Activation of ether functionality of allyl vinyl ethers by chiral bis(organoaluminum) Lewis acids: Application to asymmetric Claisen rearrangement

Article abstract of DOI:10.1016/S0040-4020(02)00981-X

Chiral bis(organoaluminum) Lewis acids have been newly designed and synthetic utility of their eminent activation ability of an ether functionality has been successfully demonstrated by the application to asymmetric Claisen rearrangement of allyl vinyl ethers.

Full text of DOI:10.1016/S0040-4020(02)00981-X

Tetrahedron 58 (2002) 8307–8312
Activation of ether functionality of allyl vinyl ethers by chiral
bis(organoaluminum) Lewis acids: application to asymmetric
Claisen rearrangement
*
Eiji Tayama, Akira Saito, Takashi Ooi and Keiji Maruoka
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, 606-8502 Kyoto, Japan
Received 23 May 2002; accepted 4 June 2002
Abstract—Chiral bis(organoaluminum) Lewis acids have been newly designed and synthetic utility of their eminent activation ability of an
ether functionality has been successfully demonstrated by the application to asymmetric Claisen rearrangement of allyl vinyl ethers. q 2002
Elsevier Science Ltd. All rights reserved.
Apparently, the Claisen rearrangement serves as an
excellent stereoselective route to a,b-unsaturated carbonyl
compounds from allylic alcohols, and offers a crucial step in
the stereo- and regiochemically defined synthesis of a wide
variety of natural products along with numerous recent
developments of new variants of the [3,3]-sigmatropic
rearrangement.1 However, studies regarding its asymmetric
version, especially using chiral Lewis acids, have been
limited despite the potential mechanistic and synthetic
importance.2 Recently, we reported that (2,7-dimethyl-1,8-
biphenylenedioxy)bis(dimethylaluminum) was capable of
strongly activating not only carbonyl compounds but also
substrates possessing ether moiety such as allyl vinyl ethers
via double coordination as shown in Scheme 1.3a This
finding prompted us to pursue the design of a new chiral
bis(organoaluminum) Lewis acid, which could promote
facile Claisen rearrangement of allyl vinyl ethers in an
asymmetric fashion via eminent activation of the ether
functionality. In this article, we wish to describe the results
of this study.
Scheme 1.
Keywords: Claisen rearrangement; carbonyl compounds; chiral Lewis acids.
*
Corresponding author. Tel./fax: þ81-75-753-4041; e-mail: maruoka@kuchem.kyoto-u.ac.jp
0040–4020/02/$ - see front matter q 2002 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(02)00981-X

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E. Tayama et al. / Tetrahedron 58 (2002) 8307–8312
Scheme 2. (a) tBuPh2SiCl, Imidazole, DMF. (b) NaH, MOMCl, THF. (c) BuLi, ether, then I2, THF. (d) conc. HCl, dioxane. (e) Ac2O, pyridine, cat DMAP,
CH2Cl2. (f) bis(tributylstannyl)acetylene, Pd(OAc)2, PPh3, BHT, LiCl, dioxane. (g) MeLi, THF-ether.
Table 1. Asymmetric Claisen rearrangement of allyl vinyl ether 3 with chiral bis(organoaluminum) Lewis acid (S,S)-1
Entry
Substrate 3
Bis-Al Lewis acid
Condition (8C, h)
Product
% Yielda
% eeb (configuration)c
1
2
3
4
5
6
7
R¼c-C6H11 (3a)
R¼t-Bu (3b)
R¼Ph (3c)
1a
1b
1a
1b
1a
1b
1b
278, 0.1; 245, 4
278, 0.1; 245, 4
278, 1.5; 245, 4
278, 1.5; 245, 4
278, 0.1; 245, 1
278, 0.1; 245, 1
278, 0.1; 245, 2
235, 1; 223, 1
4a
4a
4b
4b
4c
4c
4d
82
66
75
70
92
50
63
62 (S)
71 (S)
80 (S)
85 (S)
51 (S)
57 (S)
83
R¼SiMe3 (3d)
The reaction was carried out in CH2Cl2 with (S,S)-1 (1.1 equiv.) in the presence of PPh3 (2.2 equiv.) under the given reaction conditions.
Isolated yield.
a
b
Determined by capillary GLC analysis after conversion to its acetal of (2R,4R)-pentanediol.
Determined by the comparison with the reported one.2c,d
c
The requisite optically pure bis(binaphthol) (S,S)-2b4 can be
synthesized from commercially available (S)-binaphthol in
7-step sequences, as illustrated in Scheme 2. Treatment of
(1.1 equiv.) with allyl vinyl ether 3a (R¼c-C6H11) in the
presence of PPh3 (2.2 equiv.) in CH2Cl2 at 278 to 2458C
for 4 h gave rise to a rearrangement product 4a (R¼
c-C6H11) (82% yield), whose enantiomeric purity was
determined to be 62% ee by capillary GLC analysis after
conversion to its acetal of (2R,4R)-pentanediol (entry 1,
Table 1, Scheme 3).6
i
(S,S)-2b in CH2Cl2 with Bu2AlCl (2 equiv.) in hexane at
258C for 30 min generated a chiral bis(organoaluminum)
reagent (S,S)-1a (R2¼iBu). In evaluating the potential of
(S,S)-1a as a chiral activator in the asymmetric Claisen
rearrangement, we employed PPh3 as an additive according
to Nozaki’s protocol to avoid the fragmentation of 3 prior to
the desired rearrangement.5 Thus, reaction of (S,S)-1a
Switching the bis(organoaluminum) Lewis acid from
(S,S)-1a to (S,S)-1b brought the increase of enantioselec-
tivity to 71% ee for this substrate, though the chemical yield
turned out to be moderate (entry 2). Use of toluene in place
of CH2Cl2 decreased the enantioselectivity (58% ee). It
should be emphasized that preparation of mono(organo-
aluminum) counterpart (S)-6a from monosilylated (S)-bi-
i
naphthol 5 and Bu2AlCl, and subsequent treatment with
PPh3 and allyl vinyl ether 3a (R¼c-C6H11) under similar
reaction conditions resulted in the Claisen product 4a (R¼
c-C6H11) in only 9% yield with the enantiomeric excess (ee)
of 22% ee, indicating that the strong activation ability of
chiral bis(organoaluminum) Lewis acid of type 1 is
responsible for obtaining a synthetically useful level of
chemical yield and enantioselectivity (Scheme 4).
Other selected examples are summarized in Table 1.
Generally, (S,S)-1a and (S,S)-1b seemed to be complements
of each other in terms of reactivity and selectivity. Higher
enantioselectivity was observed in the rearrangement of the
Scheme 3.

E. Tayama et al. / Tetrahedron 58 (2002) 8307–8312
8309
Scheme 4.
substrate with more sterically hindered substituent R
(entries 3, 4 vs. 1, 2). Notably, a facile asymmetric synthesis
of functionalized allylic silanes 4d (R¼SiMe3) appears
feasible by the present method (entry 7).
1.2. Preparation of allyl vinyl ethers
(E)-3-Cyclohexenyl-2-propenyl vinyl ether (3a), (E)-3-tert-
butyl-2-propenyl vinyl ether (3b), (E)-cinnamyl vinyl ether
(3c) and (E)-3-trimethylsilyl-2-propenyl vinyl ether (3d)
were known compounds and synthesized according to the
literature procedure.2b
In conclusion, we have designed new chiral bis(organo-
aluminum) Lewis acid of type 1 whose effectiveness as an
efficient chiral activator for the substrates having ether
functionality has been investigated by conducting asym-
metric Claisen rearrangement of allyl vinyl ethers in
comparison with 6 as a corresponding mono(organo-
aluminum) Lewis acid. Scope and limitations of this unique
system have also been revealed.
1
1.2.1. (E)-3-Cyclohexyl-2-propenyl vinyl ether (3a). H
NMR (400 MHz, CDCl3) d 6.46 (1H, dd, J¼14.4, 6.8 Hz,
CH2vCH), 5.71 (1H, dd, J¼15.6, 6.6 Hz, c-Hex-CHvCH),
5.55 (1H, dtd, J¼15.6, 6.0, 1.2 Hz, c-Hex-CHvCH), 4.21
(1H, dd, J¼14.4, 2.0 Hz, cis-CH2vCH), 4.17 (2H, d, J¼
6.0 Hz, CH2O), 4.00 (1H, dd, J¼6.8, 2.0 Hz, trans-
CH2vCH), 2.04–1.94 (1H, m, CH), 1.77–1.62 (5H, m,
equatorial-CH2), 1.33–1.03 (5H, m, axial-CH2); IR (liquid
film) 3117, 2926, 2853, 1636, 1611, 1448, 1379, 1319,
1. Experimental
1.1. General
1198, 1053, 970, 812 cm21
.
1.2.2. (E)-3-tert-Butyl-2-propenyl vinyl ether (3b). 1H
NMR (400 MHz, CDCl3, 6:4 mixture of rotamers) d 6.47
(1H, dd, J¼14.4, 6.8 Hz, CH2vCH), 5.778 (0.4H, dt,
J¼15.6, 2.4 Hz, t-Bu–CHvCH), 5.775 (0.6H, dt, J¼15.6,
2.4 Hz, t-Bu–CHvCH), 5.515 (0.6H, dt, J¼15.6, 6.2 Hz,
t-Bu–CHvCH), 5.512 (0.4H, dt, J¼15.6, 6.2 Hz, t-Bu–
CHvCH), 4.24–4.17 (3H, m, cis-CH2vCH and CH2O),
4.011 (0.6H, dd, J¼6.4, 2.0 Hz, trans-CH2vCH), 4.008
(0.4H, dd, J¼6.4, 2.0 Hz, trans-CH2vCH), 1.031 (5.4H, s,
t-Bu), 1.028 (3.6H, s, t-Bu); IR (liquid film) 3119, 3036,
2961, 2905, 2868, 1636, 1612, 1475, 1464, 1364, 1321,
Infrared (IR) spectra were recorded on a Shimazu FT-IR
1
8200A spectrometer. H NMR spectra were measured on a
JEOL JNM-FX400 (400 MHz) spectrometers. Tetramethyl-
1
silane was used as internal standard of H NMR (d¼0).
Splitting patterns are indicated as s, singlet; d, doublet; t,
triplet; q, quartet; m, multiplet; br, broad peak. Analytical
gas–liquid phase chromatography (GLC) was performed on
Shimazu GC-14B instruments equipped with a flame
ionization detector and a capillary column of PEG-HT
(0.25£25,000 mm) using nitrogen as carrier gas. Optical
rotations were measured on a JASCO DIP-1000 digital
polarimeter. For thin layer chromatography (TLC) analysis
throughout this work, Merck precoated TLC plates (silica
gel 60 GF254, 0.25 mm) were used. The products were
purified by preparative column chromatography on silica
gel 60 E, Merck Art 9385. The high-resolution mass spectra
(HRMS) analysis were accomplished at the Graduate
School of Engineering, Kyoto University. Reaction
involving air- or moisture-sensitive compounds were
conducted in appropriate round-bottomed flask with
magnetic stirring bars under an atmosphere of dry argon.
In experiments requiring dry solvents, ether and tetra-
hydrofuran (THF) were purchased from KANTO Chemical
Co., Inc., Japan as anhydrous solvent. Methylene chloride,
1200, 1153, 1059, 974, 814 cm21
.
1.2.3. (E)-Cinnamyl vinyl ether (3c). 1H NMR (400 MHz,
CDCl3) d 7.40 (2H, d, J¼7.6 Hz, Ph), 7.32 (2H, t, J¼7.6 Hz,
Ph), 7.27–7.23 (1H, m, Ph), 6.66 (1H, d, J¼16.0 Hz,
Ph–CHvCH), 6.52 (1H, dd, J¼14.4, 6.8 Hz, CH2vCH),
6.32 (1H, dt, J¼16.0, 6.0 Hz, Ph–CHvCH), 4.40
(2H, d, J¼6.0 Hz, CH2O), 4.28 (1H, d, J¼14.4 Hz,
cis-CH2vCH), 4.07 (1H, d, J¼6.8 Hz, trans-CH2vCH);
IR (liquid film) 3028, 2912, 2860, 1636, 1614, 1495,
1450, 1373, 1319, 1194, 1153, 1055, 966, 822, 743,
692 cm21
.
1.2.4. (E)-3-Trimethylsilyl-2-propenyl vinyl ether (3d).
1H NMR (400 MHz, CDCl3) d 6.47 (1H, dd, J¼14.4,
6.8 Hz, CH2vCH), 6.12 (1H, dt, J¼18.8, 4.8 Hz,
Me3Si–CHvCH), 5.98 (1H, dt, J¼18.8, 1.4 Hz,
Me3Si–CHvCH), 4.25 (2H, dd, J¼4.8, 1.4 Hz, CH2O),
4.22 (1H, dd, J¼14.4, 2.0 Hz, cis-CH2vCH), 4.03 (1H, dd,
J¼4.8, 2.0 Hz, trans-CH2vCH), 0.08 (9H, s, SiMe3); IR
(liquid film) 2957, 2899, 1636, 1614, 1366, 1319, 1250,
˚
1,4-dioxane and DMF were stored over 4 A molecular
sieves. Pyridine was stored over KOH pellets. In the
asymmetric Claisen process, methylene chloride as solvent
was freshly distilled from calcium hydride before use.
Diisobutylaluminum chloride (i-Bu2AlCl) and dimethyl-
aluminum chloride (Me2AlCl) were kindly supplied from
Tosoh-Finechem. Co. Ltd, Japan. Other simple chemicals
were purchased and used as such.
1200, 989, 962, 864, 839, 770, 694 cm21
.

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E. Tayama et al. / Tetrahedron 58 (2002) 8307–8312
1.3. Preparation of optically pure bis(binaphthol)
(S,S)-2b (R05H)
The resulting pale-brown suspension was cooled to 2788C
and a solution of iodine (323 mg, 2.1 mmol) in THF (2 mL)
was added dropwise slowly. The mixture was warmed to
room temperature and stirring was continued for 3 h. The
excess iodine was reduced by addition of saturated Na2SO3
and the mixture was extracted with Et2O. The combined
extracts were washed with brine, dried over Na2SO4 and
concentrated. The crude product was dissolved into
1,4-dioxane (4.6 mL) and conc. HCl (2.3 mL) was added.
After stirring at 508C for 15 h, the resulting mixture was
diluted with H2O and extracted with Et2O. The combined
extracts were washed with brine and dried over Na2SO4.
Evaporation of solvents and purification of the residue by
column chromatography on silica gel (hexane/CH2Cl2¼2:1
as eluent) gave (S)-8 (692 mg, 1.06 mmol, 77% yield) as
1.3.1. (S)-2-tert-Butyldiphenylsilyloxy-20-hydroxy-1,10-
binaphthyl [(S)-5].7 To a solution of (S)-binaphthol
(4.29 g, 15.0 mmol) and imidazole (2.04 g, 30 mmol) in
DMF (30 mL) was added tert-butyldiphenylsilyl chloride
(4.1 mL, 16 mmol) and the mixture was stirred at 508C for
4 h under argon. After the resulting mixture was cooled
to room temperature, saturated NH4Cl was added and
extractive workup was performed with Et2O. The combined
extracts were washed with brine and dried over Na2SO4.
Evaporation of solvents and purification of the residue by
column chromatography on silica gel (hexane/CH2Cl2¼2:1
as eluent) gave (S)-5 (7.27 g, 13.9 mmol, 92% yield) as
1
1
colorless crystal. [a]2D0¼þ36.48 (c 1.0, CHCl3); H NMR
colorless crystal. [a]2D5¼þ31.48 (c 1.0, CHCl3); H NMR
(400 MHz, CDCl3) d 7.93 (1H, d, J¼9.2 Hz, Ar–H), 7.88
(1H, dd, J¼8.4, 1.6 Hz, Ar–H), 7.77 (1H, dt, J¼7.6, 1.6 Hz,
Ar–H), 7.64–7.60 (3H, m, Ar–H), 7.54–7.51 (2H, m,
Ar–H), 7.44–7.26 (12H, m, Ar–H), 7.20 (1H, m, Ar–H),
6.89 (1H, d, J¼8.8 Hz, Ar–H), 5.02 (1H, s, OH), 0.49 (9H,
s, t-Bu); IR (KBr) 3531, 3055, 2957, 2930, 2891, 2856,
1620, 1591, 1504, 1472, 1460, 1429, 1362, 1339, 1277,
(400 MHz, CDCl3) d 8.48 (1H, s, Ar–H), 7.77 (2H, d, J¼
7.2 Hz, Ar–H), 7.64–7.60 (3H, m, Ar–H), 7.50 (2H, dd,
J¼7.2, 1.6 Hz, Ar–H), 7.43 (1H, tt, J¼7.2, 1.6 Hz, Ar–H),
7.38–7.25 (10H, m, Ar–H), 7.14 (1H, dd, J¼8.4, 0.8 Hz,
Ar–H), 6.88 (1H, d, J¼8.8 Hz, Ar–H), 5.49 (1H, s, OH),
0.52 (9H, s, t-Bu); IR (KBr) 3504, 3051, 2963, 2932, 2856,
1620, 1591, 1502, 1466, 1427, 1356, 1340, 1279, 1261,
1246, 1202, 1146, 1115, 1078, 1034, 1003, 816, 746,
702 cm21. HRMS (FAB) calcd for C36H31IO2Si (Mþ):
650.1138, found: 650.1133.
1263, 1248, 1207, 1148, 1115, 1005, 814, 745, 700 cm21
.
1.3.2. (S)-2-tert-Butyldiphenylsilyloxy-20-methoxy-
methoxy-1,10-binaphthyl [(S)-7]. To a solution of (S)-5
(849 mg, 1.62 mmol) in THF (8 mL) was added NaH
(60 wt% in oil, 84 mg, 2.1 mmol) at 08C and the mixture
was warmed to room temperature and stirred there for 0.5 h.
It was then cooled again to 08C and chloromethyl methyl
ether (0.14 mL, 1.9 mmol) was added. After stirring at room
temperature for 12 h, saturated NH4Cl was added slowly at
08C and then extractive workup was conducted with
Et2O. The combined extracts were washed with brine and
dried over Na2SO4. Evaporation of solvents and purification
of the residue by silica gel column chromatography
(hexane/CH2Cl2¼4:1–1:1 as eluent) gave (S)-7 (833 mg,
1.46 mmol, 90% yield) as colorless crystal. [a]2D3¼255.28
(c 1.0, CHCl3); 1H NMR (400 MHz, CDCl3) d 7.96 (1H, d,
J¼9.2 Hz, Ar–H), 7.89 (1H, d, J¼8.0 Hz, Ar–H), 7.76–
7.73 (1H, m, Ar–H), 7.64–7.61 (3H, m, Ar–H), 7.57–7.53
(3H, m, Ar–H), 7.42–7.20 (12H, m, Ar–H), 6.84 (1H, d,
J¼9.2 Hz, Ar–H), 5.11 (1H, d, J¼6.8 Hz, CH), 5.04 (1H, d,
J¼6.8 Hz, CH), 3.19 (3H, s, Me), 0.45 (9H, s, t-Bu); IR
(KBr) 3053, 2957, 2930, 2893, 2856, 1622, 1591, 1506,
1474, 1460, 1429, 1356, 1339, 1279, 1265, 1250, 1240,
1150, 1115, 1074, 1034, 1005, 812, 746, 702 cm21. HRMS
(FAB) calcd for C38H36O3Si (Mþ): 568.2434, found:
568.2435.
1.3.4. (S)-2-Acetoxy-20-tert-butyldiphenylsilyloxy-3-iodo-
1,10-binaphthyl [(S)-9]. To a solution of (S)-8 (634 mg,
0.974 mmol) in CH2Cl2 (2 mL) was added 4-dimethyl-
aminopyridine (2 mg, 0.002 mmol), pyridine (0.12 mL,
1.5 mmol) and acetic anhydride (0.14 mL, 1.5 mmol)
sequentially, and the solution was stirred for 6 h at room
temperature. The resulting solution was concentrated and
purification of the residue by column chromatography on
silica gel (hexane/CH2Cl2¼3:1–1.5:1 as eluent) afforded
(S)-9 (634 mg, 0.915 mmol, 94% yield) as colorless crystal.
[a]2D5¼þ39.48 (c 1.0, CHCl3); 1H NMR (400 MHz, CDCl3)
d 8.54 (1H, s, Ar–H), 7.84 (1H, d, J¼8.4 Hz, Ar–H),
7.74–7.69 (3H, m, Ar–H), 7.54–7.24 (15H, m, Ar–H),
6.78 (1H, d, J¼9.2 Hz, Ar–H), 1.85 (3H, s, CH3CO), 0.52
(9H, s, t-Bu); IR (KBr) 3071, 2955, 2930, 2856, 1774, 1624,
1593, 1508, 1470, 1429, 1360, 1354, 1340, 1279, 1261,
1248, 1182, 1115, 1082, 1036, 1009, 824, 748, 702 cm21
.
HRMS (FAB) calcd for C38H33IO3Si (Mþ): 692.1244,
found: 692.1252.
1.3.3. (S)-2-tert-Butyldiphenylsilyloxy-20-hydroxy-30-
iodo-1,10-binaphthyl [(S)-8]. To a solution of (S)-7
(791 mg, 1.39 mmol) in Et2O (4.5 mL) was added a 1.6 M
hexane solution of n-BuLi (1.1 mL, 1.8 mmol) at room
temperature under argon and the mixture was stirred for 3 h.

E. Tayama et al. / Tetrahedron 58 (2002) 8307–8312
8311
1.3.5. (S,S)-3-Bis(2-acetoxy-20-tert-butyldiphenylsilyl-
oxy-1,10-binaphthyl)acetylene [(S,S)-2a (R05Ac)]. To a
solution of (S)-9 (7.44 g, 10.7 mmol) in dry 1,4-dioxane
(53 mL) was added triphenylphosphine (0.59 g, 2.3 mmol),
lithium chloride (2.72 g, 64 mmol), BHT (a few crystals)
and palladium diacetate (0.24 g, 1.1 mmol) at room
temperature. The mixture was degassed and filled with
argon quickly and then refluxed for 4 h. The resulting
mixture was cooled to room temperature and filtered
through a pad of Celite. The filtrate was concentrated and
the residue was purified by column chromatography on
silica gel (hexane/CH2Cl2¼2:1–1:1 as eluent) to give
(S,S)-2a (R0¼Ac) (4.85 g, 4.20 mmol, 79% yield) as yellow
triphenylphosphine (315 mg, 1.2 mmol) in CH2Cl2 (5 mL)
was added a 2.0 M hexane solution of i-Bu2AlCl or
Me2AlCl (0.55 mL, 1.1 mmol) at room temperature and,
after 0.5 h of stirring, the solution was used as described
above.
1.6. General procedure for the asymmetric Claisen
rearrangement of allyl vinyl ethers with chiral
bis(organoaluminum) reagent (S,S)-1a or 1b
To a solution of the chiral bis(organoaluminum) reagent
(S,S)-1a or 1b (0.55 mmol) in degassed CH2Cl2 (5 mL) was
added an allyl vinyl ether (0.50 mmol) at 2788C. After a
few minutes, the mixture was warmed up to 2458C and
stirred under the conditions indicated in Table 1. The
reaction mixture was poured into 1N HCl, extracted with
CH2Cl2 and dried over Na2SO4. Evaporation of solvents and
purification of the residue by column chromatography on
silica gel (hexane or pentane/CH2Cl2 as eluent) gave
Claisen product in the yields shown in Table 1. The Claisen
products, 3-cyclohexyl-4-pentenal (4a), 3-tert-butyl-4-pen-
tenal (4b), 3-phenyl-4-pentenal (4c) and 3-trimethylsilyl-4-
pentanal (4d) are all known compounds. The ee was
determined by the following procedure. The Claisen product
was converted to the acetal of (2)-(2R,4R)-pentanediol
(1.5 equiv.) with triethylorthoformate (2.0 equiv.) and
catalytic p-toluenesulfonic acid monohydrate in benzene
(0.1–0.2 M) at room temperature. Its ee was established by
capillary GLC analysis based on separated two peaks. The
absolute configuration was also determined by GLC
analysis based on the retention time under reported
conditions.2d
1
solid. [a]2D5¼243.68 (c 1.0, CHCl3); H NMR (400 MHz,
CDCl3) d 8.29 (2H, s, Ar–H), 7.94 (2H, d, J¼8.0 Hz,
Ar–H), 7.71–7.68 (6H, m, Ar–H), 7.56–7.46 (8H, m,
Ar–H), 7.42–7.21 (22H, m, Ar–H), 6.78 (2H, d, J¼8.8 Hz,
Ar–H), 1.77 (6H, s, CH3CO), 0.48 (18H, s, t-Bu); IR (KBr)
3051, 2957, 2932, 2893, 2858, 1774, 1622, 1593, 1508,
1470, 1429, 1362, 1340, 1273, 1250, 1210, 1195, 1184,
1115, 997, 824, 746, 700 cm21. HRMS (FAB) calcd for
C78H67O6Si2 ([MþH]þ): 1155.4476, found: 1155.4480.
1.3.6. (S,S)-3-Bis(20-tert-butyldiphenylsilyloxy-2-
hydroxy-1,10-binaphthyl)acetylene [(S,S)-2b (R05H)].
To a solution of (S,S)-2a (R0¼Ac) (4.85 g, 4.20 mmol) in
THF (24 mL) was added a 1.4 M ether solution of MeLi
(24 mL, 34 mmol) at 2788C and the mixture was allowed to
warm to room temperature. After stirring for 1 h, it was
cooled to 08C and the excess MeLi was quenched by the
slow addition of saturated NH4Cl. Then, 1N HCl was added
at room temperature and the mixture was extracted with
Et2O. The combined extracts were washed with brine and
dried over Na2SO4. Evaporation of solvents and purification
of the residue by silica gel column chromatography
(hexane/CH2Cl2¼2:1 to 1:1 as eluent) furnished (S,S)-2b
(R0¼H) (3.28 g, 3.10 mmol, 73% yield) as colorless crystal.
[a]2D2¼þ36.48 (c 1.0, CHCl3); 1H NMR (400 MHz, CDCl3)
d 8.19 (2H, s, Ar–H), 7.88 (2H, d, J¼8.0 Hz, Ar–H), 7.75
(2H, d, J¼8.4 Hz, Ar–H), 7.58–7.54 (10H, m, Ar–H),
7.39–7.15 (24H, m, Ar–H), 6.86 (2H, d, J¼8.8 Hz, Ar–H),
6.27 (2H, s, OH), 0.48 (18H, s, t-Bu); IR (KBr) 3510, 3443,
3055, 2957, 2932, 2858, 1622, 1593, 1502, 1468, 1427, 1340,
1273, 1246, 1115, 997, 824, 746, 700 cm21. HRMS (FAB)
calcd for C74H62O4Si2 (Mþ): 1070.4187, found: 1070.4189.
1.7. General method for the asymmetric Claisen
rearrangement of allyl vinyl ethers with chiral
mono(organoaluminum) reagent (S)-6a or 6b
Chiral mono(organoaluminum) reagent (S)-6a or 6b
(1.1 mmol) was used instead of chiral bis(organoaluminum)
reagent (S,S)-1a or 1b in the procedure described above.
1
1.7.1. 3-Cyclohexyl-4-pentenal (4a). H NMR (400 MHz,
CDCl3) d 9.69 (1H, dd, J¼2.6, 1.8 Hz, CHO), 5.67 (1H,
ddd, J¼17.2, 10.4, 8.4 Hz, CH2vCH), 5.06 (1H, dd, J¼
10.4, 1.4 Hz, trans-CH2vCH), 5.00 (1H, d, J¼17.2 Hz, cis-
CH2vCH), 2.52–2.35 (3H, m, CHCH2CHO), 1.78–1.62
(5H, m, CH and equatorial-CH2), 1.34–0.89 (6H, m, axial-
CH2); IR (liquid film) 3078, 2926, 2853, 2718, 1726, 1639,
1450, 1410, 1267, 1028, 1001, 918 cm21; GLC reten-
tion times: tR¼16.9 min [(R)-4a-(2R,4R)-acetal], 20.5
min [(S)-4a-(2R,4R)-acetal] at the column temperature of
1308C.
1.4. Preparation of chiral bis(organoaluminum) reagent
(S,S)-1a or (S,S)-1b
To a degassed solution of (S,S)-2b (R0¼H) (589 mg,
0.55 mmol) and triphenylphosphine (315 mg, 1.2 mmol)
in CH2Cl2 (5 mL) was added a 2.0 M hexane solution of
i-Bu2AlCl or Me2AlCl (0.55 mL, 1.1 mmol) at room
temperature. Isobutane or methane gas evolved immedi-
ately. The resulting pale-yellow solution was stirred for
0.5–1.0 h at the same temperature and used as a solution of
chiral bis(organoaluminum) reagent (S,S)-1a or 1b in
CH2Cl2 without any purification.
1
1.7.2. 3-tert-Butyl-4-pentenal (4b). H NMR (400 MHz,
CDCl3) d 9.65 (1H, dd, J¼3.4, 1.4 Hz, CHO), 5.69 (1H,
ddd, J¼17.0, 10.2, 9.2 Hz, CH2vCH), 5.10 (1H, dd, J¼
10.2, 1.8 Hz, trans-CH2vCH), 5.03 (1H, ddd, J¼17.0,
1.8 Hz, cis-CH2vCH), 2.55–2.50 (1H, m, t-BuCH),
2.42–2.29 (2H, m, CH2), 0.90 (9H, s, t-Bu); IR (liquid
film) 3080, 3020, 2963, 2930, 2872, 1726, 1638, 1468,
1367, 1217, 920, 758, 669 cm21; GLC retention times:
tR¼3.7 min [(R)-4b-(2R,4R)-acetal], 4.5 min [(S)-4b-
(2R,4R)-acetal] at the column temperature of 1308C.
1.5. Preparation of chiral mono(organoaluminum)
reagent (S)-6a or (S)-6b
To a degassed solution of (S)-5 (577 mg, 1.1 mmol) and

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E. Tayama et al. / Tetrahedron 58 (2002) 8307–8312
1.7.3. 3-Phenyl-4-pentenal (4c). 1H NMR (400 MHz,
CDCl3) d 9.73 (1H, t, J¼2.0 Hz, CHO), 7.32 (2H, t, J¼
7.4 Hz, Ph), 7.25–7.20 (3H, m, Ph), 5.99 (1H, ddd, J¼17.0,
10.4, 6.8 Hz, CH2vCH), 5.12 (1H, dd, J¼10.4, 0.8 Hz,
trans-CH2vCH), 5.07 (1H, dd, J¼17.0, 0.8 Hz, cis-
CH2vCH), 3.96 (1H, dt, J¼7.6, 6.8 Hz, CHPh), 2.87 (1H,
ddd, J¼16.6, 7.6, 2.0 Hz, CH), 2.81 (1H, ddd, J¼16.6,
7.6, 2.0 Hz, CH); IR (liquid film) 3084, 3063, 3030, 2826,
2727, 1724, 1638, 1601, 1493, 1452, 1408, 1030, 997, 922,
762, 702 cm21; GLC retention times: tR¼35.4 min [(S)-4c-
(2R,4R)-acetal], 36.7 min [(R)-4c-(2R,4R)-acetal] at the
column temperature of 1308C.
Academic: New York, 1981. (c) Lutz, R. P. Chem. Rev. 1984,
84, 205. (d) Hill, R. K. Asymmetric Synthesis, Morrison, J. D.,
Ed.; Academic: New York, 1984; Vol. 3, p 503. (e) Murray,
A. W. Org. React. Mech. 1986, 429. Murray, A. W. Org. React.
Mech. 1987, 457. (f) Moody, C. J. Adv. Heterocycl. Chem.
1987, 42, 203. (g) Ziegler, F. E. Chem. Rev. 1988, 88, 1423.
(h) Kallmerten, J.; Wittman, M. D. Stud. Nat. Prod. Chem.
1989, 3, 233. (i) Blechert, S. Synthesis 1989, 71. (j) Wipf, P.
Comprehensive Organic Synthesis, Trost, B. M., Fleming, I.,
Paquette, L. A., Eds.;, 1991; Vol. 5, p 827 Chapter 7.2.
2. (a) Maruoka, K.; Banno, H.; Yamamoto, H. J. Am. Chem. Soc.
1990, 112, 7791. (b) Maruoka, K.; Banno, H.; Yamamoto, H.
Tetrahedron: Asymmetry 1991, 2, 647. (c) Maruoka, K.; Saito,
S.; Yamamoto, H. J. Am. Chem. Soc. 1995, 117, 1165. (d) Saito,
S. Ph.D. Dissertation, Nagoya University, 1998.
1.7.4. 3-Trimethylsilyl-4-pentenal (4d). 1H NMR (400
MHz, CDCl3) d 9.67 (1H, dd, J¼2.8, 1.8 Hz, CHO), 5.77
(1H, ddd, J¼17.2, 10.4, 8.4 Hz, CH2vCH), 4.96 (1H, ddd,
J¼10.4, 1.2, 1.2 Hz, trans-CH2vCH), 4.86 (1H, ddd, J¼
17.2, 1.2, 1.2 Hz, cis-CH2vCH), 2.50 (1H, ddd, J¼16.4,
11.2, 2.8 Hz, CH2), 2.41 (1H, ddd, J¼16.4, 4.0, 1.8 Hz,
CH2), 2.13 (1H, ddddd, J¼11.2, 8.4, 4.0, 1.2, 1.2 Hz,
CHSiMe3), 0.03 (9H, s, SiMe3); IR (liquid film) 3080, 2957,
2899, 2812, 2716, 1726, 1628, 1408, 1250, 1136, 1105,
1036, 1001, 899, 841, 752, 692 cm21; GLC retention times:
tR¼5.8 min (major isomer), 7.2 min (minor isomer) at the
column temperature of 1108C.
3. (a) Ooi, T.; Takahashi, M.; Maruoka, K. J. Am. Chem. Soc.
1996, 118, 11307. See also: (b) Ooi, T.; Tayama, E.; Takahashi,
M.; Maruoka, K. Tetrahedron Lett. 1997, 38, 7403. (c) Ooi, T.;
Miura, T.; Maruoka, K. Angew. Chem., Int. Ed. Engl. 1998, 37,
2347. (d) Ooi, T.; Itagaki, Y.; Miura, T.; Maruoka, K.
Tetrahedron Lett. 1999, 40, 2137. (e) Ooi, T.; Miura, T.;
Takaya, K.; Maruoka, K. Tetrahedron Lett. 1999, 40, 7695.
(f) Ooi, T.; Miura, T.; Itagaki, Y.; Ichikawa, H.; Maruoka, K.
Synthesis 2002, 279.
4. Saied, Simard and Wuest elegantly demonstrated that a doubly
hydrogen-bonded complex of 3,3,5,5,-tetramethylcyclohexa-
none can be formed with 2,20-(1,2-ethynediyl)bis[6-(1,1-di-
methylethyl)-4-methylphenol]: Saied, O.; Simard, M.; Wuest,
J. D. J. Org. Chem. 1998, 63, 3756. and references cited therein.
5. (a) Takai, K.; Mori, I.; Oshima, K.; Nozaki, H. Tetrahedron
Lett. 1981, 22, 3985. (b) Takai, K.; Mori, I.; Oshima, K.;
Nozaki, H. Bull. Chem. Soc. Jpn 1984, 57, 446.
Acknowledgements
This work was partially supported by a grant-in-aid for
Scientific Research from the Ministry of Education, Culture,
Sports, Science and Technology, Japan.
6. Attempted reaction of 3a (R¼c-C6H11) with (S,S)-1a in the
absence of PPh3 resulted only in C–O bond cleavage without
any rearrangement.
References
7. Tamai, Y.; Nakano, T.; Miyano, S. J. Chem. Soc., Perkin Trans.
1 1994, 439.
1. Reviews: (a) Bartlett, P. A. Tetrahedron 1980, 36, 3.
(b) Gajewski, J. J. Hydrocarbon Thermal Isomerizations.