Copper-catalyzed regiodivergent silacarboxylation of allenes with carbon dioxide and a silylborane

Article abstract of DOI:10.1021/ja512040c

A regiodivergent silacarboxylation of allenes under a CO₂ atmosphere with PhMe₂Si-B(pin) as a silicon source in the presence of a copper catalyst at 70 °C has been developed. The regioselectivity of the reaction is successfully rever

Full text of DOI:10.1021/ja512040c

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Communication
Copper-Catalyzed Regiodivergent Silacarboxylation
of Allenes with Carbon Dioxide and a Silylborane
Yosuke Tani, Tetsuaki Fujihara, Jun Terao, and Yasushi Tsuji
J. Am. Chem. Soc., Just Accepted Manuscript • DOI: 10.1021/ja512040c • Publication Date (Web): 03 Dec 2014
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Copper-Catalyzed Regiodivergent Silacarboxylation of Allenes with
Carbon Dioxide and a Silylborane
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Yosuke Tani, Tetsuaki Fujihara, Jun Terao and Yasushi Tsuji*
Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University,
Nishikyo-ku, Kyoto 615-8510, Japan.
Supporting Information Placeholder
Scheme 1. Regiodivergent Silylcupration of Allenes
ABSTRACT: The regiodivergent silacarboxylation of allenes is devel-
oped under carbon dioxide atmosphere with PhMe2Si–B(pin) as a sili-
con source in the presence of a copper catalyst at 70 °C. The regioselec-
tivity of the reaction is successfully reversed by the proper choice of lig-
and; carboxylated vinylsilanes are obtained with rac-Me-DuPhos as the
ligand, whereas carboxylated allylsilanes are provided by employing
PCy3. Thus, two different carboxylated silanes can be selectively and re-
giodivergently synthesized from a single allene substrate.
Silylcupration across carbon–carbon multiple bonds1 is a reliable
and powerful process that forms both C–Si and C–Cu bonds, with the
latter amenable to further in situ C–C bond-forming events. Conven-
tionally,
a stoichiometric amount of a silylcuprate such as
(PhMe2Si)2Cu(CN)Li2 is used in the reaction.1a-e Catalytic silylcupra-
tions employing a silylborane2 as a silicon source have been postulated
in the Cu-catalyzed hydrosilylations of alkynes1f-i and allenes.1j,k How-
ever, utilization of the resulting C–Cu bonds in subsequent C–C bond
formation remained mostly unexplored.1k,l
made regiodivergent at all. Among the catalytic carboxylation of allenes
using CO2,10 there are only two precedents of selective reaction.11 Mori
and Sato reported the selective Ni-catalyzed carboxylation of trime-
thylsilylallenes.11a Iwasawa demonstrated the hydrocarboxylation of al-
lenes in the presence of a Pd catalyst bearing a PSiP-pincer ligand.11b
These reactions proceeded with good selectivity, but only one particular
regioisomer was afforded. Herein, we report a regiodivergent silacarbox-
ylation of allenes with CO2 in the presence of a copper catalyst. The re-
gioselectivity can be highly controlled and even reversed by the proper
choice of ligand; both the carboxylated vinylsilanes (2) and allylsilanes
(3) are synthesized regiodivergently from a single substrate (Scheme
1b). Notably, there are no reported precedents for the silacarboxylation
of allenes nor the regiodivergent carboxylation.12a,b
Among unsaturated substrates for silylcupration, allene derivatives
are very versatile reaction partners. Frequently, addition reaction across
allenes provides many regio- and stereoisomers. Controlling these selec-
tivities is therefore challenging but once achieved, structurally diverse
array of the products become accessible.3 Regioselective silylcuprations
of allenes provide vinyl-4 or allylsilanes,4a,d,5 which play indispensable
roles in organic synthesis. If a regiodivergent6 allene silylcupration fol-
lowed by functionalization of the resulting Cu–C moiety could be real-
ized, both the functionalized vinyl- and allylsilanes would be obtained
selectively from a single substrate. Pioneering studies by Fleming and
Pulido showed that the silylcupration of 1,2-propadiene (CH2=C=CH2:
unsubstituted allene) with a stoichiometric amount of a silylcyanocu-
prate proceeded in a regiodivergent manner (Scheme 1a).7 The higher
order silylcyanocuprate afforded vinylsilanes (Scheme 1a, top),7a-c
whereas the lower order analogue provided allylsilanes (Scheme 1a, bot-
tom).7d,e Unfortunately, substituents on the 1,2-propadiene considera-
bly disturbed the regioselectivity, thus the regiodivergency appeared
only with CH2=C=CH2.7a-e Furthermore, the reaction temperature also
significantly affected the regiodivergency.7d,e
Initially, we examined the reaction of 1,1-pentamethyleneallene
(1a) and PhMe2Si–B(pin) under CO2 (1 atm, closed) with 5 mol % of
Cu(OAc)2·H2O and 5 mol % of a ligand at 70 °C (Table 1). The carbox-
ylated vinylsilane (2a) and allylsilane (3a) were obtained, and their
yields were determined by GC after conversion to the corresponding
methyl esters (2a-Me and 3a-Me) with Me3SiCHN2. The nature of the
ligands successfully controlled the regioselectivity. The vinylsilane (2a)
was regioselectively obtained with rac-Me-DuPhos13 in 72% yield with
93% regioselectivity (i.e., isomeric ratio of 2a-Me/3a-Me; entry 1).
When we used Cu(OAc) as a catalyst precursor, the yield was slightly
decreased to 58%, while the regioselectivity remained high (91%, entry
During studies on catalytic C–C bond-forming reactions using
CO2,8,9 we discovered the Cu-catalyzed silacarboxylation of alkynes with
a silylborane.9c The reaction was highly regioselective, but could not be
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2). Another chelating ligand, dppBz, produced 2a in good yield (75%),
Table 2. Regiodivergent Silacarboxylation of Allenes to Carbox-
ylated Vinylsilanes (2) and Allylsilanes (3)a
but with slightly decreased regioselectivity (83%, entry 3). Dcpe was not
effective at all in terms of yield and regioselectivity (entry 4). In contrast,
when the monodentate phosphine PPh3 was employed as the ligand, the
regioselectivity was switched, giving the allylsilane 3a (2a-Me/3a-Me =
16/84) as the major product, albeit in 24% yield (entry 5). Gratifyingly,
tricyclohexylphosphine (PCy3) as the ligand increased the yield to 64%
while maintaining 85% regioselectivity (entry 6). Finally, both the yield
and the regioselectivity were significantly improved to 90% and 98%, re-
spectively, with THF as the solvent and a mixture of CuCl/NaOAc as
the Cu precursor (entry 8). A use of 10 mol % of PCy3 decreased both
the yield and the selectivity, suggesting the importance of a vacant coor-
dination site on copper (entry 9). These results clearly indicate that re-
giodivergent silacarboxylation can be realized by simply tuning the cat-
alyst system with the proper ligands.
"Conditions A"
"Conditions B"
PCy3/CuCl/
NaOAc
rac-Me-DuPhos/ R1
CO2H
CO2H
SiMe2Ph
R2
3, isolated yieldb
Cu(OAc)2·H2O
R1
R2
1
R1
R2
hexane
THF
SiMe2Ph
2, isolated yield
CO2 (1 atm)
PhMe2Si–B(pin)
(2/3 > 95/5)
(3/2 > 97/3)
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CO2H
CO2H
SiMe2Ph
SiMe2Ph
3a, 94%
1a
2a, 76%c
CO2H
CO2H
SiMe2Ph
O
O
O
O
SiMe2Ph
2b , 79%d,e
3b, 66%
1b
O
CO2H
CO2H
SiMe2Ph
Table 1. Effect of Ligands on Cu-Catalyzed Silacarboxylation of
1,1-Pentamethyleneallene (1a)a
SiMe2Ph
(Z)-3c, 82%
2c, 66%
1c
CO2H
CO2H
SiMe2Ph
Ph
SiMe2Ph
2d, 76%e
Ph
Ph
(Z)-3d, 81%
1d
CO2H
CO2H
SiMe2Ph
SiMe2Ph
2e, 76%e
(Z)-3e, 73%
1e
entry
1
2d
ligand
rac-Me-DuPhos
rac-Me-DuPhos
dppBz
yield (%)b
2a-Me/3a-Mec
93/7
72
58
75
15
24
64
70
90
59
CO2H
CO2H
SiMe2Ph
O
O
91/9
SiMe2Ph
2f, 83%e
O
O
(Z)-3f, 58%e,f
1f
3
83/17
50/50
16/84
15/85
6/94
Br
Br
Br
4
dcpe
CO2H
CO2H
SiMe2Ph
5
PPh3
O
O
O
O
SiMe2Ph
(Z)-3g 67%e
1g
O
2g, 52%e
6
7e
8e,f
9e,f
PCy3
PCy3
CO2H
CO2H
SiMe2Ph
PCy3
2/98
SiMe2Ph
2h, 61%
(Z)-3h, 93%
1h
1i
PCy3 (10 mol %)
11/89
CO2H
CO2H
SiMe2Ph
SiMe2Ph
2i, 82%
(Z)-3i, 92%
aReaction conditions: 1a (0.20 mmol), PhMe2Si–B(pin) (1.0 equiv), lig-
and (5 mol %) and Cu(OAc)2·H2O (5 mol %) in hexane (0.40 M) under CO2
(1 atm, closed) at 70 °C for 16–18 h. bCombined yield of 2a-Me and 3a-
Me determined by GC analysis after esterification using Me3SiCHN2.
cDetermined by GC analysis. dCuOAc (5 mol %) was used instead of
CO2H
CO2H
SiMe2Ph
(Z)-3j
+
2j
SiMe2Ph
2j, 62%
total 73%g
1j
(Z)-3j/2j = 68/32
f
Cu(OAc)2·H2O. eIn THF. 5 mol % of CuCl and 15 mol % of NaOAc were
CO2H
CO2H
SiMe2Ph
used instead of Cu(OAc)2·H2O.
Ph
(Z)-3k
+
2k
SiMe2Ph
2k, 64%
Ph
Ph
1k
1l
total 72%
(Z)-3k/2k = 48/52
After these optimization, regioselective syntheses of the carbox-
ylated vinylsilanes 2 were performed under Conditions A, using the
same catalyst system as in Table 1, entry 1, and employing rac-Me-
DuPhos as the ligand (Table 2, left column). From 1,1-disubstituted al-
lenes (1a–h), the corresponding vinylsilanes (2a–h) were afforded re-
gioselectively (2/3 > 95/5) in good yields after silica-gel column chro-
matography. Functionalities such as ketal (2b),14 alkenyl (2e), bromo
(2f) and ester (2g) groups were tolerated during the catalytic reaction.
As for monosubstituted allenes (1i–l), the regioselectivity was perfect
giving vinylsilane 2i–l exclusively in good to high yields.
TBDPSO CO2H
CO2H
SiMe2Ph
(Z)-3l
+
2l
SiMe2Ph
2l, 77%
TBDPSO
TBDPSO
total 75%
(Z)-3l/2l = 42/58
aConditions A: rac-Me-DuPhos (5 mol %) and Cu(OAc)2·H2O (5
mol %) in hexane (0.40 M); Conditions B: PCy3 (5 mol %), CuCl (5 mol %)
and NaOAc (15 mol %) in THF (0.40 M). In both conditions, 1 (0.20 mmol)
and PhMe2Si–B(pin) (1.1 equiv) were reacted under CO2 (1 atm, closed) at
70 °C for 16–18 h. bZ/E > 96/4 if any. c2a/3a = 93/7. dIsolated after acidic
work-up.14 ePhMe2Si–B(pin) (1.5 equiv). f(Z)-3f/(E)-3f/2f = 90/3/7.
gPCy2(o-tol) was used instead of PCy3. TBDPS = tert-butyldiphenylsilyl.
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The regioselectivity switch observed for 1a in Table 1 (entry 1 vs.
ditions B preferentially afforded 7a (6a/7a = 21/79). Subsequent reac-
tions with exchange of the atmosphere in the flask containing 6a and 7a
from Ar to CO2 did not convert most 6a and 7a, and 2a and 3a were not
detected at all (Scheme 2b).15 These observations, therefore, clearly in-
dicate that 2 and 3 are not generated via 6 and 7.20
8) was quite general for 1,1-disubstituted allenes (1a–h) under Condi-
tions B, using the same catalyst system as entry 8 in Table1, and utilizing
PCy3 as the ligand (Table 2, right column). The reactions now provided
the corresponding allylsilanes (3a–h) with excellent regioselectivities
(3/2 > 98/2, except for 3f/2f = 93/7). Unsymmetrically substituted al-
lenes such as 1c–h may afford E/Z mixtures. The present catalyst system
distinguished even subtle differences such as between the methyl and
the primary alkyl substituents of 1c–g, affording (Z)-isomers preferen-
tially (Z/E > 80/20) in the crude mixtures. The Z/E ratios of 3h was
much higher (95/5). Gratifyingly, (Z)-3c–h were easily isolated by sil-
ica-gel column chromatography in good yields with high (Z) ratios (Z/E
> 96/4). The structure of (Z)-3h was further confirmed by X-ray crys-
tallography.15 Under Conditions B, ketal (3b),14 alkenyl (3e), bromo
(3f) and ester (3g) groups remained intact.16 The monosubstituted al-
lene bearing a tertiary alkyl substituent (1i) afforded the corresponding
(Z)-allylsilane ((Z)-3i) with 97% regioselectivity in 92% yield. However,
1j bearing a secondary alkyl substituent gave (Z)-3j only preferentially:
(Z)-3j/2j = 68/32 in 73% total yield. Furthermore, allenes having a pri-
mary alkyl-substituent (1k and 1l) afforded the two regioisomers in low
selectivities: (Z)-3k/2k = 48/52 in 72% total yield and (Z)-3l/2l =
42/58 in 75% total yield. Thus, steric hindrance at the 1-position of al-
lenes would be essential to provide 3 regioselectively. Unfortunately, the
reactions using 1-methyl-1-phenylallene, 1-tert-butyl-3-(p-tolyl)allene,
and 1,3-dimethyl-1-(2-phenethyl)allene were not regiodivergent.
Scheme 2. Control Experiments in the Absence of CO2
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A possible catalytic cycle is shown in Scheme 3. The silylcopper spe-
cies (I) is generated in situ by the reaction of PhMe2Si–B(pin) with a Cu
precursor (step 0).21 Next, I adds across a terminal double bond of the
allene 1 (step 1). Under Conditions A with Me-DuPhos as the ligand,
the Cu atom adds at the terminal carbon of 1, generating the allylcopper
intermediate (II). Then, CO2 inserts at the γ-position of II to provide
the copper carboxylate species (III), possibly via a six-membered ring
transition state (step 2). Finally, σ-bond metathesis of III with
PhMe2Si–B(pin) affords the boron carboxylate (IV) and regenerates I
(step 3). In sharp contrast, under Conditions B using PCy3 as the ligand,
the regioselectivity of the silylcupration is reversed, providing the vinyl
copper intermediate (V) (step 1'). The regioselectivity reversal in steps
1 and 1' might be attributed to the difference in relative steric bulk be-
tween the CuL (L = Me-DuPhos or PCy3) and SiMe2Ph moieties. The
insertion of CO2 to V (step 2') followed by the σ-bond metathesis of VI
with PhMe2Si–B(pin) provides the boron carboxylate (VII) and regen-
erates I (step 3'). In the absence of CO2, some II and V could be trapped
as 6 and 7 (steps 4 and 4'), suggesting that the regiodivergency occurs at
the silylcupration stage (steps 1 and 1').
The preparation of 3 can be carried out on gram scale: 1.19 g of (Z)-
3c and 1.05 g of (Z)-3h were synthesized from 1c (0.691 g, 5.0 mmol)
and 1h (0.548 g, 4.0 mmol), respectively (eq 1). γ-Oxidation of (Z)-3h
through an epoxidation–desilylative ring-opening cascade17 furnished
the tertiary allylic alcohol 4h in 76% isolated yield (eq 2). On the other
hand, α-oxidation using the Tamao-Fleming protocol18 led to the corre-
sponding primary allylic alcohol (E)-5h in 55% yield with retention of
the olefin configuration (eq 3). Usually, the α-oxidation of allylic
phenylsilanes by the Tamao-Fleming protocol is unreliable, since allylic
C–Si bonds are preferentially cleaved over Ph–Si bonds.19 The α-oxida-
tion of 3h proceeded smoothly, possibly owing to a deactivation of the
allylic moiety by conjugation with the carboxylic acid functionality.19b
Thus, the regiodivergent oxidations (eqs 2 and 3) and the regiodiver-
gent silacarboxylation (Scheme 1b) can provide a wide range of prod-
ucts (2, 3, 4, and 5) from a single allene substrate (1).
Scheme 3. A Possible Reaction Mechanism
To gain insight into the reaction mechanism, several control exper-
iments were carried out (Scheme 2). When the reactions were run in the
absence of CO2 (i.e., under Ar), using the same Conditions A or B as in
Table 2, the reactions were less clean: the PhMe2Si–B(pin) adducts with
1a (6a and 7a) were obtained in 25% and 63% yields, respectively, with
different regioselectivities (Scheme 2a). Conditions A led to the for-
mation of 6a with excellent regioselectivity (6a/7a = 95/5), while Con-
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(6) Selected recent regiodivergent transformations. (a) Fujino, D.; Yorimitsu,
Preliminarily, an enantioselective silacarboxylation of 1d was car-
ried out with (R,R)-Me-DuPhos under Conditions A, and 2d was af-
forded in 18% ee (unoptimized).
H.; Osuka, A. J. Am. Chem. Soc. 2014, 136, 6255. (b) Xu, K.; Thieme, N.; Breit,
B. Angew. Chem., Int. Ed. 2014, 53, 7268. (c) Xu, K.; Thieme, N.; Breit, B. Angew.
Chem., Int. Ed. 2014, 53, 2162. (d) Li, B.; Park, Y.; Chang, S. J. Am. Chem. Soc.
2014, 136, 1125. (e) Zhao, Y.; Weix, D. J. J. Am. Chem. Soc. 2014, 136, 48. (f)
Gutiérrez-Bonet, Á.; Flores-Gaspar, A.; Martin, R. J. Am. Chem. Soc. 2013, 135,
12576. (g) Yang, Y.; Buchwald, S. L. J. Am. Chem. Soc. 2013, 135, 10642.
(7) (a) Fleming, I.; Pulido, F. J. J. Chem. Soc., Chem. Commun. 1986, 1010. (b)
Cuadrado, P.; Gonzàlez, A. M.; Pulido, F. J.; Fleming, I. Tetrahedron Lett. 1988,
29, 1825. (c) Fleming, I.; Rowley, M.; Cuadrado, P.; González-Nogal, A. M.; Pu-
lido, F. J. Tetrahedron, 1989, 45, 413. (d) Blanco, F. J.; Cuadrado, P.; Gonzàlez,
A. M.; Pulido, F. J.; Fleming, I. Tetrahedron Lett. 1994, 35, 8881. (e) Barbero, A.;
García, C.; Pulido, F. J. Tetrahedron 2000, 56, 2739.
(8) For reviews, see: (a) Tsuji, Y.; Fujihara, T. Chem. Commun. 2012, 48, 9956.
(b) Zang, L.; Hou, Z. Chem. Sci. 2013, 4, 3395. (c) Huang, K.; Sun, C.-L.; Shi, Z.-
J. Chem. Soc. Rev. 2011, 40, 2435. (d) Cokoja, M.; Bruckmeier, C.; Rieger, B.;
Herrmann, W. A.; Kühn, F. E. Angew. Chem., Int. Ed. 2011, 50, 8510.
(9) (a) Fujihara, T.; Xu, T.; Semba, K.; Terao, J.; Tsuji, Y. Angew. Chem., Int.
Ed. 2011, 50, 523. (b) Fujihara, T.; Nogi, K.; Xu, T.; Terao, J.; Tsuji, Y. J. Am.
Chem. Soc. 2012, 134, 9106. (c) Fujihara, T.; Tani, Y.; Semba, K.; Terao, J.; Tsuji,
Y. Angew. Chem., Int. Ed. 2012, 51, 11487. (d) Nogi, K.; Fujihara, T.; Terao, J.;
Tsuji, Y. Chem. Commun. 2014, 50, 13052.
(10) Transition metal-catalyzed carboxylations of allenes with CO2 have been
reported although their catalytic activities and product selectivities were not sat-
isfactory: (a) Tsuda, T.; Yamamoto, T.; Saegusa, T. J. Organomet. Chem. 1992,
429, C46. (b) Dérien, S.; Clinet, J.-C.; Duñach, E.; Périchon, J. Synlett 1990, 361.
(c) Sasaki, Y. J. Mol. Catal. 1989, 54, L9. (d) Aresta, M.; Quaranta, E.; Ciccarese,
A. C1 Mol. Chem. 1985, 1, 283. (e) Döhring, A.; Jolly, P. W. Tetrahedron Lett.
1980, 21, 3021.
(11) (a) Takimoto, M.; Kawamura, M.; Mori, M.; Sato, Y. Synlett, 2005, 13,
2019. (b) Takaya, J.; Iwasawa, N. J. Am. Chem. Soc. 2008, 130, 15254.
(12) (a) We have reported preliminary results on the regiodivergent carboxy-
lation of allenes as a poster: Tani, Y.; Fujihara, T.; Terao, J.; Tsuji, T. In 19th In-
ternational Symposium on Homogeneous Catalysis, Ottawa, Canada, July 6–11,
2014; Abstract 278. (b) At the same symposium, Martin and co-workers also re-
ported a related regiodivergent carboxylation of allylic esters as a poster: Cornella,
J.; Moragas, T.; Ruben, M. In 19th International Symposium on Homogeneous Ca-
talysis, Ottawa, Canada, July 6–11, 2014; Abstract 291.
In conclusion, we have developed a regiodivergent silacarboxylation
of allenes using PhMe2Si–B(pin) under CO2 atmosphere in the pres-
ence of a copper catalyst. The regioselectivity is highly controlled by the
proper choice of ligand; both the carboxylated vinylsilanes (2) and al-
lylsilanes (3) can be synthesized regiodivergently from a single substrate.
Further studies on the reaction mechanism and optimization of the en-
antioselective reaction are now in progress.
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ASSOCIATED CONTENT
Supporting Information
Experimental procedures and characterization of the products. This ma-
terial is available free of charge via the Internet at http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
ytsuji@scl.kyoto-u.ac.jp
Notes
The authors declare no competing financial interests.
ACKNOWLEDGMENT
This work was supported by Grant-in-Aid for Scientific Research (A)
and on Innovative Areas (“Molecular activation directed toward
straightforward synthesis”) from MEXT, Japan. Y.T. was grateful to a
JSPS Research Fellow.
REFERENCES
(1) (a) Barbero, A.; Pulido, F. J. Acc. Chem. Res. 2004, 37, 817. (b) Fleming, I.
Synthetic Application of Silylcuprates and Stannylcuprates. In Organocopper Re-
agents; Taylor, R. J., Ed. Oxford: New York, 1994; pp 257–276. (c) Liepins, V.;
Bäckvall, J.-E. Eur. J. Org. Chem. 2002, 3527. (d) Liepins, V.; Bäckvall, J.-E. Chem.
Commun. 2001, 265. (e) Fleming, I.; Newton, T. W.; Roessler, F. J. Chem. Soc.,
Perkin Trans. 1, 1981, 2527. (f) Linstadt, R. T. H.; Peterson, C. A.; Lippincott, D.
J.; Jette, C. I.; Lipshutz, B. H. Angew. Chem., Int. Ed. 2014, 53, 4159. (g) Calde-
rone, J. A.; Santos, W. L. Angew. Chem., Int. Ed. 2014, 53, 4154. (h) Wang, P.; Yeo,
X.-L.; Loh, T.-P. J. Am. Chem. Soc. 2011, 133, 1254. (i) Nozaki, K.; Wakamatsu,
K.; Nonaka, T.; Tückmantel, W.; Oshima, K.; Uchimoto, K. Tetrahedron Lett.
1986, 27, 2007. (j) Xu, Y.-H.; Wu, L.-H.; Wang, J.; Loh, T.-P. Chem. Commun.
2014, 50, 7195. (k) Rae, J.; Hu, Y. C.; Procter, D. J. Chem. Eur. J. 2014, 20, 13143.
(l) Tani, Y.; Yamaguchi, T.; Fujihara, T.; Terao, J.; Tsuji, Y. Chem. Lett. 2014,
Advance Publication. DOI: 10.1246/cl.141018
(2) PhMe2Si–B(pin) is commercially available from Aldrich (No. 683434).
For reviews on the utility of silylboranes in organic synthesis, see: (a) Oestreich,
M.; Hartmann, E.; Mewald, M. Chem. Rev. 2013, 113, 402. (b) Ohmura, T.;
Suginome, M. Bull. Chem. Soc. Jpn. 2009, 82, 29.
(3) For reviews on synthesis and utility of allenes, see: (a) Ma, S. Chem. Rev.
2005, 105, 2829. (b) Jeganmohan, M.; Cheng, C.-H. Chem. Commun. 2008,
3101. (c) Yu, S.; Ma, S. Angew. Chem., Int. Ed. 2012, 51, 3074.
(4) (a) Fleming, I.; Dunogues, J.; Smithers, R. Org. React. 1989, 37, 57. (b)
Colvin, E. W. Silicon in Organic Synthesis; Butterworths: London, 1981; pp 44–
82. (c) Colvin, E. W. Silicon Reagents in Organic Synthesis; Academic: London,
1988, pp 7–19. (d) Langkopf, E.; Schinzer, D. Chem. Rev. 1995, 95, 1375. (e)
Blumenkopf, T. A.; Overman, L. E. Chem. Rev. 1986, 86, 857.
(5) (a) Colvin, E. W. Silicon in Organic Synthesis; Butterworths: London,
1981; pp 97–124. (b) Colvin, E. W. Silicon Reagents in Organic Synthesis; Aca-
demic: London, 1988, pp 25–37. (c) Chabaud, L.; James, P.; Landais, Y. Eur. J.
Org. Chem. 2004, 3173.
(13) Burk, M. J.; Feaster, J. E.; Nugent, W. A. Harlow, R. L. J. Am. Chem. Soc.
1993, 115, 10125.
(14) The acetal moiety of 2b was intact during the catalytic reaction, but was
mostly converted to the corresponding ketone (2b’) through the work-up. To
our delight, the acetal moiety of 3b was robust to a similar work-up procedure.
(15) See the Supporting Information for details.
(16) Besides entries in Tables 2, four allenes (1m–p) including those bearing
silyl ether (1m) and ester (1n) groups also provided the corresponding al-
lylsilanes (3m–p) selectively in high yields under Conditions B.15
(17) (a) Payne, G. B.; Williams, P. H. J. Org. Chem. 1959, 24, 54. (b) Kirshen-
baum, K. S.; Sharpless, K. B. J. Org. Chem. 1985, 50, 1979. (c) Toró, A.; Ambrus,
G. Tetrahedron Lett. 1992, 33, 5265.
(18) (a) Tamao, K.; Ishide, N.; Tanaka, T.; Kumada, M. Organometallics
1983, 2, 1694. (b) Fleming, I.; Henning, R.; Plaut, H. J. Chem. Soc., Chem. Com-
mun. 1984, 29. (c) Fleming, I.; Henning, R.; Parker, D. C.; Plaut, H. E. Sanderson,
P. E. J. J. Chem. Soc., Perkin Trans. 1 1995, 317.
(19) (a) Okamoto, K.; Tamura, E.; Ohe, K. Angew. Chem., Int. Ed. 2013, 52,
10639. (b) Kim, S.; Emeric, G.; Fuchs, P. L. J. Org. Chem. 1992, 57, 7362.
(20) Cu-catalyzed carboxylations of organoboranes have been reported, alt-
hough all of them required a stoichiometric amount of a base. See: (a) Ohishi, T.;
Nishiura, M.; Hou, Z. Angew. Chem., Int. Ed. 2008, 47, 5792. (b) Takaya, J.;
Tadami, S.; Ukai, K.; Iwasawa, N. Org. Lett. 2008, 10, 2697. (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. (e) Duong, H. A.;
Huleatt, P. B.; Tan, Q.-W.; Shuying, E. L. Org. Lett. 2013, 15, 4034.
(21) PhMe2Si–B(pin) was reported to react with [(IPr)CuOtBu] affording
[(IPr)CuSiMe2Ph], which was fully characterized including single-crystal X-ray
structural determination: Kleeberg, C.; Cheung, M. S.; Lin, Z.; Marder, T. B. J.
Am. Chem. Soc. 2011, 133, 19060.
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