Functional group tolerable synthesis of allylsilanes through copper-catalyzed -selective allyl-alkyl coupling between allylic phosphates and alkylboranes

Article abstract of DOI:10.1055/s-0031-1290818

A copper-catalyzed -selective allyl-alkyl coupling between -silylated allylic phosphates and alkylboron compounds (alkyl-9-BBN, prepared by hydroboration of alkenes with 9-BBN-H) produced allylsilanes. The reaction tolerated various functional groups in b

Full text of DOI:10.1055/s-0031-1290818

SPECIAL TOPIC
▌1535
special topic
Functional Group Tolerable Synthesis of Allylsilanes through Copper-
Catalyzed γ-Selective Allyl–Alkyl Coupling between Allylic Phosphates and
Alkylboranes
Functionalized Allylsilanes
Kazunori Nagao, Hirohisa Ohmiya,* Masaya Sawamura*
Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
Fax +81(11)7063749; E-mail: ohmiya@sci.hokudai.ac.jp; E-mail: sawamura@sci.hokudai.ac.jp
Received: 06.03.2012; Accepted after revision: 13.03.2012
phate as a leaving group gave a slightly decreased product
Abstract: A copper-catalyzed γ-selective allyl–alkyl coupling be-
yield compared to the cyclic phosphate (80% yield). The
tween γ-silylated allylic phosphates and alkylboron compounds (al-
reaction of (E)-3a proceeded with significantly decreased
kyl-9-BBN, prepared by hydroboration of alkenes with 9-BBN-H)
produced allylsilanes. The reaction tolerated various functional
E-selectivity (E/Z = 71:29) (data not shown).23
groups in both the alkylboranes and the allylic phosphates, and af-
forded functionalized allylsilanes.
H
Ph
+
B
Key words: allylsilane, copper, allylic substitution, alkylborane,
regioselectivity
B
B
THF
60 °C, 1 h
Ph
H
1a
2a
O
P
O
SiMe3
CuOAc (10 mol%)
Allylsilanes are versatile synthetic intermediates in organ-
ic synthesis.1 Thus, the development of facile and efficient
methods for the synthesis of allylsilanes is important.
Among the available methods for preparing allylsilanes,2–14
two types of the SN2′ displacement strategies, γ-substi-
tutions of γ-silylated allylic alcohol derivatives with
organocuprate reagents15,16 and silylations of allylic alco-
hol derivatives with silylcuprate reagents,17,18 are particu-
larly useful because the substrates and the reagents are
readily available and the reactions are highly reliable in
terms of product yield and selectivity.
t-BuOK (0.3 mmol)
O
O
Me3Si
Ph
+
2a
4aa
THF, 60 °C, 6 h
(0.32 mmol)
89% (100% conv.)
3a (0.2 mmol)
γ/α >99:1; E/Z >99:1
Scheme 1
The hydroboration-coupling one-pot protocol affords a
variety of allylsilanes (Table 1). Allylic phosphates 3b–d
with other silyl substituents such as PhMe2Si, Ph2MeSi,
and BnMe2Si instead of Me3Si at the γ-position were also
converted to the corresponding allylsilanes derivatives
4ab, ac, ad in high yields (entries 1–3). The reaction tol-
erates a variety of functional groups including ester,
methoxy, silyl ether, phthalimide, acetal, thiophene, bro-
mo, and amide moieties in alkenes and allylic phosphates
(entries 4–13).
Previously, we developed the copper-catalyzed allyl–
alkyl coupling reaction between allylic phosphates and
alkylboranes (alkyl-9-BBN) that proceeds with excellent
γ- and E-selectivities.19a Herein, we report that this cop-
per-catalyzed protocol is applicable to the reaction be-
tween γ-silylated allylic phosphates and alkylboranes
(alkyl-9-BBN), which appeared to be a straightforward,
functional group-tolerable approach to allylsilanes.19–22
The wide availability of alkylboranes via the established
alkene hydroboration reaction is an attractive feature of
this transformation.
The tolerance of the reaction toward steric demand in both
the alkylboranes 2 and allylic phosphates 3 is also shown
in Table 1. The sterically more demanding alkylborane
2b, which was derived from the alkene 1b bearing a ter-
tiary alkyl substituent, served as a substrate to afford the
corresponding allylsilanes 4ba in high yield (entry 4). The
reaction of the β-branched alkylborane 2i, which was pre-
pared from α-methylstyrene (1i), was also successful af-
fording 4ia as a 1:1 diastereomeric mixture (Table 1, entry
12). Unfortunately, however, the use of secondary alkyl-
borane reagents prepared from internal alkenes resulted in
no reaction (data not shown). The allylic phosphate 3e
with a CH2CH2OTIPS group instead of a Me group at the
α-position also underwent the reaction (entry 13). A steri-
cally more demanding α-substituent such as an i-Pr group
was also tolerated (entry 14).
Alkylborane 2a (0.32 mmol), which was prepared via hy-
droboration of styrene (1a) with 9-borabicyclo[3.3.1]non-
ane (9-BBN-H) dimer and γ-trimethylsilyl allylic
substrate 3a (0.2 mmol) bearing a cyclic phosphate leav-
ing group were subjected to the standard reaction condi-
tions for the copper-catalyzed allyl–alkyl coupling
[2a/3a/CuOAc/t-BuOK (1.6:1:0.1:1.5), THF, 60 °C]
(Scheme 1).19a The reaction afforded allylsilane 4aa in
89% yield (based on 3a; 100% conversion of 3a) with
complete γ- and E-selectivities. The use of a diethyl phos-
SYNTHESIS 2012, 44, 1535–1541
Advanced online publication: 19.04.2012
0
0
3
9
-
7
8
8
1
1
4
3
7
-
2
1
0
X
DOI: 10.1055/s-0031-1290818; Art ID: SS-2012-C0224-ST
© Georg Thieme Verlag Stuttgart · New York

1536
K. Nagao et al.
SPECIAL TOPIC
Table 1 Synthesis of Allylsilanesa
Yield (%)b,c
Entry
Alkene
Phosphate
Product
O
P
SiMe2Ph
SiMePh2
SiMe2Bn
O
O
O
O
O
PhMe2Si
1
1a
94
Ph
4ab
3b
O
P
O
O
Ph2MeSi
2
3
4
1a
92
94
82
Ph
4ac
3c
O
P
O
O
BnMe2Si
1a
Ph
4ad
3d
SiMe3
O
MeO
O
O
P
MeO
O
Me3Si
3a
O
O
4ba
1b
MeO
MeO
SiMe3
5
6
7
3a
81
87
78
MeO
MeO
1c
4ca
MeO
SiMe2Ph
1c
3b
3a
MeO
4cb
SiMe3
TIPSO
TIPSO
3
3
1d
4da
O
O
SiMe3
N
N
8
3a
72
3
3
O
O
1e
1f
4ea
O
SiMe2Bn
O
O
9
O
3d
3b
79
2
2
4fd
SiMe2Ph
OAc
OAc
S
S
73d
10
1g
4gb
Synthesis 2012, 44, 1535–1541
© Georg Thieme Verlag Stuttgart · New York

SPECIAL TOPIC
Functionalized Allylsilanes
1537
Yield (%)b,c
88
Table 1 Synthesis of Allylsilanesa (continued)
Entry
11
Alkene
Phosphate
Product
SiMe3
3a
Br
Br
1h
4ha
SiMe3
79d
Ph
12
13
3a
Ph
1i
4ia
O
O
O
SiMe3
O
P
O
O
OTIPS
2
Ph
N
Ph
N
O
2
Me3Si
3e
2
76
OTIPS
2
t-BuO
t-BuO
O
1j
4je
O
P
O
SiMe2Ph
O
O
PhMe2Si
Ph
14
1a
92
4af
3f
a The reaction was carried out with 3 (0.2 mmol), alkylborane 2 (0.32 mmol), CuOAc (10 mol%), and t-BuOK (0.3 mmol, 1 M in THF) in THF
at 60 °C for 6 h. Alkylborane 2 was prepared in advance by hydroboration of 1 with 9-BBN dimer in THF at 60 °C for 1 h and used without
purification.
b Isolated yield based on 3.
c Isomeric ratios (γ/α = >99:1, E/Z = >99:1). Determined by 1H NMR spectroscopy or GC analysis of the crude product.
d Diastereomeric ratio (1:1).
tography (GPC) was performed by LC-908 (Japan Analytical In-
dustry Ltd., two in-line JAIGEL-2H, CHCl3, 3.5 mL/min, UV and
RI detectors). Alkenes 1a–j are literature known compounds. Allyl-
silane 4ab is reported in literature.14
In conclusion, we have developed a versatile, functional
group-tolerable approach to allylsilanes through a copper-
catalyzed γ-selective cross-coupling reaction between γ-
silylated allylic phosphates and alkylboranes.
γ-Silylated Allylic Phosphates 3a–d; (Z)-2-{[4-(Dimethylphenyl-
silyl)but-3-en-2-yl]oxy}-5,5-dimethyl -1,3,2-dioxaphosphinane
2-Oxide (3b); Typical Procedure
All reactions were carried out under N2 or argon atmosphere. Mate-
rials were obtained from commercial suppliers or prepared accord-
ing to standard procedures, unless otherwise noted. t-BuOK (1.0 M
THF solution) and CuOAc were purchased from Aldrich Chemical
Co., stored under N2, and used as received. THF was purchased
from Kanto Chemical Co. and stored under argon. NMR spectra
were recorded on a Varian Gemini 2000 spectrometer, operating at
300 MHz for 1H NMR and 75.4 MHz for 13C NMR. Chemical shift
values for 1H and 13C are referenced to Me4Si and the residual sol-
vent resonances, respectively. Chemical shifts are reported in δ
ppm. Mass spectra were obtained with Thermo Fisher Scientific Ex-
active, Jeol JMS-T100LP, or Jeol JMS-700TZ at the Instrumental
Analysis Division, Equipment Management Center, Creative Re-
search Institution, Hokkaido University. Elemental analysis was
performed at the Instrumental Analysis Division, Equipment Man-
agement Center, Creative Research Institution, Hokkaido Universi-
ty. Melting point was measured on a Yanaco MP-500D apparatus.
TLC analyses were performed on commercial glass plates bearing
0.25 mm layer of Merck Silica gel 60F254. Silica gel (Kanto Chem-
ical Co., Silica gel 60 N, spherical, neutral) and Al2O3 (Nacalai
Tesuque, Alumina Activated 200) were used for column chroma-
tography. GLC analyses were conducted on a Shimadzu GC-14B
equipped with a flame ionization detector. Gel permeation chroma-
THP-protection of commercially available but-3-yn-2-ol followed
by silylations gave γ-silylated propargylic alcohol derivatives.
Next, DIBAL-H reduction followed by deprotection afforded γ-si-
lylated allylic alcohols. Finally, allylic phosphates 3a–d were pre-
pared by the phosphorylation of the γ-silylated allylic alcohols (vide
infra for the product yield of the phosphorylation). The phosphory-
lation of (Z)-4-(dimethylphenylsilyl)but-3-en-2-ol to 3b is repre-
sentative.
To a solution of (Z)-4-(dimethylphenylsilyl)but-3-en-2-ol (413 mg,
2.0 mmol) in THF (16.0 mL) and TMEDA (4.0 mL) was added n-
BuLi (1.3 mL, 1.63 M, 2.1 mmol) at –78 °C. After stirring at –78 °C
for 45 min, 2-chloro-5,5-dimethyl-1,3,2-dioxaphosphinane 2-oxide
(Aldrich Chemical Co., 480 mg, 2.6 mmol) was added to the reac-
tion mixture. The mixture was stirred for an additional 5 min at
–78 °C, then warmed to r.t., and stirred for 3 h. The resulting solu-
tion was quenched with sat. aq NH4Cl (15 mL). The aqueous layer
was extracted with EtOAc (3 × 20 mL). The organic layers were
combined and washed with brine (20 mL), dried (MgSO4), filtered,
and concentrated under vacuum to leave an oil. After passing
through a short plug of Al2O3 with Et2O (40 mL), the solvent was
evaporated, and the residue was purified with GPC to provide 3b
(517 mg, 1.46 mmol, 73%) as a colorless oil.
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2012, 44, 1535–1541

1538
K. Nagao et al.
SPECIAL TOPIC
1H NMR (300 MHz, CDCl3): δ = 0.44 (s, 3 H), 0.48 (s, 3 H), 0.84
(s, 3 H), 1.23 (s, 3 H), 1.28 (d, J = 6.3 Hz, 3 H), 3.69–4.04 (m, 4 H),
5.04 (dq, J = 9.0, 6.3 Hz, 1 H), 5.86 (d, J = 14.2 Hz, 1 H), 6.38 (dd,
J = 14.2, 9.0 Hz, 1 H), 7.26–7.37 (m, 3 H), 7.54–7.56 (m, 2 H).
13C NMR (75.4 MHz, CDCl3): δ = –1.54, –1.27, 20.26 (d, J = 4.0
Hz), 21.58, 22.19 (d, J = 4.0 Hz), 31.92 (d, J = 5.7 Hz), 75.18 (d, J =
5.1 Hz), 77.35 (d, J = 6.8 Hz), 77.73 (d, J = 6.8 Hz), 128.00, 129.24,
130.37, 133.75, 138.54, 147.67 (d, J = 5.7 Hz).
H), 3.82–3.94 (m, 4 H), 4.01–4.10 (m, 2 H), 5.13 (m, 1 H), 5.76 (d,
J = 14.4 Hz, 1 H), 6.34 (dd, J = 14.4, 9.3 Hz, 1 H).
13C NMR (75.4 MHz, CDCl3): δ = –0.15, 11.77, 17.88, 20.35,
21.57, 31.95 (d, J = 5.7 Hz), 39.71 (d, J = 6.3 Hz), 59.03, 76.04 (d,
J = 5.7 Hz), 77.39 (d, J = 5.1 Hz), 77.58 (d, J = 6.9 Hz), 133.44,
145.14 (d, J = 2.7 Hz).
HRMS-ESI: m/z [M + Na]+ calcd for C22H47O5PSi2 + Na:
501.25973; found: 501.25919.
HRMS-ESI: m/z [M + Na]+ calcd for C17H27O4PSi + Na: 377.44290;
(S)-(Z)-2-{[1-(Dimethylphenylsilyl)-4-methylpent-1-en-3-
yl]oxy}-5,5-dimethyl-1,3,2-dioxaphosphinane 2-Oxide (3f)
THP-protection of 4-methylpent-1-yn-3-ol followed by silylation
gave the γ-silylated propargylic alcohol derivative. Next, DIBAL-H
reduction followed by deprotection afforded the γ-silylated allylic
alcohol. Finally, the phosphorylation of the γ-silylated allylic alco-
hol (468 mg, 2.0 mmol) provided the allylic phosphate 3f (451 mg,
1.18 mmol, 59%); white solid; mp 91.5–91.7 °C.
1H NMR (300 MHz, CDCl3): δ = 0.46 (s, 3 H), 0.50 (s, 3 H), 0.81
(d, J = 6.6 Hz, 3 H), 0.85 (s, 3 H), 0.89 (d, J = 6.6 Hz, 3 H), 1.24 (s,
3 H), 1.77 (sext, J = 6.6 Hz, 1 H), 3.71–4.06 (m, 4 H), 4.68–4.76 (m,
1 H), 5.95 (d, J = 14.4 Hz, 1 H), 6.37 (dd, J = 14.4, 9.6 Hz, 1 H),
7.34–7.37 (m, 3 H), 7.57–7.58 (m, 2 H).
13C NMR (75.4 MHz, CDCl3): δ = –1.43, –1.31, 17.15, 17.99, 20.34
(d, J = 1.1 Hz), 21.63, 31.92 (d, J = 5.7 Hz), 33.47 (d, J = 5.7 Hz),
77.27 (d, J = 6.3 Hz), 77.68 (d, J = 6.8 Hz), 82.59 (d, J = 6.3 Hz),
127.95, 129.18, 132.94, 133.90, 138.69, 144.54 (d, J = 2.9 Hz).
HRMS-ESI: m/z [M + Na]+ calcd for C19H31O4PSi + Na: 405.16269;
found: 405.16241.
found: 377.13084.
(Z)-5,5-Dimethyl-2-{[4-(trimethylsilyl)but-3-en-2-yl]oxy}-1,3,2-
dioxaphosphinane 2-Oxide (3a)
Yield: 345 mg (59%); white solid; mp 45.6–45.8 °C.
1H NMR (300 MHz, CDCl3): δ = 0.17 (s, 9 H), 0.87 (s, 3 H), 1.25
(s, 3 H), 1.44 (d, J = 5.1 Hz, 3 H), 3.78–4.11 (m, 4 H), 5.13 (dq, J =
9.0, 5.1 Hz, 1 H), 5.71 (d, J = 14.1 Hz, 1 H), 6.29 (dd, J = 14.1, 9.0
Hz, 1 H).
13C NMR (75.4 MHz, CDCl3): δ = –0.20, 20.21 (d, J = 1.1 Hz),
21.55, 22.59 (d, J = 4.6 Hz), 31.91 (d, J = 5.7 Hz), 75.14 (d, J = 5.1
Hz), 77.36 (d, J = 6.8 Hz), 77.75 (d, J = 6.8 Hz), 132.39, 146.26 (d,
J = 5.7 Hz).
HRMS-ESI: m/z [M + Na]+ calcd for C12H25O4PSi + Na: 315.11574;
found: 315.11519.
(Z)-5,5-Dimethyl-2-{[4-(methyldiphenylsilyl)but-3-en-2-
yl]oxy}-1,3,2-dioxaphosphinane 2-Oxide (3c)
Yield: 687 mg (83%); colorless oil.
1H NMR (300 MHz, CDCl3): δ = 0.78 (s, 3 H), 0.81 (s, 3 H), 1.19
(d, J = 6.3 Hz, 3 H), 1.21 (s, 3 H), 3.66–3.98 (m, 4 H), 4.93 (dq, J =
9.0, 6.3 Hz, 1 H), 6.08 (d, J = 14.4 Hz, 1 H), 6.53 (dd, J = 14.4, 9.0
Hz, 1 H), 7.33–7.39 (m, 6 H), 7.53–7.58 (m, 4 H).
13C NMR (75.4 MHz, CDCl3): δ = –2.57, 20.26 (d, J = 1.1 Hz),
21.53, 21.88 (d, J = 4.0 Hz), 31.88 (d, J = 5.7 Hz), 75.20 (d, J = 5.1
Hz), 77.34 (d, J = 6.8 Hz), 77.64 (d, J = 6.8 Hz), 128.04, 128.10,
128.14, 129.49, 129.60, 134.61, 134.75, 136.30, 136.68, 149.30 (d,
J = 6.3 Hz).
Allylsilanes; (E)-Trimethyl(1-phenylhex-4-en-3-yl)silane (4aa);
Typical Procedure
In a glove box, (9-BBN-H)2 (40.3 mg, 0.165 mmol), THF (0.06
mL), and styrene (1a; 0.041 mL, 0.36 mmol) were sequentially
placed in a screw-top test tube containing a magnetic stirring bar.
Also in the glove box, CuOAc (2.5 mg, 0.02 mmol) was placed in
another vial containing a magnetic stirring bar. Both the two vials
were then sealed with a cap equipped with a Teflon-coated silicon
rubber septum, and were removed from the glove box. After stirring
the THF solution at 60 °C for 1 h to prepare the alkylborane 2a, t-
BuOK (1 M in THF, 0.3 mL, 0.3 mmol) prepared in advance at 25
°C was added. Next, this mixture was transferred to the vial contain-
ing the Cu salt. Finally, allylic phosphate 3a (56.1 mg, 0.2 mmol)
was added. After stirring for 6 h at 60 °C, CH2Cl2 (0.3 mL) was add-
ed to the mixture. Then, the mixture was filtered through a short
plug of silica gel, which was washed with Et2O (8 mL). After re-
moval of the solvent under reduced pressure, flash chromatography
on silica gel (hexane) provided 4aa (41.5 mg, 0.178 mmol, 89%) as
a colorless oil.
HRMS-ESI: m/z [M + Na]+ calcd for C22H29O4PSi + Na: 439.14704;
found: 439.14649.
(Z)-2-{[4-(Benzyldimethylsilyl)but-3-en-2-yl]oxy}-5,5-dimeth-
yl-1,3,2-dioxaphosphinane 2-Oxide (3d)
Yield: 667 mg (91%); colorless oil.
1H NMR (300 MHz, CDCl3): δ = 0.16 (s, 3 H), 0.17 (s, 3 H), 0.87
(s, 3 H), 1.24 (s, 3 H), 1.37 (d, J = 6.3 Hz, 3 H), 2.19 (s, 2 H), 3.76–
4.09 (m, 4 H), 5.08 (dq, J = 9.0, 6.3 Hz, 1 H), 5.68 (d, J = 14.4 Hz,
1 H), 6.32 (dd, J = 14.4, 9.0 Hz, 1 H), 7.00–7.10 (m, 3 H), 7.19–7.24
(m, 2 H).
13C NMR (75.4 MHz, CDCl3): δ = –2.05, –2.00, 20.25, 21.55, 22.51
(d, J = 4.6 Hz), 26.17, 31.94 (d, J = 5.7 Hz), 75.20 (d, J = 5.1 Hz),
77.38 (d, J = 6.8 Hz), 77.75 (d, J = 6.8 Hz), 124.19, 128.22, 128.28,
130.46, 139.51, 147.16 (d, J = 5.7 Hz).
1H NMR (300 MHz, CDCl3): δ = –0.05 (s, 9 H), 1.40–1.46 (m, 1 H),
1.52–1.78 (m, 2 H), 1.71 (d, J = 4.8 Hz, 3 H), 2.43 (ddd, J = 13.5,
9.6, 6.9 Hz, 1 H), 2.77 (ddd, J = 13.5, 9.3, 4.5 Hz, 1 H), 5.23 (dd,
J = 15.0, 7.8 Hz, 1 H), 5.30 (dq, J = 15.0, 4.8 Hz, 1 H), 7.15–7.19
(m, 3 H), 7.25–7.30 (m, 2 H).
13C NMR (75.4 MHz, CDCl3): δ = –3.37, 18.11, 31.08, 32.71,
35.59, 123.16, 125.60, 128.29, 128.59, 132.17, 143.18.
HRMS-ESI: m/z [M + Na]+ calcd for C18H29O4PSi + Na: 391.14704;
found: 391.14649.
Anal. Calcd for C15H24Si: C, 77.51; H, 10.41. Found: C, 77.70; H,
10.76.
(Z)-5,5-Dimethyl-2-{[5-(triisopropylsilyloxy)-1-(trimethylsi-
lyl)pent-1-en-3-yl]oxy}-1,3,2-dioxaphosphinane 2-Oxide (3e)
THP-protection of 5-[(triisopropylsilyl)oxy]pent-1-yn-3-ol fol-
lowed by silylation gave the γ-silylated propargylic alcohol deriva-
tive. Next, DIBAL-H reduction followed by deprotection afforded
the γ-silylated allylic alcohol. Finally, the phosphorylation of the γ-
silylated allylic alcohol (661 mg, 2.0 mmol) provided the allylic
phosphate 3e (171 mg, 1.0 mmol, 50%) as a colorless oil.
(E)-Dimethylphenyl(1-phenylhex-4-en-3-yl)silane (4ab)
Yield: 55.4 mg (94%); colorless oil.
1H NMR (300 MHz, CDCl3): δ = 0.21 (s, 3 H), 0.24 (s, 3 H), 1.53–
1.76 (m, 3 H), 1.69 (d, J = 4.8 Hz, 3 H), 2.39 (ddd, J = 13.5, 9.0, 7.2
Hz, 1 H), 2.72 (ddd, J = 13.5, 9.6, 4.2 Hz, 1 H), 5.22 (dd, J = 15.0,
7.5 Hz, 1 H), 5.29 (dq, J = 15.0, 4.8 Hz, 1 H), 7.07–7.10 (m, 2 H),
7.13–7.18 (m, 1 H), 7.22–7.26 (m, 2 H), 7.29–7.34 (m, 3 H), 7.37–
7.45 (m, 2 H).
1H NMR (300 MHz, CDCl3): δ = 0.18 (s, 9 H), 0.88 (s, 3 H), 1.06–
1.14 (m, 21 H), 1.23 (s, 3 H), 1.81–1.91 (m, 1 H), 1.96–2.07 (m, 1
Synthesis 2012, 44, 1535–1541
© Georg Thieme Verlag Stuttgart · New York

SPECIAL TOPIC
Functionalized Allylsilanes
1539
13C NMR (75.4 MHz, CDCl3): δ = –5.37, –4.39, 18.09, 30.91,
32.07, 35.34, 123.90, 125.58, 127.63, 128.25, 128.60, 128.89,
131.61, 134.15, 138.13, 142.90.
1 H), 6.63–6.66 (m, 2 H), 6.74–6.77 (m, 1 H), 7.30–7.38 (m, 3 H),
7.38–7.49 (m, 2 H).
13C NMR (75.4 MHz, CDCl3): δ = –5.37, –4.39, 18.01, 28.47,
31.22, 32.28, 35.10, 55.68, 55.83, 111.09, 111.68, 120.12, 123.37,
127.60, 128.86, 131.77, 134.12, 135.63, 138.33, 146.99, 148.75.
Anal. Calcd for C20H26Si: C, 81.57; H, 8.96. Found: C, 81.45; H,
9.04.
Anal. Calcd for C23H32O2Si: C, 74.95; H, 8.75. Found: C, 75.11; H,
8.77.
(E)-Methyldiphenyl(1-phenylhex-4-en-3-yl)silane (4ac)
Yield: 65.6 mg (92%); colorless oil.
1H NMR (300 MHz, CDCl3): δ = 0.48 (s, 3 H), 1.59–1.71 (m, 1 H),
1.66 (d, J = 4.2 Hz, 3 H), 1.78–1.86 (m, 1 H), 2.05–2.10 (m, 1 H),
2.45 (dt, J = 13.8, 8.4 Hz, 1 H), 2.76 (ddd, J = 13.8, 9.0, 4.8 Hz, 1
H), 5.27–5.29 (m, 2 H), 7.07–7.49 (m, 15 H).
13C NMR (75.4 MHz, CDCl3): δ = –5.82, 18.09, 30.21, 30.96,
35.04, 124.89, 125.65, 127.63, 127.76, 128.25, 128.73, 129.08,
129.20, 130.97, 135.07, 135.10, 135.84, 136.40, 142.62.
(E)-Triisopropyl[(6-(trimethylsilyl)non-7-en-1-yl)oxy]silane
(4da)
Yield: 67.5 mg (78%); colorless oil.
1H NMR (300 MHz, CDCl3): δ = –0.06 (s, 9 H), 1.05–1.07 (m, 21
H), 1.15–1.57 (m, 9 H), 1.65 (d, J = 4.8 Hz, 3 H), 3.66 (t, J = 13.2
Hz, 2 H), 5.16 (dd, J = 14.7, 6.9 Hz, 1 H), 5.23 (dq, J = 14.7, 4.8 Hz,
1 H).
13C NMR (75.4 MHz, CDCl3): δ = –3.32, 11.90, 17.92, 18.02,
25.56, 28.81, 29.08, 32.88, 32.89, 63.50, 122.35, 132.63.
Anal. Calcd for C25H28Si: C, 84.21; H, 7.91. Found: C, 83.88; H,
7.95.
HRMS-APCI: m/z [M]+ calcd for C21H46OSi2: 370.3087; found:
370.3083.
(E)-Benzyldimethyl(1-phenylhex-4-en-3-yl)silane (4ad)
Yield: 58.0 mg (94%); colorless oil.
1H NMR (300 MHz, CDCl3): δ = –0.12 (s, 3 H), –0.10 (s, 3 H),
1.48–1.80 (m, 3 H), 1.72 (d, J = 5.1 Hz, 3 H), 2.06 (s, 2 H), 2.42
(ddd, J = 13.5, 9.0, 7.2 Hz, 1 H), 2.77 (ddd, J = 13.5, 9.6, 4.2 Hz, 1
H), 5.25 (dd, J = 16.2, 8.4 Hz, 1 H), 5.31 (dq, J = 16.2, 5.1 Hz, 1 H),
6.93–6.95 (m, 2 H), 7.03–7.08 (m, 1 H), 7.15–7.21 (m, 5 H), 7.26–
7.31 (m, 2 H).
13C NMR (75.4 MHz, CDCl3): δ = –5.40, –5.29, 18.12, 23.69,
31.14, 31.31, 35.41, 123.91, 123.93, 125.67, 128.20, 128.27,
128.33, 128.62, 131.69, 140.37, 142.96.
(E)-2-[6-(Trimethylsilyl)non-7-en-1-yl]isoindoline-1,3-dione
(4ea)
Yield: 49.5 mg (72%); white solid; mp 54.2–54.4 °C.
1H NMR (300 MHz, CDCl3): δ = –0.08 (s, 9 H), 1.14–1.49 (m, 9 H),
1.63 (d, J = 5.1 Hz, 3 H), 3.67 (t, J = 7.2 Hz, 2 H), 5.13 (dd, J = 15.0,
6.9 Hz, 1 H), 5.20 (dq, J = 15.0, 5.1 Hz, 1 H), 7.71 (m, 2 H), 7.85
(m, 2H).
13C NMR (75.4 MHz, CDCl3): δ = –3.35, 17.80, 26.70, 28.48,
28.65, 28.90, 32.85, 38.06, 122.47, 123.20, 132.26, 132.42, 133.90,
168.63.
Anal. Calcd for C21H28Si: C, 81.75; H, 9.15. Found: C, 81.53; H,
9.40.
Anal. Calcd for C20H29NO2Si: C, 69.92; H, 8.51; N, 4.08. Found: C,
70.14; H, 8.68; N, 3.99.
(E)-Methyl 3,3-Dimethyl-6-(trimethylsilyl)non-7-enoate (4ba)
Yield: 44.3 mg (82%); colorless oil.
1H NMR (300 MHz, CDCl3): δ = –0.05 (s, 9 H), 0.98 (s, 6 H), 1.04–
1.26 (m, 3 H), 1.42–1.47 (m, 2 H), 1.66 (d, J = 4.8 Hz, 3 H), 2.19 (s,
2 H), 3.65 (s, 3 H), 5.15 (dd, J = 15.3, 7.8 Hz, 1 H), 5.21 (dq, J =
15.3, 4.8 Hz, 1 H).
(E)-[9-(1,3-Dioxan-2-yl)non-2-en-4-yl](benzyl)dimethylsilane
(4fd)
Yield: 57.0 mg (79%); colorless oil.
1H NMR (300 MHz, CDCl3): δ = –0.11 (s, 3 H), –0.10 (s, 3 H),
1.16–1.63 (m, 12 H), 1.66 (d, J = 4.8 Hz, 3 H), 2.02–2.16 (m, 1 H),
2.06 (s, 2 H), 3.76 (td, J = 12.3, 2.1 Hz, 2 H), 4.10 (dd, J = 10.8, 5.1
Hz, 2 H), 4.50 (t, J = 5.1 Hz, 1 H), 5.16 (dd, J = 15.3, 7.8 Hz, 1 H),
5.21 (dq, J = 15.3, 4.8 Hz, 1 H), 6.97–7.00 (m, 2 H), 7.03–7.08 (m,
1 H), 7.18–7.23 (m, 2 H).
13C NMR (75.4 MHz, CDCl3): δ = –5.32, –5.28, 18.02, 23.75,
23.82, 25.74, 28.77, 29.08, 29.24, 31.70, 35.17, 66.86, 102.47,
123.09, 123.86, 128.14, 128.29, 132.08, 140.49.
13C NMR (75.4 MHz, CDCl3): δ = –3.26, 18.02, 23.04, 27.12,
27.22, 33.24, 33.47, 42.34, 45.77, 51.01, 122.49, 132.51, 173.09.
Anal. Calcd for C15H30O2Si: C, 66.61; H, 11.18. Found: C, 66.59;
H, 11.20.
(E)-[7-(3,4-Dimethoxyphenyl)hept-2-en-4-yl]trimethylsilane
(4ca)
Yield: 49.7 mg (81%); colorless oil.
Anal. Calcd for C22H36O2Si: C, 73.28; H, 10.06. Found: C, 73.21;
H, 10.33.
1H NMR (300 MHz, CDCl3): δ = –0.06 (s, 9 H), 1.26–1.54 (m, 4 H),
1.65 (d, J = 4.8 Hz, 3 H), 1.71–1.78 (m, 1 H), 2.46 (ddd, J = 15.0,
8.1, 6.6 Hz, 1 H), 2.58 (ddd, J = 15.0, 9.6, 5.1 Hz, 1 H), 3.86 (s, 3
H), 3.87 (s, 3 H), 5.17 (dd, J = 15.3, 7.2 Hz, 1 H), 5.24 (dq, J = 15.3,
4.8 Hz, 1 H), 6.70–6.72 (m, 2 H), 6.77–6.80 (m, 1 H).
13C NMR (75.4 MHz, CDCl3): δ = –3.34, 18.01, 28.42, 31.34,
32.75, 35.23, 55.68, 55.82, 111.08, 111.69, 120.14, 122.59, 132.34,
135.69, 146.99, 148.75.
(E)-5-(Dimethylphenylsilyl)-1-(thiophen-2-yl)oct-6-en-1-yl Ace-
tate (4gb)
Yield: 56.4 mg (73%); colorless oil.
1H NMR (300 MHz, CDCl3): δ = 0.22 (s, 3 H), 0.23 (s, 3 H), 1.07–
1.50 (m, 5 H), 1.62 (d, J = 4.8 Hz, 1.5 H), 1.63 (d, J = 4.8 Hz, 1.5
H), 1.79–1.93 (m, 2 H), 2.02 (s, 3 H), 5.07–5.24 (m, 2 H), 5.94 (t,
J = 7.2 Hz, 0.5 H), 5.95 (t, J = 7.2 Hz, 0.5 H), 6.92–6.98 (m, 2 H),
7.23–7.26 (m, 1 H), 7.34–7.35 (m, 3 H), 7.44–7.48 (m, 2 H).
13C NMR (75.4 MHz, CDCl3): δ = –5.46, –5.41, –4.46, –4.42, 17.97
(2 C), 21.09 (2 C), 24.87, 25.00, 28.29, 28.31, 32.02, 32.24, 35.68,
35.90, 71.09, 71.30, 123.56, 123.62, 125.11, 125.20, 125.77,
125.91, 126.50, 126.52, 127.63, 127.65, 128.91, 131.43, 131.49,
134.09, 134.11, 138.15, 138.19, 143.64, 143.84, 170.41, 170.44.
Anal. Calcd for C18H30O2Si: C, 70.53; H, 9.87. Found: C, 70.52; H,
10.02.
(E)-[7-(3,4-Dimethoxyphenyl)hept-2-en-4-yl]dimethyl(phe-
nyl)silane (4cb)
Yield: 64.1 mg (87%); colorless oil.
1H NMR (300 MHz, CDCl3): δ = 0.22 (s, 3 H), 0.24 (s, 3 H), 1.28–
1.70 (m, 5 H), 1.64 (d, J = 4.8 Hz, 3 H), 2.38 (ddd, J = 14.4, 8.4, 6.0
Hz, 1 H), 2.51 (ddd, J = 14.4, 9.3, 4.5 Hz, 1 H), 3.84 (s, 3 H), 3.85
(s, 3 H), 5.18 (dd, J = 15.3, 7.5 Hz, 1 H), 5.22 (dq, J = 15.3, 4.8 Hz,
HRMS-ESI: m/z [M + Na]+ calcd for C22H30O2SSi + Na: 409.16335;
found: 409.16280.
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2012, 44, 1535–1541

1540
K. Nagao et al.
SPECIAL TOPIC
(E)-[1-(4-Bromophenyl)hex-4-en-3-yl]trimethylsilane (4ha)
Yield: 54.8 mg (88%); colorless oil.
References
(1) For reviews on the synthesis of allylsilanes, see: (a) Masse,
C. E.; Panek, J. S. Chem. Rev. 1995, 95, 1293. (b) Fleming,
I.; Barbero, A.; Walter, D. Chem. Rev. 1997, 97, 2063.
(c) Chabaund, L.; James, P.; Landais, Y. Eur. J. Org. Chem.
2004, 3173.
(2) For Pd-catalyzed couplings between vinyl halides and
silylmethyl Grignard reagents, see: (a) Hayashi, T.; Konishi,
M.; Ito, H.; Kumada, M. J. Am. Chem. Soc. 1982, 104, 4962.
(b) Hayashi, T.; Konishi, M.; Okamoto, Y.; Kabeta, K.;
Kumada, M. J. Org. Chem. 1986, 51, 3772.
1H NMR (300 MHz, CDCl3): δ = –0.07 (s, 9 H), 1.35–1.42 (m, 1 H),
1.49–1.73 (m, 2 H), 1.70 (d, J = 5.1 Hz, 3 H), 2.40 (ddd, J = 13.5
9.0, 7.2 Hz, 1 H), 2.71 (ddd, J = 13.5, 9.3, 4.5 Hz, 1 H), 5.20 (dd,
J = 15.6, 8.1 Hz, 1 H), 5.26 (dq, J = 15.6, 5.1 Hz, 1 H), 7.02–7.05
(m, 2 H), 7.36–7.40 (m, 2 H).
13C NMR (75.4 MHz, CDCl3): δ = –3.40, 18.09, 30.83, 32.47,
34.84, 119.27, 123.39, 130.40, 131.32, 131.95, 142.02.
HRMS-EI: m/z [M]+ calcd for C15H23BrSi: 310.0752; found:
310.0752.
(3) For Pd-catalyzed hydrosilylations of 1,3-dienes, see:
(a) Hayashi, T.; Kabeta, K.; Yamamoto, T.; Tamao, K.;
Kumada, M. Tetrahedron Lett. 1983, 24, 5661. (b) Hayashi,
T.; Kebeta, K. Tetrahedron Lett. 1985, 26, 3023.
(E)-Trimethyl(6-phenylhept-2-en-4-yl)silane (4ia)
Yield: 38.9 mg (79%); colorless oil.
1H NMR (300 MHz, CDCl3): δ = –0.13 (s, 4.5 H), –0.06 (s, 4.5 H),
1.09–1.27 (m, 1 H), 1.15 (d, J = 6.9 Hz, 1.5 H), 1.21 (d, J = 6.9 Hz,
1.5 H), 1.44–1.64 (m, 2 H), 1.68 (d, J = 5.1 Hz, 1.5 H), 1.69 (d, J =
5.1 Hz, 1.5 H), 2.71–2.87 (m, 1 H), 5.03–5.34 (m, 2 H), 7.11–7.15
(m, 1 H), 7.17–7.21 (m, 2 H), 7.26–7.32 (m, 2 H).
13C NMR (75.4 MHz, CDCl3): δ = –3.53, –3.40, 18.08, 19.12,
23.60, 30.52, 30.66, 37.27, 37.46, 38.03, 38.40, 122.96, 123.03,
125.73, 125.76, 126.97, 127.48, 128.24, 128.35, 131.85, 132.23,
147.11, 149.29.
(c) Hayashi, T.; Hengrasmee, S.; Matsumoto, Y. Chem. Lett.
1990, 1377. (d) Hayashi, T.; Matsumoto, Y. Tetrahedron:
Asymmetry 1990, 1, 151. (e) Hayashi, T.; Han, J. W.;
Takeda, A.; Tang, J.; Nohmi, K.; Mukaide, K.; Tsuji, H.;
Uozumi, Y. Adv. Synth. Catal. 2001, 343, 279.
(4) For Pd-catalyzed silylations of allylic substrates with
disilanes, see: (a) Matsumoto, Y.; Ohno, A.; Hayashi, T.
Organometallics 1993, 12, 4051. (b) Hayashi, T.; Ohno, A.;
Lu, S.; Matsumoto, Y.; Fukuyo, E.; Yanagi, K. J. Am. Chem.
Soc. 1994, 116, 4221. (c) Tsuji, Y.; Kajita, S.; Isobe, S.;
Funato, M. J. Org. Chem. 1993, 58, 3607. (d) Tsuji, Y.;
Funato, M.; Ozawa, M.; Ogiyama, H.; Kajita, S.; Kawamura,
T. J. Org. Chem. 1996, 61, 5779. (e) Moser, R.; Nishikata,
T.; Lipshutz, B. H. Org. Lett. 2010, 12, 28. (f) Selander, N.;
Paasch, J. R.; Szabó, K. J. J. Am. Chem. Soc. 2011, 133, 409.
(5) For Pd-catalyzed hydrogenolysis of silyl-substituted allylic
carbonates, see: Hayashi, T.; Iwamura, H.; Uozumi, Y.
Tetrahedron Lett. 1994, 35, 4813.
Anal. Calcd for C16H26Si: C, 77.97; H, 10.63. Found: C, 78.09; H,
10.89.
(E)-tert-Butyl Benzyl{10-[(triisopropylsilyl)oxy]-6-(trimethylsi-
lyl)dec-7-enoyl}carbamate (4je)
Yield: 91.7 mg (76%); colorless oil.
1H NMR (300 MHz, CDCl3): δ = –0.06 (s, 9 H), 1.06 (s, 21 H),
1.12–1.70 (m, 7 H), 1.41 (s, 9 H), 2.25 (d, J = 6.9 Hz, 2 H), 2.88 (td,
J = 7.8, 2.1 Hz, 2 H), 3.65 (t, J = 6.9 Hz, 2 H), 4.88 (s, 2 H), 5.21–
5.24 (m, 2 H), 7.23–7.32 (m, 5 H).
13C NMR (75.4 MHz, CDCl3): δ = –3.37, 11.86, 17.91, 24.98,
27.78, 28.58, 28.85, 32.92, 36.80, 38.21, 47.21, 64.03, 82.99,
124.36, 127.10, 127.60, 128.33, 133.52, 138.53, 153.25, 176.45.
(6) For Ni-catalyzed couplings of allylic ethers with
chlorosilanes, see: (a) Terao, J.; Watabe, H.; Watanabe, H.;
Kambe, N. Adv. Synth. Catal. 2004, 346, 1674. (b) Naitoh,
Y.; Bando, F.; Terao, J.; Otsuki, K.; Kuniyasu, H.; Kambe,
N. Chem. Lett. 2007, 36, 236.
HRMS-ESI: m/z [M + Na]+ calcd for C34H61NO4Si2 + Na:
(7) For Pd-catalyzed silaborations of allenes, see: (a) Ohmura,
T.; Taniguchi, H.; Suginome, M. J. Am. Chem. Soc. 2006,
128, 13682. (b) Suginome, M.; Matsumoto, A.; Ito, Y.
J. Am. Chem. Soc. 1996, 118, 3061. (c) Suginome, M.;
Iwanami, T.; Ohmori, Y.; Matsumoto, A.; Ito, Y. Chem.–
Eur. J. 2005, 11, 2954.
(8) For Pd-catalyzed allyl transfer reactions from silyl-
substituted homoallyl alcohols to aryl halides, see: Hayashi,
S.; Hirano, K.; Yorimitsu, H.; Oshima, K. J. Am. Chem. Soc.
2007, 129, 12650.
626.40368; found: 626.40313.
(E)-Dimethyl(6-methyl-1-phenylhept-4-en-3-yl)(phenyl)silane
(4af)
Yield: 59.4 mg (92%); colorless oil.
1H NMR (300 MHz, CDCl3): δ = 0.22 (s, 3 H), 0.24 (s, 3 H), 0.96
(d, J = 6.6 Hz, 3 H), 0.98 (d, J = 6.6 Hz, 3 H), 1.50–1.78 (d, J = 6.6
Hz, 3 H), 2.22–2.34 (m, 1 H), 2.36–2.44 (m, 1 H), 2.67–2.76 (m, 1
H), 5.15 (dd, J = 15.3, 7.8 Hz, 1 H), 5.22 (dd, J = 15.3, 6.0 Hz, 1 H),
7.08–7.10 (m, 2 H), 7.13–7.18 (m, 1 H), 7.22–7.27 (m, 2 H), 7.30–
7.34 (m, 3 H), 7.42–7.45 (m, 2 H).
13C NMR (75.4 MHz, CDCl3): δ = –5.34, –4.53, 22.87, 23.03,
30.81, 31.41, 31.70, 35.18, 125.58, 127.29, 127.60, 128.25, 128.63,
128.89, 134.18, 137.17, 138.07, 142.89.
(9) For silylene insertions into allylic ethers, see: Bourque, L.
E.; Cleary, P. A.; Woerpel, K. A. J. Am. Chem. Soc. 2007,
127, 12602.
(10) For reactions of silyl chlorides with allylic samarium
reagents, see: Takaki, K.; Kusudo, T.; Uebori, S.;
Nishiyama, T.; Kamata, T.; Yokoyama, M.; Takehira, K.;
Makioka, Y.; Fujiwara, Y. J. Org. Chem. 1998, 63, 4299.
(11) For Ireland–Claisen rearrangement of Z-vinylsilanes, see:
(a) Panek, J. S.; Clark, T. D. J. Org. Chem. 1992, 57, 4323.
(b) Sparks, M. A.; Panek, J. S. J. Org. Chem. 1991, 56, 3431.
(12) For Wittig olefination of α-silylaldehyde, see: Bhushan, V.;
Lohray, B. B.; Enders, D. Tetrahedron Lett. 1993, 34, 5067.
(13) For Rh- or Cu-catalyzed carbenoid insertions into Si–H
bonds, see: (a) Davies, H. M.; Hansen, T.; Rutberg, J.;
Bruzinski, P. R. Tetrahedron Lett. 1997, 38, 1741.
(b) Bulugahapitiya, P.; Landais, Y.; Parra-Rapado, L.;
Planchenault, D.; Weber, V. J. Org. Chem. 1997, 62, 1630.
(c) Wu, J.; Chen, Y.; Panek, J. S. Org. Lett. 2010, 12, 2112.
HRMS-EI: m/z [M]+ calcd for C22H30Si: 322.21168; found:
322.2115.
Acknowledgment
This work was supported by Grants-in-Aid for Scientific Research
(B) and for Young Scientists (B), JSPS. We thank MEXT for finan-
cial support in the form of a Global COE grant (Project No. B01:
Catalysis as the Basis for Innovation in Materials Science).
Synthesis 2012, 44, 1535–1541
© Georg Thieme Verlag Stuttgart · New York

SPECIAL TOPIC
Functionalized Allylsilanes
1541
(14) For synthesis of chiral allyl- and crotylsilanes through the
borylation of lithiated carbamates, see: Aggarwal, V. K.;
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(b) Smitrovich, J. H.; Woerpel, K. A. J. Org. Chem. 2000,
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(16) For enantioselective copper-catalyzed allylic alkylations of
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transition metal catalyzed γ-selective and stereospecific
allylic substitutions: (f) Li, D.; Ohmiya, H.; Sawamura, M.
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Y.; Tanaka, T.; Sawamura, M. J. Am. Chem. Soc. 2008, 130,
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Sawamura, M. J. Am. Chem. Soc. 2010, 132, 879.
(i) Makida, Y.; Ohmiya, H.; Sawamura, M. Chem.–Asian J.
2011, 6, 410.
(20) For Cu-catalyzed conjugate additions with alkylboron
compounds (alkyl-9-BBN) to imidazol-2-yl α,β-unsaturated
ketones, see: (a) Ohmiya, H.; Yoshida, M.; Sawamura, M.
Org. Lett. 2011, 13, 482. (b) Ohmiya, H.; Shido, Y.;
Yoshida, M.; Sawamura, M. Chem. Lett. 2011, 40, 928. For
Cu-catalyzed carboxylations with alkylboron compounds
(alkyl-9-BBN) to CO2: (c) Ohmiya, H.; Tanabe, M.;
Sawamura, M. Org. Lett. 2011, 13, 1086. (d) Ohishi, T.;
Zhang, L.; Nishiura, M.; Hou, Z. Angew. Chem. Int. Ed.
2011, 50, 8114. For Cu-catalyzed γ-selective coupling
between alkylboron compounds (alkyl-9-BBN) and
propargylic phosphates: (e) Ohmiya, H.; Yokobori, U.;
Makida, Y.; Sawamura, M. Org. Lett. 2011, 13, 6312.
(f) Uehling, M. R.; Marionni, S. T.; Lalic, G. Org. Lett.
2011, 13, 362.
Organocopper Chemistry; Krause, N., Ed.; Wiley-VCH:
Weinheim, 2002, 79–144.
(18) For other silylations of allylic substrates with silylcuprate
reagents, see: (a) Laycock, B.; Kitching, W.; Wickham, G.
Tetrahedron Lett. 1983, 24, 5785. (b) Clive, D. L. J.; Zhang,
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(c) Lipshutz, B. H.; Sclafani, J. A.; Takanami, T. J. Am.
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Adv. Synth. Catal. 2005, 347, 637. (e) Schmidtmann, E. S.;
Oestreich, M. Chem. Commun. 2006, 46, 3643. (f) Vyas, D.
J.; Oestreich, M. Chem. Commun. 2010, 46, 568. For copper-
catalyzed silylation of allylic chlorides with a silylboronate:
(g) Vyas, D. J.; Oestreich, M. Angew. Chem. Int. Ed. 2010,
49, 8513.
(21) For the synthesis of α-arylated allylsilanes through Pd-
catalyzed γ-selective and stereospecific allyl–aryl coupling
between γ-silylated allylic esters and arylboronic acids, see:
Li, D.; Tanaka, T.; Ohmiya, H.; Sawamura, M. Org. Lett.
2010, 12, 3344.
(22) For an approach to allenylsilanes by the Rh-catalyzed
coupling between propargylic carbonates and a
silylboronate, see: Ohmiya, H.; Ito, H.; Sawamura, M. Org.
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(19) For Cu-catalyzed γ-selective allylic substitutions with
organoboron compounds, see: (a) Ohmiya, H.; Yokobori,
(23) For the concept of allylic 1,3-strain in acyclic stereocontrol,
see: Hoffmann, R. W. Chem. Rev. 1989, 89, 1841.
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2012, 44, 1535–1541