LDA-mediated domino carbolithiation reactions of vinylidenecyclopropanes with but-3-yn-2-one and 1-phenylprop-2-yn-1-one

Article abstract of DOI:10.1016/j.tetlet.2009.11.012

A novel domino carbolithiation reaction of vinylidenecyclopropanes 1 with but-3-yn-2-one and 1-phenylprop-2-yn-1-one by treating with LDA in THF was observed to give the corresponding adducts in moderate to good yields. The scope and limitations as well as the plausible mechanism have been discussed on the basis of control experiments.

Full text of DOI:10.1016/j.tetlet.2009.11.012

Tetrahedron Letters 51 (2010) 321–324
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Tetrahedron Letters
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LDA-mediated domino carbolithiation reactions of vinylidenecyclopropanes
with but-3-yn-2-one and 1-phenylprop-2-yn-1-one
*
Bei-Li Lu, Jian-Mei Lu, Min Shi
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
a r t i c l e i n f o
a b s t r a c t
Article history:
A novel domino carbolithiation reaction of vinylidenecyclopropanes 1 with but-3-yn-2-one and 1-phe-
nylprop-2-yn-1-one by treating with LDA in THF was observed to give the corresponding adducts in mod-
erate to good yields. The scope and limitations as well as the plausible mechanism have been discussed
on the basis of control experiments.
Received 13 October 2009
Revised 3 November 2009
Accepted 3 November 2009
Available online 10 November 2009
Ó 2009 Elsevier Ltd. All rights reserved.
Organolithium chemistry is of unquestionable importance in
organic synthesis.1 Owing to the strongly polarized lithium-carbon
bond, organolithium compounds are used as highly reactive nucle-
ophiles and strong bases in most of C–C bond forming reactions.
Their applications range from simple deprotonation and anionic
polymerization reactions to carbolithiations and asymmetric syn-
theses. Recently, LDA (lithium diisopropylamide)-mediated reac-
tion of vinylidenecyclopropanes2 with a variety of electrophiles
has been extensively disclosed. For example, we previously re-
ported the LDA-mediated selective carbolithiation reactions of
vinylidenecyclopropanes 1 with a variety of electrophiles to give
the corresponding adducts in good yields under mild conditions
along with the further transformation of these products.3
During our ongoing investigation, we found that the LDA-med-
iated domino carbolithiation reactions of vinylidenecyclopropanes
1 with but-3-yn-2-one 2a and 1-phenylprop-2-yn-1-one 2b could
take place smoothly to afford a variety of interesting products in
moderate to good yields and moderate diastereoselectivities. Here-
in, we wish to report these novel results in this Letter along with a
mechanistic discussion.
was found that the corresponding domino addition products 3b–i
were obtained in 70–85% yields (Table 2, entries 1–8). The substit-
uents on the aromatic rings did not have significant influence on
the reaction outcomes. As for VDCPs 1f and 1i in which R4 = Me,
the corresponding domino adducts 3f and 3i were produced ste-
reospecifically as trans-configuration on the basis of previous re-
sults3 and NMR spectroscopic data in 85% and 81% yield,
respectively (Table 2, entries 5 and 8).
Moreover, using 1-phenylprop-2-yn-1-one 2b instead of 2a, the
corresponding domino adducts 4a–e were formed in 55–63% yields
under the standard conditions as shown in Table 3.
Their structures were determined by 1H and 13C NMR spectros-
copy and HRMS. The crystal structure of 3a was determined by
X-ray diffraction (Fig. 1) and its CIF data are presented in the Sup-
plementary data.4
Table 1
Optimization of the reaction conditions of LDA-mediated domino reactions of VDCP la
with but-3-yn-2-one 2a
HO
We started our work by examining the LDA-mediated reaction
of vinylidenecyclopropane (VDCP) 1a (1.0 equiv) with but-3-yn-
2-one 2a (2.0 equiv) at À78 °C in tetrahydrofuran (THF). It was
found that product 3a derived from a domino addition reaction
was formed in 80% yield (Table 1, entry 1). Further investigation
on the reaction conditions revealed that increasing the employed
amount of 2a to 2.5 or 3.0 equiv afforded 3a in 88% yield under
the standard conditions (Table 1, entries 2 and 3).
O
O
2a
Ph
Ph
Ph
LDA
Ph
Ph
THF, -78 oC, 2 h -78 oC, 2 h
Ph
1a
3a
Entrya
Molar ratio of 1a and 2a
Yieldb (%)
1
2
3
1:2.0
1:2.5
1:3.0
80
88
88
Having these optimized reaction conditions in hand, we next
examined the generality of this interesting domino reaction and
the results of these experiments are summarized in Table 2. It
a
After vinylidenecyclopropane 1a (0.2 mmol) was lithiated by LDA (0.4 mmol) at
À78 °C for 2 h, but-3-yn-2-one 2a (0.4–0.6 mmol) was added into the reaction
mixture. Then, the reaction was quenched by the addition of saturated aqueous
ammonium chloride solution after 2 h.
* Corresponding author.
E-mail address: Mshi@mail.sioc.ac.cn (M. Shi).
b
Yield of isolated products.
0040-4039/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2009.11.012

322
B.-L. Lu et al. / Tetrahedron Letters 51 (2010) 321–324
Table 2
another addition products 6a and 6b in 61% and 72% total yield,
respectively as depicted in Table 4, suggesting that the substituent
on the terminal of alkyne can significantly affect the reaction
outcome.
LDA-mediated domino reactions of VDCPs 1 with but-3-yn-2-one 2a
HO
O
R4
O
R3
Using hex-3-yn-2-one 2e as the electrophile in the LDA-medi-
ated reactions with VDCPs 1a, 1k, and 1l under the standard con-
ditions, the addition products 7a–c derived from LDA-mediated
1,2-addition and the products 8a–c derived from LDA-mediated
1,4-addition (Michael addition) were obtained as product mixtures
in good yields and 1.22:1–2.67:1 ratios (Table 5, entries 1–3).
However, using VDCPs 1b, 1g, and 1m as the substrates to react
with 2e under the standard conditions, the corresponding 1,4-
addition products 9a–9c were formed exclusively in good yields
(Table 6, entries 1–3).
R1
R2
LDA
2a
R1
R2
-78 oC, 2 h
THF, -78 oC, 2 h
R3
3
1
R4
Entrya
1 (R1/R2/R3/R4)
Yieldb (%)
1
2
3
4
5
6
7
8
1b (C6H5/C6H5/C6H5/C6H5)
3b, 70
3c, 75
3d, 76
3e, 79
3f, 85
3g, 81
3h, 81
3i, 81
1c (C6H5/C6H5/p-FC6H4/p-FC6H4)
1d (C6H5/C6H5/p-ClC6H4/p-ClC6H4)
1e (p-MeC6H4/p-MeC6H4/C6H5/C6H5)
1f (p-FC6H4/p-FC6H4/C6H5/Me)
1g (C6H5/C6H5/p-MeC6H4/p-MeC6H4)
1h (p-FC6H4/p-FC6H4/p-MeC6H4/p-MeC6H4)
1i (p-MeC6H4/p-MeC6H4/C6H5/Me)
Table 4
LDA-mediated domino reactions of VDCPs 1a with Yn-2-ones 2c and 2d
a
HO
Ph
After vinylidenecyclopropanes 1 (0.2 mmol) were lithiated by LDA (0.4 mmol)
at À78 oC for 2 h, but-3-yn-2-one 2a (0.5 mmol) was added into the reaction mix-
ture. Then, the reactions were quenched by the addition of saturated aqueous
ammonium chloride solution after 2 h.
R5
O
Ph
R5
Ph
Ph
R5
Ph
b
Yield of isolated products.
Ph
O
5
Ph
Ph
Ph
LDA
2
+
Table 3
THF, -78 oC, 2 h -78 oC, 2 h
LDA-mediated domino reactions of VDCPs 1 with 1-phenylprop-2-yn-1-one 2b
R5
OH
1a
Ph
HO
Ph
Ph
Ph
Ph
O
Ph
R4
R3
O
R1
R2
LDA
2b
Ph
6
R1
R2
THF, -78 oC, 2 h -78 oC, 2 h
R3
Entrya
2 (R5)
Yieldb (%) (5:6)
4
1
R4
1
2
2c (Ph)
5a and 6a, 61 (1.30:1)c
5b and 6b, 72 (1.76:1)c
2d (TMS)
Entrya
1 (R1/R2/R3/R4)
Yieldb (%)
a
After vinylidenecyclopropane 1a (0.2 mmol) was lithiated by LDA (0.4 mmol) at
1
2
3
4
5
1a (C6H5/C6H5/C6H5/Me)
1b (C6H5/C6H5/C6H5/C6H5)
1d (C6H5/C6H5/p-ClC6H4/p-ClC6H4)
1g (C6H5/C6H5/p-MeC6H4/p-MeC6H4)
1j (p-ClC6H4/p-C!C6H4/C6H5/C6H5)
4a, 55
4b, 63
4c, 59
4d, 57
4e, 58
À78 oC for 2 h, yn-2-one 2c or 2d (0.5 mmol) was added into the reaction mixture.
Then, the reaction was quenched by the addition of saturated aqueous ammonium
chloride solution after 2 h.
b
Yield of isolated products.
c
These products were isolated as product mixtures and their ratios were
determined by 1H NMR spectroscopic data.
a
After vinylidenecyclopropanes 1 (0.2 mmol) were lithiated by LDA (0.4 mmol)
at À78 oC for 2 h, 1-phenylprop-2-yn-1-one 2b (0.5 mmol) was added into the
reaction mixture. Then, the reactions were quenched by the addition of saturated
aqueous ammonium chloride solution after 2 h.
b
Table 5
Yield of isolated products.
LDA-mediated reactions of VDCPs la, lk, and 11 with hex-3-yn-2-one 2e
OH
R1
R3
R2
R3
7
R1
R2
LDA
THF, -78 oC, 2 h
2e O
-78 oC, 2 h
O
1
R1
R2
R3
8
Entrya
1 (R1/R2/R3)
Yieldb (%) (7:8)
1
2
3
1a (C6H5/C6H5/C6H5)
1k (C6H5/C6H5/p-MeC6H4)
1l (C6H5/C6H5/p-CIC6H4)
7a and 8a, 85 (1.22:1)c
7b and 8b, 83 (2.67:1)c
7c and 8c, 81 (1.24:1)c
a
After vinylidenecyclopropane 1a, 1k, or 1l (0.2 mmol) was lithiated by LDA
Figure 1. ORTEP drawing of 3a.
(0.4 mmol) at À78 °C for 2 h, hex-3-yn-2-one 2e (0.5 mmol) was added into the
reaction mixture. Then, the reactions were quenched by the addition of saturated
aqueous ammonium chloride solution after 2 h.
It should be also noted that using 1,3-diphenylprop-2-yn-1-one
2c and 1-phenyl-3-(trimethylsilyl)prop-2-yn-1-one 2d as the sub-
strates led to the domino addition products 5a and 5b along with
b
Yield of isolated products.
These products were isolated as product mixtures and their ratios were
c
determined by 1H NMR spectroscopic data.

B.-L. Lu et al. / Tetrahedron Letters 51 (2010) 321–324
323
Table 6
Moreover, as for VDCPs 1n and 1o having aliphatic groups, the
corresponding 1,2- and 1,4-addition compounds 10, 11, and 9d
were obtained in the reaction with 2e either as the product mix-
tures or as the sole product at room temperature (20 °C) or at
40 °C in moderate yields without the formation of the domino
addition product (Scheme 2). The configuration of 11 was deter-
mined by NOESY spectrum (see Supplementary data).
LDA-mediated reactions of VDCPs lb, lg, and lm with hex-3-yn-2-one2e
O
R4
R3
R1
R2
R1
R2
LDA
2e
O
R4
THF, -78 oC, 2 h
-78 oC, 2 h
1
R3
9
On the basis of these results, a plausible mechanism for the for-
mation of the domino addition product is outlined in Scheme 3
using the reaction of 1 with 2a and 2c as a model. First, the lithia-
tion of cyclopropyl ring of vinylidenecyclopropane 1 gives the cor-
responding cyclopropyl carbanion intermediate A by treatment
with LDA.5 Intermediate A can be transformed into anionic inter-
mediates B-1 and B-2 and there is an equilibrium between all these
anionic species as intermediates A, B-1, and B-2.6 When 2a is used
as an electrophile, intermediate C-1 is formed by the Michael addi-
tion (1,4-addition) of intermediate B-1 with 2a, which subse-
quently undergoes 1,2-addition with another molecule of 2a to
give the corresponding domino addition product 3 (Scheme 3, path
a). Using 2c as an electrophile, the 1,2-addition of intermediate B-2
with 2c can take place to give the corresponding product 6 via
intermediate C-2 (Scheme 3, path b) along with product 3 via the
domino addition process (path a). On the other hand, intermediate
D can also be formed by lithiation of intermediate C-2 (R4 is an al-
kyl group), which undergoes a [1,5]-lithium shift to give product 6
as well (Scheme 3, path b).3b
Entrya
1 (R1/R2/R3/R4)
Yieldb (%)
1
2
3
1b (C6H5/C6H5/C6H5/C6H5)
1g (C6H5/C6H5/p-MeC6H4/p-MeC6H4)
1m (p-FC6H4/p-FC6H4/C6H5/C6H5)
9a, 74
9b, 75
9c, 78
a
After vinylidenecyclopropanes 1b, 1g, or 1m (0.2 mmol) were lithiated by LDA
(0.4 mmol) at À78 °C for 2 h, hex-3-yn-2-one 2e (0.5 mmol) was added into the
reaction mature. Then, the reactions were quenched by the addition of saturated
aqueous ammonium chloride solution after 2 h.
b
Yield of isolated products.
The results shown in Tables 5 and 6 suggested that when
R4 = Me, [1,5]-H shift or [1,5]-Li shift could provide a driving force
for the formation of addition product 7.3b More interestingly, we
found that compound 8 could be transformed into compound 7
in a NMR tube with CDCl3 after 24 h presumably via a 3,3-sigma-
tropic rearrangement (see Supplementary data), suggesting that
compound 7 is thermodynamically more stable than 8.
On the other hand, using ethyl propiolate 2f as the electrophile
instead of 2a, no reaction occurred under the standard conditions
or even in the presence of Lewis acid BF3ÁOEt2, presumably due
to that 2f is less electrophilic than 2a (Scheme 1).
The substituent on the terminal of alkyne can retard the reac-
tion rate of Michael addition process and impair such domino addi-
tion reaction. Therefore, only using 2a and 2b as the electrophiles,
the domino addition product was formed exclusively.
In summary, we have disclosed a novel domino carbolithiation
reaction of vinylidenecyclopropanes 1 with but-3-yn-2-one and 1-
OEt
O
2f
Ph
Ph
LDA
THF, -78 oC, 2 h
R3
R3
N.R.
N.R.
-78 oC, 2 h
R1
R2
R4
R1
R2
Ph
R4
LDA
1a
.
.
LDA
THF, -78 oC, 2 h
2f
1
1a
BF3.Et2O
Li
A
-78 oC, 2 h
R1
Scheme 1. LDA-mediated reactions of VDCP 1a with Ethyl Propiolate 2f.
Li
Li
R1
.
R3
R2
R2
R4
R4
Ph
R3
B-1
O
B-2
Bu
1,2-addition
path b
1,4-addition
path a
Ph
Bu
O
O
Ph
Ph
Ph
2c
9d
OH
2a
Bu
Bu
O
LDA
2e
Me
Ph
THF, rt, 2 h
rt, 2 h
Me
Ph
1n
OLi
LiO
.
Bu
R1
Ph
Ph
Bu
10
.
9d and 10 were isolated as product
mixtures and their ratios were determined
by 1H NMR spectroscopic data.
R1
Ph
R3
R2
R2
C-1
H2O LDA
Ph
R4
46% Yield (1.21:1)
R4
R3
C-2
OLi
R1
Ph
2a
1,2-addition
HO
1'
1
2'
.
OH
[1,5]-H shift
3
2
R4'
R2
Bu
Bu
4
O
O
Ph
Ph
Ph
Ph
H
C3H7
LDA
THF, 40 oC, 2 h
2e
40 oC, 2 h
R3
Li
D
R1
R2
Bu
11, 43% Yield
6
1o
R3
R4
3
Scheme 2. LDA-mediated reactions of VDCPs 1n and 1o having aliphatic group
with Hex-3-yn-2-one 2e.
Scheme 3. A plausible reaction mechanism.

324
B.-L. Lu et al. / Tetrahedron Letters 51 (2010) 321–324
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phenylprop-2-yn-1-one by treating with LDA in THF. The scope
and limitations of this reaction have been carefully examined.
The domino addition products 3 and 4 are important compounds
in organic and medicinal chemistry.7,8 The potential utilization
and extension of the scope of this synthetic methodology are cur-
rently under investigation.
Acknowledgments
We thank the Shanghai Municipal Committee of Science and
Technology (06XD14005, 08dj1400100-2), National Basic Research
Program of China (973)-2009CB825300, and the National Natural
Science Foundation of China (20872162, 20672127, 20821002,
and 20732008).
3. (a) Lu, J.-M.; Shi, M. Org. Lett. 2008, 10, 1943–1946; (b) Lu, J.-M.; Shi, M. Chem.
Eur. J. 2009, 15, 6065–6073; (c) Shi, M.; Yao, L.-F. Chem. Eur. J. 2008, 14, 8725–
8731; (d) Yao, L.-F.; Shi, M. Chem. Eur. J. 2009, 15, 3875–3881.
4. The crystal data of 3a have been deposited in CCDC with number 675542.
Empirical formula: C38H32Cl2O2; formula weight: 591.54; crystal size:
0.479 Â 0.433 Â 0.251; crystal color, habit: colorless, prismatic; crystal
system: triclinic; lattice type: primitive; lattice parameters: a = 8.7749(11) Å,
b = 13.4723(16) Å,
c
c = 14.3018(17) Å,
a
= 91.855(2)o,
b = 105.300(2)o,
Supplementary data
o
3
= 100.532(2) , V = 1597.5(3) Å ; space group: P1; Z = 2; Dcalc = 1.230 g/cm3;
ꢀ
F000 = 620; R1 = 0.0719, wR2 = 0.1926. Diffractometer: Rigaku AFC7R.
5. Huang, J.-W.; Shi, M. Org. Biomol. Chem. 2005, 3, 399–400.
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.tetlet.2009.11.012.
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a solution of
vinylidenecyclopropanes (0.2 mmol) in THF (2.0 mL) was added LDA
1
(0.4 mmol) at À78 °C, and the resulting reaction mixture was stirred at À78 °C
for about 2 h. Then ynone 2 (0.5 mmol) was added and the reaction solution was
further stirred for 2 h at the same reaction temperature. Then the reaction was
quenched by the addition of the aqueous solution of ammonium chloride and
warmed to room temperature. The reaction solution was diluted with ether
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solvent was removed under reduced pressure and the residue was purified by
flash column chromatography.Compound 3a: Yellow oil. 1H NMR (300 MHz,
CDCl3, TMS): d 1.73 (3H, s, CH3), 2.27 (3H, s, CH3), 2.31 (3H, s, CH3), 2.61 (1H, s,
CH), 3.28 (1H, s, CH), 5.96 (1H, s, CH), 6.57 (1H, s, CH), 7.23–7.38 (9H, m, Ar),
7.41–7.48 (6H, m, Ar). 13C NMR (75 MHz, CDCl3, TMS): d 18.8, 29.7, 34.7, 50.6,
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M. E.; Hardie, J. A.; Jones, M. J. Org. Chem. 1971, 36, 3061–3062; (i) Sugita, H.;
Mizuno, K.; Saito, T.; Isagawa, K.; Otsuji, Y. Tetrahedron Lett. 1992, 33, 2539–
2542; (j) Mizuno, K.; Sugita, H.; Kamada, T.; Otsuji, Y. Chem. Lett. 1994, 449–452.
and references cited therein; (k) Sydnes, L. K. Chem. Rev. 2003, 103, 1133–1150;
(l) Mizuno, K.; Sugita, H.; Hirai, T.; Maeda, H.; Otsuji, Y.; Yasuda, M.; Hashiguchi,
M.; Shima, K. Tetrahedron Lett. 2001, 42, 3363–3366; (m) Mizuno, K.; Nire, K.;
128.49, 128.52, 132.1, 140.6, 143.6, 144.8, 145.1, 148.9, 206.4. IR (CH2Cl2)
m
3456, 3285, 3082, 3058, 3026, 2987, 2931, 2855, 2318, 2211, 2113, 1953, 1699,
1597, 1490, 1446, 1362, 1228, 1184, 1127, 1030, 930, 847, 758, 698 cmÀ1. MS
(%) (EI) m/z: 444 (M+, 9), 43 (100), 226 (60), 211 (41), 367 (32), 368 (27), 105
(25), 383 (23), 91 (18); HRMS (EI) calcd for C32H28O2: 444.2089. Found:
444.2086.