Preparation, crystal structure analysis, and catalytic application of [(S)-BINAP]Ni(COD) and [(S)-BINAP]NiBr2

Article abstract of DOI:10.1021/om020164j

The preparation, crystal structure analysis, and catalytic application of [(S)-BINAP]Ni(COD) and [(S)-BINAP]NiBr₂ were discussed. The relatively low binding affinity of Ni(0) with BINAP, which was utilized in the synthesis of BINAP itself, in a

Full text of DOI:10.1021/om020164j

Organometallics 2002, 21, 3833-3836
3833
P r ep a r a tion , Cr ysta l Str u ctu r e An a lysis, a n d Ca ta lytic
Ap p lica tion of [(S)-BINAP ]Ni(COD) a n d [(S)-BINAP ]NiBr 2
Dirk J . Spielvogel, William M. Davis, and Stephen L. Buchwald*
Department of Chemistry, Massachusetts Institute of Technology,
Cambridge, Massachusetts 02139
Received February 26, 2002
Summary: The efficient preparation of [(S)-BINAP]Ni-
(COD) (1) and [(S)-BINAP]NiBr2 (2) is reported. X-ray
crystal structure analysis of these potential precatalysts
provides the first structural insights into the nickel-
BINAP system at both the 0 and +2 oxidation states.
In tr od u ction
Chiral bidentate phosphine ligands are ubiquitous in
asymmetric catalysis.1 Enantiopure 2,2′-bis(diphenylphos-
phino)-1,1′-binaphthyl (BINAP), introduced by Noyori,2
has repeatedly proven to be a highly efficient ligand in
a diverse number of transition-metal-catalyzed, enan-
tioselective transformations.3 Recent developments have
greatly facilitated the synthesis of BINAP and its
derivatives, resulting in a broader application of these
ligands in industry and academics.4 While palladium-
5
,
rhodium-,6 and ruthenium-BINAP7 systems com-
F igu r e 1. Enantioselective R-arylation of R-substituted
γ-butyrolactones.
prise the majority of successful asymmetric catalytic
reactions,3 other metals have been utilized to a lesser
degree. For example, there have been few reports8 of
successful nickel-BINAP catalyzed enantioselective
transformations, despite the low cost of nickel and high
reactivity of Ni(0) complexes toward aryl and vinyl
chlorides.9 Presumably, the relatively low binding af-
finity of Ni(0) with BINAP, which has been utilized in
the synthesis of BINAP itself,4a in addition to the air
sensitivity of Ni(0) complexes in general, detracts from
its utility.
Recently, while investigating the enantioselective
R-arylation of R-substituted γ-butyrolactones, we have
found that 5 mol % of in situ generated [(S)-BINAP]Ni-
(COD) (1) in combination with ZnBr2 constitutes a
highly efficient catalytic system.10 The quaternized
products are isolated in excellent enantioselectivities
and moderate to excellent yields.
* To whom correspondence should be addressed. E-mail:
sbuchwal@mit.edu. Phone: 617-253-1885. Fax: 617-253-3297.
(1) Catalytic Asymmetric Synthesis; Ojima, I., Ed.; Wiley: New
York, 2000.
Two points are worth noting. (i) The addition of 15
mol % ZnBr2 as a THF solution is instrumental for the
dramatic increase in the rate of the reaction, ultimately
leading to a higher isolated yield of the product (Figure
1, entry 3). Initial findings suggest that ZnBr2 acts as
a Lewis acid, facilitating halide abstraction from the
oxidative addition product [(S)-BINAP]Ni(Ar)(X). (ii) It
was found that under similar conditions use of a Pd-
(S)-BINAP catalyst provided the opposite enantiomer,
albeit with lower enantioselectivity (entry 4). In our
endeavor to gain further mechanistic and structural
insight, we sought to prepare and characterize [(S)-
BINAP]Ni(COD) (1) and [(S)-BINAP]NiBr2 (2).
(2) Miyashita, A.; Yasuda, A.; Takaya, H.; Toriumi, K.; Ito, T.;
Souchi, T.; Noyori, R. J . Am. Chem. Soc. 1980, 102, 7932-7934.
(3) (a) Akutagawa, S. Appl. Catal., A 1995, 128, 171-207. (b)
Kumobayashi, H.; Miura, T.; Sayo, N.; Saito, T.; Zhang, X. Synlett 2001,
1055-1064.
(4) (a) Cai, D.; Payack, J . F.; Bender, D. R.; Hughes, D. L.;
Verhoeven, T. R. Reider, P. J . J . Org. Chem. 1994, 59, 7180-7181. (b)
Ager, D. J .; East, M. B.; Eisenstadt, A.; Laneman, S. A. Chem.
Commun. 1997, 2359-2360. (c) Cai, D.; Payack, J . F.; Bender, D. R.;
Hughes, D. L.; Verhoeven, T. R.; Reider, P. J . Org. Synth. 1999, 76, 6.
(5) (a) Use of Pd-BINAP for the asymmetric Heck reaction: He-
gedus, L. S. Transition Metals in the Synthesis of Complex Organic
Molecules; University Science Books: Sausalito, CA, 1999; Chapter
4.6. (b) Use of Pd-BINAP for the asymmetric allylic alkylation: ref
5a, Chapter 9.3.
(6) Use of Rh-BINAP for the asymmetric isomerization: Akuta-
gawa, S. Top. Catal. 1998, 4, 271-274.
(7) Use of Ru-BINAP for the asymmetric hydrogenation: Hegedus,
L. S. Transition Metals in the Synthesis of Complex Organic Molecules;
University Science Books: Sausalito, CA, 1999; Chapter 3.2.
(8) Lautens, M.; Rovis, T. J . Am. Chem. Soc. 1997, 119, 11090-
11091.
Resu lts a n d Discu ssion
Reaction of Ni(COD)2 with (S)-BINAP in toluene at
room temperature results in the clean formation of [(S)-
BINAP]Ni(COD) (1), which can be isolated in 65% yield
(9) (a) Hegedus, L. S. Transition Metals in the Synthesis of Complex
Organic Molecules; University Science Books: Sausalito, CA, 1999;
Chapter 2.3. (b) Mann, G.; Hartwig, J . F. J . Org. Chem. 1997, 62,
5413-5418. (c) Wolfe, J . P.; Buchwald, S. L. J . Am. Chem. Soc. 1997,
119, 6054-6058. (d) Saito, S.; Oh-tani, S.; Miyaura, N. J . Org. Chem.
1997, 62, 8024-8030.
(10) Spielvogel, D. J .; Buchwald, S. L. J . Am. Chem. Soc. 2002, 124,
3500-3501.
10.1021/om020164j CCC: $22.00 © 2002 American Chemical Society
Publication on Web 08/06/2002

3834 Organometallics, Vol. 21, No. 18, 2002
Notes
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for [(S)-BINAP ]NiBr 2 (2)
Bond Distances
Ni-Br
2.3355(5)
2.3355(5)
2.1652(8)
2.1652(8)
P-C(1)
P-C(11)
P-C(21)
1.840(3)
1.823(3)
1.809(3)
Ni-Br(1)
Ni-P
Ni-P(1)
Bond Angles
Br-Ni-Br(1)
Br-Ni-P
96.46(3)
91.70(2)
Br-Ni-P(1)
P-Ni-P(1)
151.95(2)
93.57(5)
[(S)-BINAP]NiBr2 (2) presents itself as an ideal
candidate not only for additional structural insight but
also as a potentially useful precatalyst.14 In situ zinc
reduction of 2 yields an active Ni(0)-BINAP catalyst
with concomitant formation of a stoichiometric amount
of ZnBr2, which is a valuable additive in the arylation
chemistry (Figure 1, entry 3). [(S)-BINAP]NiBr2 (2) is
readily prepared by reaction of anhydrous NiBr2 with
(S)-BINAP in THF at 60 °C. Trituration of the crude
material with toluene provided a dark green, air-stable,
crystalline material in 88% yield. We were unable to
obtain a 31P NMR spectrum, presumably due to the
paramagnetic character of 2; it should also be noted that
the 1H NMR signals are significantly broadened.15
Recrystallization from CH2Cl2/hexane at 4 °C gives
nearly black,16 octahedral crystals suitable for X-ray
analysis.
F igu r e 2. ORTEP drawing of [(S)-BINAP]Ni(COD) (1)
with 50% thermal ellipsoids. All hydrogen atoms are
omitted for clarity.
Ta ble 1. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for [(S)-BINAP ]Ni(COD) (1)
Bond Distances
Structural analysis (bond distances and angles are
given in Table 2) determined 2 to be C2 symmetric with
the nickel center being coordinated in a strongly dis-
torted square-planar configuration. This is best il-
lustrated by the large dihedral angle (38.3°) between
the coordination planes of P-Ni-P(1) and Br-Ni-Br-
(1) (Figure 3b). Furthermore, the four angles at nickel
involving Br, Br(1), P, and P(1) add up to 373.4°.17 The
dihedral angle between the naphthyl planes was deter-
mined to be 79.1°. The bite angle of the BINAP ligand
(93.57(5)°) lies within the range of the ligand-preferred
bite angle (92 ((3)°).11 It is, however, greatly reduced
by comparison to 1. Notably, the interplanar angle
between the two backbone benzene rings in BIPHEMP
(bis(diphenylphosphino)biaryl)) complex of Ni(II) is
smaller (76.4°) and the bite angle is significantly larger
(99.1 ((3)°).18 The Ni-P (2.1652(8) Å) and Ni-Br
(2.3355(5) Å) bond distances are in the typical range for
dibromonickel complexes bearing diphosphine ligands.19
By comparison, [(R)-BINAP]PdCl2 exists in a markedly
less skewed geometry compared to 2.20 It is unclear,
however, to what degree this is caused by the halide-
halide repulsion (Cl-Cl vs Br-Br)21 or the metal center
(Pd(0) vs Ni(0)) itself.22
Ni-C(1)
Ni-C(2)
Ni-C(5)
Ni-C(6)
Ni-P(1)
Ni-P(2)
2.123(9)
2.106(9)
2.120(8)
2.092(10)
2.176(3)
2.172(3)
P(1)-C(11)
P(1)-C(31)
P(1)-C(51)
P(2)-C(21)
P(2)-C(41)
P(2)-C(61)
1.851(10)
1.829(9)
1.845(9)
1.807(9)
1.869(8)
1.821(9)
Bond Angles
97.0(3)
139.0(3)
38.5(4)
C(1)-Ni-P(1)
C(1)-Ni-P(2)
C(1)-Ni-C(2)
C(1)-Ni-C(5)
C(1)-Ni-C(6)
P(1)-Ni-P(2)
93.8(4)
84.6(4)
97.37(10)
by simple filtration under an inert atmosphere. Recrys-
tallization from toluene/ether/hexane provided bur-
gundy crystals suitable for X-ray analysis. While both
the solution and the amorphous, solid material are
highly unstable under atmospheric conditions, the
prepared crystals proved stable enough to be mounted
outside the glovebox. Selected bond distances and angles
are summarized in Table 1.
Structural analysis of 1 (see Figure 2) shows the
nickel center coordinated in a tetrahedral geometry (θ
) 83.1°). The BINAP bite angle (97.37(10)°) lies within
the range of the ligand preferred bite angle (92 ((3)°).11
The Ni-P bond distances (2.1652(8) Å) are in agreement
with comparable compounds.12 Although 1 constitutes
the first Ni-BINAP structure to be determined, it would
be of great interest to also gain structural information
for the Ni-BINAP system in the +2 oxidation state,
especially since the important steps in the catalytic cycle
(transmetalation, reductive elimination) are initiated
from Ni(II) species.13
Initial experiments were undertaken to determine the
potential use of [(S)-BINAP]NiBr2 (2) as a precatalyst
(14) (a) Indolese, A. F.; Consiglio, G. Organometallics 1994, 13,
2230-2234. (b) Ghosh, A. K.; Matsuda, H. Org. Lett. 1999, 1, 2157-
2159. (c) Majumdar, K. K.; Cheng, C.-H. Org. Lett. 2000, 2, 2295-
2298.
(15) In ref 14b, Ghosh et al. report a 31P signal for [(R)-BINAP]NiCl2
at 26.9 ppm. 2 may also exist in a dynamic, conformational equilibrium
in solution. Variable-temperature NMR experiments will hopefully
bring clarification.
(11) (a) Van Leeuwen, P. W. N. M.; Kamer, P. C. K.; Reek, J . N. H.;
Dierkes, P. Chem. Rev. 2000, 100, 2741-2769. (b) Dierkes, P.; Van
Leeuwen, P. W. N. M. J . Chem. Soc., Dalton Trans. 1999, 1519-1529.
The dihedral angle for 1 between the naphthyl planes was determined
to be 75.5°. The COD bite angle in 1 is 92.2°.
(16) The dark color of the material is in agreement with other known
Ni(II) complexes in a tetrahedral distortion.20
(12) Kempe, R.; Sieler, J .; Walther, D. Z. Kristallogr. 1996, 211,
565-566.
(13) For the proposed catalytic cycle see: Fox, J . M.; Huang, X.;
Chieffi, A.; Buchwald, S. L. J . Am. Chem. Soc. 2000, 122, 1360-1370.
(17) Near square-planar geometries result in a sum of angles near
360°, while tetrahedral geometries give a sum of angles near 436°.
(18) Knierzinger, A.; Scho¨nholzer, P. Helv. Chim. Acta 1992, 75,
1211-1220.

Notes
Organometallics, Vol. 21, No. 18, 2002 3835
ee, S configuration) and the absolute stereochemistry
was consistent with the previous results obtained.
Future work will focus on the optimization of a
protocol for the efficient in situ reduction of 2 in order
to facilitate the use of the Ni-BINAP system for
asymmetric catalysis. Furthermore, work is underway
to prepare the oxidative-addition product [(S)-BINAP]-
Ni(Ar)(X). It is hoped that its structural analysis will
shed further light on the key steps and intermediates
in the catalytic cycle.
Exp er im en ta l Section
Gen er a l Com m en ts. Reactions were carried out in oven-
dried glassware cooled under argon. Elemental analyses were
performed by Atlantic Microlabs, Inc., Norcross, GA. IR spectra
were recorded with an ASI REACTIR instrument using
1
samples dissolved in dichloromethane. H NMR spectra were
recorded at ambient temperature on a Bruker 400 MHz
instrument with chemical shifts reported relative to TMS or
to the residual solvent peak. 31P NMR spectra were recorded
on a Varian 300 MHz instrument with shifts reported relative
to H3PO4 as an external standard. Optical rotations were
recorded on a Perkin-Elmer 241 polarimeter. A standard
hemisphere of X-ray data was collected at -90 °C on a Bruker-
Nonius SMART/CCD instrument. The structures were solved
with direct methods and difference Fourier techniques using
SHELXTL. The data were deposited with the Cambridge
Crystallographic Data Centre (http://www.ccdc.cam.ac.uk).
Anhydrous toluene, THF, and diethyl ether were purchased
from J . T. Baker in CYCLE-TRAINER solvent delivery kegs
and vigorously purged with argon for 2 h. The solvents were
further purified by passing them under argon pressure through
two packed columns of neutral alumina (for THF) or through
neutral alumina and copper(II) oxide (for toluene).23 The
solvents were transferred by syringe from the solvent purifica-
tion system to the reaction flask. Ni(COD)2 and anhydrous
NiBr2 were purchased from Strem Chemical, Inc., stored, and
weighed inside a nitrogen-filled glovebox. All chemicals were
used without further purification.
P r ep a r a tion of [(S)-2,2′-Bis(d ip h en ylp h osp h in o)-1,1′-
bin aph th yl](1,5-cyclooctadien yl)n ickel (1). A Schlenk tube
equipped with a magnetic stirbar was charged with 274 mg
(0.396 mmol) of (S)-BINAP and imported into a glovebox,
where 100 mg (0.360 mmol) of Ni(COD)2 and toluene (2 mL)
were added. The tube was closed with a Teflon screw cap
andthe reaction mixture was heated to 60 °C for 10 min and
then stirred overnight at room temperature. During the initial
heating the reaction mixture turned dark red, and over the
course of the reaction, a dark red precipitate formed. The
reaction mixture was filtered over a frit (M) and the residue
washed with toluene (0.5 mL) to yield 185 mg (65%) of the
title compound (1) as a red-brown solid. Preparation of single
crystals suitable for X-ray studies was performed inside a
glovebox. A solution of 30 mg 1 in toluene (0.5 mL) and diethyl
ether (0.5 mL) was allowed to vapor-diffuse with n-hexane over
the course of 4 days to produce deep red platelike crystals. 1H
NMR (C6D6, 400 MHz): δ 8.48 (app t, 2H, J ) 8.4 Hz), 8.07
(app. t, 4H, J ) 7.7 Hz), 7.60 (app. d, 2H, J ) 8.7 Hz), 7.41
(app. d, 2H, J ) 8.0 Hz), 7.35-7.22 (m, 10H), 7.01 (app. t, 2H,
J ) 7.1 Hz), 6.58-6.42 (m, 10H), 8.48 (t, 2H, J ) 8.4 Hz), 5.02
(m, 2H), 4.87 (m, 2H), 2.14-1.97 (m, 6H), 1.72 (m, 2H). 31P
F igu r e 3. ORTEP drawing of [(S)-BINAP]NiBr2 (2) with
50% thermal ellipsoids: (a, top) side-on view; (b, bottom)
top view. All hydrogen atoms are omitted for clarity.
for the arylation chemistry. Reduction of 2 using excess
zinc in THF at 60 °C in the presence of additional (S)-
BINAP resulted in the formation of a light red solution,
which over time turned dark. The one-pot reaction
(reduction plus arylation) has so far proven difficult.
Arylation of R-methyl-γ-butyrolactone with 3-chloroani-
sole by this protocol resulted in a poor yield (21%).
Fortunately, the enantioselectivity remains high (93%
(19) (a) [(-)-DIOP]NiBr2: Pilz, F. A.; Frauenrath, H.; Reim, S. Z.
Kristallogr. 1998, 213, 775-776. The structure is reported as distorted
tetrahedral: Ni-Br distances 2.338(1) Å, Ni-P distances 2.288(2) Å,
Br-Ni-P angle 123.14(5)°. (b) Ni(PPh3)4: J arvis, J . A. J .; Mais, R. H.
B.; Owston, P. G. J . Chem. Soc. A 1968, 1473-1486. The structure is
reported as paramagnetic tetrahedral: Ni-Br distances 2.35(1) Å,
Ni-P distances 2.31(1) Å, Br-Ni-Br angle 126°. For comparison, see
the following. (c) [(-)-DIOP]NiBr2: Gamlich, V.; Consiglio, G. Helv.
Chim. Acta 1979, 62, 1016-1024. The structure reported is distorted
tetrahedral: Ni-Cl1,2 distances 2.20(3) Å, Ni-P1 distance 2.30(3) Å
and Ni-P2 distance 2.28(3) Å, Cl1-Ni-P1 angle 112(3)° and Cl2-Ni-
P2 angle 99(3)°.
NMR (C6D6, 400 MHz): δ 33.7 ppm. Anal. Calcd for C52H44
-
(20) Ozawa, F.; Kubo, A.; Matsumoto, Y.; Hayashi, T. Organome-
tallics 1993, 12, 4188-4196.
(22) For ligand field theory as it relates to nickel, see: Greenwood,
N. N.; Earnshaw, A. Chemistry of the Elements; Pergamon Press: New
York, 1984; Chapter 27.3.4.
(23) (a) Pangborn, A. B.; Giardello, M. A.; Grubbs, R. H.; Rosen, R.
K.; Timmers, F. J . Organometallics 1996, 15, 1518. (b) Alaimo, P. J .;
Peters, D. W.; Arnold, J .; Bergman, R. G. J . Chem. Educ. 2001, 78,
64.
(21) The van der Waals radius for Br is 1.95 Å.20 The Br-Br distance
in 2 is 3.484 Å. The resulting interaction between the halides causes
distortion. For (PPh3)2NiBr2 the interaction of the p orbitals results
in a distorted-tetrahedral geometry: J arvis, J . A. J .; Mais, R. H. B.;
Owston, P. G. J . Chem. Soc. A 1968, 1473.

3836 Organometallics, Vol. 21, No. 18, 2002
Notes
NiP2: C, 79.10; H, 5.62. Found: C, 79.01; H, 5.79. Crystal
data: C52H40NiP2, Mr ) 785.49, trigonal, P31, a ) 10.603(6)
Å, R ) 90°, b ) 10.603(6) Å, â ) 90°, c ) 30.11(2) Å, γ ) 120°,
V ) 2931(3) Å3, Z ) 3, Dc ) 1.335 Mg/m3, λ ) 0.710 73 Å, T )
183(2) K, deep red plates; 5141 independent measured reflec-
tions, F2 refinement, R1 ) 0.0681, wR2 ) 0.1655, CCDC No.
180383.
gel (3 × 0.5 cm) with ethyl acetate as eluent. The eluate was
concentrated under reduced pressure. Chromatography (1.5
× 30 cm, ethyl acetate/hexane 1/4) of the crude mixture on
silica yielded 42.6 mg (83%) of the title compound as a colorless
oil. 1H NMR (CDCl3, TMS, 400 MHz): δ 7.30 (m, 1H), 6.99
(m, 2H), 6.84 (m, 1H), 4.34 (ddd, 1H, J ) 9.0, 7.8, 3.9 Hz),
4.16 (ddd, 1H, J ) 8.9, 8.9, 6.5 Hz), 3.82 (s, 3H), 2.69 (ddd,
1H, J ) 12.9, 6.5, 3.9 Hz), 2.41 (ddd, 1H, J ) 12.9, 8.7, 7.8
Hz), 1.62 (s, 3H). 13C NMR (100 MHz, CDCl3): δ 180.3, 160.3,
143.0, 130.3, 118.5, 112.8, 112.6, 66.7, 65.5, 55.7, 47.9, 38.5,
25.9. IR (cm-1): 2975, 2941, 2916, 1769, 1602, 1584, 1490,
1453, 1382, 1293, 1241, 1223, 1200, 1175, 1084, 1048, 1032,
P r ep a r a tion of [(S)-(-)-2,2′-Bis(d ip h en ylp h osp h in o)-
1,1′-bin a p h th yl]n ick el(II) Br om id e (2). A Schlenk tube
equipped with a magnetic stirbar was charged with 220 mg
(0.353 mmol) of (S)-BINAP and imported into a glovebox,
where 70.1 mg (0.321 mmol) of NiBr2 (anhydrous) and THF
(2 mL) were added. The tube was closed with a Teflon screw
cap and the reaction mixture heated to 60 °C for 24 h. During
the course of the reaction the initially brownish slurry turned
dark green, and some dark green precipitate formed. The
reaction mixture was cooled to room temperature. After
removal of the solvent under reduced pressure the dark green
residue was triturated with toluene (2.5 mL). Filtration over
a medium frit yielded 237 mg (88%) of the title compound as
a fine crystalline, dark green, air-stable material. For the
preparation of single crystals several drops of hexane were
added to a nearly saturated solution of 2 in dichloromethane
(0.2 mL). The crystals were allowed to grow at 4 °C over the
course of 3 days. Mp: >250 °C (toluene). 1H NMR (CDCl3,
TMS, 400 MHz): δ 9.29 (bs, 4H), 8.72 (bs, 2H), 8.28 (m, 5H),
8.14 (bs, 5H), 7.87 (bs, 4H), 7.65 (m, 2H), 6.60 (m, 4H), 6.03
(bs, 2H), 5.80 (m, 2H), 5.49 (m, 2H). IR (cm-1): 1501, 1482,
783, 737. [R]20 ) -7.3° (c ) 2.5, CH2Cl2). HPLC (DAICEL
D
OD column): tmajor ) 13.7 min, tminor ) 17.0 min (10% iPA/
Hex, 0.7 mL/min), 96% ee. Anal. Calcd for C12H14O2: C, 69.88;
H, 6.84. Found: C, 69.58; H, 6.91.
On e-P ot P r otocol for th e in Situ Zin c Red u ction -
Ar yla tion . An oven-dried, resealable Schlenk tube containing
a magnetic stirbar was cooled to room temperature and then
was charged with (S)-BINAP (20.4 mg, 39 µmol), [(S)-BINAP]-
NiBr2 (40.8 mg, 48 µmol), and zinc dust (6.3 mg, 97 µmol). The
tube was sealed, evacuated, and back-filled with argon. While
purging with argon, THF (250 µL) was added by syringe. The
tube was sealed and heated to 60 °C for 5 min, during which
time a homogeneous, red solution (with some visible zinc dust
remaining) formed. The reaction vessel was removed from the
oil bath, and sequentially 3-chloroanisole (30.6 µL, 0.25 mmol)
and dodecane (50 µL, internal standard) were added under
argon. After 5 min at room temperature R-methyl-γ-butyro-
lactone (47.0 µL, 0.5 mmol), NaHMDS (105.4 mg, 0.575 mmol),
and toluene (750 µL) were added while purging with argon.
The tube was sealed and heated to 60 °C for 20 h. The reaction
mixture turns dark upon addition of the base. The reaction
mixture was cooled to room temperature and was then filtered
through a pad of silica gel (3 × 0.5 cm) with ethyl acetate as
eluent. The eluate was concentrated under reduced pressure.
Chromatography of the residue on silica gel (1.5 × 30 cm, ethyl
acetate/hexane) yielded 10.8 mg (21%) of the title compound
as a colorless oil. Spectral and GC data are identical with those
of previously prepared material.
1437, 1314, 1098, 1027, 999, 872, 818. [R]20 ) -230.9° (c )
D
0.55, CH2Cl2). Anal. Calcd for C44H32Br2NiP2: C, 62.83; H, 3.83.
Found: C, 63.05; H, 3.99. Crystal data: C44H32Br2NiP2, Mr )
841.17, tetragonal, P43212, a ) 11.7738(11) Å, R ) 90°, b )
11.7738(11) Å, â ) 90°, c ) 26.137(4) Å, γ ) 90°, V ) 3623.1-
(7) Å3, Z ) 4, Dc ) 1.542 Mg/m3, λ ) 0.710 73 Å, T ) 183(2) K,
dark green octagons; 2619 independent measured reflections,
F2 refinement, R1 ) 0.0236, wR2 ) 0.0539, CCDC No. 180470.
P r ep a r a tion of (-)-(S)-3-(3-Meth oxyp h en yl)-3-m eth -
yld ih yd r ofu r a n -2-on e (F igu r e 1, En tr y 3). An oven-dried,
resealable Schlenk tube containing a magnetic stirbar was
cooled to room temperature and then was charged with (S)-
BINAP (13.2 mg, 21.3 µmol). The tube was sealed, evacuated,
and back-filled with argon. From a freshly prepared, yellow,
homogeneous stock solution of Ni(COD)2 (0.05 M, toluene), 250
µL (12.5 µmol) was added by syringe while purging with argon.
The tube was sealed and heated to 60 °C for 5 min, during
which time the solution turned dark red. The reaction vessel
was removed from the oil bath, and sequentially R-methyl-γ-
butyrolactone (47.0 µL, 0.5 mmol), dodecane (50 µL, internal
standard), and NaHMDS (105.4 mg, 0.575 mmol) were added
under argon. From a stock solution, ZnBr2 (0.51 M, THF), 250
µL (37.5 µmol) was added by syringe while purging with argon;
the mixture was then stirred for 5 min at room temperature.
3-Chloroanisole (30.6 µL, 0.25 mmol) (0.25 mmol) was added
by syringe followed by the addition of toluene (500 µL) while
purging with argon. The tube was sealed and heated to 60 °C
for 20 h. After complete conversion had been accomplished,
as judged by GC analysis, the reaction mixture was cooled to
room temperature and was then filtered through a pad of silica
Ack n ow led gm en t. We thank the National Insti-
tutes of Health (Grant No. GM 46059) for support of
this work. We are grateful for continuing support from
Pfizer, Merck, and Bristol-Myers Squibb. A gift of (S)-
BINAP from Pfizer is gratefully acknowledged. D.J .S.
thanks the German Academic Exchange Service (DAAD)
for a postdoctoral fellowship. We thank a reviewer for
suggesting to add refs 18 and 19c to the paper.
Su p p or tin g In for m a tion Ava ila ble: Details about the
X-ray crystal structures, including ORTEP diagrams and
tables of crystal data and structure refinement details, atomic
coordinates, bond lengths and angles, and isotropic and
anisotropic diplacement parameters for 1 and 2. This material
is available free of charge via the Internet at http://pubs.acs.org.
OM020164J