Highly selective formation of propargyl- and allenyltrichlorosilanes and their regiospecific addition to various types of aldehydes: Preparation of both allenic and homopropargylic alcohols

Article abstract of DOI:10.1016/j.tet.2005.08.114

The highly selective preparation of propargyl- and allenyltrichlorosilanes via metal-catalyzed silylation of propargyl chloride has been developed. These trichlorosilyl nucleophiles were then shown to add to various types of aldehydes to afford the corres

Full text of DOI:10.1016/j.tet.2005.08.114

Tetrahedron 62 (2006) 496–502
Highly selective formation of propargyl- and
allenyltrichlorosilanes and their regiospecific addition to various
types of aldehydes: preparation of both allenic
and homopropargylic alcohols
*
Uwe Schneider, Masaharu Sugiura and Shu¯ Kobayashi
Graduate School of Pharmaceutical Sciences, The University of Tokyo, The HFRE Division, ERATO,
Japan Science and Technology Agency (JST), Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
Received 23 April 2005; revised 3 August 2005; accepted 31 August 2005
Available online 28 September 2005
Abstract—The highly selective preparation of propargyl- and allenyltrichlorosilanes via metal-catalyzed silylation of propargyl chloride has
been developed. These trichlorosilyl nucleophiles were then shown to add to various types of aldehydes to afford the corresponding allenic
and homopropargylic alcohols, respectively, in high yields with complete regiospecificity. Remarkably, these carbon–carbon bond-forming
reactions simply proceeded in N,N-dimethylformamide (DMF) without using any metal catalysts.
q 2005 Elsevier Ltd. All rights reserved.
1. Introduction
Functionalized allenes and alkynes such as allenic and
homopropargylic alcohols have proved to be extremely
versatile, key intermediates in modern organic synthesis,1
for example, in coupling reactions,2 ene–yne metathesis3
and formation of heterocycles.4 Carbon–carbon bond-
forming reactions such as the regiospecific addition of
propargyl and allenyl nucleophiles to aldehydes provide
very attractive routes to these types of compounds.1
However, drawbacks concerning the use of propargyl and
allenyl metal derivatives are potential metallotropic
rearrangement5 between these species and non-regiospecific
Scheme 1. Potential metallotropic rearrangement and selectivity problem.
addition to electrophiles resulting in formation of product
mixtures (Scheme 1).6 Moreover, accessibility to these
Lewis bases such as N,N-dimethylformamide (DMF),
propargyl and allenyl nucleophiles is highly substrate-
sulfoxides or phosphine oxides promote the nucleophilic
dependent.5,6,7
addition of allyl- and crotyltrichlorosilanes to aldehydes,9
imines10 and N-acylhydrazones (Scheme 2).11
Additionally, because of recent demands for safe and
environmentally benign organic synthesis, the use of
Remarkably, all these reactions proceeded without using
organometallic nucleophiles or metal catalysts is sometimes
any metal catalysts since these non-ionic Lewis bases,
undesirable, especially for large-scale synthesis. In this
which are defined as neutral coordinate-organocatalysts
context,8 we recently reported that neutral (non-ionic)
(NCOs),12 are able to activate the trichlorosilyl nucleophiles
by coordination to the silicon atom resulting in the
Keywords: Propargyltrichlorosilane; Allenyltrichlorosilane; Regiospecific
addition; Homopropargylic alcohols; Allenic alcohols; Carbon–carbon
Previously, we also reported selective preparation of both
bond-forming reaction.
formation of highly reactive hypervalent silicon species.
propargyl- and allenyltrichlorosilanes starting from the
*
Corresponding author. Tel.: C81 3 5841 4790; fax: C81 3 5684 0634;
e-mail: skobayas@mol.f.u-tokyo.ac.jp
same corresponding propargyl halides.13a Their
0040–4020/$ - see front matter q 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2005.08.114

U. Schneider et al. / Tetrahedron 62 (2006) 496–502
497
Scheme 2. NCO-mediated additions of allyl- and crotyltrichlorosilanes to aldehydes,9 imines,10 and N-acylhydrazones.11
nucleophilic addition to several aldehydes in order to form
the corresponding allenic and homopropargylic alcohols,
respectively, was also described. However, selectivities,
yields and substrate scope still remained to be improved.
Herein, we report a more practical and greatly improved
protocol for the silylation of propargyl chloride resulting in
significantly enhanced selectivities. Moreover, the nucleo-
philic, regiospecific addition of both propargyl- and
allenyltrichlorosilanes to various types of aldehydes
afforded the corresponding allenic or homopropargylic
alcohols exclusively.
diethyl ether (EE) or t-butyl methyl ether (TBME). On the
other hand, in acetonitrile or propionitrile the reaction was
sluggish, whereas in dichloromethane (DCM), tetrahydro-
furan (THF) or N,N-dimethylformamide (DMF) the silyl-
ation scarcely proceeded. In our previous work, a slight
excess of the amine base with respect to trichlorosilane in a
solvent mixture by using a copper(I) catalyst was necessary
to obtain a high selectivity in favor of product 2 (Table 1,
entry 1). We found that under similar conditions in EE as a
sole solvent the reaction was faster, but less selective (entry
2). We, therefore, reinvestigated the silylation conditions
and after extensive optimization, it was found that a slight
excess of trichlorosilane with respect to Hu¨nig’s base in EE
afforded propargyltrichlorosilane (2) exclusively (entry 3).
Even more significantly, only 1 mol% CuCl was sufficient
to catalyze the transformation while maintaining excep-
tional selectivity (entry 4). Previously, we found that the
Ni(II)-catalyzed formation of allenyltrichlorosilane (3) as
the major product (moderate to good selectivities) was
highly solvent- and temperature-dependent (entries 5 and 6).
However, with our newly optimized protocol just by
switching from Cu(I) to Ni(II), the exclusive formation of
trichlorosilane 3 was observed (entry 7). Here again, it is
noted that only 1 mol% of the Ni(II) catalyst was sufficient
to promote this highly selective silylation (entry 8).
2. Results and discussion
The preparation of propargyl and allenyl organometallics
from the corresponding propargyl halides typically requires
stoichiometric amounts of metals.5–7 In contrast, our
procedure needs only a catalytic amount of a metal salt
together with an amine base and trichlorosilane. In the
literature, it has been reported that propargyl chloride reacts
with trichlorosilane in the presence of triethylamine and
copper(I) chloride under thermal conditions (THF, 60 8C,
12 h) to give a mixture of propargyltrichlorosilane (2) and
allenyltrichlorosilane (3; ratio 2:3Z86:14).14 It is also
known that the distillation of a mixture of compounds 2 and
3 provokes (further) isomerization towards product 3 (ratio
2:3Z33:67).13a We wanted to reinvestigate the silylation
procedure of propargyl chloride based on our previous work
in order to develop a more practical protocol and improve
selectivities for trichlorosilanes 2 and 3 (Table 1).
Next, we turned our attention towards the use of in situ
prepared trichlorosilyl nucleophiles 2 and 3 in the reaction
with aldehydes in DMF for the synthesis of both allenic and
homopropargylic alcohols. We have previously demon-
strated that allyltrichlorosilane regiospecifically reacts with
various aldehydes in DMF without metal catalysis to afford
the corresponding homoallylic alcohols in high yields.9 In
these reactions, DMF might coordinate to the silicon atom
The initial solvent screening revealed that the silylation
proceeded efficiently only in non-polar solvents such as
Table 1. Optimization of the selective silylation of propargyl chloride (1)
Entry
Metal salt
(mol%)
i-Pr2NEt
(equiv)
HSiCl3
(equiv)
Solventa
Time
(h)
Conversion
(%)b
Ratio 2:3b
1c
2
CuCl (3)
CuCl (5)
1.0
2.0
2.0
2.0
1.1
1.1
2.0
2.0
1.1
1.5
2.2
2.2
1.0
1.0
2.2
2.2
EE/EtCN
EE
EE
12
6–8
6
12
12
n.d
6
nd
94:6
O95
O99
O99
nd
nd
O99
O99
85:15
O99:1
O99:1
3:O97
9:91
3
4
CuCl (5)
CuCl (1)
EE
5c
6c
7
NiL2 (3)d
THFe
EE
Ni(acac)2 (3)
Ni(acac)2 (5)
Ni(acac)2 (1)
EE
EE
1:O99
1:O99
8
12
a EEZdiethyl ether.
1
b Determined by H NMR analysis by aliquot dilution in CDCl3.
c Ref. 13a.
d LZPhC(O)CH]C(O)Ph.
e The reaction was carried out under reflux.

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U. Schneider et al. / Tetrahedron 62 (2006) 496–502
Scheme 3. Assumed transition states of the reactions between various trichlorosilanes and aldehydes.9,13a
Table 2. DMF-mediated allenylation of benzaldehyde (4a) with in situ prepared propargyltrichlorosilane (2)
Entry
DMF (M)
Temperature (8C)
Time (h)
Yield (%)
Ratio 5a:6aa
1b
2
3
4
0.25
0.5
0.4
0.2
0.1
0.1
0.1
0
12
60
55–63
72
80–84
83–89
92
91:9
O99:1
O99:1
O99:1
O99:1
O99:1
O99:1
10
10
10
10
0
12–48
24
24
24
24
5
6
7c
0
24
80
a Determined by 1H NMR analysis of the isolated material.
b Best previously data published by our group: 1.2 equiv of 2 were used (see Ref. 13a).
c Three equivalents of in situ prepared propargyltrichlorosilane (2) were used.
of the allyltrichlorosilane resulting in the formation of a
Table 3. DMF-mediated allenylation of various aldehydes 4 with in situ
prepared propargyltrichlorosilane (2)
highly reactive hypervalent silicon species, which in turn
smoothly adds to aldehydes via a supposed cyclic transition
state A (Scheme 3). We assumed that the same kind of
intermediates could be formed with trichlorosilyl nucleo-
philes 2 and 3 and these transition states B and C are
represented in Scheme 3.†,13a
We first examined the conditions for the reaction between
in situ prepared propargyltrichlorosilane (2) and benz-
aldehyde (4a) as a model substrate, the results are shown in
Table 2.
Entry
Substrate 4: R
Yield (%)
Ratio 5:6a
1
2
3
4
5
6
7
4a: Ph
92
88
55
80
61
90
79
O99:1
O99:1
O99:1
O99:1
O99:1
O99:1
O99:1
4b: 4-MeOC6H4
4c: 3-Furyl
4d: n-Octyl
4e: c-Hexyl
4f: PhCH2CH2
4g: (E)-n-PrCH]CH
The allenylation proceeded smoothly in DMF at 10 8C with
moderate yields (entry 2), which are in the same range as
our previous result (entry 1). Whilst the selectivity was
lower previously (entry 1), now exclusive formation of
allenic alcohol 5a was observed (entry 2). Further
optimization revealed the importance of the amount of
DMF; with gradually increasing amounts of DMF, which is
considered to be both solvent and an NCO, the yields were
significantly improved to 89% (entries 3–5). This improve-
ment might be attributed to both a more homogenous
reaction mixture and more efficient activation of nucleo-
phile 2 by DMF.‡ Finally, conducting the reaction at 0 8C
provided the highest yield (92%, entry 6), whereas the use of
3 equiv of nucleophile 2 (instead of 1.5 equiv) was less
efficient, probably a solubility issue (entry 7). It is, however,
a Determined by 1H NMR analysis of the isolated material.
remarkable that in all cases allenic alcohol 5a was the single
product; no trace of homopropargylic alcohol 6a could be
detected.§
Next, we extended the optimized allenylation conditions to
various aldehydes, the results are represented in Table 3.
§ In this context, it is important to mention that we carried out a control
experiment with benzaldehyde (4a) by using a solution of 2 obtained after
vacuum transfer at low temperature (instead of the supernatant from
in situ preparation of 2, that might contain a trace of Cu(I)). Since we
observed that the reaction proceeded smoothly (even though the yield was
slightly lower) while maintaining the exclusive regiospecificity, it can be
considered that a trace amount of the metal salt (potentially present) does
not affect the reaction outcome.
† In these supposed SE20 type additions, propargyltrichlorosilane (2) and
allenyltrichlorosilane (3) would convert aldehydes into the corresponding
allenic and homopropargylic alcohols, respectively.
‡ It should be pointed out that the same reaction carried out in a non-
coordinating solvent such as EE or DCM (instead of DMF), under
otherwise identical conditions, proceeded only scarcely (yields !5%),
thereby underlining the crucial role of DMF.

U. Schneider et al. / Tetrahedron 62 (2006) 496–502
499
Table 4. DMF-mediated propargylation of various aldehydes 4 with in situ
prepared allenyltrichlorosilane (3)
3. Conclusion
In summary, the highly selective preparation of both
propargyl- and allenyltrichlorosilanes via metal-catalyzed
silylation of propargyl chloride has been developed. These
trichlorosilyl nucleophiles proved to add regiospecifically to
various types of aldehydes to afford the corresponding
allenic and homopropargylic alcohols, respectively, in high
yields. Remarkably, these organocatalytic carbon–carbon
bond-forming reactions simply proceeded in N,N-dimethyl-
formamide (DMF) without using any metal catalysts.
Entry
Substrate 4: R
Yield (%)
Ratio 5:6a
1
2
3
4
5
6
7
4a: Ph
90
78
65
79
56
72
70
1:O99
1:O99
1:O99
1:O99
1:O99
1:O99
1:O99
4b: 4-MeO–C6H4
4c: 3-Furyl
4d: n-Octyl
4e: c-Hexyl
4f: PhCH2CH2
4g: (E)-n-propyl–CH]CH
4. Experimental
4.1. General information
a Determined by H NMR analysis of the isolated material.
1
1H and 13C NMR spectra were recorded on JEOL JNM-
LA300 or JNM-LA400 spectrometers in CDCl3 unless
otherwise noted. Tetramethylsilane (TMS; dZ0 ppm) and
We were delighted to find that a wide range of substrates
tolerated the optimized reaction conditions. Aromatic
aldehydes 4a,b and aliphatic aldehyde 4f, containing an
aromatic moiety, were excellent substrates (88–92% yield,
entries 1,2 and 6). On the other hand, heteroaromatic
aldehyde 4c and the branched sterically demanding aliphatic
aldehyde 4e gave lower yields (entries 3 and 5). Finally,
aliphatic aldehyde 4d and a,b-unsaturated substrate 4g
proved to be very reactive under the conditions employed
providing high yields of the desired products (79–80%
yields, entries 4 and 7). It is notable that in all cases the
allenylation reactions proceeded with complete regio-
specificity; allenic alcohols 5a–g were found to be the
single products and no traces of the corresponding homo-
propargylic alcohols 6a–g could be observed.
1
CDCl3 (dZ77.0 ppm) served as internal standards for H
NMR and for 13C NMR, respectively. 1,2,4,5-Tetrachloro-
benzene was used as internal standard for monitoring, with
time, by 1H NMR analysis the in situ preparation of
trichlorosilanes 2 and 3. IR spectra were measured with a
JASCO FT/IR-610 infrared spectrometer. High-resolution
electrospray ionization mass spectroscopy analysis HRMS
(ESI) was carried out using a Bruker Daltonics BioTOF II
mass spectrometer. Column chromatography was conducted
on Silica gel 60 (Merck), and preparative thin layer
chromatography (PTLC) was carried out using Wakogel
B-5F. All reactions were conducted under an argon
atmosphere in dried glassware. Dry diethylether (EE) was
purchased from Wako Co. Ltd and was used without
distillation; dry N,N-dimethylformamide (DMF) was pur-
chased from Wako Co. Ltd and was used after distillation
from barium(II) oxide. 3-Chloroprop-1-yne (1) and N,N-di-
isopropylethylamine were purchased from Tokyo Kasei
Kogyo Co. Ltd and were used after distillation. Trichloro-
silane was purchased from Tokyo Kasei Kogyo Co. Ltd and
was used without distillation. Copper(I) chloride and
bis(2,4-pentanedionato)nickel(II) were dried at 50 8C
under vacuum for 12 h before transfer into a glovebox.
All other solvents and reagents were purified and dried
according to standard procedures.
We then examined the substrate generality concerning the
propargylation of several aldehydes. We employed the
optimized allenylation conditions, and simply used in situ
prepared allenyltrichlorosilane (3) instead of nucleophile 2
(Table 4).
As was the case in the previous allenylation study, several
aldehydes were reactive towards propargylation with
trichlorosilyl nucleophile 3. Benzaldehyde (4a) proved to
be the best substrate providing the corresponding homo-
propargylic alcohol 6a exclusively in 90% yield (entry 1).
Although the sterically hindered compound 4e gave a little
lower yield (entry 5), all other aldehydes were found to give
the corresponding homopropargylic alcohols 6 in good
yields (entries 2–4, 6, and 7). In all cases, the reactions
proceeded with complete regiospecificity.¶ This remarkable
regiospecificity in both the allenylation and the propargyl-
ation of various aldehydes with trichlorosilyl nucleophiles 2
and 3 might be explained by the approach of the silanes and
aldehydes shown in Scheme 3.
4.2. Procedure for the selective in situ preparation of
trichlorosilanes 2 and 3
To a stirred suspension of dry copper(I) chloride (10.0 mg,
100 mmol, 5 mol%) or dry bis(2,4-pentanedionato)nickel(II)
(25.7 mg, 100 mmol, 5 mol%) in dry EE (4 mL, 0.5 M) at
room temperature were added dropwise N,N-diisopropyl-
ethylamine (680 mL, 4.0 mmol, 2.0 equiv), 3-chloroprop-1-
yne (1; 143 mL, 2.0 mmol, 1.0 equiv) and trichlorosilane
(445 mL, 4.4 mmol, 2.2 equiv), successively. The mixture
was stirred at room temperature for 6 h and the product
ratios 2:3 were determined by 1H NMR analysis of an
aliquot diluted with CDCl3. Under the indicated optimized
conditions, compound 1 was completely consumed (O99%
conversion) and exclusive formation of propargyltrichloro-
silane (2; by using CuCl) or allenyltrichlorosilane (3; by
¶ As in the earlier study, a control experiment with benzaldehyde (4a) by
using a solution of 3 obtained after vacuum transfer at low temperature
(instead of the supernatant from in situ preparation of 3, that might
contain a trace of Ni(II)), revealed comparable reactivity along with the
same exceptional regiospecificity. This confirms that a trace amount of
Ni(II), potentially present, does not influence the course of the reaction.

500
U. Schneider et al. / Tetrahedron 62 (2006) 496–502
using Ni(acac)2) was observed (w75% NMR yield, O99:1
ratios for each isomer).
4.87–4.92 (m, 2H), 5.18 (s, 1H), 5.40 (dt, JZ6.5, 6.8 Hz,
1H), 6.85 (d, JZ8.7 Hz, 2H), 7.29 (d, JZ8.7 Hz, 2H); 13C
NMR (CDCl3) d 55.4, 71.8, 78.1, 95.3, 113.9, 127.2, 135.0,
159.1, 206.9; IR (neat) 3402, 2837, 1955, 1610, 1589, 1514,
1247, 1174, 1033 cmK1; HRMS (ESI) calcd for C11H12O2
[MCH]C: m/z 177.0916, found: m/z 177.0915.
4.3. Procedure for the selective synthesis of allenic
alcohols 5 or homopropargylic alcohols 6
The supernatant solution of in situ prepared trichlorosilanes
2 or 3 (1.5 equiv) in EE was added dropwise via a syringe to
stirred solutions of the corresponding aldehydes 4a–g
(1.0 equiv) in DMF (0.1 M with respect to aldehydes
4a–g) at 0 8C. The mixtures were stirred at 0 8C for 24 h,
and quenched by dropwise addition of aq HCl (1 M, 1 mL
per 0.5 mmoL of used nucleophile 2 or 3). After stirring at
0 8C for an additional 30 min, the mixtures were warmed to
room temperature and extracted with EE (three times, after
addition of H2O). The combined organic layers were
washed (brine), dried (Na2SO4), filtered and concentrated
in vacuo. The residues were purified by preparative thin-
layer chromatography (PTLC; eluant: n-hexane/ethyl
acetate 5:1–15:1) to afford the corresponding allenic
alcohols 5a–g (by using nucleophile 2) or the corresponding
homopropargylic alcohols 6a–g (by using nucleophile 3)
exclusively.
4.5.3. 1-(Furan-3-yl)buta-2,3-dien-1-ol (5c). Pale yellow
oil; 1H NMR (CDCl3) d 1.98 (br s, 1H), 4.84–4.90 (m, 2H),
5.19 (s, 1H), 5.38 (q, JZ6.5 Hz, 1H), 6.40 (d, JZ1.0 Hz,
1H), 7.37 (s, 1H), 7.45 (s, 1H); 13C NMR (CDCl3) d 67.9,
78.0, 95.1, 107.8, 128.1, 139.0, 143.1, 206.5; IR (neat) 3380,
2907, 1957, 1497, 1451, 1000, 867 cmK1; HRMS (ESI)
calcd for C8H8O2 [MCH]C: m/z 137.0603, found: m/z
137.0602.
4.4. Analytical data for the synthesized compounds
4.4.1. Trichloro(prop-2-ynyl)silane (2).13a,d 1H NMR
(CDCl3) d 2.10 (t, JZ3.3 Hz, 1H), 2.44 (d, JZ3.3 Hz, 2H).
4.5.4. Dodeca-1,2-dien-4-ol (5d).13a Colorless oil; 1H NMR
(CDCl3) d 0.81 (t, JZ6.6 Hz, 3H), 1.23–1.85 (m, 15H),
4.07–4.15 (m, 1H), 4.78 (dd, JZ2.3, 6.4 Hz, 2H), 5.17 (q,
JZ6.4 Hz, 1H); 13C NMR (CDCl3) d 14.1, 22.8, 25.5, 29.2,
29.5, 29.9, 32.0, 37.6, 70.0, 77.6, 95.0, 206.7; IR (neat)
3334, 2929, 1956, 1464, 1005, 841 cmK1; HRMS (ESI)
calcd for C12H22O [MCH]C: m/z 183.1749, found: m/z
183.1748.
4.4.2. Trichloro(propa-1,2-dienyl)silane (3).13a,d 1H NMR
(CDCl3) d 4.91 (d, JZ6.9 Hz, 2H), 5.35 (t, JZ6.9 Hz, 1H).
4.5. Allenic alcohols 5a–g
4.5.5. 1-Cyclohexylbuta-2,3-dien-1-ol (5e).13d Colorless
oil; 1H NMR (CDCl3) d 0.87–1.26 (m, 10H), 1.30–1.47 (m,
1H), 1.67 (s, 1H), 3.87 (ddd, JZ2.1, 6.4, 6.8 Hz, 1H), 4.74
(dd, JZ2.1, 6.8 Hz, 2H), 5.14 (dt, JZ6.4, 6.8 Hz, 1H); 13C
NMR (CDCl3) d 26.0, 26.6, 28.7, 44.0, 74.1, 77.5, 93.4,
207.2; IR (neat) 3360, 2924, 1955, 1453, 1015, 836,
700 cmK1; HRMS (ESI) calcd for C10H16O [MCH]C:
m/z 153.1279, found: m/z 153.1279.
4.5.1. 1-Phenylbuta-2,3-dien-1-ol (5a).13a,d,16 Colorless
oil; H NMR (CDCl3) d 2.09 (br s, 1H), 4.86 (ddd, JZ
1.0, 2.5, 6.4 Hz, 2H), 5.21 (dt, JZ2.5, 6.4 Hz, 1H), 5.38 (dt,
JZ6.4, 6.8 Hz, 1H), 7.20–7.49 (m, 5H); 13C NMR (CDCl3)
d 71.9, 78.2, 95.2, 126.1, 127.8, 128.5, 142.8, 207.1; IR
(neat) 3399, 3030, 1955, 1677, 1494, 1451, 1360, 1264,
1187, 1025, 852, 700 cmK1; HRMS (ESI) calcd for
C10H10O [MCH]C: m/z 147.0810, found: m/z 147.0814.
1
4.5.2. 1-(4-Methoxyphenyl)buta-2,3-dien-1-ol (5b).16 Pale
yellow oil; 1H NMR (CDCl3) d 2.12 (br s, 1H), 3.80 (s, 3H),
4.5.6. 1-Phenylhexa-4,5-dien-3-ol (5f).13a,d Colorless oil;
1H NMR (CDCl3) d 1.69 (br s, 1H), 1.82 (dt, JZ6.9, 7.8 Hz,

U. Schneider et al. / Tetrahedron 62 (2006) 496–502
501
2H), 2.67 (dt, JZ4.4, 7.8 Hz, 2H), 4.08–4.15 (m, 1H), 4.80
(dd, JZ2.5, 6.8 Hz, 2H), 5.20 (dt, JZ6.4, 6.8 Hz, 1H),
7.11–7.27 (m, 5H); 13C NMR (CDCl3) d 31.7, 39.0, 68.9,
77.8, 94.7, 125.9, 128.4, 128.5, 141.8, 207.1; IR (neat) 3384,
2928, 1955, 1716, 1454, 849, 700 cmK1; HRMS (ESI) calcd
for C12H14O [MCH]C: m/z 175.1123, found: m/z 175.1125.
4.6.3. 1-(Furan-3-yl)but-3-yn-1-ol (6c). Pale yellow oil; 1H
NMR (CDCl3) d 1.90 (br s, 1H), 2.02 (d, JZ2.3 Hz, 1H),
2.58–2.60 (m, 2H), 4.78 (t, JZ6.2 Hz, 1H), 6.38 (d, JZ
1.0 Hz, 1H), 7.33 (s, 1H), 7.40 (s, 1H); 13C NMR (CDCl3)
28.3, 65.3, 71.2, 80.3, 108.4, 127.3, 139.4, 143.4; IR (neat)
3400, 3308, 2111, 1450, 750, 695 cmK1; HRMS (ESI) calcd
for C8H8O2 [MCH]C: m/z 137.0603, found: m/z 137.0612.
1
4.5.7. (E)-Nona-1,2,5-trien-4-ol (5g). Pale yellow oil; H
4.6.4. Dodec-1-yn-4-ol (6d).13a Colorless oil; 1H NMR
(CDCl3) d 0.81 (t, JZ6.4 Hz, 3H), 1.19–1.70 (m, 14H), 1.98
(t, JZ2.5 Hz, 1H), 2.15–2.41 (m, 3H), 3.70 (tt, JZ5.7,
6.3 Hz, 1H); 13C NMR (CDCl3) d 14.1, 22.5, 25.6, 27.2,
28.8, 29.2, 29.8, 31.8, 36.0, 69.7, 70.5, 81.0; IR (neat) 3330,
2940, 2108, 1455, 828, 700 cmK1; HRMS (ESI) calcd for
C12H22O [MCH]C: m/z 183.1749, found: m/z 183.1750.
NMR (CDCl3) d 0.83 (t, JZ7.0 Hz, 3H), 1.36 (q, JZ7.0 Hz,
2H), 1.89–2.05 (m, 3H), 4.83 (dd, JZ2.5, 6.0 Hz, 2H), 5.28
(dt, JZ2.5, 6.0 Hz, 1H), 5.59 (dd, JZ6.3, 15.7 Hz, 1H),
5.70–5.78 (m, 1H), 5.99 (dt, JZ6.6, 15.7 Hz, 1H); 13C
NMR (CDCl3) d 13.5, 21.2, 35.3, 71.6, 78.2, 95.3, 129.0,
135.4, 207.0; IR (neat) 3365, 3011, 2891, 1952, 1498, 1453,
1003, 844, 703 cmK1; HRMS (ESI) calcd for C9H14O [MC
H]C: m/z 139.1123, found: m/z 139.1120.
4.6.5. 1-Cyclohexylbut-3-yn-1-ol (6e). Colorless oil; 1H
NMR (CDCl3) d 0.95–1.82 (m, 12H), 1.98 (t, JZ2.3 Hz,
1H), 2.32 (dd, JZ2.3, 6.0 Hz, 2H), 4.77–4.89 (m, 1H); 13C
NMR (CDCl3) d 26.0, 26.6, 28.6, 29.2, 45.4, 70.8, 72.9,
4.6. Homopropargylic alcohols 6a–g
4.6.1. 1-Phenylbut-3-yn-1-ol (6a).13a,15 Colorless oil; H
1
81.6; IR (neat) 3365, 2919, 2109, 1450, 1022, 839, 715 cmK1
;
HRMS (ESI) calcd for C10H16O [MCH]C: m/z 153.1279,
found: m/z 153.1277.
NMR (CDCl3) d 2.01 (t, JZ2.7 Hz, 1H), 2.25 (br s, 1H),
2.58 (dd, JZ2.7, 6.3 Hz, 2H), 4.81 (t, JZ6.3 Hz, 1H), 7.20–
7.37 (m, 5H); 13C NMR (CDCl3) d 29.5, 71.0, 72.3, 80.6,
125.7, 128.0, 128.5, 142.4; IR (neat) 3294, 3032, 2913,
2118, 1668, 1625, 1494, 1453, 1048, 756, 700 cmK1
;
HRMS (ESI) calcd for C10H10O [MCH]C: m/z 147.0810,
found: m/z 147.0815.
1
4.6.6. 1-Phenylhex-5-yn-3-ol (6f).13a Pale yellow oil; H
NMR (CDCl3) d 1.78–1.89 (m, 2H), 1.99 (br s, 1H), 2.05
(t, JZ2.5 Hz, 1H), 2.27–2.45 (m, 2H), 2.61–2.83 (m, 2H),
3.78 (tt, JZ5.7, 12.0 Hz, 1H), 7.11–7.25 (m, 5H); 13C NMR
(CDCl3) d 28.1, 31.9, 37.5, 69.0, 71.2, 80.5, 126.0, 128.2,
128.4, 141.5; IR (neat) 3385, 2920, 2115, 1710, 1451, 833,
699 cmK1; HRMS (ESI) calcd for C12H14O [MCH]C: m/z
175.1123, found: m/z 175.1124.
4.6.2. 1-(4-Methoxyphenyl)but-3-yn-1-ol (6b).15 Pale
yellow oil; H NMR (CDCl3) d 1.96 (t, JZ2.5 Hz, 1H),
2.48–2.64 (m, 3H), 3.71 (s, 3H), 4.74 (t, JZ6.4 Hz, 1H),
6.79 (d, JZ8.9 Hz, 2H), 7.24 (d, JZ8.9 Hz, 2H); 13C NMR
(CDCl3) d 29.5, 55.7, 71.2, 72.4, 80.4, 113.8, 126.9, 135.2,
159.4; IR (neat) 3443, 3290, 2959, 2919, 2832, 2110, 1603,
1245, 1026, 800 cmK1; HRMS (ESI) calcd for C11H12O2
[MCH]C: m/z 177.0916, found: m/z 177.0918.
1
4.6.7. (E)-Non-5-en-1-yn-4-ol (6g). Pale yellow oil; 1H
NMR (CDCl3) d 0.82 (t, JZ7.2 Hz, 3H), 1.33 (q, JZ7.2 Hz,
2H), 1.87–2.10 (m, 3H), 1.98 (t, JZ2.7 Hz, 1H), 2.37 (dd,

502
U. Schneider et al. / Tetrahedron 62 (2006) 496–502
6. For selected examples, see: (a) Masuyama, Y.; Watabe, A.;
Kurusu, Y. Synlett 2003, 1713–1715. (b) Konishi, S.; Hanawa,
H.; Maruoka, K. Tetrahedron: Asymmetry 2003, 14,
1603–1605. (c) Loh, T.-P.; Lin, M.-J.; Tan, K.-L. Tetrahedron
Lett. 2003, 44, 507–509. (d) Evans, D. A.; Sweeney, Z. K.;
Rovis, T.; Tedrow, J. S. J. Am. Chem. Soc. 2001, 123,
12095–12096. (e) McCluskey, A.; Muderawan, I. W.;
Muntari; Young, D. J. J. Org. Chem. 2001, 66, 7811–7817.
(f) Hojo, M.; Sakuragi, R.; Okabe, S.; Hosomi, A. Chem.
Commun. 2001, 357–358. (g) Masuyama, Y.; Watabe, A.; Ito,
A.; Kurusu, Y. Chem. Commun. 2000, 2009–2010. (h) Yu,
C.-M.; Yoon, S.-K.; Baek, K.; Lee, J.-Y. Angew. Chem., Int.
Ed. 1998, 37, 2392–2395.
JZ2.7, 6.0 Hz, 2H), 4.18 (dt, JZ6.0, 6.4 Hz, 1H), 5.47 (dd,
JZ6.4, 15.4 Hz, 1H), 5.64 (dt, JZ6.4, 15.4 Hz, 1H); 13C
NMR (CDCl3) d 13.6, 21.1, 29.4, 35.2, 71.1, 72.5, 80.6,
129.1, 133.7; IR (neat) 3370, 3011, 2889, 2107, 1498, 1456,
1004, 840, 709 cmK1; HRMS (ESI) calcd for C9H14O [MC
H]C: m/z 139.1123, found: m/z 139.1123.
´
´
7. For examples, see: (a) Kjellgren, J.; Sunden, H.; Szabo, K. J.
J. Am. Chem. Soc. 2005, 127, 1787–1796. (b) Banerjee, M.;
Roy, S. Org. Lett. 2004, 6, 2137–2140. (c) Kjellgren, J.;
Acknowledgements
Financial support was provided by ERATO, Japan Science
and Technology Agency (JST). U. S. is indebted to ERATO,
JST, for a postdoctoral fellowship.
´
´
Sunden, H.; Szabo, K. J. J. Am. Chem. Soc. 2004, 126,
474–475. (d) Guillemin, J.-C.; Malagu, K. Organometallics
1999, 18, 5259–5263.
8. (a) Dalko, P. I.; Moisan, L. Angew. Chem., Int. Ed. 2004, 43,
5138–5175. (b) ‘Special Issue: Asymmetric Organocatalysis’,
Adv. Synth. Catal. 2004, 346, 1007–1249. (c) ‘Special Issue:
Asymmetric Organocatalysis’, Acc. Chem. Res. 2004, 37,
References and notes
¨
487–631. (d) Berkessel, A.; Groger, H. Metal-Free Organic
Catalysts in Asymmetric Synthesis; Wiley-VCH: Weinheim,
2004. (e) Benaglia, M.; Puglisi, A.; Cozzi, F. Chem. Rev. 2003,
103, 3401–3430. (f) Dalko, P. I.; Moisan, L. Angew. Chem.,
Int. Ed. 2001, 40, 3726–3748.
1. (a) Krause, N.; Hashmi, A. S. K.; Modern Allene Chemistry;
Wiley-VCH: Weinheim, 2004; Vols. 1 and 2. (b) Krause, N.;
¨
Hoffmann-Roder, A. Tetrahedron 2004, 60, 11671–11694.
¨
(c) Hoffmann-Roder, A.; Krause, N. Angew. Chem., Int. Ed.
9. (a) Ogawa, C.; Sugiura, M.; Kobayashi, S. Chem. Commun.
2003, 192–193. (b) Kobayashi, S.; Nishio, K. J. Org. Chem.
1994, 59, 6620–6628.
2004, 43, 1196–1216. (d) Yamamoto, H. In Trost, B. M., Ed.;
Comprehensive Organic Synthesis; Pergamon: Oxford, 1991;
Vol. 2, p 81. (e) Elsevier, C. J. In Helmchen, G., Hoffmann,
R. W., Mulzer, J., Schaumann, E., Eds.; Methods of Organic
Chemistry (Houben-Weyl); Thieme: Stuttgart, 1995; Vol.
E21a, p 537. (f) Schuster, H. F.; Coppola, G. M. Allenes in
Organic Synthesis; Wiley: New York, 1984. (g) Moreau, J.-L.
In The Chemistry of Ketenes, Allenes and Related Compounds;
Patai, S., Ed.; Wiley: New York, 1980; p 363. (h) Klein, J. In
The Chemistry of the Carbon–Carbon Triple Bond; Patai, S.,
Ed.; Wiley: New York, 1978; p 343.
10. Sugiura, M.; Robvieux, F.; Kobayashi, S. Synlett 2003,
1749–1751.
11. (a) Ogawa, C.; Sugiura, M.; Kobayashi, S. Angew. Chem., Int.
Ed. 2004, 43, 6491–6493. (b) Ogawa, C.; Konishi, H.;
Sugiura, M.; Kobayashi, S. Org. Biomol. Chem. 2004, 2,
192–193. (c) Hirabayashi, R.; Ogawa, C.; Sugiura, M.;
Kobayashi, S. J. Am. Chem. Soc. 2001, 123, 9493–9499.
12. For a recent account on neutral coordinate organocatalysts
(NCO), see: Kobayashi, S.; Sugiura, M.; Ogawa, C. Adv.
Synth. Catal. 2004, 346, 1023–1034.
2. For selected examples, see: (a) Marino, J. P.; McClure, M. S.;
Holub, D. P.; Comasseto, J. V.; Tucci, F. C. J. Am. Chem. Soc.
2002, 124, 1664–1668. (b) Chang, J.; Paquette, L. A. Org. Lett.
2002, 4, 253–256.
13. (a) Kobayashi, S.; Nishio, K. J. Am. Chem. Soc. 1995, 117,
6392–6393. After our report, some other groups investigated
asymmetric organocatalytic allenylation and propargylation of
aldehydes: (b) Nakajima, M.; Saito, M.; Hashimoto, S.
Tetrahedron: Asymmetry 2002, 13, 2449–2452. (c) Denmark,
S. E.; Wynn, T. J. Am. Chem. Soc. 2001, 123, 6199–6200.
(d) Iseki, K.; Kuroki, Y.; Kobayashi, Y. Tetrahedron:
Asymmetry 1998, 9, 2889–2894.
3. For selected examples, see: (a) Poulsen, C. S.; Madsen, R.
J. Org. Chem. 2002, 67, 4441–4449. (b) Trost, B. M.;
Chisholm, J. D. Org. Lett. 2002, 4, 3743–3745. (c) Lee,
H.-Y.; Kim, B. G. Org. Lett. 2000, 2, 1951–1953.
4. For selected examples, see: (a) Trost, B. M.; Rhee, Y. H. J. Am.
Chem. Soc. 2003, 125, 7482–7483. (b) Consorti, C. S.;
Ebeling, G.; Dupont, J. Tetrahedron Lett. 2002, 43, 753–755.
(c) Trost, B. M.; Rhee, Y. H. J. Am. Chem. Soc. 1999, 121,
11680–11683.
14. Mironov, V. F.; Kalinina, L. N.; Gar, T. K. Zh. Obshch. Khim.
1971, 41, 878–881; Chem. Abstr. 1971, 75, 76907v.
15. Bandini, M.; Cozzi, P. G.; Melchiorre, P.; Tino, R.; Umani-
Ronchi, A. Tetrahedron: Asymmetry 2001, 12, 1063–1069.
16. Nakamura, H.; Kamakura, T.; Ishikura, M.; Biellmann, J.-F.
J. Am. Chem. Soc. 2004, 126, 5958–5959.
5. (a) Miao, W.; Chung, L. W.; Wu, Y.-D.; Chan, T. H. J. Am.
Chem. Soc. 2004, 126, 13326–13334 and references cited
therein.