Geminal difunctionalization of alkenylidene-type carbenoids by using interelement compounds

Article abstract of DOI:10.1002/1521-3773(20010216)40:4<790::AID-ANIE7900>3.0.CO;2-T

A 1,2 migration of a boryl or silyl group with inversion of configuration occurs in the reaction of alkylidene-type lithium carbenoids with diboron or silylborane derivatives to give the corresponding 1,1-diboryl-or 1-boryl-1-silylalkenes in good yields (

Full text of DOI:10.1002/1521-3773(20010216)40:4<790::AID-ANIE7900>3.0.CO;2-T

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Reagent 4a was prepared by lithiation of (1,1-dibromome-
thylene)cyclohexane (3a) with butyllithium (1.05 mol) in
THF/diethyl ether (2:1) at 1108C. Compound 1 (1.1 mol)
was added to this solution at 1108C and the resulting
mixture was stirred at 1108C for 10 min, gradually allowed
to warm to room temperature, and stirred for 12 h (over-
night). Work-up and chromatography (silica gel, hexane/ethyl
acetate) gave 1,1-(diborylmethylene)cyclohexane 5a in 93%
yield (Table 1, entry 1).[10] Using 2 in place of 1, we obtained
1,1-(boryl(silyl)methylene)cyclohexane 6a in 75% yield (Ta-
ble 1, entry 2). We next applied the reaction to an unsubsti-
tuted carbenoid, 1-bromo-1-lithioethene (4b), available by
Geminal Difunctionalization of Alkenylidene-
Type Carbenoids by Using Interelement
Compounds
Takeshi Hata, Hirotaka Kitagawa, Hirokazu Masai,
Takuya Kurahashi, Masaki Shimizu,* and
Tamejiro Hiyama*
Interelement compounds contain either an interelement
linkage or a homo-/heteroelement element bond, and have
recently been employed in the presence of a transition metal
catalyst extensively for the functionalization of unsaturated
carbon carbon bonds.[1] Thus, the same or different elements
can be introduced into unsaturated substrates simultaneously
and directly to give products having two metal or hetero-
atom carbon bonds that allow further elaborative synthetic
transformations. The addition of a reagent with a B B, Si B,
or Si Si bond to unsaturated carbon carbon bonds provides
an especially attractive and straightforward method to
directly introduce boryl and/or silyl groups into organic
molecules by vic- or 1,4-diboration,[2] silylboration,[3] or
disilylation.[4]
Herein we report that bis(pinacolato)diboron (1)[5] and
(dimethylphenylsilyl)(pinacolato)borane (2)[6] react with
1-halo-1-lithioalkenes 4,[7] alkylidene-type carbenoids avail-
able from 1,1-dihaloalkenes or 1-haloalkenes 3, to afford 1,1-
diborylalkenes 5[8] or 1-boryl-1-silylalkenes 6,[9] respectively.
These products are readily converted into tri- or tetra-
substituted alkenes through various transition metal catalyzed
carbon carbon bond formations (Scheme 1).
Table 1. Reaction of alkylidene-type carbenoids with the diboron or silylbor-
ane reagent.
Entry Substrate
Method[a]
/
Product[c]
Yield
[%]
Reagent[b]
Br
Br
A/1
B(OCMe2)2
1
5a
6a
93
75
M
2
A/2
3a
Br
B(OCMe2)2
3
B/1
B/2
5b
6b
91
81
H
4
M
3b
Cl
B(OCMe2)2
5
6
C/1
C/2
5c
89
Cl
6c[d] 75
M
3c
Cl
B(OCMe2)2
7
8
D/1
D/2
5d
6d[d] 89
82
H
M
n-Hex
n-Hex
3d
R1
R2
X
R1
R2
B(OCMe2)2
gem-dimetalation
Cl
B(OCMe2)2
9
C/1
C/2
5e
48
X'
M
H
M
10
6e[e] 49
3
5 (M = B(OCMe2)2)
6 (M = SiMe2Ph)
n-Hex
n-Hex
3e
(X = halogen, X' = X or H)
Br
Br
B(OCMe2)2
metalation
(X' to Li)
11
E/1
F/2
5 f
65
1,2-migration
M
12[f]
6 f[d] 44
MEMO
MEMO
3f
M–B(OCMe2)2
1 or 2
R1
R2
X
R1
R2
X
[a] A) BuLi (1.05 mol), THF/Et2O (2:1),
1108C, 10 min. B) LiTMP
B(OCMe2)2
(1.10 mol), THF/Et2O (2:1), 1108C, 15 min. C) LiTMP (2.10 mol), THF,
908C, 15 min. D) BuLi (1.05 mol),THF, 908C, 15 min. E) BuLi (1.05 mol),
THF/Et2O (2:1), 1108C, 10 min. F) BuLi (0.95 mol), Et2O, 1108C, 30 min.
[b] 1 ˆ [(Me2CO)2B]2, 2 ˆ PhMe2Si B(OCMe2)2. [c] M ˆ B(OCMe2)2 for 5;
M ˆ SiMe2Ph for 6. Yields of isolated product are given. [d] Single isomer.
[e] E/Z ˆ 1:1. [f] MEMO ˆ CH3OCH2CH2OCH2O.
Li
M
4
O
O
O
O
B
B
M–B(OCMe2)2 =
Ph Si B
O
O
1
2
treatment of vinyl bromide (3b) with lithium 2,2,6,6-tetrame-
thylpiperidide (LiTMP), and isolated 1,1-diborylethene 5b
(or 6b) in high yields (Table 1, entries 3 and 4, respectively).
As (E)-1,4-dihalo-2-butene is known to give predominately
(Z)-1-halobutadiene,[11] (E)-1,4-dichloro-2-butene (3c) was
treated with two equivalents of LiTMP at 908C to stereo-
selectively give (Z)-1-chloro-1-lithio-1,3-butadiene (4c),[12b]
which was allowed to react with 1 (or 2) and afforded
dienyldiborane 5c (or dienyl(silyl)borane 6c) in high yields
(Table 1, entries 5 and 6, respectively). Noteworthy is that the
stereochemistry of 6c was exclusively E[13] in accord with the
Scheme 1. Geminal difunctionalization of alkenylidene-type carbenoids
using interelement compounds.
[*] Dr. M. Shimizu, Prof. T. Hiyama, Dr. T. Hata, H. Kitagawa, H. Masai,
T. Kurahashi
Department of Material Chemistry
Graduate School of Engineering, Kyoto University
Sakyo-ku, Kyoto, 606-8501 (Japan)
Fax : (‡81)75-753-5555
E-mail: thiyama@npc05.kuic.kyoto-u.ac.jp
Supporting information for this article is available on the WWW under
http://www.angewandte.com/ or from the author.
790
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configuration of 4c and with a mechanism involving stereo-
In summary, lithium carbenoids 4 are shown to react with 1
or 2 successfully to afford 1,1-diborylalkenes 5 or 1-boryl-1-
silylalkenes 6 stereoselectively. Synthetic elaborations of
these alkenylborates are readily achieved for extension of
the olefinic carbon framework.
selective formation of an intermediate borate complex
[15]
followed by stereospecific 1,2-migration.[14]
,
To extend the
scope of the reaction, we treated 3d with LiTMP, and 3e with
BuLi, to produce the conjugated alkylidene-type carbenoids
4d and 4e, respectively, which were subsequently treated with
1 (or 2) to give rise to diene 5d (or 6d) and enyne 5e (or 6e),
respectively (Table 1, entries 7 ± 10). The stereochemistry (Z)
of 6d was completely controlled,[13] whereas 6e was isolated as
a stereoisomeric mixture due probably to facile isomerization
of carbenoid 4e.[12b] Stereoselective preparation of an alkyl-
idene-type carbenoid is possible when a substrate contains a
control element like an alkoxy group. For example, a stereo-
selective bromine ± lithium exchange reaction takes place
when 0.95 ± 0.98 mol of BuLi is added to 3 f in diethyl ether at
1108C.[16] The resulting (E)-1-bromo-1-lithioalkene reagent
4 f was treated with 2 to afford 6 f as a single isomer (Table 1,
entry 12).[11] Similarly, the same substrate gave 5 f upon
treatment with 1 (Table 1, entry 11).
These results clearly demonstrate that the gem-diboration
and gem-silylboration reaction involve 1,2-migration of a
boryl[17] or silyl[18] group with inversion of configuration.[19] In
particular, the configurations of 4 f and 6 f clearly demonstrate
that lithium in (E)-4 f was initially replaced by boron in 2 and
then silyl migration took place with inversion of configura-
tion.
Received: August 21, 2000 [Z15670]
[1] a) K. Tamao, Chem. Today 1999, 24 ± 31; b) K.Tamao, A. Kawachi, M.
Asahara, A. Toshimitsu, Pure Appl. Chem. 1999, 71, 393 ± 400;
c) R. R. Holmes, Main Group Chem. News 1997, 5, 19 ± 20; d) Belet-
skaya and Moberg referred to a substrate containing an interelement
linkage as an element element compound: I. Beletskaya, C. Moberg,
Chem. Rev. 1999, 99, 3435 ± 3461.
[2] a) T. Ishiyama, N.Matsuda, N. Miyaura, A. Suzuki, J. Am. Chem. Soc.
1993, 115, 11018 ± 11019; b) T.Ishiyama, M. Yamamoto, N. Miyaura,
Chem. Commun. 1996, 2073 ± 2074; c) T. Ishiyama, N. Matsuda, M.
Murata, F. Ozawa, A. Suzuki, N. Miyaura, Organometallics 1996, 15,
713 ± 720; d) T. Ishiyama, M. Yamamoto, N. Miyaura, Chem. Com-
mun. 1997, 689 ± 670; e) T. Ishiyama, T. Kitano, N. Miyaura, Tetrahe-
dron Lett. 1998, 39, 2357 ± 2360; f) T. Ishiyama, S. Momota, N.
Miyaura, Synlett 1999, 1790 ± 1792; g) T. Ishiyama, N. Miyaura, J.
Organomet. Chem. 2000, 611, 392 ± 402.
[3] a) M. Suginome, H. Nakamura, Y. Ito, Chem. Commun. 1996, 2777 ±
2778; b) S. Onozawa, Y. Hatanaka, M. Tanaka, Chem. Commun. 1997,
1229 ± 1230; c) M. Suginome, H. Nakamura, Y. Ito, Angew. Chem.
1997, 106, 2627 ± 2628; Angew. Chem. Int. Ed. Engl. 1997, 36, 2516 ±
2518; d) M. Suginome, H. Nakamura, T. Matsuda, Y. Ito, J. Am. Chem.
Soc. 1998, 120, 4289 ± 4249; e) M. Suginome, T. Matsuda, Y. Ito,
Organometallics 1998, 17, 5233 ± 5235; f) M. Suginome, T. Matsuda, H.
Nakamura, Y. Ito, Tetrahedron 1999, 58, 8787 ± 8800; g) M. Suginome,
Y. Ohmori, Y. Ito, Synlett 1999, 1567 ± 1568; h) S. Onozawa, Y.
Hatanaka, M. Tanaka, Chem. Commun. 1999, 1863 ± 1864; i) M.
Suginome, T. Matsuda, T. Yoshimoto, Y. Ito, Org. Lett. 1999, 1, 1567 ±
1569; j) M. Suginome, Y. Ito, Chem. Rev. 2000, 100, 3221 ± 3256.
[4] a) H. Watanabe, M. Kobayashi, K. Higuchi, Y. Nagai, J. Organomet.
Chem. 1980, 186, 51 ± 62; b) Y. Ito, M. Suginome, M. Murakami, J.
Org. Chem. 1991, 56, 1948 ± 1951; c) Y. Tsuji, R. M. Lago, S. Tomohiro,
H. Tsunenishi, Organometallics 1992, 11, 2353 ± 2355; d) M. Muraka-
mi, M. Suginome, K. Fujimoto, H. Nakamura, P. G. Andersson, Y. Ito,
J. Am. Chem. Soc. 1993, 115, 6487 ± 6498; e) F. Ozawa, M. Sugawara,
T. Hayashi, Organometallics 1994, 13, 3237 ± 3243.
The products 5 and 6 serve as potential substrates for the
Miyaura ± Suzuki coupling reaction.[20] Coupling of 5a with
iodobenzene afforded 1,1-diphenylmethylenecyclohexane
(7a; Scheme 2). Double conjugate addition of 5a to methyl
B(OCMe2)2
B(OCMe2)2
R
a, b, or c
R'
7a: R = R' = Ph, 80%
5a
7b: R = R' = CH2CH2COMe, 74%
8: R = CH2CH=CH2, R' = Ph, 71%
[5] H. Z. Nöth, Z. Naturforsch. B 1984, 39, 1463 ± 1466.
[6] Recently, 2 has been synthesized by a more efficient route by Ito,
Suginome, and co-workers: Abstr. Pap. 1B634 78th Jpn. Spring Ann.
Meeting (Yokohama, Japan) March 28 ± 31, 1999, Japan Chemical
Society, Tokyo, 1999; see also: M. Suginome, T. Matsuda, Y. Ito,
Organometallics 2000, 19, 4647 ± 4649.
B(OCMe2)2
Ph
Ph
d
a
SiMe2Ph
SiMe2Ph
n-Hex
n-Hex
n-Hex
[7] M. Braun, Angew. Chem. 1998, 110, 444 ± 465; Angew. Chem. Int. Ed.
1998, 37, 430 ± 451.
9, 84%
10, 84%
6d
[8] D. S. Matteson, Synthesis 1975, 147 ± 158.
Scheme 2. Miyaura ± Suzuki coupling reaction of the resulting gem-
bismetalated olefins. a) for 7a: PhI (3 mol), [Pd(PPh3)4] (3 mol%), aq.
KOH (6 mol), dioxane, 908C, 24 h. b) for 7b: MVK (4 mol), [Rh(acac)-
(CO)2]/dppb (6 mol%), MeOH/H2O, 50 8C, 24 h. c) for 8: 1)
[9] M. P. Cooke, R. K. Widener, J. Am. Chem. Soc. 1987, 109, 931 ± 933.
[10] A representative procedure is provided by the synthesis of 1,1-
{bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)methylene}cyclohex-
ane (5a). Butyllithium in hexane (1.5m, 147 mL, 0.22 mmol) was
added dropwise to a solution of 1,1-(dibromomethylene)cyclohexane
(3a) (51 mg, 0.2 mmol) in a mixture of THF (1 mL) and diethyl ether
(0.5 mL) at 1108C, and the resulting solution was stirred at 1108C
for 10 min. To the resulting solution of (bromolithiomethylene)cyclo-
hexane was added dropwise a solution of bis(pinacolato)diboron (1)
(56 mg, 0.22 mmol) in THF (1 mL). The mixture was gradually
allowed to warm to room temperature and stirred for 12 h. The
reaction mixture was quenched with a few drops of saturated aqueous
NH4Cl, diluted with diethyl ether (10 mL), and treated with water
(3 mL). The organic layer was separated, dried over anhydrous
magnesium sulfate, and concentrated to give a colorless solid, which
was purified by column chromatography (200 mesh silica gel, ethyl
acetate/hexane (1:9)) to give 5a (65 mg, 0.19 mmol, 93% yield). TLC:
Rf 0.31 (hexane/ethyl acetate (9:1)). 1H NMR: (200 MHz, CDCl3):
d ˆ 1.25 (s, 24H), 1.50 ± 1.70 (m, 6H), 2.30 ± 2.45 (m, 4H); 13C NMR
ˆ
CH2 CHCH2Br (1 mol), [Pd(PPh3)4] (3 mol%), aq. KOH (3 mol), dioxane,
708C, 24 h; 2) PhI (1 mol), [Pd(PPh3)4] (3 mol%), aq. KOH (3 mol),
dioxane, 708C, 24 h. d) TBAF (2 mol), THF, 608C, 2 h. acac ˆ acetylace-
tonate, dppb ˆ 1,4-bis(diphenylphosphanyl)butane, TBAF ˆ tetrabutylam-
monium fluoride.
vinyl ketone (MVK) was catalyzed by a Rh complex to give
1,7-diketone 7b.[21] Stepwise coupling is also possible: allyla-
tion followed by phenylation of 5a afforded 8 in a high overall
yield. Similarly, 6d coupled with iodobenzene to afford
trisubstituted 1-silylalkene 9, which after protodesilylation,
gave (E,E)-diene 10 clearly demonstrating the stereochemical
course of the sequence of reactions (Scheme 2).[22]
Angew. Chem. Int. Ed. 2001, 40, No. 4
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791

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(50 MHz, CDCl3): d ˆ 24.7, 26.4, 28.7, 37.4, 82.7, 171.5. IR: (nujol) 1615,
Nitroxide Radicals as Templating Agents in the
Synthesis of Magnets Based on Three-
Dimensional Oxalato-Bridged
1320, 1285, 1265, 1245, 1220, 1140, 1105, 1010, 985, 965, 890, 855,
‡
‡
670 cm 1; MS: m/z (%): 350 ([M ‡2], 0.2), 349 ([M ‡1], 2), 348
‡
‡
‡
([M ], 8), 347 ([M
1], 4), 333 ([M
Me], 8), 291 (100); elemental
analysis calcd for C19H34B2O4 (%): C 65.56, H 9.84; found: C 65.31, H
10.03.
Heterodimetallic Networks**
[11] a) V. L. Heasley, B. R. Lais, J. Org. Chem. 1968, 33, 2571 ± 2572;
b) M. A. Keegstra, H. D. Verkruijsse, H. Andringa, L. Brandsma,
Synth. Commun. 1991, 21, 721 ± 726.
Â
Gloria Ballester, Eugenio Coronado,* Carlos Gimenez-
Saiz, and Francisco M. Romero*
[12] Zr: a) E. Negishi, K. Akiyoshi, B. OꢁConnor, K. Takagi, G. Wu, J. Am.
Chem. Soc. 1989, 111, 3089 ± 3091; b) A. Kasatkin, R. J. Whitby, J. Am.
Chem. Soc. 1999, 121, 7039 ± 7049. 1,2-Migration using other metals
(Al, Co, Cd, Cu, Fe, Hf, Ni, Mg, Mn, Ti, V): c) E. Negishi, K. Akiyoshi,
J. Am. Chem. Soc. 1988, 110, 646 ± 647; B: d) R. L. Danheiser, A. C.
Savoca, J. Org. Chem. 1985, 50, 2401 ± 2403; e) H. C. Brown, D.
Basaaiah, S. U. Kulkarni, H. D. Lee, E. Negishi, J. J. Katz, J. Org.
Chem. 1986, 51, 5270 ± 5276; Li: f) H. M. Walborsky, M. Duraisamy,
Tetrahedron Lett. 1985, 26, 2743 ± 2746; Zn: g) T. Harada, T. Katsu-
hira, D. Hara, Y. Kotani, K. Maejima, R. Kaji, A. Oku, J. Org. Chem.
1993, 58, 4897 ± 4907; Zn/Cu: h) P. Knochel, N. Jeong, M. J. Rozema,
M. C. P. Yeh, J. Am. Chem. Soc. 1989, 111, 6474 ± 6476.
[13] The configurations of 6c, 6d, and 6 f were determined by conversion
to the corresponding coupling derivatives under Miyaura ± Suzuki
conditions and followed by protodesilylation using tetrabutylam-
monium fluoride (TBAF).
[14] a) K. Kitatani, T. Hiyama, H. Nozaki, J. Am. Chem. Soc. 1976, 98,
2362 ± 2364; b) K. Kitatani, T. Hiyama, H. Nozaki, Bull. Chem. Soc.
Jpn. 1977, 50, 1600 ± 1607.
[15] a) H. C. Brown, Organic Synthesis via Boranes, Wiley-Interscience,
New York, 1975; b) E. Negishi in Comprehensive Organometallic
Chemistry, Vol. 7 (Eds.: G. Wilkinson, F. G. A. Stone, F. W. E. Abel),
Pergamon, Oxford, 1982, 255 ± 363.
[16] a) H. Mahler, M. Braun, Tetrahedron Lett. 1987, 28, 5145 ± 5148; b) H.
Mahler, M. Braun, Chem. Ber. 1991, 124, 1379 ± 1395.
[17] A boryl anionic species was generated from 1 as reported by Miyaura
and co-workers: Abstr. Pap. 4B703 78th Jpn. Spring Ann. Meeting
(Yokohama, Japan), March 28 ± 31, 1999, Japan Chemical Society,
Tokyo, 1999.
[18] Insertion of ethyl diazoacetate into silylborane under 1,2-silyl migra-
tion has been reported: J. D. Buyak, B. Geng, Organometallics 1995,
14, 3112 ± 3115. See also: M. Suginome, T. Fukuda, H. Nakamura, Y.
Ito, Organometallics 2000, 19, 719.
[19] As sp2 carbon atoms hardly undergo normal nucleophilic substitution,
the nucleophilic substitution is considered in terms of metal ion
assisted nucleophilic substitution. See ref. [12 f].
[20] N. Miyaura, A. Suzuki, Chem. Rev. 1995, 95, 2457 ± 2483.
[21] M. Sakai, H. Hayashi, N. Miyaura, Organometallics 1997, 16, 4229 ±
4231.
[22] An alternative method for the gem-cross-coupling has been achieved
by using 1,1-dibromoalkenes: a) A. B. Friedrich, R. Neidlein, Syn-
thesis 1995, 1506 ± 1510; b) J. Uenishi, O. Yonemitsu, J. Org. Chem.
1996, 61, 5716 ± 5717; c) J. Uenishi, O. Yonemitsu, J. Org. Chem. 1998,
63, 8965 ± 8975; d) W. Shen, L. Wang, J. Org. Chem. 1999, 64, 8873 ±
8879; e) W. Shen, L. Wang, Tetrahedron Lett. 1998, 39, 7625 ± 7628;
f) W. Shen, Synlett 2000, 1506 ± 1510.
Building an extended compound with a particular crystal
structure from molecular precursors in solution is still a
challenge in many areas of chemistry.[1] Coordination chem-
istry provides a useful algorithm for this purpose (lattice
engineering) because coordination geometries are well de-
fined by strong and highly directional bonds. This concept is
especially relevant in the synthesis of molecular magnetic
materials since metal complexes provide the spin carriers
(metal ions) and ligands through which magnetic interactions
can occur.[2]
2
The ability of the oxalate (ox) ion, C2O4 , to transmit
efficiently magnetic interactions through its bridging mode
has been well documented since the pioneering work on
dinuclear copper(ii) complexes.[3] Later, the use of the
homoleptic species [M(ox)3]3 (M ˆ CrIII, FeIII) provided an
easy access to systems of higher dimensionality.[4] Only two
families of high-dimensional oxalato complexes displaying
magnetic order have been described: a) two-dimensional
(2D) heterodimetallic compounds of formula A[MIIMIII(ox)3]
(A ˆ quaternary onium cation, M ˆ metal) with a honey-
comb-layered structure[5] and b) three-dimensional (3D) ho-
II
mometallic compounds of formula A[M2 (ox)3] or A[MII-
MIII(ox)3](ClO4) (A ˆ [M(bpy)3]2‡) with a cubic chiral pack-
ing.[6] The resulting dimensionality depends on the type of
Am‡ ion used, so that these cations can be considered as
templating agents for the overall structure.[7] There is a fine
interplay between molecular recognition and chirality in this
kind of system: 2D structures are achiral but, within each
layer, all the MIII sites have the same chirality while all the MII
sites have the opposite one; in the 3D systems, both sites
adopt the same configuration. In all cases, the enantioselec-
tive synthesis of the optically active stereoisomers using chiral
building blocks is possible.[8] Besides their role as structure-
directing agents, the Am‡ ions can also introduce physical
properties of interest to the magnetic system, leading to
multiproperty materials. Along this line, we have synthesized
a family of 2D compounds where the ªinnocentº quaternary
onium cation has been replaced by redox-active species of the
decamethylmetallocenium type[9] or organic donors such as
BEDT-TTF
(2,2'-bis(5,6-dihydro-1,3-dithiolo[4,5-b][1,4]di-
[*] Prof. E. Coronado, Dr. F. M. Romero, G. Ballester,
Â
Dr. C. Gimenez-Saiz
Departament de Química Inorganica
Á
Á
Universitat de Valencia
Dr. Moliner, 50. 46100 Burjassot (Spain)
Fax : (‡34)96-386-4322
E-mail: eugenio.coronado@uv.es, fmrm@uv.es
[**] This work was supported by the European Union (TMR ERB 4061
PL97-0197) and the Ministerio de Ciencia y Tecnología (MCT)
(Project no. MAT98-0880). C.G. and F.M.R. wish to thank the MCT
Â
for a research contract (Contrato de Reincorporacion).
792
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1433-7851/01/4004-0792 $ 17.50+.50/0 Angew. Chem. Int. Ed. 2001, 40, No. 4