Unprecedented cesium and potassium fluorides catalyzed trialkylsilylation and tributylstannylation of terminal alkynes with trifluoromethyl-trialkylsilanes and -tributylstannane

Article abstract of DOI:10.1016/S0040-4020(00)00810-3

Cesium and potassium fluorides promoted trialkylsilylation and tributylstannylation of terminal alkynes with trifluoromethyl-trialkylsilanes and -tributylstannane were found to give 1-silyl- and 1-tributylatannyl-alkynes in high yield. The present reactions are applicable to 1-alkynes having a wide range of functional groups such as acetal, iodo, silyl, amino, amido and carbonyl (except for aldehyde) groups. (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0040-4020(00)00810-3

TETRAHEDRON
Pergamon
Tetrahedron 56 (2000) 8813±8819
Unprecedented Cesium and Potassium Fluorides Catalyzed
Trialkylsilylation and Tributylstannylation of Terminal Alkynes
with Tri¯uoromethyl-Trialkylsilanes and -Tributylstannane
*
Miyuki Ishizaki and Osamu Hoshino
Faculty of Pharmaceutical Sciences, Science University of Tokyo, 12 Ichigaya Funagawara-machi, Shinjuku-ku, Tokyo 162-0826, Japan
Received 9 August 2000; accepted 11 September 2000
AbstractÐCesium and potassium ¯uorides promoted trialkylsilylation and tributylstannylation of terminal alkynes with tri¯uoromethyl-
trialkylsilanes and -tributylstannane were found to give 1-silyl- and 1-tributylatannyl-alkynes in high yield. The present reactions are
applicable to 1-alkynes having a wide range of functional groups such as acetal, iodo, silyl, amino, amido and carbonyl (except for aldehyde)
groups. q 2000 Elsevier Science Ltd. All rights reserved.
Introduction
1-silylalkynes (1b, c) together with normal adduct (1d)
(Scheme 1). This result indicated tri¯uoromethyltrialkyl-
silanes would serve as effective trialklylsilylating reagent
for trialkylsilylation of 1-alkynes in the presence of
appropriate catalyst. In a similar manner, tri¯uoromethyl-
tributylstannane (Bu3SnCF3)8could be used for tributyl-
stannylation of 1-alkyne (vide infra). Here, we describe
unprecedented trialkylsilylation and tributylstannylation of
1-alkynes with tri¯uoromethyl-trialkylsilanes and -tributyl-
stannane in the presence of CsF or potassium ¯uoride (KF).
Much attention has been focused on 1-silyl- and 1-stannyl-
alkynes as versatile reagents for Lewis acid promoted
alkynylation of various electrophiles,1 substrates for
alkynylation of organic halides or tri¯ates,2 and protecting
groups for terminal alkynes.3 For their synthesis, the direct
trialkylsilylation or trialkylstannylation of terminal alkynes
is a common method, which is performed by treatment with
organometallic reagents such as BuLi,4a,b EtMgBr,4c Zn4d,e
and Cu4f followed by the reaction with chloro-trialkylsilanes
or -trialkylstannanes. Another approach toward trialkylsilyl-
ation is transition metal catalyzed reaction of terminal
alkynes with hydrosilanes.5 However, the former method
requires stoichiometric amount of organometallic reagents
for generation of acetylide and the latter reaction brings
about hydrosilylation of alkynes as side-reaction.
Results and Discussion
First, in order to investigate effect of catalyst in the present
reaction, various catalysts were examined (Scheme 2,
Table 1).9 Terminal alkyne (2a)10 was chosen as a model
compound. As shown in Table 1, the reaction without
catalyst did not proceed at all. CsF in THF and KF in
DMF were found to serve as effective catalyst in this system
to give trimethylsilylacetylene (2b) in quantitative yield
(entries 2, 5). These results suggested ¯uoride ion to play
During our studies6 on Pauson±Khand reaction of ¯uorine-
containing enynes, we found unexpected cesium ¯uoride
(CsF) catalyzed trimethylsilylation of keto-1-alkyne (1a)
with tri¯uoromethyltrimethylsilane (TMSCF3)7 to give
Scheme 1.
Keywords: 1-alkyne; trialkylsilylation; tributylstannylation; cesium ¯uoride; potassium ¯uoride.
* Corresponding authors. Tel.: 181-3-3260-6725; fax: 181-3-3258-3045; e-mail: ishizaki@ps.kagu.sut.ac.jp
0040±4020/00/$ - see front matter q 2000 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(00)00810-3

8814
M. Ishizaki, O. Hoshino / Tetrahedron 56 (2000) 8813±8819
alkynes (Table 2). Trimethylsilylation of 2a±5a smoothly
proceeded, in which vinyl, acetal, and iodo groups remained
intact (entries 1±8). The reaction of triphenylsilylacetylene
(6a) took place successfully without desilylation (entries 9,
10). The reaction of alkynol (7a) using 1.2 equiv. of
TMSCF3 produced TMS ether (7b) predominately (entry
11), while that with 2.4 equiv. of TMSCF3 gave bis(tri-
methylsilyl) compound (7c) quantitatively (entry 12).
Diyne (8a) underwent bis(trimethylsilyl)silylation to furnish
8b in quantitative yield (entries 14, 15). With 1-alkyne (9a)
having an active methyne moiety, however, Method A inter-
fered the reaction and Method B remarkably slowed the
reaction (entries 16, 17). With amine (10a) and amide
(11a), excess TMSCF3 was needed and reaction time
prolonged, although yields were still high (entries 18±21).
Unfortunately, with aldehyde (12a), Method A could not
avoid tri¯uoromethylation of carbonyl group (entry 22).
However, Method B, furnished desired product (12b)
along with tri¯uoromethylated product (12d) (entry 23).14
In a similar manner, silylation of ketone (13a) by Method B
gave 1-trimethylsilylalkyne (13b) and 13c, respectively
(entries 24). Also, silylation of 1a by Method B proceeded
successfully to give 1b predominantly together with 1c
(entry 25). (Fig. 1)
Scheme 2.
Table 1. Effects of catalyst (unless otherwise noted, all reactions were
carried out at rt using 2a (1 equiv.), catalyst (0.16 equiv.), and TMSCF3
(1.5 equiv.) under argon)
Entry
Catalyst
Solvent
Time (h)
Yield (%)a
1
2
None
CsF
KF
KF
KF
CsCl
CsOH
TBAF
THF
THF
THF
THF
DMF
THF
THF
THF
24
0.5
15
24
0.5
24
24
24
0
100
23 (76)
28 (36)
98
0
trace
0
3b
4c
5
6
7
8
a Isolated yield. Value in parenthesis was recovery of starting material.
b With 0.4 equiv. of KF.
c With 1 equiv. of KF.
Advantage of the present reaction is as follows: 1) A
catalytic amount of promoter (CsF or KF): 2) Method A is
simple work-up procedure (see Experimental): 3) the
reaction is applicable to 1-alkynes bearing many functional
groups such as acetal, iodo, silyl, amino, amido and
carbonyl (except for aldehyde) groups.
an important role. Since the reaction with TBAF11 did not
proceed, the presence of a small amount of water was
assumed to suppress the reaction. Because when CsF was
not dried before using, incomplete reaction was observed
sometimes.
Plausible reaction mechanism for trimethylsilylation of
1-alkynes is depicted in Fig. 2. Initially, reaction of
TMSCF3 with MF (MˆCs or K) generates pentacoordinated
silicate species (A),15 which reacted 1-alkynes to afford
acetylide containing pentacoordinated silicate species (B).
Then, B reacts with TMSCF3 to furnish 1-trimethylsilyl-
alkynes and A.
To apply the present reaction to other substrates, various
1-alkynes were synthesized as depicted in Scheme 3.
Namely, propargylation of acetal tosylamide (14)12 gave
4a, acidic hydrolysis of which afforded an aldehyde (12a)
in 93% yield. Reduction of 12a with NaBH4 furnished an
alcohol (7a), which was converted to an iodide (5a) by
standard way. Alternatively, methylation and oxidation of
12a afforded methyl ketone (13a). A carbamate (11a) was
obtained from 4-aminophenylacetylene (10a)13 with Boc2O
in 89% yield.
We additionally examined the reaction of 2a with TESCF3
and Bu3SnCF3 (Scheme 4, Table 3). In the case of triethyl-
silylation, long reaction time was required in both Method A
and B (2 mol% of catalyst) (entries 1, 3). Increase of amount
of CsF (10 mol%) markedly improved in both reaction time
and yield (entry 2), although the reaction using KF was
independent on the amount of the catalyst (entry 4). In a
similar manner, tributylstannylation of 2a was performed to
furnish 2d (entries 5, 6),
After examination on amount of catalyst in the reaction, we
found that the catalyst could be decreased to 2 mol%. Thus,
the reaction (Method A; CsF in THF or Method B; KF in
DMF) was carried out on various 1-alkynes with TMSCF3
(1.2±4.8 equiv.) to give corresponding 1-trimethylsilyl-
Scheme 3. (a) 3-bromopropyne, K2CO3, DMF, 1008C, 1.5 h, 97% (b) 3 M HCl, THF, D, 2 h 93% (c) NaBH4, MeOH, 08C, 0.5 h, 83% (d) l2, imidazole, PPh3,
CH2Cl2, 08C, 2 h, 93% (e) MeMgBr, THF, rt, 1 h; Dess±Martin periodinane, CH2Cl2, rt, 1 h, 75% (f) Boc2O, THF, D, 3 h, 89%.

M. Ishizaki, O. Hoshino / Tetrahedron 56 (2000) 8813±8819
8815
Table 2. Silylation of various 1-alkynes (all reactions were carried out at rt in THF (Method A) or DMF (Method B), unless otherwise noted)
Entry
Substrate
Method
TMSCF3 (equiv.)
Time (h)
Product
Yield (%)a
1
2
3
4
5
6
7
8
2a
2a
3a
3a
4a
4a
5a
5a
6a
6a
7a
7a
7a
8a
8a
9a
A
B
A
B
A
B
A
B
A
B
A
A
B
A
B
A
B
A
B
A
B
A
B
B
B
1.2
1.2
1.2
1.2
1.2
2.4
1.2
1.2
1.2
1.2
1.2
2.4
4.0
3.2
2.5
4.8
3.6
2.4
3.0
3.0
3.0
2.7
2.7
1.6
1.6
0.5
0.5
0.1
0.1
0.5
1.5
0.5
1.5
0.2
0.2
0.2
0.5
3
1.5
0.5
24
24
1.5
18
18
18
6
2b
2b
3b
3b
4b
4b
5b
5b
6b
6b
7b
7c
7c
8b
8b
9b
100
99
100
100
100
99
100
98
9
100
100
100
100
100
100
100
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24c
25c
b
±
9a
9b
40 (14)
100
87
88 (8)
87 (11)
33137
26159
72116
74111
10a
10a
11a
11a
12a
12a
13a
1a
10b
10b
11b
11b
12c112d
12b112d
13b113c
1b11c
3
21
18
a Isolated yield. Value in parentheses was recovery of starting material.
b Complex mixture.
c The reaction was performed at 08C.
Figure 1.
Conclusion
Experimental
General
In summary, we have demonstrated that trialkylsilylation
and tributylstannylation of 1-alkynes with tri¯uoromethyl-
trialkylsilanes and -tributylstannane using a catalytic
amount of CsF or KF proceeded in high yield. The present
reactions are convenient and applicable to the 1-alkynes
possessing a wide range of functional groups.
1H NMR spectra were taken with a JEOL EX-270
(270 MHz) spectrometer in CDCl3 solution with tetra-
methylsilane as an internal standard. Mass spectra were
measured on a Hitachi M-80 or a JEOL JMS D-300

8816
M. Ishizaki, O. Hoshino / Tetrahedron 56 (2000) 8813±8819
N-Iodoethyl-N-(2-propynyl)tosylamide (5a). To a solu-
tion of 7a (5.18 g, 20 mmol), PPh3 (6.30 g, 24 mmol) and
pyridine (2 mL) in CH2Cl2 (200 mL) was added at 08C I2
(6.10 g, 24 mmol) in one portion. After being stirred for 2 h,
the reaction was quenched with 10% Na2S2O3. The solvent
was washed with 1 M HCl and brine, successively, dried,
and evaporated under reduced pressure to give a residue,
which was puri®ed by column chromatography
(AcOEt:hexaneˆ1:3) to afford 5a (6.88 g, 93.2%) as color-
less crystals; mp 70±718C; 1H NMR d 7.71, 7.29 (each 2H,
d, Jˆ8.3 Hz), 4.12 (1H, d, Jˆ2.3 Hz), 3.52, 3.29 (each 2H, t,
Jˆ7.9 Hz), 2.41 (3H, s), 2.10 (1H, t, Jˆ2.3 Hz); 13C NMR d
144.3, 135.7, 130.0, 129.7, 127.8, 77.0, 74.8, 49.7, 37.8,
21.9; MS m/z 362 (M1); high-resolution mass m/z calcd
for C12H14INO2S (M1) 362.9790, found: 362.9790.
N-Hydroxyethyl-N-(2-propynyl)tosylamide (7a). To a
solution of 12a (12.80 g, 50 mmol) in MeOH (250 mL)
was added at 08C NaBH4 (0.95 g, 25 mmol) in one portion.
After being stirred for 0.5 h, the reaction was quenched with
water. The solvent was evaporated under reduced pressure
to give a residue, which was taken up in CHCl3. The organic
extract was washed with brine, dried, and evaporated in
vacuo to furnish 7a (10.78 g, 83.2%) as colorless crystals;
mp 67±688C; 1H NMR d 7.75, 7.31 (each 2H, d, Jˆ8.3 Hz),
4.42 (1H, d, Jˆ2.3 Hz), 3.80, 3.36 (each 2H, t, Jˆ5.3 Hz),
2.43 (3H, s), 2.09 (1H, t, Jˆ2.3 Hz); 13C NMR d 144.32
135.7, 129.9, 128.0, 127.4, 77.2, 60.8, 49.2, 38.2, 21.8; MS
m/z 253 (M1); high-resolution mass m/z calcd for
C12H15NO3S (M1) 253.0773, found: 253.0770.
Figure 2.
Scheme 4.
Table 3. Triethylsilylation and tributylstannylation of 2a
Entry Cat.(mol%) Reagent (equiv.) Solvent Time (h) Yield (%)a
N-tert-Butoxycarbonyl-4-ethynylaniline (11a). A mixture
of 10a (0.353 g, 3.0 mmol) and Boc2O (2.006 g, 10.8 mmol)
in THF (3 mL) was re¯uxed for 3 h. Then the solvent was
removed in vacuo to give an oily residue, which was puri-
®ed by column chromatography (AcOEt:hexaneˆ1:15 then
1:5) to afford 11a (0.581 g, 88.8%) as colorless crystals; mp
1
2
3
4
5
6
CsF (2)
CsF (10)
KF (2)
KF (10)
CsF (10)
KF (2)
TESCF3 (2.5)
TESCF3 (2.5)
TESCF3 (2.5)
TESCF3 (2.5)
Bu3SnCF3 (2.5) THF
Bu3SnCF3 (2.0) DMF
THF
THF
DMF
DMF
72
2.5
24
24
48
10
42 (58)
97
89
85
69 (20)
89
1
978C; H NMR d 7.40, 7.31 (each 2H, d, Jˆ8.3 Hz), 6.55
(1H, s), 3.01 (1H, s), 1.51 (9H, s); MS m/z 217 (M1); high-
resolution mass m/z calcd for C13H15NO2 (M1) 217.1103,
found: 217.1100.
a Isolated yield. Value in parentheses was recovery of starting material.
spectrometer. Column chromatography was performed over
silica gel (Merck Kiegelsel 60). CsF and KF were dried with
heat gun in vacuo prior to use. THF was distilled from Na
wire before use. DMF was stored over MS 4A. Starting
materials (3a, 6a) were purchased from Aldrich Co., and
2a,10 8a,15 9a,16 and 10a13 were synthesized according to
reported procedure.
N-Formylmethyl-N-(2-propynyl)tosylamide (12a).
A
mixture of 4a (25.01 g, 84 mmol) and 3 M HCl (200 mL)
in THF (250 mL) was re¯uxed for 2 h. Then the solvent was
removed in vacuo. The mixture was extracted with Et2O.
The organic extract was washed with water and brine,
successively, dried, and evaporated under reduced pressure
to give an oily residue, which was puri®ed by column
chromatography (500 g, AcOEt:hexaneˆ1:1) to afford 12a
1
N-Dimethoxylethyl-N-(2-propynyl)tosylamide (4a).
A
(20.12 g, 93.0%) as colorless oil; H NMR d 9.66 (1H, t,
mixture of 14 (22.53 g, 87 mmol), 3-bromopropyne
(12.42 g, 82 mmol), and K2CO3 (12.00 g, 61 mmol) in
DMF (300 mL) was heated at 1008C for 1.5 h. After water
was added to the mixture, the mixture was extracted with
Et2O. The organic extract was washed with water and brine,
successively, dried, and evaporated under reduced pressure
to give 4a (25.01 g, 96.8%) as colorless crystals; mp 55±
Jˆ1.3 Hz), 7.71, 7.33 (each 2H, d, Jˆ8.3 Hz), 4.17 (1H, d,
Jˆ2.3 Hz), 3.96 (2H, d, Jˆ1.3 Hz), 2.44 (3H, s), 2.17 (1H, t,
Jˆ2.3 Hz); MS m/z 251 (M1); high-resolution mass m/z
calcd for C12H13NO3S (M1) 251.0616, found: 251.0622.
N-2-Oxopropyl-N-(2-propynyl)tosylamide (13a). To a
solution of 12a (5.14 g, 20 mmol) in THF (80 mL) was
added 40 mL of MeMgBr (1 M in THF, 40 mmol). After
being stirred for 1 h, the reaction was quenched with 1 M
HCl. The mixture was extracted with Et2O. The organic
extract was washed with water and brine, successively,
dried, and evaporated under reduced pressure to give an
1
568C; H NMR d 7.74, 7.29 (each 2H, d, Jˆ8.3 Hz), 4.56
(1H, t, Jˆ5.4 Hz), 4.26 (2H, d, Jˆ2.3 Hz), 3.41 (6H, s), 3.27
(2H, d, Jˆ5.4 Hz), 2.42 (3H, s), 2.00 (1H, t, Jˆ2.3 Hz); MS
m/z 297 (M1); high-resolution mass m/z calcd for
C14H19NO4S (M1) 297.1035, found: 297.1033.

M. Ishizaki, O. Hoshino / Tetrahedron 56 (2000) 8813±8819
8817
alcohol, which was treated with Dess±Martin periodinane
(12.78 g, 30 mmol) in CH2Cl2 (200 mL) for 1 h. The
mixture was washed with 10% Na2S2O3 and brine, succes-
sively, dried, and evaporated under reduced pressure to give
a residue, which was puri®ed by column chromatography
(AcOEt:hexaneˆ1:2) to afford 13a (4.08 g, 75.2%) as color-
resolution mass m/z calcd for C19H29O4NSSi (M1)
383.1592, found: 383.1587.
N-(2-Iodoethyl)-N-[3-(trimethylsilyl)-2-propynyl]tosyl-
amide (5b). Mp 87±888C; 1H NMR d 7.78, 7.38 (each 2H,
d, Jˆ8.3 Hz), 4.20 (2H, s), 3.59, 3.57 (each 2H, t,
Jˆ7.8 Hz), 2.49 (3H, s), 0.10 (9H, s); 13C NMR d 143.4,
135.2, 129.4, 127.3, 97.5, 91.0, 48.9, 37.9, 21.2, 1.3, 20.7;
MS m/z 435 (M1); high-resolution mass m/z calcd for
C15H22O2INSSi (M1) 435.0177, found: 435.0185.
1
less crystals; mp 638C; H NMR d 7.71, 7.31 (each 2H, d,
Jˆ8.3 Hz), 4.17 (1H, d, Jˆ2.3 Hz), 4.03 (2H, s), 2.43, 2.22
(each 3H, s), 2.12 (1H, t, Jˆ2.3 Hz); MS m/z 265 (M1);
high-resolution mass m/z calcd for C13H15NO3S (M1)
265.0073, found: 265.0077.
1-Trimethylsilyl-2-triphenylsilylacetylene (6b). Mp 67±
1
688C; H NMR d 7.80±7.92 (10H, m), 7.45±7.60 (15H,
m), 0.45 (9H, s); 13C NMR d 135.5, 133.4, 128.8, 127.9,
119.5, 108.1, 20.2; MS m/z 356 (M1); high-resolution mass
m/z calcd for C23H24Si2 (M1) 356.1417, found: 356.1417
General procedure for trimethylsilylation of 1-alkynes17
Method A. A mixture of acetylene (0.5 mmol), catalyst
(0.01 mmol), and TMSCF3 (0.6±2.4 mmol) in THF
(2 mL) was stirred at rt. After the reaction was completed,
the catalyst was ®ltered off by suction. The ®ltrate was
evaporated under reduced pressure to give 1-silylacetylene
in essentially pure form. For the reaction of 10a±13a, puri-
®cation was performed by column chromatography.
N-(2-Propynyl)-N-[2-(trimethylsilyloxy)ethyl]tosylamide
1
(7b). Oil; H NMR d 7.73, 7.28 (each 2H, d, Jˆ8.3 Hz),
4.22 (2H, d, Jˆ2.3 Hz), 3.78, 3.31 (each 2H, t, Jˆ5.9 Hz),
2.41 (3H, s), 2.09 (2H, t, Jˆ2.3 Hz), 0.11 (9H, s); 13C
NMR d 143.3, 135.9, 129.3, 127.4, 73.8, 73.5, 61.8, 48.1,
38.0, 21.3, 20.8; MS m/z 325 (M1); high-resolution mass
m/z calcd for C15H23O3NSSi (M1) 325.1163, found:
325.1168.
Method B. A mixture of acetylene (0.5 mmol), catalyst
(0.01 mmol), and TMSCF3 (0.6±2.0 mmol) in DMF
(2 mL) was stirred at rt. After the reaction was completed,
the reaction was quenched with water. The mixture was
extracted with Et2O. The organic extract was washed with
water and brine, successively, dried (MgSO4), and evapo-
rated under reduced pressure to afford 1-silylacetylene in
essentially pure form. For the reaction of 9a±13a, puri®ca-
tion was performed by column chromatography.
N-[2-(Trimethylsilyloxy)ethyl]-N-[3-(trimethylsilyl)-2-
propynyl]tosylamide (7c). Oil; 1H NMR d 7.67, 7.22 (each
2H, d, Jˆ8.3 Hz), 4.17 (2H, s), 3.73, 2.44 (each 2H, t,
Jˆ6.1 Hz), 2.34 (3H, s), 0.06, 20.05 (each 9H, s); 13C
NMR d 142.3, 136.0, 129.4, 127.7, 98.5, 90.2, 61.4, 48.0,
38.9, 21.2, 0.4, 20.8; MS m/z 397 (M1); high-resolution
mass m/z calcd for C18H31O3NSSi2 (M1) 397.1560, found:
397.1563.
N-(4-Oxo-2-pentenyl)-N-[3-(trimethylsilyl)-2-propynyl]-
tosylamide (1b). Mp 93±948C; 1H NMR d 7.76, 7.24 (each
2H, d, Jˆ7.9 Hz), 6.59 (1H, dt, Jˆ6, 15.8 Hz), 6.15 (1H, d,
Jˆ15.8 Hz), 4.03 (2H, s), 3.93(2H, d, Jˆ6 Hz), 2.35, 2.17
(each 3H, s), 20.07 (9H, s); 13C NMR d 197.5, 143.6, 140.4,
132.8, 129.5, 127.5, 97.1, 91.4, 47.3, 37.6, 33.5, 26.9, 21.2,
20.7; IR 2929, 2864, 1705, 1624, 1448, 1412 cm21; MS m/z
363 (M1); high-resolution mass m/z calcd for
C18H25NO3SSi (M1) 363.1324, found: 363.1320.
Dimethyl 2,2-Bis-[3-(trimethylsilyl)-2-propynyl]malonate
1
(8b). Mp 508C; H NMR d 3.70 (6H, s), 2.93 (4H, s), 0.08
(9H, s); 13C NMR d 168.5, 100.8, 87.8, 56.5, 52.4, 23.7,
20.4; MS m/z 352 (M1); high-resolution mass m/z calcd for
C17H28O4Si2 (M1) 352.1521, found: 352.1526.
Dimethyl 2-[3-(trimethylsilyl)-2-propynyl]malonate (9b).
1
Oil; H NMR d 3.73 (6H, s), 3.56 (1H, t, Jˆ7.9 Hz), 2.76
N-(2-Propenyl)-N-[3-(trimethylsilyl)-2-propynyl]tosyl-
amide (2b). Mp 608C; H NMR d 7.72, 7.28 (each 2H, d,
(2H, d, Jˆ7.9 Hz), 0.09 (9H, s); 13C NMR d 168.2, 102.0,
87.1, 52.6, 51.1, 18.8, 20.2; MS m/z 242 (M1); high-
resolution mass m/z calcd for C11H18O4Si (M1) 242.0980,
found: 242.0974.
1
Jˆ8.3 Hz), 5.68±5.83 (1H, m), 5.21±5.31 (2H, m), 4.09
(2H, s), 3.81 (2H, d, Jˆ6.6 Hz), 2,41 (3H, s), 20.02 (9H,
s); 13C NMR d 143.3, 136.1, 131.9, 129.5, 127.7, 119.8,
97.7, 90.9, 48.8, 37.6, 36.7, 21.5, 20.5; MS m/z 321
(M1); high-resolution mass m/z calcd for C16H23NO2SSi
(M1) 321.1219 found: 321.1222.
1
4-(Trimethylsilylethynyl)aniline (10b). Mp 83±848C; H
NMR d 7.27, 6.55 (each 2H, d, Jˆ8.6 Hz), 3.76 (2H, brs),
0.24 (9H, s); 13C NMR d 146.8, 133.1, 114.3, 111.9, 106.2,
91.3, 0.0; MS m/z 189 (M1); high-resolution mass m/z calcd
for C11H15NSi (M1) 189.0981, found: 189.0974.
Trimethylsilylphenylacetylene (3b). Oil; 1H NMR d
7.48±7.52 (2H, m), 7.29±7.33 (3H, m), 0.29 (9H, s); MS
m/z 174 (M1); high-resolution mass m/z calcd for C11H14Si
(M1) 174.0865, found: 174.0865.
N-tert-Butoxycarbonyl-4-(trimethylsilylethynyl)aniline
1
(11b). Mp 160±1618C; H NMR d 7.38, 7.30 (each 2H, d,
Jˆ8.6 Hz), 6.65 (1H, s), 1.50, 0.23 (each 9H, s); 13C NMR d
152.4, 138.7, 132.8, 117.8, 117.3, 105.1, 93.1, 80.8, 28.7,
0.0; MS m/z 289 (M1); high-resolution mass m/z calcd for
C16H23O2NSi (M1) 289.1500, found: 289.1498.
N-(3,3-Dimethoxyethyl)-N-[3-(trimethylsilyl)-2-propynyl]-
tosylamide (4b). Mp 86±878C; 1H NMR d 7.66, 7.21 (each
2H, d, Jˆ8.3 Hz), 4.49 (1H, t, Jˆ5.6 Hz), 4.19 (2H, s), 3.33
(6H, s), 3.20 (2H, d, Jˆ5.6 Hz), 2.33 (3H, s), 20.10 (9H, s);
13C NMR d 143.0, 135.8, 120.2, 127.6, 103.8, 98.2, 90.0,
54.1, 47.0, 38.6, 21.1, 20.8; MS m/z 383 (M1); high-
N-(2-Oxoethyl)-N-[3-(trimethylsilyl)-2-propynyl]tosyl-
amide (12b). Oil; 1H NMR d 9.65 (1H, d, Jˆ1 Hz),

8818
M. Ishizaki, O. Hoshino / Tetrahedron 56 (2000) 8813±8819
7.69, 7.30 (each 2H, d, Jˆ8.3 Hz), 4.17 (2H, s), 3.88 (2H,
d, Jˆ1 Hz), 2.41 (3H, s), 0.00 (9H, s); 13C NMR d
197.6, 144.2, 134.8, 128.8, 127.7, 97.1, 92.3, 50.9,
39.7, 21.5, 20.5; MS m/z 323 (M1); high-resolution mass
m/z calcd for C15H21O3NSSi (M1) 323.1010, found:
323.1011.
References
1. (a) Birkofer, L.; Ritter, A.; Uhlenbrauck, H. Chem. Ber. 1963,
96, 3280. (b) Chan, T. H.; Fleming, I. Synthesis 1976, 761.
(c) Utimoto, K.; Tanaka, M.; Kitai, M.; Nozaki, H. Tetrahedron
Lett. 1978, 2301. (d) Kong, B.; Neumann, W. P. Tetrahedron Lett.
1967, 495.
N-[3,3,3-tri¯uoro-2-(trimethylsilyloxy)propyl]-N-(2-pro-
pynyl)tosylamide (12c). Mp 88±898C; H NMR d 7.73,
2. (a) Hatanaka, Y.; Hiyama, T. Synlett 1991, 845. (b) Hatanaka,
Y.; Hiyama, T. J. Org. Chem. 1988, 53, 918. (c) Hatanaka, Y.;
Hiyama, T. Tetrahedron Lett. 1990, 31, 2719. (d) Nishihara, Y.;
Ikegashira, K.; Mori, A; Hiyama, T. Chem. Lett. 1997, 1233.
(e) Nishihara, Y.; Ikegashira, K.; Mori, A; Hiyama, T. Tetrahedron
Lett. 1998, 39, 4075. (f) Nishihara, Y.; Ikegashira, K.; Hirabayashi,
K.; Ando, J.; Mori, A; Hiyama, T. J. Org. Chem. 2000, 65, 1780.
(g) Koseki, Y.; Omino, K.; Anzai, S.; Nagasaka, T. Tetrahedron
Lett. 2000, 41, 2377. (h) Bumagin, N. A.; Bumagina, I. G.;
Beletskaya, I. O. Dokl. Nauk. SSSR 1983, 272, 1384. (i) Scott,
W. J.; Crisp, G. T.; Stille, J. K. J. Am. Chem. Soc. 1984, 106, 4630.
3. (a) Eaborn, C.; Thompson, A. R.; Walton, D. R. M. J. Chem.
Soc. C 1967, 1364. (b) Schmidt, H. M.; Arens, J. F. Rec. Trav.
Chim. Pay-Bas 1967, 86, 1138. (c) Holmes, A. B.; Raphael, R. A.;
Welland, N. K. Tetrahedron Lett. 1976, 1539.
1
7.27 (each 2H, d, Jˆ8.3 Hz), 4.20±4.40 (1H, m), 4.23
(2H, d, Jˆ2.5 Hz), 3.30±3.50 (2H, m), 2.42 (3H, s), 2.11
(1H, t, Jˆ2.5 Hz), 0.00 (9H, s); 13C NMR d 144.3, 134.7,
129.8, 127.8, 97.4, 91.9, 69.3 (q, Jˆ30.6 Hz), 54.7, 46.7,
39.8, 21.5, 20.6; MS m/z 393 (M1); high-resolution mass
m/z calcd for C16H22F3O3NSSi (M1) 393.1041, found:
393.1042.
N-[3,3,3-tri¯uoro-2-(trimethylsilyloxy)propyl]-N-[3-(tri-
methylsilyl)-2-propynyl]tosylamide (12d). Oil; H NMR
1
d 7.71, 7.27 (each 2H, d, Jˆ8.3 Hz), 4.35 (1H, d,
Jˆ18.7 Hz), 4.26±4.41 (1H, m), 4.04 (1H, d,
Jˆ18.7 Hz), 3.13±3.46 (2H, m), 2.39 (3H, s), 20.04,
20.05 (each 9H, s); MS m/z 465 (M1); high-resolution
mass m/z calcd for C19H30F3O3NSSi2 (M1) 465.1431,
found: 465.1437.
4. (a) Zweifel, G.; Lewis, W. J. Org. Chem. 1978, 43, 2739.
(b) Bottaro, J. C.; Hanson, R. N.; Seitz, D. E. J. Org. Chem.
1981, 46, 5221. (c) Miller, R. B.; Reichenbach, T. Tetrahedron
Lett. 1974, 543. (d) Sugita, H.; Hatanaka, Y.; Hiyama, T.
N-(2-Oxopropyl)-N-[3-(trimethylsilyl)-2-propynyl]tosyl-
amide (13b). Mp 84±858C; 1H NMR d 7.70, 7.30 (each 2H,
d, Jˆ8.3 Hz), 4.16 (2H, s), 3.97 (2H, s), 3.42(2H, s), 2.23
(3H, s), 0.01 (9H, s); 13C NMR d 203.3, 143.8, 135.0, 129.6,
127.5, 97.2, 91.7, 55.4, 38.9, 27.0, 21.4, 20.6; MS m/z 337
(M1); high-resolution mass m/z calcd for C16H23O3NSSi
(M1) 337.1162, found: 337.1168.
È
Tetrahedron Lett. 1995, 36, 2769. (e) Maeorg, U.; Viirlaid, S.;
Hagu, H.; Verkruijsse, H. D.; Brandsma, L. J. Organomet.
Chem. 2000, 601, 341. (f) Sugita, H.; Hatanaka, Y.; Hiyama, T.
Chem. Lett. 1996, 379.
Â
5. (a) Esterulas, M. A.; NuÈrnberg, O.; Olvan, M.; Oro, L. A.;
Warner, H. Organometallics 1993, 12, 3264. (b) Chatani, N.;
Yamaguchi, S.; Fukumoto, Y.; Murai, S. Organometallics 1995,
Â
14, 4418. (c) Esterulas, M. A.; Olvan, M.; Oro, L. A.; Tolosa, J.
J. Organomet. Chem. 1995, 14, 4418.
N-[2-tri¯uoromethyl-2-(trimethylsilyloxy)propyl]-N-[3-
(trimethylsilyl)-2-propynyl]tosylamide (13c). Mp 60±
6. Ishizaki, M.; Suzuki, D.; Hoshino, O. In preparation; for the
intramolecular Pauson±Khand reaction of exo-cyclic enynes;
Ishizaki, M.; Iwahara, K.; Kyoumura, K.; Hoshino, O. Synlett
1999, 587.
1
618C; H NMR d 7.75, 7.33 (each 2H, d, Jˆ8.3 Hz), 4.45
(1H, d, Jˆ18.7 Hz), 4.26 (1H, d, Jˆ18.7 Hz), 3.52, 3.44
(each 1H, d, Jˆ14.4 Hz), 2.46, 1.59 (each 3H, s), 0.22,
0.01 (each 9H, s); 13C NMR d 143.6, 136.0, 129.6, 127.9,
127.5, 97.8, 91.2, 77.0 (q, Jˆ28.1 Hz), 50.3, 39.7, 21.5,
19.7, 1.8, 20.5; MS m/z 479 (M1); high-resolution mass
m/z calcd for C20H32F3O3NSSi2 (M1) 479.1591, found:
479.1594.
7. TMSCF3 has been known as tri¯uoromethylating reagent of
carbonyl compounds; (a) Prakash, G. K. S.; Krishnamurti, R.;
Olah, G. A. J. Am. Chem. Soc. 1989, 111, 393. (b) Singh, R. P.;
Cao,G.; Kirchmeier, R. L.; Shreeve, J. M. J. Org. Chem. 1999, 64,
2873. (c) Singh, R. P.; Kirchmeier, R. L.; Shreeve, J. M. Org. Lett.
1999, 1, 1047.
N-(2-Propenyl)-N-[3-(triethylsilyl)-2-propynyl]tosylamide
8. Prakash, G. K. S.; Yudin, A. K.; Def®eux, D.; Olah, G. A.
Synlett 1996, 151.
1
(2c). Oil; H NMR d 7.70, 7.25 (each 2H, d, Jˆ8.2 Hz),
5.68±5.83 (1H, m), 5.19±5.29 (2H, m), 4.12 (2H, s), 3.82
(2H, d, Jˆ6.3 Hz), 2.38 (3H, s), 0.82 (9H, t, Jˆ7.8 Hz), 0.40
(6H, q, Jˆ7.8 Hz); 13C NMR d 143.1, 135.9, 131.7, 129.3,
127.4, 120.0, 98.6, 88.1, 48.6, 36.5, 21.2, 7.0, 3.8; MS m/z
363 (M1); high-resolution mass m/z calcd for C19H29O3NSi
(M1) 363.1692, found: 363.1688.
9. For the CsF catalyzed reaction of 2a, other trimethylsilylating
reagents (TMSCl, TMSCN or TMSOTf) did not give any desired
product.
10. Kataoka, T.; Yoshimatsu, M.; Noda, Y.; Sato, T.; Shimizu, H.;
Hori, M. J. Chem. Soc., Perkin Trans. 1 1993, 121.
11. We used 1 M TBAF solution in THF (containing 5% water)
after stored over MS 4A.
N-(2-Propenyl)-N-[3-(tributylstannanyl)-2-propynyl]-
tosylamide (2d). Mp 59±608C; 1H NMR d 7.75, 7.27 (each
2H, d, Jˆ8.5 Hz), 5.66±5.81 (1H, m), 5.21±5.31 (2H, m),
4.14 (2H, s), 3.84 (2H, d, Jˆ6.6 Hz), 2,42 (3H, s), 1.16±1.64
(15H, m), 0.84±0.94 (12H, m); 13C NMR d 162.4, 143.6,
136.1, 131.9, 129.5, 127.8, 120.0, 73.7, 49.0, 35.8, 27.9,
27.2, 21.5, 16.7, 12.7; MS m/z 537 (M1); high-resolution
mass m/z calcd for C25H41NO2SSn (M1) 537.1891, found:
537.1880.
12. Shono, T.; Matsumura, Y.; Katoh, S.; Takeuchi, K.; Sasaki,
K.; Kamada, T.; Shimizu, R. J. Am. Chem. Soc. 1990, 112, 2368.
13. Takahashi, S.; Kuroyama, Y.; Sonogashira, K.; Hagihara, N.
Synthesis 1980, 627.
14. Use of TMSCF3 less than 2 equiv. resulted incomplete
reaction, although the reason was not clear.
15. The authors thank a referee for his useful suggestion on
reaction mechanism; Cf. (a) Maggiarosa, N.; Tyrra, W.; Naumann,
D.; Kirij, N. V.; Yagupolskii, Y. L. Angew. Chem. Int. Ed. Engl.

M. Ishizaki, O. Hoshino / Tetrahedron 56 (2000) 8813±8819
8819
1999, 2252. (b) Adams, D. J.; Clark, J. H.; Hansen, L. B.; Sanders,
V. C.; Tavener, S. J. J. Fluorine Chem. 1998, 92, 123.
16. Atkinson, R. S.; Grimshire, M.; J J. Chem. Soc., Perkin Trans.
1 1986, 1215.
17. Triethylsilylation and tributylstannylation were performed by
a procedure similar to that described in general procedure for
trimethylsilylation.