼ 3:7 Hz, 1H), 7.17–7.29 (m, 5H);13C NMR(68 MHz,
CDCl3) ꢂ 12.5, 13.7, 16.6, 19.8, 32.4, 36.3, 46.5, 58.2, 60.4, 70.8,
125.8, 128.3 (ꢃ2), 128.3 (ꢃ2), 141.6, 215.5; HRMS (FAB) Calcd for
C16H25O2: (Mþ + H) 249.1855. Found: m=z 249.1851.
2-(1-Ethylprop-1-enyloxy)-4,4,5,5-tetramethyl[1,3,2]dioxa-
borolane (3b): Isolated asa colorless oil: bp60 ꢁC/267 Pa; 1H NMR
(270 MHz, CDCl3) ꢂ 0.93–1.06 (m, 5H), 1.21 (s, 12H), 1.45 (d,
J ¼ 6:7 Hz, 3H), 4.64 (q, J ¼ 6:7 Hz, 1H); 13C NMR (68 MHz,
C6D6) ꢂ 10.7, 11.7, 24.74 (ꢃ4), 28.6, 82.7, 82.8, 103.1, 152.2.
2-(Cyclohex-1-enyloxy)-4,4,5,5-tetramethyl[1,3,2]dioxabor-
olane (3c): Isolated as a colorless oil: bp 140 ꢁC/53 Pa; 1H NMR
(270 MHz, C6D6) ꢂ 1.05 (s, 12H), 1.34–1.56 (m, 6H), 2.21–2.26 (m,
2H),5.46–5.49(m, 1H);13C NMR(68 MHz, C6D6)ꢂ22.5, 23.3, 24.0,
24.76, 24.79, 26.0, 27.1, 28.8, 41.9, 82.7, 83.0, 107.0, 149.6.
4,4,5,5-Tetramethyl-2-(1-propylbut-1-enyloxy)[1,3,2]dioxa-
borolane (3d): Isolated asa colorless oil: bp130ꢁC/93 Pa; 1H NMR
(270 MHz, C6D6)ꢂ0.81 (t, J ¼ 7:4 Hz, 3H),0.93 (t, J ¼ 7:4 Hz, 3H),
1.09 (s, 12H), 1.46–1.64 (m, 2H), 1.86–1.99 (m, 2H), 2.23 (t, J ¼ 7:4
Hz, 2H), 4.67 (t, J ¼ 7:1 Hz, 1H); 13C NMR (68 MHz, C6D6) ꢂ 14.2,
14.6, 17.6, 18.0, 24.70, 24.72, 24.8 (ꢃ2), 44.6, 82.8, 83.0, 112.3,
149.2.
Typical Procedure of Aldol Reaction between ꢀ-Iodo Ke-
tones and Aldehydes Using 9-BBN (Method A). To a solution of
2-iodo-1-phenylpropan-1-one (0.25 mmol) and 2,6-lutidine (0.38
mmol) in THF (3 mL) was added 9-BBN (0.5 M in THF, 0.38 mmol)
under argon atmosphere at room temperature. After the mixture was
stirred for 2 h, the reaction mixture was cooled down to ꢂ78 ꢁC, and
benzaldehyde (0.28 mmol) was added dropwise. The same work up
as described above gave 3-hydroxy-2-methyl-1,3-diphenylpropan-1-
one (10)20 (95%, syn=anti ¼ 97=3) as a colorless oil: IR (neat, cmꢂ1
)
3467, 1678; 1H NMR (270 MHz, CDCl3) ꢂ 1.20 (d, J ¼ 7:3 Hz, 3H),
3.69 (s, 1H), 3.70 (dq, J ¼ 7:3, 3.1 Hz, 1H), 4.98 (m, 0.03H), 5.24 (d,
J ¼ 2:3 Hz, 0.97H), 7.61–7.22 (m, 8H), 7.93 (d, J ¼ 8:6 Hz, 2H);
13C NMR (68 MHz, CDCl3) ꢂ 11.2, 47.0, 73.0, 125.9 (ꢃ2), 127.2,
128.1 (ꢃ2), 128.3 (ꢃ2), 128.7 (ꢃ2), 133.5, 135.4, 141.6, 205.5.
Typical Procedure of Aldol Reaction between ꢀ-Iodo Ke-
tones and Aldehydes Using 9-BBN (Method B). To a solution of
2-iodo-1-phenylpropan-1-one (0.25 mmol), 2,6-lutidine (0.38 mmol)
and benzaldehyde (0.28 mmol) in THF(3mL) was added9-BBN (0.5
M in THF, 0.38 mmol) under argon atmosphere at ꢂ10 ꢁC. After the
mixture was stirred for 2 h, the same work up as described above gave
3-hydroxy-2-methyl-1,3-diphenylpropan-1-one (10) (95%).
Aldol Reaction between Isolated Pinacolatoboron Enolates
and Aldehydes. The isolated pinacolatoboron enolate (0.25 mmol)
was dissolved in toluene (3 mL), and this solution was added to a
solution of an aldehyde (0.28 mmol) in toluene (3 mL). After the
reaction mixture was stirred for 3 h at room temperature, the reaction
was quenched by adding phosphate buffer (pH 7). The mixture was
extracted with ether (3 mL ꢃ 3), and the combined organic layer was
concentrated in vacuo. The residue was dissolved in methanol (3
mL), and the solution was treated with 30% hydrogen peroxide (2
mL) at 0 ꢁC. The mixture was extracted with ether (3 mL ꢃ 3), and
the combined organic layer was washed with saturated sodium
hydrogencarbonate (3 mL) and brine, dried over Na2SO4, and
concentratedinvacuo. The crudeproduct was purifiedby preparative
TLC to afford the corresponding ꢁ-hydroxy ketone.
3-Hydroxy-1,3-diphenylpropan-1-one (9):20 IR (neat, cmꢂ1
)
3509, 1681; 1H NMR (270 MHz, CDCl3) ꢂ 3.33 (d, J ¼ 4:5 Hz, 1H),
3.34 (d, J ¼ 7:9 Hz, 1H), 3.70 (d, J ¼ 3:0 Hz, 1H), 5.34–5.29 (m,
1H), 7.58–7.22 (m, 8H), 7.91 (d, J ¼ 7:0 Hz, 2H); 13C NMR (68
MHz, CDCl3) ꢂ 47.3, 69.9, 125.6 (ꢃ2), 128.5, 128.0 (ꢃ2), 128.4
(ꢃ2), 128.5 (ꢃ2), 133.4, 136.3, 142.8, 199.8.
1-Hydroxy-2-methyl-1-phenylpentan-3-one (11):20 Isolated
as a mixture of diasteromers (syn=anti ¼ 93=7): IR (neat, cmꢂ1
)
3462, 1707; 1H NMR (270 MHz, CDCl3) ꢂ 1.00 (t, J ¼ 7:3 Hz, 3H),
1.08 (d, J ¼ 7:3 Hz, 3H), 2.29 (q, J ¼ 7:3 Hz, 0.07H), 2.37 (q, J ¼
7:3 Hz, 0.93H), 2.55 (q, J ¼ 7:3 Hz, 0.07H), 2.84 (dq, J ¼ 7:3, 4.1
Hz, 1H), 3.17 (d, J ¼ 2:5 Hz, 1H), 4.75 (dd, J ¼ 8:2, 4.3 Hz, 0.07H),
5.05 (dd, J ¼ 3:8, 2.1 Hz, 0.93H), 7.22–7.36 (m, 5H); 13C NMR (68
MHz, CDCl3) ꢂ 7.6, 10.7, 35.5, 52.2, 73.3, 125.8 (ꢃ2), 127.2, 128.1,
128.4, 141.6, 216.1.
3-Hydroxy-2-methyl-1,5-diphenylpentan-1-one (5):11 Iso-
lated as a mixture of diastereomers (syn/anti = 98/2): IR (neat, cmꢂ1
)
3448, 1666; 1H NMR (270 MHz, CDCl3) ꢂ 1.27 (d, J ¼ 7:3 Hz, 3H),
1.64–1.76 (m, 1H), 1.89–2.03 (m, 1H), 2.65–2.76 (m, 1H), 2.85–2.95
(m, 1H), 3.26 (s, 0.98H), 3.44 (dq, J ¼ 7:3, 2.6Hz, 0.98H), 3.52–3.57
(m, 0.02H), 3.82–3.92 (m, 0.02H), 4.06–4.10 (m, 0.98H), 7.15–7.31
(m, 5H), 7.44–7.49 (m, 2H), 7.55–7.61 (m, 1H), 7.89–7.95 (m, 2H);
13C NMR (68 MHz, CDCl3) ꢂ 11.2, 32.4, 36.1, 44.6, 70.5, 125.8,
128.25 (ꢃ2), 128.29 (ꢃ2), 128.34 (ꢃ2), 128.4, 128.7, 133.4, 135.5,
141.8, 205.7.
3-Hydroxy-1,2,3-triphenylpropan-1-one (12):21 Isolated as a
mixture of diasteromers (syn=anti ¼ 72=28): IR (neat, cmꢂ1) 3448,
1
3301, 1673; H NMR (270 MHz, CDCl3) ꢂ 3.31 (d, J ¼ 3:7 Hz,
0.28H), 3.38 (d, J ¼ 2:1 Hz, 0.72H), 4.57 (d, J ¼ 6:1 Hz, 0.28H),
4.81 (d, J ¼ 5:5 Hz, 0.72H), 5.54 (dd, J ¼ 5:5, 2.1 Hz, 0.72H), 5.96
(d, J ¼ 6:1 Hz, 0.28H), 7.13–7.49 (m, 13H), 7.82–8.01 (m, 2H);
13C NMR (68 MHz, CDCl3) ꢂ 60.8, 74.6, 126.2, 126.5, 127.36,
127.43, 127. 5, 127.8, 127.9, 128.0, 128.4, 128.5, 128.6, 129.6, 130.5,
133.2, 134.0, 136.0, 141.1, 142.5, 200.3.
5-Hydroxy-4-methyl-7-phenylheptan-3-one (6):20 Isolated as
a mixture of diastereomers (syn=anti ¼ 83=17): IR (neat, cmꢂ1
)
3440, 3340, 1705; 1H NMR (270 MHz, CDCl3) ꢂ 1.04 (t, J ¼ 7:3 Hz,
3H), 1.13 (d, J ¼ 7:0 Hz, 0.51H), 1.15 (d, J ¼ 7:3 Hz, 2.49H), 1.52–
1.65 (m, 1H), 1.77–1.89 (m, 1H), 2.39–2.75 (m, 4H), 2.77–2.85 (m,

820 Bull. Chem. Soc. Jpn., 76, No. 4 (2003)
Crossed Aldol Reaction via Boron Enolates
3-Hydroxy-2,4-dimethyl-1-phenylpentan-1-one (13):20 Syn-
isomer: IR (neat, cmꢂ1) 3448, 3340, 1673; 1H NMR (270 MHz,
CDCl3) ꢂ 0.96 (t, J ¼ 6:6 Hz, 3H), 1.03 (d, J ¼ 6:6 Hz, 3H), 1.25 (d,
J ¼ 6:8 Hz, 3H), 1.72–1.82 (m, 1H), 3.96–4.04 (m, 1H), 7.26–7.62
(m, 3H), 7.95–7.99 (m, 2H); 13C NMR (68 MHz, CDCl3) ꢂ11.3, 18.0,
18.6, 33.1, 42.0, 72.4, 128.0 (ꢃ2), 128.5 (ꢃ2), 133.4, 136.7, 201.1.
3-Cyclohexyl-3-hydroxy-2-methyl-1-phenylpropan-1-one
(14):20 Isolated as a mixture of diastereomers (syn=anti ¼ 97=3): IR
en-1-one (20): Syn-isomer: IR (neat, cmꢂ1) 3864, 3440, 1666, 1604;
1H NMR (270 MHz, CDCl3) ꢂ 1.23 (d, J ¼ 7:2 Hz, 3H), 2.44 (s, 1H),
3.52 (td, J ¼ 7:2, 3.3 Hz, 1H), 3.81 (s, 3H), 4.71 (ddd, J ¼ 5:3, 3.5,
1.7 Hz, 1H), 6.18 (dd, J ¼ 16:0, 5.6 Hz, 1H), 6.65 (dd, J ¼ 16:0, 1.3
Hz, 1H), 6.89 (d, J ¼ 8:9 Hz, 2H), 7.12–7.33 (m, 5H), 7.89 (d, J ¼
8:9 Hz, 2H); 13C NMR (68 MHz, CDCl3) ꢂ 12.0, 44.9, 55.5, 72.2,
113.8 (ꢃ2), 120.2, 126.3 (ꢃ2), 127.4, 128.3 (ꢃ2), 128.5, 129.2,
130.6, 130.7 (ꢃ2), 136.6, 203.6; HRMS (FAB) Calcd for C19H21O3:
(Mþ) 297.1491. Found: m=z 297.1493.
1
(neat, cmꢂ1) 3442, 1704; H NMR (270 MHz, CDCl3) ꢂ 1.23 (d,
J ¼ 7:1 Hz, 3H), 0.90–1.37 (m, 5H), 1.42–1.54 (m, 1H), 1.66–1.80
(m, 4H), 2.05 (d, J ¼ 13:0 Hz, 1H), 3.03 (s, 0.03H), 3.13 (d, J ¼ 2:3
Hz, 0.97H), 3.55–3.58 (m, 0.06H), 3.64–3.72 (m, 1.94H), 7.26–7.62
(m, 3H), 7.92–7.93 (m, 2H); 13C NMR (68 MHz, CDCl3) ꢂ10.6, 25.9,
26.2, 26.4, 29.2, 29.5, 40.2, 41.3, 75.4, 128.2, 128.3, 128.6 (ꢃ2),
133.3, 135.7, 205.7.
3-Hydroxy-2-methyl-1,5-diphenylpent-4-en-1-one (15):20
Isolated as a mixture of diastereomers (syn=anti ¼ 97=3): IR (neat,
cmꢂ1) 3509, 1667; 1H NMR (270 MHz, CDCl3) ꢂ 1.31 (d, J ¼ 2:0
Hz, 3H), 3.48 (q, J ¼ 8:4 Hz, 0.03H), 3.64 (dq, J ¼ 7:1, 3.3 Hz,
0.97H), 4.78–4.81 (m, 0.97H), 4.57–4.61 (m, 0.03H), 6.24 (dd,
J ¼ 16:0, 5.6 Hz, 1H), 6.71 (dd, J ¼ 16:0, 1.2 Hz, 0.97H), 6.82 (d,
J ¼ 15:8 Hz, 0.03H), 7.20–7.62 (m, 8H), 7.95–7.98 (m, 2H);
13C NMR (68 MHz, CDCl3) ꢂ 11.9, 45.4, 72.2, 126.34 (ꢃ2), 127.5,
128.39 (ꢃ2), 128.42 (ꢃ2), 128.7 (ꢃ2), 130.0, 130.9, 133.5, 135.6,
136.5, 205.1.
3-Hydroxy-1-(4-methoxyphenyl)-2-methyl-3-phenylpropan-
1-one (16): Syn-isomer: IR (neat, cmꢂ1) 3656, 3463, 1658, 1596;
1H NMR (270 MHz, CDCl3) ꢂ 1.07 (d, J ¼ 7:3 Hz, 3H), 2.44 (s, 1H),
3.54 (td, J ¼ 7:3, 3.1 Hz, 1H), 3.77 (s, 3H), 5.11 (d, J ¼ 3:3 Hz, 1H),
6.83 (d, J ¼ 8:9 Hz, 2H), 7.12–7.14 (m, 5H), 7.81 (d, J ¼ 8:9 Hz,
2H); 13C NMR (68 MHz, CDCl3) ꢂ11.3, 46.5, 55.5, 73.1, 113.8 (ꢃ2),
113.9, 125.9 (ꢃ2), 127.1, 128.0 (ꢃ2), 130.7 (ꢃ2), 141.7, 163.7,
204.1; HRMS (FAB) Calcd for C17H19O3: (Mþ) 271.1334. Found:
m=z 271.1324.
3-Hydroxy-1-(4-methoxyphenyl)-2-methyl-5-phenylpentan-
1-one (17): Syn-isomer: IR (neat, cmꢂ1) 3471, 3401, 1658, 1596;
1H NMR (270 MHz, CDCl3) ꢂ 1.27 (d, J ¼ 7:1 Hz, 3H), 1.66–1.99
(m, 2H),2.59–2.76(m, 1H), 2.86–2.94(qd, J ¼ 7:1, 2.7Hz, 1H), 3.50
(br, 1H), 3.88 (s, 3H), 4.06 (dt, J ¼ 8:7, 3.3 Hz, 1H), 6.94 (d, J ¼ 8:9
Hz, 2H), 7.16–7.32 (m, 5H), 7.90 (d, J ¼ 8:9 Hz, 2H); 13C NMR (68
MHz, CDCl3) ꢂ 11.4, 32.4, 36.1, 44.1, 55.5, 70.6, 113.8 (ꢃ2), 125.7,
128.2 (ꢃ2), 128.3 (ꢃ2), 128.4, 130.7 (ꢃ2), 141.8, 163.6, 204.3;
HRMS (FAB) Calcd for C19H23O3: (Mþ) 299.1647. Found: m=z
299.1631.
1-Cyclohexyl-1-hydroxy-2-methylpentan-3-one (21):20 Iso-
lated as a mixture of diastereomers (syn=anti ¼ 85=15): IR (neat,
1
cmꢂ1) 3409, 3255, 1704; H NMR (270 MHz, CDCl3) ꢂ 0.99 (t,
J ¼ 7:3 Hz, 3H), 1.15 (d, J ¼ 7:1 Hz, 3H), 0.79–1.22 (m, 5H), 1.23–
1.98 (m, 5H), 2.00 (br, J ¼ 13:2 Hz, 1H), 2.46 (m, 2H), 2.67 (dq,
J ¼ 7:1, 3.0 Hz, 1H), 2.74 (d, J ¼ 3:0 Hz, 1H), 3.35 (m, 0.15H), 3.52
(dt,J ¼ 8:6, 3.0Hz, 0.85H);13C NMR (68 MHz, CDCl3)ꢂ7.58, 9.46,
26.1, 26.4, 29.0, 29.5, 34.8, 40.0, 46.6 (ꢃ2), 75.0, 216.7.
5-Hydroxy-4-methyl-7-phenylhept-6-en-3-one (22):20 Iso-
lated as a mixture of diastereomers (syn=anti ¼ 72=28): IR (neat,
1
cmꢂ1) 3440, 3370, 1697; H NMR (270 MHz, CDCl3) ꢂ 1.06 (t,
J ¼ 7:3 Hz, 2.16H), 1.62(d, J ¼ 7:3 Hz, 0.84H),1.18(d, J ¼ 8:6 Hz,
2.16H), 1.26 (t, J ¼ 7:1 Hz, 0.84H), 2.43–2.64 (m, 2H), 2.73–2.82
(m, 1H), 2.96 (s, 0.72H), 4.37 (br, 0.28H), 4.61 (br, 0.72H), 6.16 (dd,
J ¼ 5:9, 16.0 Hz, 0.72H), 6.17 (dd, J ¼ 16:0, 7.3 Hz, 0.28H), 6.61
(dd, J ¼ 16:0 Hz, 0.28H), 6.63 (dd, J ¼ 16:0, 1.2 Hz, 0.72H), 7.21–
7.39 (m, 5H); 13C NMR (68 MHz, CDCl3) ꢂ 7.6, 11.0, 35.5, 50.5,
72.4, 126.3, 126.4, 127.6, 128.4, 128.5, 128.9, 131.0, 136.5, 215.6.
3-Hydroxy-2,2-dimethyl-1,3-diphenylpropan-1-one (23):15
IR (neat, cmꢂ1) 3540, 3494, 3424, 1673; 1H NMR (270 MHz, CDCl3)
ꢂ 1.10 (s, 3H), 1.16 (s, 3H), 2.93 (d, J ¼ 3:4 Hz, 1H), 5.03 (d, J ¼ 3:4
Hz, 1H), 7.19–7.47 (m, 10H); 13C NMR (68 MHz, CDCl3) ꢂ 19.6,
24.2, 52.5, 78.8, 127.1 (ꢃ2), 127.68, 127.74, 127.93 (ꢃ2), 127.97,
130.5, 139.7, 140.2, 211.9.
3-Hydroxy-2,2-dimethyl-1,5-diphenylpentan-1-one (24):21
IR (neat, cmꢂ1) 3579, 3401, 3355, 1666; 1H NMR (270 MHz, CDCl3)
ꢂ 1.30 (s, 6H), 1.71–1.75 (m, 1H), 2.37–2.41 (m, 1H), 2.58–2.85 (m,
1H), 2.96 (ddd, J ¼ 14:4, 9.3, 5.8 Hz, 1H), 3.89 (t, J ¼ 6:5 Hz, 1H),
7.14–7.49 (m, 8H), 7.58 (dd, J ¼ 8:3, 1.3 Hz, 2H); 13C NMR (68
MHz, CDCl3) ꢂ 21.2, 25.7, 33.0, 33.6, 41.9, 52.0, 125.7, 127.3, 128.0,
128.25, 128.35, 130.8, 138.8, 141.9, 210.8.
3-Hydroxy-2,2,4-trimethyl-1-phenylpentan-1-one (25):10 IR
(neat, cmꢂ1) 3471, 3363, 1666; 1H NMR (270 MHz, CDCl3) ꢂ 0.89
(d, J ¼ 6:8 Hz, 3H), 0.94 (d, J ¼ 6:8 Hz), 1.32 (s, 3H), 1.39 (s, 3H),
1.62–1.93 (m, 1H), 2.91 (d, J ¼ 5:7 Hz, 1H), 3.66–3.67 (m, 1H),
7.29–7.47 (m, 3H), 7.59 (d, J ¼ 6:8 Hz, 2H); 13C NMR (68 MHz,
CDCl3) ꢂ 17.8, 22.4, 23.3, 24.3, 30.2, 51.5, 82.2, 127.5 (ꢃ2), 128.0
(ꢃ2), 130.7, 139.3, 211.8.
3-Hydroxy-1-(4-methoxyphenyl)-2,4-dimethylpentan-1-one
(18):22
Syn-isomer: IR (neat, cmꢂ1) 3563, 3424, 1658, 1596;
1H NMR (270 MHz, CDCl3) ꢂ 0.91 (d, J ¼ 6:7 Hz, 3H), 0.99 (d,
J ¼ 6:7 Hz, 3H), 1.20 (d, J ¼ 6:9 Hz, 3H), 1.65–1.81 (m, 1H), 3.35
(s, 1H), 3.56–3.64 (m, 2H), 3.85 (s, 3H), 6.92 (d, J ¼ 8:9 Hz, 2H),
7.90 (d, J ¼ 8:9 Hz, 2H); 13C NMR (68 MHz, CDCl3) ꢂ 11.0, 19.1,
19.2, 30.7, 41.2, 55.5, 76.7, 113.8 (ꢃ2), 128.6, 130.6 (ꢃ2), 163.6,
204.3.
3-Cyclohexyl-3-hydroxy-2,2-dimethyl-1-phenylpropan-1-
one (26): IR (neat, cmꢂ1) 3610, 3432, 3370, 1666; 1H NMR (270
MHz, CDCl3) ꢂ 1.09–1.28 (m, 4H), 1.31 (s, 3H), 1.38 (s, 3H), 1.36–
1.70 (m, 6H), 1.80–1.90 (m, 1H), 2.36–2.40 (m, 1H), 3.63 (d, J ¼ 3:8
Hz, 1H), 7.37–7.45 (m, 3H),7.59(dd, J ¼ 8:3, 1.7Hz, 2H);13C NMR
(68 MHz, CDCl3) ꢂ23.4, 24.1, 24.7, 26.2, 26.7, 27.2, 28.4, 32.3, 40.5,
41.9, 82.2, 127.5 (ꢃ2), 127.9 (ꢃ2), 130.7, 139.3, 211.7; HRMS
(FAB) Calcd for C17H25O2: (Mþ + H) 261.1855. Found: m=z
261.1858.
3-Hydroxy-2,2-dimethyl-1,5-diphenylpent-4-en-1-one (27):21
IR (neat, cmꢂ1) 3710, 3540, 3363, 1673; 1H NMR (270 MHz, CDCl3)
ꢂ 1.30 (s, 3H), 1.31 (s, 3H), 2.79 (br, 1H), 4.51 (d, J ¼ 7:0 Hz, 1H),
6.20 (dd, J ¼ 15:8, 7.0Hz, 1H),6.57 (d, J ¼ 15:8 Hz, 1H), 7.16–7.40
(m, 9H), 7.56–7.60 (m, 1H); 13C NMR (68 MHz, CDCl3) ꢂ20.7, 23.9,
52.0, 78.3, 126.4, 127.39, 127.44, 127.7, 128.0, 128.5, 129.0, 130.8,
3-Cyclohexyl-3-hydroxy-1-(4-methoxyphenyl)-2-methylpro-
pan-1-one (19): Syn-isomer: IR (neat, cmꢂ1) 3833, 3401, 1658,
1596; 1H NMR (270 MHz, CDCl3) ꢂ 0.87–1.13 (m, 2H), 1.03–1.25
(m, 4H), 1.19 (d, J ¼ 7:0 Hz, 3H), 1.62–1.75 (m, 4H), 3.32 (s, 1H),
3.57–3.64 (m, 2H), 3.85 (s, 1H), 6.92 (d, J ¼ 8:9 Hz, 2H), 7.89 (d,
J ¼ 8:9 Hz, 2H);13C NMR(68 MHz, CDCl3) ꢂ10.8, 25.9, 26.1, 26.4,
29.1, 29.5, 40.1, 40.6, 55.5, 75.5, 113.8, 128.6, 130.6, 163.6, 204.4;
HRMS (FAB) Calcd for C19H25O3: (Mþ) 277.1804. Found: m=z
277.1807.
3-Hydroxy-1-(4-methoxyphenyl)-2-methyl-5-phenylpent-4-

T. Mukaiyama et al.
Bull. Chem. Soc. Jpn., 76, No. 4 (2003)
821
132.9, 136.4, 210.6.
8.03 (dd, J ¼ 7:9, 1.3 Hz, 1H); 13C NMR (68 MHz, CDCl3) ꢂ 26.0,
28.9, 52.8, 73.8, 126.5, 126.7, 127.4, 127.7, 128.4, 128.6, 128.7,
132.2, 132.5, 133.9, 136.4, 144.2, 201.6; HRMS (FAB) Calcd for
C19H18O2: (Mþ) 278.1307. Found: m=z 278.1311.
2-[Hydroxy(phenyl)methyl]-3,4-dihydronaphthalen-1(2H)-
one (28):15 Isolated as a mixture of diastereomers (syn=anti ¼
16=84): IR (neat, cmꢂ1) 3571, 3455, 1673; 1H NMR (270 MHz,
CDCl3) ꢂ 1.62–1.72 (m, 2H), 2.70–2.96 (m, 3H), 4.95 (d, J ¼ 8:8 Hz,
0.84H), 5.68 (d, J ¼ 2:8 Hz, 0.16H), 7.19–7.52 (m, 9H), 8.03–8.08
(m, 1H); 13C NMR (68 MHz, CDCl3) ꢂ 22.3, 28.9, 53.8, 76.5, 126.7,
127.1 (ꢃ2), 127.4, 127.9, 128.1 (ꢃ2), 128.6, 132.1, 133.9, 140.9,
144.3, 202.2.
2-(Hydroxy-o-tolylmethyl)-3,4-dihydronaphthalen-1(2H)-
one (33): Syn-isomer: IR (neat, cmꢂ1) 3602, 3548, 3478, 1673;
1H NMR (270 MHz, CDCl3) ꢂ 1.59–1.91 (m, 2H), 2.30 (s, 3H), 2.65–
2.98 (m, 3H), 5.98 (s, 1H), 7.04–7.35 (m, 5H), 7.44–7.57 (m, 2H),
8.07 (d, J ¼ 7:7 Hz, 1H); 13C NMR (68 MHz, CDCl3) ꢂ 19.1, 21.8,
29.1, 52.3, 67.8, 125.7, 126.4, 126.5, 126.7, 126.8, 126.9, 127.3,
132.7, 133.6, 134.0, 139.8, 144.3, 199.6; HRMS (FAB) Calcd for
C18H19O2: (Mþ + H) 267.1385. Found: m=z 267.1396. Anti-isomer:
IR (neat, cmꢂ1) 3579, 3548, 3517, 1666; 1H NMR (270 MHz, CDCl3)
ꢂ1.53–1.88(m, 2H),2.36 (s, 3H),2.78–2.92 (m, 3H), 5.27(d, J ¼ 9:1
Hz, 1H), 7.13–7.36 (m, 5H), 7.47–7.54 (m, 2H), 8.07 (d, J ¼ 7:8 Hz,
1H); 13C NMR (68 MHz, CDCl3) ꢂ 19.9, 26.0, 29.2, 54.2, 71.2, 126.5,
126.7, 126.8, 127.4, 127.5, 128.6, 130.2, 132.2, 134.0, 144.3, 150.4,
165.6, 202.8; HRMS (FAB) Calcd for C18H19O2: (Mþ + H)
267.1385. Found: m=z 267.1396.
2-(1-Hydroxy-3-phenylpropyl)-3,4-dihydronaphthalen-1-
(2H)-one (29):23
Isolated as a mixture of diastereomers
(syn=anti ¼ 23=77): IR (neat, cmꢂ1) 3448, 3355, 1673; 1H NMR
(270 MHz, CDCl3) ꢂ 1.75–2.17 (m, 4H), 2.48–2.56 (m, 1H), 2.66–
2.77 (m, 1H), 2.80–3.00 (m, 2H), 3.96 (td, J ¼ 8:2, 3.3 Hz, 0.77H),
4.25 (td, J ¼ 6:3, 3.1 Hz, 0.23H), 7.16–7.31 (m, 7H), 7.46 (td,
J ¼ 7:4, 1.5 Hz, 1H), 7.98 (dd, J ¼ 7:8, 1.0 Hz, 1H); 13C NMR (68
MHz, CDCl3) ꢂ 25.7, 29.0, 31.5, 35.8, 52.8, 71.2, 125.6, 126.6, 127.2,
128.2 (ꢃ2), 128.4 (ꢃ2), 128.5, 132.2, 133.7, 142.1, 144.0, 202.1.
2-(1-Hydroxy-2-methylpropyl)-3,4-dihydronaphthalen-1-
(2H)-one (30):15 Syn-isomer: IR (neat, cmꢂ1) 3448, 3332, 1673;
1H NMR (270 MHz, CDCl3) ꢂ 0.90 (d, J ¼ 6:7 Hz, 3H), 1.09 (d,
J ¼ 6:7 Hz, 3H), 1.62–1.97 (m, 1H), 2.12–2.21 (m, 2H), 2.69 (td,
J ¼ 8:7, 1.6 Hz, 1H), 3.05 (t, J ¼ 6:9 Hz, 2H), 4.07 (dd, J ¼ 9:3, 2.3
Hz), 7.23–7.34 (m, 2H), 7.47 (td, J ¼ 7:6, 1.6 Hz, 1H), 8.02 (dd,
J ¼ 7:9, 1.6 Hz, 1H); 13C NMR (68 MHz, CDCl3) ꢂ 19.1, 19.8, 22.0,
29.1, 30.0, 50.7, 74.9, 126.5, 127.1, 128.5, 128.7, 132.8, 133.4, 133.7,
200.8. Anti-isomer: IR (neat, cmꢂ1) 3586, 3478, 1673; 1H NMR (270
MHz, CDCl3) ꢂ 0.97 (d, J ¼ 6:7 Hz, 3H), 1.07 (d, J ¼ 6:7 Hz, 3H),
1.67–1.97 (m, 2H), 2.14–2.22 (m, 1H), 2.54–2.64 (m, 1H), 3.00–3.06
(m, 2H), 3.77 (dd, J ¼ 7:9, 3.5 Hz, 1H), 7.23–7.34 (m, 2H), 7.49 (td,
J ¼ 7:4, 1.4 Hz, 1H), 8.02 (dd, J ¼ 7:4, 1.4 Hz, 1H); 13C NMR (68
MHz, CDCl3) ꢂ 14.9, 20.2, 25.8, 28.9, 29.6, 50.7 (ꢃ2), 126.4, 126.6,
127.3, 128.5, 128.6, 133.7, 202.8.
2-[Hydroxy(mesityl)methyl]-3,4-dihydronaphthalen-1(2H)-
one (34): Syn-isomer: IR (neat, cmꢂ1) 3440, 3363, 1673; 1H NMR
(270 MHz, CDCl3) ꢂ 2.14–2.19 (m, 2H), 2.24 (s, 3H), 2.37 (s, 6H),
2.81–3.08 (m, 3H), 5.98 (d, J ¼ 3:1 Hz, 1H), 6.82 (s, 2H), 7.21–7.32
(m, 2H), 7.46 (td, J ¼ 7:6, 1.5 Hz, 1H), 8.00 (dd, J ¼ 7:6, 1.2 Hz,
1H); 13C NMR (68 MHz, CDCl3) ꢂ 21.3 (ꢃ2), 23.8, 28.8, 53.6, 69.6,
126.5, 127.3 (ꢃ2), 128.7 (ꢃ2), 130.2 (ꢃ2), 133.4 (ꢃ2), 136.2, 136.3,
144.1, 199.2; HRMS (FAB) Calcd for C20H23O2: (Mþ + H)
295.1698. Found: m=z 295.1692. Anti-isomer: IR (neat, cmꢂ1
)
3586, 3455, 1666; 1H NMR (270 MHz, CDCl3) ꢂ 1.59–1.72 (m, 2H),
2.24 (s, 3H), 2.42 (s, 6H), 2.85–2.94 (m, 2H), 3.17–3.28 (m, 1H), 4.64
(br, 1H), 5.50 (d, J ¼ 9:4 Hz, 1H), 6.82 (s, 2H), 7.19 (t, J ¼ 7:6 Hz,
1H), 7.33(t, J ¼ 7:6 Hz, 1H), 7.48 (td, J ¼ 7:4, 1.5 Hz, 1H), 8.07 (dd,
J ¼ 8:0, 1.5 Hz, 1H); 13C NMR (68 MHz, CDCl3) ꢂ 20.8, 21.2, 26.0,
29.4, 51.6, 71.1, 126.7 (ꢃ2), 127.3 (ꢃ2), 128.6 (ꢃ2), 132.2, 132.8,
133.8 (ꢃ2), 136.8, 144.3, 203.2; HRMS (FAB) Calcd for C20H23O2:
(Mþ + H) 295.1698. Found: m=z 295.1702.
2-(Cyclohexylhydroxymethyl)-3,4-dihydronaphthalen-1-
(2H)-one (31): Syn-isomer: IR (neat, cmꢂ1) 3486, 3455, 1666;
1H NMR (270 MHz, CDCl3) ꢂ 0.92–1.75 (m, 10H), 2.09–2.18 (m,
3H), 2.62–2.70 (m, 1H), 3.02 (t, J ¼ 5:9 Hz, 2H), 4.13 (dd, J ¼ 9:2,
2.5 Hz, 1H), 7.21–7.31 (m, 2H), 7.45 (td, J ¼ 7:4, 1.4 Hz, 1H), 7.99–
8.02 (m, 1H); 13C NMR (68 MHz, CDCl3) ꢂ 22.1, 25.9, 26.2, 26.5,
29.0, 30.1, 39.3, 50.3, 73.7, 126.5, 127.1, 128.7, 133.4 (ꢃ2), 144.0,
200.9; HRMS (FAB) Calcd for C17H23O2: (Mþ) 259.1698. Found:
m=z 259.1690. Anti-isomer: IR (neat, cmꢂ1) 3579, 3486, 1658;
1H NMR (270 MHz, CDCl3) ꢂ 1.20–1.94 (m, 12H), 2.12–2.18 (m,
1H), 2.60 (ddd, J ¼ 12:2, 7.6, 4.6Hz), 3.00 (dd, J ¼ 9:9, 5.1Hz, 2H),
3.72 (dd, J ¼ 7:6, 3.3 Hz, 1H), 7.21–7.32 (m, 2H), 7.47 (td, J ¼ 7:6,
1.4 Hz, 1H), 7.99 (dd, J ¼ 7:6, 1.4 Hz, 1H); 13C NMR (68 MHz,
CDCl3) ꢂ 25.6, 25.9, 26.4, 26.5, 26.8, 29.0, 30.4, 39.8, 50.2, 75.8,
126.6, 127.3, 128.5 (ꢃ2), 133.7, 144.0, 200.9; HRMS (FAB) Calcd
for C17H23O2: (Mþ) 259.1698. Found: m=z 259.1690.
2-(1-Hydroxycinnamyl)-3,4-dihydronaphthalen-1(2H)-one
(32): Syn-isomer: IR (neat, cmꢂ1) 3818, 3509, 3332, 1673; 1H NMR
(270 MHz, CDCl3) ꢂ 2.04–2.20 (m, 2H), 2.82 (ddd, J ¼ 13:1, 5.0, 3.3
Hz, 1H), 4.88–4.89 (m, 1H), 6.30 (dd, J ¼ 15:8, 6.2 Hz, 1H), 6.67
(dd, J ¼ 15:8, 1.2 Hz, 1H), 7.21–7.50 (m, 8H), 8.03 (dd, J ¼ 7:8, 1.3
Hz, 1H); 13C NMR (68 MHz, CDCl3) ꢂ 24.3, 29.2, 52.8, 72.5, 126.4,
126.6, 127.2, 127.5, 128.4, 128.7, 128.8, 131.5, 132.6, 133.7, 136.5,
144.2, 200.3; HRMS (FAB) Calcd for C19H18O2: (Mþ) 278.1307.
Found: m=z 278.1311. Anti-isomer: IR (neat, cmꢂ1) 3571, 3471,
1673; 1H NMR (270 MHz, CDCl3) ꢂ 1.77–1.93 (m, 1H), 2.17–2.27
(m, 1H), 2.66 (ddd, J ¼ 13:2, 7.8, 4.5 Hz, 1H), 2.97–3.03 (m, 2H),
4.66 (td, J ¼ 5:8, 3.0 Hz, 1H), 6.26 (dd, J ¼ 16:0, 7.4 Hz, 1H), 6.66
(d, J ¼ 16:0 Hz, 1H), 7.20–7.42 (m, 7H), 7.49 (td, J ¼ 7:6, 1.5 Hz),
3-Hydroxy-1,5-diphenylpentan-1-one (35):24 IR (neat, cmꢂ1
)
3602, 3525, 1681; 1H NMR (270 MHz, CDCl3) ꢂ 1.74–2.01 (m, 2H),
2.69–2.95 (m, 2H), 3.10 (m, 2H), 3.41 (d, J ¼ 3:0 Hz, 1H), 4.24 (ddd,
J ¼ 12:0, 8.2, 4.3 Hz, 1H), 7.15–7.60 (m, 8H), 7.93 (d, J ¼ 7:3 Hz,
2H); 13C NMR (68 MHz, CDCl3) ꢂ 31.9, 38.1, 45.2, 67.0, 125.7,
127.9, 128.1, 128.27, 128.36, 128.4 (ꢃ2), 128.5 (ꢃ2), 133.4, 136.5,
141.7, 200.6.
3-Hydroxy-4-methyl-1-phenylpentan-1-one (36):25 IR (neat,
1
cmꢂ1) 3378, 3347, 1674; H NMR (270 MHz, CDCl3) ꢂ 0.91 (d,
J ¼ 5:9 Hz, 3H), 0.94 (d, J ¼ 5:9 Hz, 3H), 1.69–1.77 (m, 1H), 2.95
(dd, J ¼ 17:5, 9.3 Hz, 1H), 3.09 (dd, 17.5, 2.6 Hz, 1H), 3.92 (ddd,
J ¼ 9:0, 5.6, 2.6 Hz, 1H), 7.20–7.53 (m, 3H), 7.88 (dd, J ¼ 8:6, 1.5
Hz, 2H); 13C NMR (68 MHz, CDCl3) ꢂ 27.9, 28.6, 33.1, 42.0, 72.3,
127.9, 128.0, 128.5 (ꢃ2), 133.3, 136.7, 201.0.
3-Cyclohexyl-3-hydroxy-1-phenylpropan-1-one (37):24 IR
(neat, cmꢂ1) 3440, 1681; 1H NMR (270 MHz, CDCl3) ꢂ 1.06–1.30
(m, 5H), 1.48 (m, 1H), 1.68–1.95 (m, 5H), 3.05 (dd, J ¼ 17:5, 9.2 Hz,
1H), 3.19 (dd, J ¼ 17:5, 2.6 Hz, 1H), 3.99 (m, 1H), 7.44–7.98 (m,
5H); 13C NMR (68 MHz, CDCl3) ꢂ 26.2, 26.3, 26.5, 28.4, 29.1, 42.1,
43.1, 71.8, 127.9 (ꢃ2), 128.5 (ꢃ2), 133.3, 136.8, 201.2.
3-Hydroxy-1,5-diphenylpent-4-en-1-one (38):26
IR (neat,
cmꢂ1) 3463, 1681; 1H NMR (270 MHz, CDCl3) ꢂ 3.20–3.38 (m, 2H),
3.48 (s, 1H), 4.98 (br, 1H), 6.31 (dd, J ¼ 15:8, 5.9 Hz, 1H), 6.71 (d,
J ¼ 15:8 Hz, 1H), 7.23–7.61 (m, 8H), 7.96 (d, J ¼ 7:9 Hz, 2H);
13C NMR (68 MHz, CDCl3) ꢂ 45.2, 68.6, 126.4 (ꢃ2), 127.6, 128.0
(ꢃ2), 128.4 (ꢃ2), 128.6 (ꢃ2), 130.1, 130.3, 133.5, 136.4 (ꢃ2), 199.8.

822 Bull. Chem. Soc. Jpn., 76, No. 4 (2003)
Crossed Aldol Reaction via Boron Enolates
1-Hydroxy-1,5-diphenylpentan-3-one (39):27 IR (neat, cmꢂ1
)
2
3
D. A. Evans, Top. Curr. Chem., 13, 36 (1982).
a) D. A. Evans, J. V. Nelson, T. R. Taber, ‘‘Stereoselective
3440, 1704; 1H NMR (270 MHz, CDCl3) ꢂ 2.71–2.93 (m, 6H), 3.26
(s, 1H),5.14(dd, J ¼ 8:7, 5.3Hz, 1H), 7.14–7.37(m, 10H);13C NMR
(68 MHz, CDCl3) ꢂ 29.5 (ꢃ2), 45.1, 51.3, 69.9, 125.5, 126.1, 127.5,
128.2 (ꢃ2), 128.4 (ꢃ4), 140.5, 142.6, 210.0.
Aldol Condensation,’’ in ‘‘Topics in Stereochemistry,’’ ed by N. L.
Eliel and S. H. Wilen, John Wiley & Sons, Inc., New York (1982)
Vol. 13, p. 1. b) S. Masamune, C. U. Kim, K. E. Wilson, G. O.
Spessard, P. E. Georhiou, and G. S. Bates, J. Am. Chem. Soc., 97,
3512 (1975). c) S. Masamune, H. Yamamoto, S. Kamata, and A.
Fukuzawa, J. Am. Chem. Soc., 97, 3513 (1975).
5-Hydroxy-1,7-diphenylheptan-3-one (40):28 IR (neat, cmꢂ1
)
3355, 1697; 1H NMR (270 MHz, CDCl3) ꢂ 1.51–1.87 (m, 3H), 2.53
(d, J ¼ 7:3 Hz, 1H), 2.53 (d, J ¼ 3:8 Hz, 1H), 2.62–2.91 (m, 6H),
4.03 (m, 1H), 7.14–7.30 (m, 10H); 13C NMR (68 MHz, CDCl3) ꢂ
29.5, 31.7, 38.0, 45.0, 49.3, 66.8, 125.7, 126.1, 128.1, 128.26, 128.31,
128.4, 140.5, 141.6, 128.4, 210.8.
4
a) J. Hooz and L. Linke, J. Am. Chem. Soc., 90, 5936 (1968).
b) J. Hooz and D. M. Gunn, Chem. Comm., 1969, 139. c) J. Hooz and
G. F. Morrison, Can. J. Chem., 48, 868 (1970). d) J. Hooz and J. N.
Bridson, J. Am. Chem. Soc., 95, 602 (1973).
5-Hydroxy-6-methyl-1-phenylheptan-3-one (41):29 IR (neat,
cmꢂ1) 3487, 1704; 1H NMR (270 MHz, CDCl3) ꢂ 0.88 (d, J ¼ 6:9
Hz, 3H), 0.91 (d, J ¼ 6:9 Hz, 3H), 1.66 (m, 1H), 2.51 (m, 2H), 2.78
(m, 2H), 2.90 (m, 2H), 3.80 (ddd, J ¼ 9:6, 5.6, 4.0Hz, 1H), 7.15–7.31
(m, 5H); 13C NMR (68 MHz, CDCl3) ꢂ 17.8, 18.3, 29.6, 33.1, 45.1,
46.3, 72.2, 126.0, 128.1 (ꢃ2), 128.4 (ꢃ2), 140.6, 211.2.
5
6
W. Fenzl and R. Koster, Liebigs Ann. Chem., 1975, 1322.
¨
a) A. Suzuki, A. Arase, H. Matsumoto, M. Itoh, H. C. Brown,
´
M. M. Rogic, and M. W. Rathke, J. Am. Chem. Soc., 89, 5708
(1967). b) T. Mukaiyama, K. Inomata, and M. Muraki, J. Am. Chem.
Soc., 95, 967 (1973). c) T. Mukaiyama, K. Inomata, and M. Muraki,
Bull. Chem. Soc. Jpn., 46, 1807 (1973).
1-Cyclohexyl-1-hydroxy-5-phenylpentan-3-one (42):30 IR
(neat, cmꢂ1) 3409, 1704; 1H NMR (270 MHz, CDCl3) ꢂ 0.94–1.34
(m, 6H), 1.59–1.79 (m, 5H), 2.52 (d, J ¼ 8:4 Hz, 1H), 2.53 (m, 2H),
2.74–2.80 (m, 2H), 2.87–2.93 (m, 3H), 3.80 (m, 1H), 7.16–7.31 (m,
5H); 13C NMR (68 MHz, CDCl3) ꢂ 26.1, 26.2, 26.5, 28.3, 28.9, 29.6,
43.0, 45.1, 46.4, 71.7, 126.0, 128.1 (ꢃ2), 128.4 (ꢃ2), 140.6, 211.3.
7
a) T. Mukaiyama and T. Inoue, Chem. Lett., 1976, 559. b) T.
Mukaiyama and T. Inoue, Bull. Chem. Soc. Jpn., 53, 174 (1980).
D. A. Evans, J. Bartroli, and T. L. Shih, J. Am. Chem. Soc.,
103, 1566 (1981).
8
9
2590 (1996).
A. Abiko, J.-F. Liu, and S. Masamune, J. Org. Chem., 61,
5-Hydroxy-1,7-diphenylhept-6-en-3-one (43):31
IR (neat,
cmꢂ1) 3340, 3232, 1704; 1H NMR (270 MHz, CDCl3) ꢂ 2.68–2.70
(m, 2H), 2.74–2.81 (m, 2H), 2.88–2.94 (m, 2H), 3.15 (d, J ¼ 3:6 Hz,
1H), 4.70–4.78 (m, 1H), 6.17 (dd, J ¼ 15:8, 6.1 Hz, 1H), 6.60 (d,
J ¼ 15:8 Hz, 1H), 7.15–7.37 (m, 10H); 13C NMR(68MHz,CDCl3)ꢂ
29.4, 45.1, 49.2, 68.5, 126.1, 126.3 (ꢃ2), 127.6, 128.1 (ꢃ2), 128.39
(ꢃ2), 128.42 (ꢃ2), 129.9, 130.2, 136.3, 140.5, 209.8.
10 Y. Aoki, K. Oshima, and K. Utimoto, Chem. Lett., 1995, 463.
11 T. Mukaiyama, S. Imachi, K. Yamane, and M. Mizuta,
Chem. Lett., 2002, 698.
12 R. W. Hoffmann, K. Ditrich, and S. Froech, Tetrahedron, 41,
5517 (1985).
13 D. A. Evans and G. C. Fu, J. Org. Chem., 55, 5678 (1990).
14 D. A. Evans, J. V. Nelson, E. Vogel, and T. R. Taber, J. Am.
Chem. Soc., 103, 3099 (1981).
15 M. Hojo, H. Harada, H. Ito, and A. Hosomi, J. Am. Chem.
Soc., 119, 5459 (1997).
16 J. C. Lee and Y. S. Jin, Synth. Comm., 29, 2769 (1999).
17 A. Bekaert, O. Barberan, M. Gervais, and J. Brion,
Tetrahedron Lett., 41, 2903 (2000).
18 A. Gutman, G. Nisnevich, M. Etinger, I. Zaltzman, L.
Judvich, and B. Pertsikov, PCT Int. Appl., (2001) WO 0155101 A2,
62pp.
1,5-Diphenylpenta-2,4-dien-1-one:32 IR (neat, cmꢂ1) 1650,
1573; 1H NMR (270 MHz, CDCl3) ꢂ 7.02–7.12 (m, 3H), 7.32–7.41
(m, 3H), 7.46–7.52 (m, 4H), 7.55–7.66 (m, 2H), 7.96–8.02 (m, 2H);
13C NMR (68 MHz, CDCl3) ꢂ 125.3, 126.8 (ꢃ2), 127.2 (ꢃ2), 128.3
(ꢃ2), 128.5 (ꢃ2), 128.7 (ꢃ2), 129.1, 132.5, 136.0, 141.8, 144.7,
190.3.
1,5-Diphenylpent-1-en-3-one:33 IR (neat, cmꢂ1) 3440, 3347,
1666, 1612; 1H NMR (270 MHz, CDCl3) ꢂ 7.48–7.57 (m, 3H), 7.37–
7.40 (m, 3H), 7.12–7.33 (m, 5H), 6.73 (d, J ¼ 16:6 Hz, 1H), 3.00 (s,
4H); 13C NMR (68 MHz, CDCl3) ꢂ 30.2, 42.5, 126.0 (ꢃ2), 128.1
(ꢃ2), 128.3 (ꢃ2), 128.4 (ꢃ2), 128.8 (ꢃ2), 130.4, 134.3, 141.0,142.5,
199.1.
19 S. E. Denmark, R. A. Stavenger, K. Wong, and X. Su, J. Am.
Chem. Soc., 121, 4982 (1999).
1,7-Diphenylhepta-4,6-dien-3-one:34 IR (neat, cmꢂ1) 3787,
1673, 1596; 1H NMR (270 MHz, CDCl3) ꢂ 7.45 (dd, J ¼ 1:8, 8.1 Hz,
2H), 7.16–7.38 (m, 9H), 6.80–6.96 (m, 2H), 6.27 (d, J ¼ 15:3 Hz,
1H), 2.89–3.02 (m, 4H); 13C NMR (68 MHz, CDCl3) ꢂ 30.2, 42.3,
126.0, 126.4, 126.5, 127.1, 128.2 (ꢃ2), 128.3 (ꢃ2), 128.7 (ꢃ2),
129.1, 129.3, 135.8, 141.1, 141.2, 142.6, 199.1.
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This study was supported in part by the Grant of the 21st
Century COE Program from the Ministry of Education, Culture,
Sports, Science and Technology (MEXT). The authors wish to
thank to Dr. Jun-ichi Matsuo for assistance in the preparation of
this manuscript, and to Mr. Masahiro Mizuta for the assistance
during this experiment, and to Ms. Mie Nishimura, Yamanouchi
Pharmaceutical Co., LTD. for mass spectrometry analysis.
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