Generation and reactions of alkynylsamariums

Article abstract of DOI:10.1016/S0040-4020(00)00971-6

Three methods have been developed for generating alkynylsamariums: (1) reduction of iodoalkynes with SmI₂ in the presence of HMPA, (2) deprotonation at the terminal position of 1-alkynes either by tetrahydrofurylsamarium generated by PhI and Sm

Full text of DOI:10.1016/S0040-4020(00)00971-6

TETRAHEDRON
Pergamon
Tetrahedron 56 (2000) 9927±9935
Generation and Reactions of Alkynylsamariums
*
Munetaka Kunishima, Daisuke Nakata, Shinobu Tanaka, Kazuhito Hioki and Shohei Tani
Faculty of Pharmaceutical Sciences, Kobe Gakuin University, Nishi-ku, Kobe 651-2180, Japan
Received 28 August 2000; accepted 17 October 2000
2
AbstractÐThree methods have been developed for generating alkynylsamariums: (1) reduction of iodoalkynes with SmI in the presence of
HMPA, (2) deprotonation at the terminal position of 1-alkynes either by tetrahydrofurylsamarium generated by PhI and SmI in THF, or, (3)
2
deprotonation by butyllithium followed by metal±metal exchange with SmI . Alkynylsamariums arising from iodoalkynes with SmI
3
2
undergo coupling with carbonyl compounds under both Barbier and Grignard conditions in benzene-HMPA or THF-HMPA as a solvent
system. Tetrahydrofurylsamarium generated from iodobenzene and SmI in THF can deprotonate from terminal alkynes to yield alkynylsa-
mariums whereas other alkylsamariums, such as ethyl-, isopropyl-, cyclohexyl-, and cyclopentylsamarium do not work well. Metal±metal
exchange between an alkynyllithium and SmI is also effective; the reactive species in this case would be alkynylsamariums rather than
2
3
alkynyllithiums. To reveal the properties of alkynylsamariums, we examined the stability and reactivity of alkynylsamariums toward various
electrophiles. q 2000 Elsevier Science Ltd. All rights reserved.
1
1
Introduction
successfully proceeded. Recently, we reported coupling
reactions of alkynyl iodides with carbonyl compounds via
1
2
In the past decade, many types of reactions involving
alkynylsamariums. We now report our further studies on
the generation and the reactivity of alkynylsamariums.
1
±7
organosamariums have been developed. The most useful
and common reactions of organosamariums for carbon±
carbon bond formation are the samarium Barbier reaction
8
(
SBR) and the samarium Grignard reaction (SGR). The
Results and Discussion
principal advantages of SBR and SGR in comparison with
conventional reactions of magnesium or lithium lie in their
ability to effect rapid, mild and chemoselective reduction of
organohalides. Both inter- and intramolecular versions of
these reactions using primary and secondary alkyl halides
have been well established. Combining SGR or SBR with
Reduction of organohalides with SmI is probably the most
2
common method for generating organosamariums. Thus we
have chie¯y employed the reaction of 1-iodoalkynes with
SmI to generate alkynylsamariums. More direct methods of
2
generating alkynylsamariums that avoid the preparation of
1-iodoalkynes from 1-alkynes would be both useful and
practical. For this reason, we explored other methods
involving deprotonation of 1-alkynes at the terminal
sp-carbon by an organosamarium or by a base, like butyl-
lithium followed by metal±metal exchange.
other anionic or radical processes induced by SmI enables
2
the construction of complex molecules in a one-pot reaction
(
sequential reaction).5,6 Curran and Totleben studied the
generation, reactivity and stability of alkylsamariums exten-
3
c
sively. In particular, they examined the reactions of alkyl-
samariums with several kinds of electrophiles. In contrast
to these thorough studies on alkylsamarium, reactions
involving aryl-, vinyl-, or alkynylsamariums are very
limited. Because aryl or vinyl radicals abstract a hydrogen
SBR and SGR of 1-iodoalkynes
Reaction of iododecyne (1a, 1.0 equiv.) and dibutyl ketone
2, 1.5 equiv.) with SmI (4 equiv.) carried out by the SBR
2
from THF when it is used as a solvent faster than they are
reduced by SmI , these reactive radicals resulting from a
(
9
2
single electron transfer (SET) from SmI to aryl or vinyl
2
halides are dif®cult to transform into the corresponding
1
0
organosamariums. We were able to overcome this dif®-
culty by using a benzene-HMPA system, in which the
coupling of aryl or vinyl halides with carbonyl compounds
Keywords: samarium and compounds; Grignard reactions/reagents;
alkynes; alkynyl halides.
* Corresponding author. Tel.: 181-78-974-1551; fax: 181-78-974-5689;
e-mail: kunisima@kgu-p.pharm.kobegakuin.ac.jp
Scheme 1.
0040±4020/00/$ - see front matter q 2000 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(00)00971-6

9
928
M. Kunishima et al. / Tetrahedron 56 (2000) 9927±9935
Table 1. Samarium Barbier reactions of 1-iodoalkynes in benzene
a
Run
1
R of iodoalkynes
Yield of alkyne adduct (%)
1a
1a
76
b
76
2
3
4
1b Ph
2
75
78
2
5
6
1a
1a
EtCHO 6
58
65
7
1a
67
a
Isolated yield. 1:ketone or aldehyde:SmI
A mixture (84:16) of axial/equatorial alcohols, whose stereochemistry is not determined.
2
ˆ1.0:1.5:4.0.
b
method in benzene-HMPA (9:1) afforded 5-butylpentadec-
6-yn-5-ol (3) in 78% yield, as illustrated in Scheme 1, Run
SBR conditions presumably because of their high reactivity
toward SmI , were allowed to couple with iodoalkyne under
the SGR conditions. Under SGR conditions, coupling of
alkynylsamariums (13a) with a hydroxyketone (11) occurs
more quickly than protonation by the hydroxy group.
2
1
5
1
3
1. Similarly, both aliphatic ketones (2, 4, 5) and aldehydes
(
6, 7) gave the corresponding propargyl alcohols in fairly
good yields (see Table 1). In the case of a keto ester (8),
alkynylation took place chemoselectively at the ketone.
Alkynylation was found to proceed under SGR conditions
(Scheme 1, Run 2). Thus treatment of 1a with SmI in
2
benzene-HMPA for 10 min, followed by sparging with dry
air in an effort to decompose excess SmI with oxygen prior
2
to addition of 2, afforded 3 in 70% yield.
1
4
ꢀ1†
In contrast to alkenyl and arylsamariums, which generally
do not form in THF, alkynylsamariums can be generated in
THF and undergo coupling with ketones in good yield,
using either the Barbier or the Grignard method (Scheme
These ®ndings clearly indicate that alkynylsamariums act as
an intermediate in both benzene-HMPA and THF-HMPA.
To examine the stability of alkynylsamariums, we added
acetophenone (9) at de®ned times to a stirred reaction
9
1, Run 3, 4). The SBR reaction of 1a and 2 with a large
excess amount of SmI performed in THF-HMPA (9:1)
gave the alcohol (3) in 84% yield, and no THF-adduct
mixture of 1a and SmI . Yields of the alkyne adduct (14)
2
as a function of the reaction time indicate the half-life period
of decynylsamarium in THF to be 5 h at 258C.
2
(
SmI was quenched with D O instead of the addition of
12) was detected. When the reaction mixture of 1a and
2
2
Generation of alkynylsamariums from terminal alkynes
ketone (2), incorporation of 60% deuterium atom at the
terminal sp-carbon of 1-decyne (65% yield) was observed
Because the terminal C±H bonds of alkynes are more acidic
than the C±H bonds of alkanes, we assumed that deproto-
nation of alkynes by alkylsamariums could afford alkynyl-
samariums. A mixture of an alkyl iodide and 1-decyne (15a)
(
Eq. (1)). No signi®cant difference between benzene and
THF was observed; however, the SGR procedure seems to
produce better results than the SBR procedure. As shown in
Table 2, both aromatic ketone (9) and a,b-unsaturated
ketone (10), which were found to be unsuitable for the
in THF was treated with SmI for 30 min followed by
2
addition of 9. As summarized in Table 3, Runs 1±5, this
process was unsuccessful when primary, secondary and
tertiary iodides were used. In contrast to the results obtained
with alkyl iodides, 49% yield of the alkynyl adduct (14) was
obtained by using iodobenzene. The yield of 14 was
improved to 81% by increasing the amounts of reagents
Table 2. Samarium-mediated coupling reactions of 1-iododecyne (1a) and
carbonyl compounds
a
Yield of alkyne adduct (%)
b
SBR in benzene SGR in benzene SGR in THF
c
d
[
(
iodobenzene (3 equiv.), SmI (6 equiv.) and acetophenone
2
3 equiv.)]. To further examine the reaction pathway, we
d
0
0
0
64
46
92
55
46
carried out additional experiments, as illustrated in Eqs.
2) and (3). Treatment of iodobenzene and 15a with SmI2
in the presence of dibutyl ketone gave the THF adduct (12)
(
d
d
in 41% yield without the formation of the alkyne adduct.
Iodobenzene with SmI in THF is known to generate tetra-
e
46
2
hydrofurylsamarium (16) as a result of a hydrogen atom
abstraction from THF by a phenyl radical. Tetrahydro-
a
b
c
d
e
Isolated yield.
a:ketone or aldehyde:SmI
a:ketone or aldehyde:SmI
A complex mixture composed of many products was obtained.
a:ketone or aldehyde:SmI
ˆ2.0:1.0:5.0.
9
1
1
2
ˆ1.0:1.5:4.0.
furylsamarium (16), probably formed in the same way,
underwent coupling with ketone faster than deprotonation
2
ˆ1.0:1.5:2.5.
16
from 15a in the presence of ketones. In the absence of
1
2

M. Kunishima et al. / Tetrahedron 56 (2000) 9927±9935
9929
Table 3. Attempt to generate decynylsamarium by deprotonation with
alkylsamariums
Table 4. Grignard-type coupling of alkynylsamariums generated by the
mediation of iodobenzene
Run
RI
Yield
1
R COR
2
a
Yield (%)
R
1
2
3
EtI
i-PrI
0%
12%
0%
18%
trace
49%
81%
trace
a
c-C
c-C
6
H
H
11
I
9
9
9
76
60
40
4
5
6
5
9
I
t-BuI
PhI
PhI
3
Me Si-
b
9
2
72
56
7
c
8
PhI
C
C
8
H
H
17
17
±
±
b
8
2
Ac O
43
a
The ratio of decyne:RI:9:SmI
The ratio of decyne:RI:9:SmI
Performed in THP in place of THF.
2
is 1:1.5:1.5:3.
is 1:3:3:6.
b
c
a
The corresponding propargyl alcohols were formed.
Decynyl methyl ketone was obtained.
2
b
ketones, the deprotonation proceeded to give decynyl-
samarium. In fact, stepwise addition of the reactants to a
solution of SmI in the order of iodobenzene, 15a, and 9
Actually, neither the ethyl nor isopropyl adduct was
detected as a by-product in either conditions.
2
yielded 14 (25%) as a major product; no THF adduct (17)
was observed (Eq. (3)). Interestingly, the reaction
performed in THP in place of THF gave only a trace of
14 along with starting materials (Table 3, Run 8). The
poor result in THP also indicates the mediation of THF.
We attempted the reaction using cyclohexyl iodide because
the compound is known to undergo both SBR and SGR
3
c
reaction in good yields. Surprisingly, no decynyl adduct
was formed along with the 24% yield of the cyclohexyl
adduct. As described above, decynylsamarium should be
stable during the reaction and give its adduct in a reasonable
yield; therefore, proton transfer from 15a to cyclohexyl-
samarium would be quite slow. It is not clear why only
ꢀ
2†
1
6 deprotonates effectively from 15a while other alkyl-
samariums do not. It is possible that the etheral oxygen of
THF participates in or promotes the deprotonation step. The
generation of 14, albeit in a low yield (18%), when cyclo-
pentyl iodide was used may indicate that ®ve-membered
cycloalkylsamariums are more liable to deprotonation.
The poor yield observed in THP may support the latter
supposition. Otherwise, the unsuccessful result in THP
can be attributed to decreasing the rate of a hydrogen
atom abstraction of phenyl radical from THP.6a Some
examples for SGR using the iodobenzene-alkyne-SmI2
system are shown in Table 4. Phenyl- and trimethylsilyl-
acetylene as well as aliphatic alkynes were available.
ꢀ
3†
An alternative method of generating alkynylsamariums by
1
7,18
deprotonation is via a metal±samarium exchange.
examine this possibility, we treated 1-decynyllithium with
To
The result with t-butyl iodide (Table 3, Run 5), in which
neither the t-butyl adduct nor the decynyl adduct was
formed, is in good agreement with the fact that tertiary
alkyl iodides are not converted into alkylsamariums by
SmI , generated from Sm and I , at 2788C for 0.5 h. The
3
2
mixture was then treated with 9 to give 14 in 77% yield (Eq.
(4)). The actual reactive species adding to the ketone can be
considered decynylsamarium (13a) rather than decynyl-
lithium, as discussed in the next section.
3
c
SmI2. Curran and Totleben reported that ethyl and iso-
propyl iodide underwent SBR in fair to good yield whereas
no coupling occurred by SGR because of their instability
3
c
under the SGR conditions. Their results indicate that ethyl-
and isopropylsamarium can be generated from the corre-
sponding halides with SmI but are too unstable to undergo
2
ꢀ
4†
coupling with ketones under SGR conditions. Therefore, the
poor results with ethyl and isopropyl iodide (Runs 1, 2) can
be attributed to the decomposition of the alkylsamarium
intermediates before deprotonation from 1-alkynes.

9
930
M. Kunishima et al. / Tetrahedron 56 (2000) 9927±9935
Table 5. Attempt to trap decynylsamarium with various electrophiles
a
Reported by Curran and Totleben; Ref. 3c. The `unsuccessful' indicates that either poor yields of product or no product was obtained.
1
b
1
a:SmI
2
:E ˆ1:2:1.
c
1
1
A 2/1 mixture of S
a:SmI
2
:E ˆ1:2.5:1.5.
d
0
N
2 /S 2 regioisomers.
N
e
f
Silylation of per¯uoroalkylsamarium was reported to be successful: Ref. 17.
O as an acid anhydride.
The result using (i-PrO)
2
g
h
i
Molander and McKie also reported: Ref. 3d.
The result using PhCOCl as an acid chloride.
NC: not conducted.
0
moderate yield with a low S 2/S 2 selectivity. TMSCl,
N N
Coupling reaction of alkynylsamariums with
electrophiles
which does not couple with an alkylsamarium, underwent
coupling with 13a in 71%.
1
8b,19
By contrast, diphenyl-
To survey the chemical property of alkynylsamariums, we
explored reactions of decynylsamarium with several kinds
of electrophiles. 1-Iododecyne was treated with SmI for
disul®de, which reacts with an alkylsamarium, did not
react with 1-decynylsamarium. An acid anhydride was
found to successfully react to give the corresponding
alkynyl ketone along with the bisdecynylated tertiary alco-
hol whereas an acid chloride yielded neither the ketone nor
the alcohol. The reactivity of alkynylsamariums toward an
acid anhydride and an acid chloride is similar to that of
2
1
±10 min followed by addition of an electrophile, and the
reaction mixture was stirred for 1±2 h. Results are summar-
ized in Table 5 along with those of alkylsamariums reported
3
c
by Curran and Totleben for comparison. As is evident, the
reactivity of alkynylsamariums is considerably different
from that of alkylsamariums. The H NMR spectra of the
3
c,d
alkylsamariums.
Reaction with the activated ester
1
derived from 3-phenylpropionic acid and 4-nitrophenol or
N-hydroxysuccinimide resulted in the formation of bis-
decynylated alcohol. The reaction with 3-phenylpropyl
bromide or benzyl bromide was unsuccessful, giving the
corresponding alkyl iodides that were probably formed by
halogen-exchange. Although reductive coupling of benzyl
bromide giving 1,2-diphenylethane was reported in the case
of an alkylsamarium,3c no such product was obtained with
alkynylsamariums under the conditions we employed.
crude products indicated that the common by-product was
1-decyne along with unreacted starting material 1-iodode-
cyne in every case. Allyl bromide, which was reported to
afford a trace amount of coupling product with alkylsamar-
ium, was found to couple with 1-decynylsamarium in 71%
yield. Prenyl bromide reacted with 1-decynylsamarium
selectively at the allylic position (S 2 process) in 88%
N
yield whereas an alkylsamarium was shown to react in a

M. Kunishima et al. / Tetrahedron 56 (2000) 9927±9935
9931
Alkynylsamariums generated from iodoalkynes and SmI2
coupled with ketone in good yield under SGR conditions
and did not couple with 3-phenylpropyl or benzyl bromide
(see Table 5, Run 10, 11). On the other hand, decynyllithium
underwent coupling with these alkyl bromides (Eq. (5)).
SmI to its anion (16), which undergoes deprotonation from
2
the alkyne to lead to the corresponding alkynylsamarium.
Evidence supporting the possibility of this mechanism
involving deprotonation by 16 was provided by the reac-
tions using iodobenzene and 1-decyne, as described in Eq.
(3) and Tables 3 and 4. However, the reaction of iodo-
When decynyllithium was treated with SmI followed by
3
addition of these alkyl bromides, no coupling product was
formed (Eq. (5)). These results indicate that the reactivity of
decynyl anion generated from lithium±samarium exchange
is more similar to that of decynylsamarium generated from
benzene and 1-decyne with SmI in the presence of a ketone
2
gave the THF adduct only (Eq. (2)) whereas SBR of
iodoalkynes with ketones in THF afforded the alkyne adduct
only without THF adduct. This inconsistency indicates the
possibility that another mechanism is involved, one that
does not generate the alkynyl radicals shown in path a.
1-iododecyne than that of decynyllithium. The observed
reactivity of alkynylsamariums toward electrophiles is
useful for chemoselective alkynylation. For example,
when decynylsamarium 13a generated from 1a under
SGR conditions was treated with a mixture of allyl bromide
2
1
Since alkynyl radicals are very unstable, a radical (18)
resulting from complexation of SmI and iodoalkyne (1)
2
could receive the second electron from another SmI faster
2
2
2
(
1.5 equiv.) and 3-phenylpropyl bromide (1.5 equiv.),
than elimination of SmI giving an alkynyl radical.
3
tridec-1-en-4-yne was selectively produced in 79% yield
with no detectable amount of 1-phenyl-4-tridecyne, whereas
the reaction using decynyllithium under similar conditions
gave the both coupling compounds (Eq. (6)). For another
example, in contrast to the chemoselective reaction of
decynylsamarium with keto ester of 8 (Table 1, run 7), a
reaction of decynyllithium with 8 resulted in the formation
of a complex mixture of unidenti®ed products.
ꢀ
5†
Scheme 2.
Conclusion
In this paper, we have described the generation, stability,
and reactivity of alkynylsamariums. As noted, three
methods are available for generating alkynylsamariums:
(
1) reduction of alkynyl halides with SmI in THF or
2
ꢀ
6†
benzene in the presence of HMPA, (2) deprotonation at
the terminal position of 1-alkynes by tetrahydrofurylsamar-
ium generated by iodobenzene and SmI in THF, (3) metal±
2
metal exchange between alkynyllithium and SmI3.
Reaction of alkynyl halides with ketones or aldehydes took
place under SGR conditions as well as SBR conditions. The
scope of SGR is broader than the SBR, however, because
SGR is applicable to carbonyl compounds that are either
Mechanistic considerations in the generation of
alkynylsamariums from iodoalkynes
susceptible to reduction by SmI or that possess hydroxyl
2
group. Tetrahydrofurylsamarium was found to be the most
effective in deprotonating terminal alkynes among various
alkylsamariums such as ethyl-, isopropyl-, cyclohexyl-, and
cyclopentylsamarium.
It is reasonable to assume that the alkynylsamariums would
be generated by successive single electron transfers from
SmI to alkynyl iodides via alkynyl radicals in benzene-
2
2
0
HMPA (Scheme 2, path b). In the case of THF-HMPA,
however, a similar mechanism leading to the formation of
alkynylsamariums seems to be unlikely, if alkynyl radicals,
which are a very energetic species and therefore very reac-
tive toward THF, are involved. A more likely explanation
for the generation of alkynylsamariums in THF is shown in
path c. An initially formed alkynyl radical would abstract a
hydrogen atom from THF to afford an alkyne and tetra-
hydrofuryl radical. The radical would then be reduced by
Because the reactivity of alkynyl anion generated by the
metal±metal exchange toward electrophiles was similar to
that formed by reduction of iodoalkynes rather than that of
alkynyllithium, the reactive species arising from the metal±
metal exchange is most probably an alkynylsamarium.
Alkynylsamariums successfully coupled with allyl halides,
prenyl bromide, TMSCl, and acetic anhydride as well as
carbonyl compounds (under SGR conditions). Diphenyl
2
1

9
932
M. Kunishima et al. / Tetrahedron 56 (2000) 9927±9935
2
1
disul®de, alkyl bromides, acetyl chloride did not undergo
coupling. The observed reactivity of alkynylsamariums
toward electrophiles is considerably different from that of
alkynyllithiums as well as alkylsamariums, and therefore,
seems to be synthetically useful to achieve chemoselective
alkynylation that cannot be effected by alkynyllithiums. In
2171 cm ; HRMS calcd for C H I 227.9436, found
8 5
227.9437; Anal. Calcd for C H I: C, 42.14; H, 2.21.
8
Found: C, 41.96; H, 2.27.
5
1
1-Iodo-3-cyclopentylpropyne (1c). A colorless oil;
NMR (CDCl ) d 1.19±1.30 (m, 2H), 1.48±1.69 (m, 4H),
H
3
addition, both the methods using SmI (reduction of alkynyl
2
1.73±1.83 (m, 2H), 2.04 (sept, 1H, Jˆ7.0 Hz), 2.36 (d, 2H,
2
1
iodides and deprotonation of alkyne with iodobenzene/THF
system) that allow generating alkynylsamariums under non-
basic conditions at room temperature are practically useful.
Jˆ7.0 Hz); IR (®lm) 2184, 2152 cm ; HRMS calcd for
C H I 234.9906, found 233.9886.
8 11
General procedure for samarium Barbier reactions. 5-
Butyl-6-pentadecyn-5-ol (3)
Experimental
A mixture of 1a (21.2 mg, 0.080 mmol) and 2 (17.2 mg,
0.12 mmol) in benzene (1.5 mL) was added to SmI in
2
benzene (3 mL of 0.11 M solution, 0.32 mmol) containing
General methods
1
-Iodoalkynes (1a±c) were prepared from 1-alkynes
HMPA (291 mL, 1.62 mmol) at rt. After 25 min, the
reaction mixture was poured into aqueous NaHCO solution
according to the previously published procedure.23
3
2
-Benzyloxy-1-heptyne was prepared from 5-hexyn-1-ol
4
6
and benzyl bromide. Ethyl 7-oxooctanoate (8), 4-nitro-
and extracted with ether. The organic layer was washed with
water and brine, dried over MgSO , and concentrated.
2
5
4
2
phenyl 3-phenylpropionate, and O-(3-phenylpropionyl)-
6
Puri®cation of the residue by preparative TLC (hexane/
AcOEtˆ8:2) gave 17.6 mg (0.063 mmol, 78% yield) of 3
2
N-hydroxysuccinimide were prepared from the corre-
7
2
sponding acids by esteri®cation using DCC. SmI was
8
1
as a colorless oil: H NMR (CDCl ) d 0.88 (t, 3H,
3
3
prepared from samarium metal and I prior to use according
2
Jˆ7.0 Hz), 0.92 (t, 6H, Jˆ7.3 Hz), 1.24±1.51 (m, 20H),
2
9
to the literature. Other chemicals were obtained from
1
7.0 Hz); IR (®lm) 3415, 2230 cm ; MS m/z 262
.56±1.63 (m, 4H), 1.81 (br s, 1H), 2.19 (t, 2H, Jˆ
2
1
commercial sources. Dry benzene, THF, Et O was prepared
2
by distillation from sodium/benzophenone prior to use.
HMPA was distilled from CaH prior to use. Chemical shifts
1
[
12.94. Found: C, 81.08; H, 12.69.
(M2H O) ]; Anal. Calcd for C H O: C, 81.36; H,
2 19 36
2
1
13
of H (400 MHz) and C NMR (100 MHz) spectra were
recorded in ppm (d) down®eld from TMS as an internal
standard. Preparative thin-layer chromatography (TLC)
was performed on Merck precoated silica gel F-254 plates.
1
-Benzyl-6-pentadecyn-5-ol. A pale yellow oil; H NMR
5
(
CDCl ) d 0.89 (t, 3H, Jˆ7.1 Hz), 0.93 (t, 3H, Jˆ7.3 Hz),
3
1
2
.20±1.70 (m, 18H), 1.76 (br s, 1H), 2.16 (t, 2H, Jˆ7.1 Hz),
.86 (d, 1H, Jˆ13.1 Hz), 2.95 (d, 1H, Jˆ13.1 Hz), 7.23±
2
1
Preparation of SmI in benzene-HMPA
2
7.36 (m, 5H); IR (®lm) 3460 2220 cm ; HRMS calcd for
C H O 314.2610, found 314.2605; Anal. Calcd for
2
2
34
A solution of 1,2-diiodoethane (3.0 g, 10.6 mmol) in
benzene (96 mL) containing 10% HMPA (10.7 mL,
C H O: C, 84.02; H, 10.90. Found: C, 83.77; H, 11.05.
22 34
5
1
7.8 mmol) was added slowly to samarium powder (2.4 g,
6.0 mmol) at 1008C under nitrogen ¯ow. The mixture was
4-t-Butyl-1-(1-decynyl)cyclohexanol. The stereochemistry
of diastereomers is not determined. The major isomer: 61%
re¯uxed with stirring overnight to give a purple solution.
Concentration of the solution was determined by back-
titration (treatment with an excess solution of iodine in
dry toluene, then the remaining iodine was titrated with
sodium thiosulfate).
yield; R ˆ0.18 (hexane/AcOEtˆ9:1); colorless crystals; mp
f
1
44.5±45.08C; H NMR (CDCl ) d 0.87 (s, 9H), 0.88 (t, 3H,
3
Jˆ6.8 Hz), 0.98 (tt, 1H, Jˆ11.9, 3.4 Hz), 1.22±1.55 (m,
16H), 1.68±1.76 (m, 2H), 1.77(br s, 1H), 1.93±2.00 (m,
2H), 2.22 (t, 2H, Jˆ7.0 Hz); IR (KBr) 3247, 2964, 2859,
2
1
2
240, 1469 cm ; Anal. Calcd for C H O: C, 82.13; H,
20 36
General procedure for the preparation of 1-iodo-1-
alkyne 1-Iodo-1-decyne (1a)
12.40. Found: C, 81.94; H, 12.21. The minor isomer: 11%
1
yield; R ˆ0.42 (hexane/AcOEtˆ9:1); a colorless oil; H
f
NMR (CDCl ) d 0.85 (s, 9H), 0.88 (t, 3H, Jˆ7.1 Hz),
3
BuLi (1.6 M in hexane, 12.0 mmol) was added to a solution
of 1-decyne (10.0 mmol) in THF (20 mL) at 2108C. After
0.98 (tt, 1H, Jˆ12.1, 3.1 Hz), 1.21±1.42 (m, 12H), 1.43±
1.70 (m, 7H), 1.94±2.01 (m, 2H), 2.17 (t, 2H, Jˆ7.1 Hz); IR
2
1
1
(
h at 210±08C, iodine (13.0 mmol) dissolved in THF
5 mL) was added dropwise at 2788C, and the reaction
(®lm) 3400, 2240 cm ; HRMS calcd for C H O
20 36
292.2766, found 292.2748; Anal. Calcd for C H O: C,
20 36
mixture was stirred overnight at rt. The reaction mixture
was poured into saturated Na S O , and extracted with
ether. A crude mixture was distilled under reduced pressure
82.13; H, 12.40. Found: C, 81.87; H, 12.36.
2
2
3
1
3-Butyl-1-phenyl-1-heptyn-3-ol. A pale yellow oil;
H
1
to give 1a as a colorless oil: H NMR (CDCl ) d 0.88 (t, 3H,
3
NMR (CDCl ) d 0.95 (t, 6H, Jˆ7.3 Hz), 1.39 (sext, 4H,
3
Jˆ7.0 Hz), 1.21±1.43 (m, 10H), 1.46±1.56 (m, 2H), 2.35 (t,
Jˆ7.4 Hz), 1.50±1.60 (m, 4H), 1.70±1.77 (m, 4H), 2.02
2
1
2
H, Jˆ7.1 Hz); IR (®lm) 2925, 2856, 2200, 1465 cm ;
(s, 1H), 7.27±7.33 (m, 3H), 7.39±7.44 (m, 2H); IR (®lm)
3390, 2210 cm ; HRMS calcd for C H O 244.1827,
2
1
Anal. Calcd for C H I: C, 45.47; H, 6.49. Found: C,
1
0
17
17 24
45.22; H, 6.56.
found 244.1823; Anal. Calcd for C H O: C, 83.55; H,
1
7
24
9
.90. Found: C, 83.29; H, 9.87.
1
-Iodo-2-phenylacetylene (1b). A pale yellow oil; H NMR
CDCl ) d 7.25±7.35 (m, 3H), 7.39±7.46 (m, 2H); IR (®lm)
3
1
(
1
4-Butyl-1-cyclopentyl-2-octyn-4-ol. A colorless oil; H

M. Kunishima et al. / Tetrahedron 56 (2000) 9927±9935
9933
Figure 1. Linear rate plot for the formation of 4 after a de®nite time stirring of a decynylsamarium intermediate.
2
3H), 7.64±7.68 (m, 2H); IR (®lm) 3409, 2242 cm ; MS m/z
1
NMR (CDCl ) d 0.92 (t, 6H, Jˆ7.2 Hz), 1.22±1.40 (m, 6H),
3
1
240 [(M2H O) ]; Anal. Calcd for C H O: C, 83.67; H,
10.14. Found: C, 83.37; H, 10.42.
1
1
2
.42±1.68 (m, 12H), 1.72±1.83 (m, 2H), 1.82 (br s, 1H),
.97±2.09 (m, 1H), 2.20 (d, 2H, Jˆ6.7 Hz); IR (®lm) 3430,
2
18 26
2
1
230 cm ; MS m/z 232 [(M2H O) ]; Anal. Calcd for
1
2
1
1-(1-Decynyl)-2-cyclohexen-1-ol. A colorless oil; H NMR
C H O: C, 81.54; H, 12.07. Found: C, 81.45; H, 12.36.
30
1
7
(
CDCl ) d 0.88 (t, 3H, Jˆ7.1 Hz), 1.20±1.40 (m, 10H),
3
1
-Tridecyn-3-ol. A colorless oil; H NMR (CDCl ) d 0.88
4
(
1
(
1.45±1.54 (m, 2H), 1.71±1.80 (m, 2H), 1.85±1.93 (m,
1H), 1.94 (s, 1H), 1.96±2.06 (m, 3H), 2.20 (t, 2H,
Jˆ7.2 Hz), 5.73 (dt, 1H, Jˆ9.9, 1.9 Hz), 5.80 (dt, 1H,
3
t, 3H, Jˆ7.0 Hz), 1.00 (t, 3H, Jˆ7.4 Hz), 1.21±1.43 (m,
0H), 1.50 (quint, 2H, Jˆ7.4 Hz), 1.63±1.76 (m, 3H), 2.20
2
1
td, 2H, Jˆ7.1, 2.0 Hz), 4.27±4.34 (m, 1H); IR (®lm) 3360,
Jˆ9.9, 3.5 Hz); IR (®lm) 3382, 2235, 1648 cm ; HRMS
2
1
1
250 cm ; MS m/z 178 [(M2H O) ]; Anal. Calcd for
1
2
C H O: C, 79.53; H, 12.32. Found: C, 79.64; H, 12.62.
calcd for C H [(M2H O) ] 216.1878, found 216.1881;
16 24
2
2
Anal. Calcd for C H O: C, 81.99; H, 11.18. Found: C,
16 26
1
3
24
8
1.64; H, 11.28.
1
-Phenyl-4-tridecyn-3-ol. A colorless oil; H NMR
1
(
1
(
1
4-Methyl-5-tetradecyn-1,4-diol. A pale yellow oil; H
CDCl ) d 0.88 (t, 3H, Jˆ7.0 Hz), 1.20±1.44 (m, 10H),
3
.47±1.56 (m, 2H), 1.75 (d, 1H, Jˆ5.4 Hz), 1.92±2.07
NMR (CDCl ) d 0.88 (t, 3H, Jˆ7.1 Hz), 1.20±1.42 (m,
3
m, 2H), 2.22 (td, 2H, Jˆ7.1, 2.0 Hz), 2.79 (t, 2H,
10H), 1.45±1.54 (m, 2H), 1.49 (s, 3H), 1.65 (br s, 1H),
1.68±1.93 (m, 4H), 2.18 (t, 2H, Jˆ7.1 Hz), 2.65 (br s,
Jˆ7.9 Hz), 4.32±4.40 (m, 1H), 7.16±7.23 (m, 3H), 7.25±
2
.31 (m, 2H); IR (®lm) 2230 cm ; HRMS calcd for
1
21
1H), 3.64±3.79 (m, 2H); IR (®lm) 3385, 2230 cm ; MS
7
C H O 272.2140, found 272.2143; Anal. Calcd for
1
m/z 207 [(M2H O) ]; Anal. Calcd for C H O : C,
74.95; H, 11.74. Found: C, 74.66; H, 11.99.
1
9
28
2
15 28
2
C H O: C, 83.77; H, 10.36. Found: C, 83.48; H, 10.34.
28
1
9
Ethyl 7-hydroxy-7-methyl-8-heptadecynoate. A pale
Stability of alkynylsamarium. A solution of 1a (20 mg,
0.08 mmol) in THF (0.5 mL) was added to SmI2
(0.102 M, 1.4 mL, 0.14 mmol) in THF containing HMPA
(137 mL, 0.79 mmol) at 258C. After a de®nite time of stir-
ring (10 min, 30 min, 60 min, 180 min, and 600 min), 9
(9.1 mg, 0.08 mmol) was added. The reaction mixture was
stirred for 30 min, then poured into water and extracted with
1
yellow oil; H NMR (CDCl ) d 0.88 (t, 3H, Jˆ7.0 Hz),
3
1
1
2
3
3
7
.26 (t, 3H, Jˆ7.1 Hz), 1.23±1.44 (m, 12H), 1.45 (s, 3H),
.46±1.70 (m, 8H), 1.84 (s, 1H), 2.18 (t, 2H, Jˆ7.1 Hz),
.30 (t, 2H, Jˆ7.7 Hz), 4.12 (q, 2H, Jˆ7.1 Hz); IR (®lm)
467, 2238, 1737 cm ; HRMS calcd for C H O
3
2
1
2
0
36
24.2664, found 324.2646; Anal. Calcd for C H O : C,
3
2
0
36
4.03; H, 11.18. Found: C, 73.51; H, 11.06.
ether. The organic layer was washed with water and brine,
and dried over MgSO . The yields of 14 determined by H
1
4
General procedure for samarium Grignard reactions.
-Butyl-6-pentadecyn-5-ol (3)
NMR using dibenzyl ether (5.1 mg, 0.028 mmol) as an
internal standard were 62% (10 min), 59% (30 min), 49%
5
(60 min), 48% (180 min), and 15% (600 min), respectively.
The half-life period (ln 2/k) of decynylsamarium was calcu-
lated to be 301 min from linear rate plot (Fig. 1).
A solution of 1a (23.4 mg, 0.089 mmol) in benzene
(
(
(
1.0 mL) was added to a solution of SmI in benzene
2
3 mL of 0.12 M solution, 0.35 mmol) containing HMPA
300 mL, 1.72 mmol) at rt. After 10 min, dry air was intro-
Coupling reaction of decynylsamarium with various
electrophiles
duced until the deep purple color of SmI disappeared,
2
followed by addition of 2 (18.9 mg, 0.13 mmol). The reac-
tion mixture was stirred for 10 min, poured into aqueous
NaHCO solution, and extracted with ether. Puri®cation of
3
Reactions were conducted by a method similar to that of the
SGR.
the residue by preparative TLC (hexane/AcOEtˆ8:2) gave
3
0
Tridec-1-en-4-yne. A colorless oil; H NMR (CDCl ) d
1
17.3 mg (0.062 mmol, 70% yield) of 3. 2-Phenyl-3-dode-
cyn-2-ol (14): a yellow oil; H NMR (CDCl ) d 0.88 (t, 3H,
3
1
0.88 (t, 3H, Jˆ6.8 Hz), 1.21±1.43 (m, 10H), 1.45±1.55 (m,
2H), 2.18 (tt, 2H, Jˆ2.4, 7.0 Hz), 2.91±2.97 (m, 2H), 5.09
(dq, 1H, Jˆ1.8, 10.0 Hz), 5.31 (dq, 1H, Jˆ1.8, 16.9 Hz),
3
Jˆ7.1 Hz), 1.20±1.47 (m, 10H), 1.51±1.59 (m, 2H), 1.74 (s,
3H), 2.27 (t, 2H, Jˆ7.1 Hz), 2.27 (s, 1H), 7.24±7.39 (m,

9
934
M. Kunishima et al. / Tetrahedron 56 (2000) 9927±9935
1
3
z1
found 308.1732; for C H O [(M2Me) ] 293.1542, found
20 21 2
293.1533.
5
1
.83 (ddt, 1H, Jˆ5.2, 10.0, 16.9 Hz); C NMR (CDCl ) d
3
4.1, 18.8, 22.7, 23.2, 28.9, 29.1 (2C), 29.2, 31.9, 76.5, 83.0,
2
15.5, 133.5; IR (®lm) 1643 cm ; Anal. Calcd for C H :
1
1
C, 87.56; H, 12.44. Found: C, 87.09; H, 12.49.
13 22
1
2,4-Diphenyl-3-butyn-2-ol. A colorless oil; H NMR
CDCl ) d 1.87 (s, 3H), 2.46 (s, 1H), 7.28±7.35 (m, 4H),
7.36±7.42 (m, 2H), 7.45±7.51 (m, 2H), 7.70±7.76 (m, 2H);
(
3
1
-Methyltetradec-2-en-5-yne. A colorless oil; H NMR
2
(
2
1
CDCl ) d 0.88 (t, 3H, Jˆ6.8 Hz), 1.21±1.40 (m, 10H),
IR (®lm) 3411, 2229 cm ; Anal. Calcd for C H O: C,
16 14
3
1
3
5
1
1
.43±1.52 (m, 2H), 1.61±1.63 (m, 3H), 1.69±1.71 (m,
H), 2.14 (tt, 2H, Jˆ2.4, 7.1 Hz), 2.83±2.88 (m, 2H),
86.45; H, 6.35. Found: C, 86.15; H, 6.44.
1
.15±5.21 (m, 1H); C NMR (CDCl ) d 14.1, 17.6, 17.9,
3
2-Phenyl-4-trimethylsilyl-3-butyn-2-ol. A colorless oil;
H NMR (CDCl ) d 0.20 (s, 9H), 1.75 (s, 3H), 2.35 (s,
3
1
8.8, 22.7, 25.5, 28.9, 29.1 (2C), 29.2, 31.9, 78.8, 79.9,
20.0, 133.2; IR (®lm) 2927, 2856, 1456 cm ; MS m/z
%): 206 (18, M ), 107 (52), 93 (100).
3
2
1
1H), 7.26±7.32 (m, 1H), 7.33±7.39 (m, 2H), 7.63±7.68
(m, 2H); IR (®lm) 3396, 2165 cm ; Anal. Calcd for
1
21
(
C H OSi: C, 71.50; H, 8.31. Found: C, 71.78; H, 8.44.
3
1
18
1
-Decynyltrimethylsilane. A colorless oil; H NMR
1
(
1
2-Phenyl-5-cyclopentyl-3-pentyn-2-ol. A colorless oil; H
NMR (CDCl ) d 1.24±1.36 (m, 2H), 1.49±1.70 (m, 4H),
3
CDCl ) d 0.14 (s, 9H), 0.88 (t, 3H, Jˆ7.0 Hz), 1.20±1.57
3
2
1
(m, 12H), 2.21 (t, 2H, Jˆ7.1 Hz); IR (®lm) 2175 cm ;
Anal. Calcd for C H Si: C, 74.20; H, 12.45. Found: C,
1.74 (s, 3H), 1.75±1.85 (m, 2H), 2.08 (sept, 1H, Jˆ7.4 Hz),
1
3
26
7
4.12; H, 12.72.
2.28 (s, 1H), 2.28 (d, 2H, Jˆ6.8 Hz), 7.25±7.30 (m, 1H),
21
16 20
7.32±7.38 (m, 2H), 7.63±7.69 (m, 2H); IR (®lm) 3407,
2245 cm ; Anal. Calcd for C H O: C, 84.16; H, 8.83.
3
Dodec-3-yn-2-one. A colorless oil; H NMR (CDCl ) d
1
1
3
0
2
.89 (t, 3H, Jˆ6.8 Hz), 1.20±1.45 (m, 10H), 1.53±1.62 (m,
Found: C, 84.19; H, 8.75.
1
3
H), 2.32 (s, 3H), 2.35 (t, 2H, Jˆ7.1 Hz); C NMR (CDCl )
3
d 14.1, 18.9, 22.6, 27.7, 28.9, 29.0, 29.1, 31.8, 32.8, 81.4,
9
2
4.2, 184.9; IR (®lm) 2210, 1677 cm ; MS m/z 180 (M ).
1
1
General procedure for the generation of an alkynyl-
1
31
samarium by Li ±Sm exchange. 2-Phenyl-3-dodecyn-
2-ol (14)
1
1-Methyl-9,12-henicosadiyn-11-ol. A colorless oil; H
1
NMR (CDCl ) d 0.88 (t, 6H, Jˆ6.9 Hz), 1.21±1.42 (m,
3
BuLi (1.5 M in hexane, 0.24 mL, 0.36 mmol) was added to
15a (50.0 mg, 0.36 mmol) in THF (1 mL) at 2788C. After
10 min at 2108C, the reaction mixture was added to SmI
3
2
0H), 1.47±1.57 (m, 4H), 1.72 (s, 3H), 2.20 (t, 4H,
2
1
Jˆ7.2 Hz), 2.32 (s, 1H); IR (®lm) 3417, 2927, 2856 cm ;
z1
HRMS calcd for C H O [(M2Me) ] 303.2688, found
2
1
35
(
1
0.41 mmol) in THF (1 mL) containing HMPA (200 mL,
.15 mmol) at 2788C. After stirring for 30 min 2788C, 9
303.2682.
1
1-Phenethyl-9,12-henicosadiyn-11-ol. A colorless oil; H
(19.8 mg, 0.16 mmol) was added. The reaction mixture was
allowed to warm to rt, and then, stirred for 30 min. The
reaction mixture was quenched, and extracted with ether.
The organic layer was washed with water and brine, dried
1
NMR (CDCl ) d 0.87 (t, 6H, Jˆ6.8 Hz), 1.20±1.45 (m,
3
20H), 1.48±1.58 (m, 4H), 2.14±2.20 (m, 2H), 2.24 (t, 4H,
Jˆ7.1 Hz), 2.36 (s, 1H), 2.87±2.94 (m, 2H),7.16±7.31 (m,
2
H); IR (®lm) 3426, 3025, 2927, 2856 cm ; HRMS calcd
1
over MgSO
by preparative TLC (hexane/AcOEtˆ8:2) gave 14
32.7 mg, 77% yield).
, and concentrated. Puri®cation of the residue
4
5
for C H O 408.3392, found 408.3369.
2
9
44
(
General procedure for the generation of an alkynyl-
samarium by deprotonation using PhI/SmI in THF.
2
2-Phenyl-3-dodecyn-2-ol (14)
References
A solution of iodobenzene (88.5 mg, 0.43 mmol) and 15a
1. For a review on Barbier- and Grignard-type reactions mediated
by SmI : Krief, A.; Laval, A.-M. Chem. Rev. 1999, 99, 745±777.
2. For recent reviews on SmI : (a) Kagan, H. B.; Namy, J. L.
(20.0 mg, 0.145 mmol) in THF (0.5 mL) was added to SmI2
(0.11 M, 7.9 mL, 0.87 mmol) in THF containing HMPA
(791 mL, 4.55 mmol) at rt. After 5 min, dry air (ca.
2
2
Tetrahedron 1986, 42, 6573±6614. (b) Kagan, H. B. New J.
Chem. 1990, 14, 453±460. (c) Soderquist, J. A. Aldrichimica
Acta 1991, 24, 15±23. (d) Molander, G. A. Comprehensive
Organic Synthesis; Trost B. M., Fleming I., Eds.; Pergamon:
Oxford, 1991; Vol. 1, p 251. (e) Molander, G. A. Chem. Rev.
1992, 92, 29±68. (f) Molander, G. A. Org. React. 1994, 46,
211±367. (g) Kunishima, M.; Tani S. J. Synth. Org. Chem., Jpn.
10 mL) was introduced, and then, 9 (52.1 mg, 0.43 mmol)
was added. The reaction mixture was stirred for 30 min,
quenched with water, and extracted with ether. The organic
layer was washed with water and brine, dried over MgSO4,
and concentrated Puri®cation of the residue by preparative
TLC (hexane/AcOEtˆ8:2) gave 14 (30.3 mg, 81% yield).
1
999, 57, 127±135.
1
8-Benzyloxy-2-phenyl-3-octyn-2-ol. A colorless oil; H
NMR (CDCl ) d 1.61±1.80 (m, 4H), 1.74 (s, 3H), 2.26 (s,
3. (a) Molander, G. A.; McKie, J. A. J. Org. Chem. 1991, 56,
4112±4120. (b) Curran, D. P.; Fevig, T. L.; Totleben, M. J. Synlett
1990, 773±774. (c) Curran, D. P.; Totleben, M. J. J. Am. Chem.
Soc. 1992, 114, 6050±6058. (d) Molander, G. A.; McKie, J. A.
J. Org. Chem. 1992, 57, 3132±3139. (e) Curran, D. P.; Fevig T. L.;
Jasperse C. P.; Totleben M. J. Synlett 1992, 943±961. (f)
Hasegawa, E.; Curran, D. P. J. Org. Chem. 1993, 58, 5008±
5010. (g) Curran, D. P.; Gu, X.; Zhang, W.; Dowd, P. Tetrahedron
3
1
2
H), 2.31 (t, 2H, Jˆ7.0 Hz), 3.50 (t, 2H, Jˆ6.1 Hz), 4.50 (s,
1
3
H), 7.24±7.38 (m, 8H), 7.62±7.68 (m, 2H); C NMR
(
CDCl ) d 18.6, 25.4, 29.0, 33.5, 69.8, 70.0, 72.9, 84.1,
3
85.3, 125.0, 127.5 (2C), 127.6, 128.2, 128.4, 138.6, 146.2;
IR (®lm) 3417, 2240, 1095 cm ; MS m/z 290
2
1
1
1
[
(M2H O) ]; HRMS calcd for C H O (M ) 308.1776,
2 21 24 2

M. Kunishima et al. / Tetrahedron 56 (2000) 9927±9935
9935
1
997, 53, 9023±9042. (h) Shabangi, M.; Kuhlman, M. L.; Flowers,
R. A., II. Org. Lett. 1999, 1, 2133±2135.
. For recent work of SmI -mediated Barbier and Grignard reac-
12. Kunishima, M.; Tanaka, S.; Kono, K.; Hioki, K.; Tani, S.
Tetrahedron Lett. 1995, 36, 3707±3710.
7
13. HMPA is essential for the preparation of SmI in benzene as
a
4
2
2
tions or related reactions, see: (a) Kito, M.; Sakai, T.; Shirahama,
H.; Miyashita, M.; Matsuda, F. Synlett 1997, 219±220. (b)
Hamann-Gaudinet, B.; Namy, J.-L.; Kagan, H. B. Tetrahedron
Lett. 1997, 38, 6585±6588. (c) Matsubara, S.; Yoshioka, M.;
Utimoto. K. Angew. Chem., Int. Ed. Engl. 1997, 36, 617±618.
well as for the reduction of iodoalkynes similarly to the reduction
9
b
of organohalides.
14. To eliminate the possibility of Barbier type reaction, excess
SmI2 was decomposed by introducing dry air just before the
addition of a ketone while the deep purple of SmI was remained
2
(
d) Urban, D.; Skrydstrup, T.; Beau, J.-M. J. Org. Chem. 1998,
observable after treatment of the halide with SmI . If the color of
2
6
1
1
3, 2507±2516. (e) Kasuga, Y.; Matsubara, S.; Utimoto, K. Synlett
998, 841±842. (f) Du, X.; Armstrong, R. W. Tetrahedron Lett.
998, 39, 2281±2284. (g) Fukuzawa, S.-I.; Tatsuzawa, M.; Hirano,
2
SmI had already disappeared at this point, this step was omitted.
Although oxidative decomposition of alkylsamariums has been
reported by Molander and McKie (Ref. 3d), the admission of dry
air seems to have had a negligible effect on the product yield in our
case as similar to the results observed by Hasegawa and Curran
K. Tetrahedron Lett. 1998, 39, 6899±6900. (h) Park, H. S.; Lee,
I. S.; Kwon, D. W.; Kim, Y. H. Chem. Commun. 1998, 2745±2746.
(
i) Yang, S.-M.; Fang, J. M. J. Org. Chem. 1999, 64, 394±399. (j)
H e lion, F.; Namy, J.-L. J. Org. Chem. 1999, 64, 2944±2946.
. For reviews on sequential reactions using SmI , see: (a)
(
Ref. 3f).
5. It is known that aromatic ketones or aldehydes and conjugated
enones are highly reducible by SmI . See Ref. 3c.
1
5
2
2
Molander, G. A.; Harris, C. R. Chem Rev. 1996, 96, 307±338.
b) Skrydstrup, T. Angew. Chem., Int. Ed. Engl. 1997, 36, 345±
1
1
6. No reaction occurred without iodobenzene.
7. Metal-samarium exchange giving organosamariums were
(
3
3
6
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