Organolanthanide-catalyzed intramolecular hydrophosphination/cyclization of phosphinoalkenes and phosphinoalkynes [12]

Full text of DOI:10.1021/ja993633q

1824
J. Am. Chem. Soc. 2000, 122, 1824-1825
Organolanthanide-Catalyzed Intramolecular
Hydrophosphination/Cyclization of Phosphinoalkenes
and Phosphinoalkynes
Michael R. Douglass and Tobin J. Marks*
Department of Chemistry
Northwestern UniVersity
EVanston, Illinois 60208-3113
ReceiVed October 11, 1999
Although the catalytic addition of P-H bonds to C-C multiple
bonds is a highly desirable transformation, it is generally difficult
to accomplish with transition metal complexes.1 In contrast,
organolanthanide-mediated intramolecular hydroamination/cy-
clization of aminoalkenes,2 aminoalkynes,3 and aminoallenes4 has
been shown to have significant selectivity and generality, raising
the intriguing question of whether the corresponding hydrophos-
phination processes might also be feasible. Thermodynamic
considerations for a prospective organolanthanide-catalyzed hy-
drophosphination process (Figure 1) predict insertion (step i) to
be exothermic (∼-33 kcal/mol for alkynes) or approximately
thermoneutral (alkenes, ∼+2 kcal/mol) and subsequent Ln-C
protonolysis (step ii) to be exothermic (∼-7 kcal/mol for alkynes;
-17 kcal/mol for alkenes).5,6 The resulting phosphorus hetero-
cycles belong to a class of interest as alkaloid mimics7 and as
ligand building blocks in asymmetric catalysis.8 Herein we report
the catalytic intramolecular hydrophosphination/cyclization of
phosphinoalkenes and phosphinoalkynes using organolanthanide
precatalysts of the type Cp′2LnCH(TMS)2 (Cp′ ) η5-C5Me5; Ln
) La, Sm, Y; TMS ) SiMe3) and Me2Si(Me4C5)(tBuN)-
SmNTMS2, and observations on factors affecting the scope,
diastereoselectivity, and kinetics of these transformations vis-a`-
vis the nitrogen analogues.9,10
Figure 1. Proposed catalytic cycle for organolanthanide-mediated
hydrophosphination/cyclization of phosphinoalkenes and phosphi-
noalkynes.
Although the synthesis of primary and secondary phosphines
has been explored, few general routes are available.11 The
synthesis of secondary phenyl alkenyl phosphines (eq 1) can be
accomplished by reaction of KPPh2 with the desired alkenyl
fragment bearing an appropriate leaving group, followed by Na/
NH3(l) or Li/THF12 cleavage of a single phenyl substituent.
Protolytic workup yields the desired secondary phosphine.13
Primary phosphines were synthesized via dicholoroalane reduction
of phosphonate precursors (eq 2),14 in turn prepared via Arbuzov
reaction of P(OEt)3 with the corresponding alkenyl or alkynyl
halide.13,15
(1) Hydrophosphination mediated by Pd, Pt, Ni complexes: (a) Wicht, D.
K.; Kourkine, I. V.; Lew, B. M.; Nthenge, J. M.; Glueck, D. S. J. Am. Chem.
Soc. 1997, 119, 5039-5040. (b) Han, L.-B.; Tanaka, M. J. Am. Chem. Soc.
1996, 118, 1571-1572. (c) Hoye, P. A.; Pringle, P. G.; Smith, M. B.; Worboys,
K. J. Chem. Soc., Dalton Trans. 1993, 74, 269-74. (d) Pringle, P. G.; Smith,
M. B. J. Chem. Soc., Chem. Commun. 1990, 1701-1702.
(2) (a) Giardello, M. A.; Conticello, V. P.; Brard, L.; Gagne´, M. R.; Marks,
T. J. J. Am. Chem. Soc. 1994, 116, 10241-10254. (b) Gagne´, M. R.; Stern,
C. L.; Marks, T. J. J. Am. Chem. Soc. 1992, 114, 275-294. (c) Gagne´, M.
R.; Marks, T. J. J. Am. Chem. Soc. 1989, 111, 4108-4109.
(3) (a) Li, Y.; Marks, T. J. J. Am. Chem. Soc. 1998, 120, 1757-1771. (b)
Li, Y.; Marks, T. J. J. Am. Chem. Soc. 1996, 118, 9295-9306. (c) Li, Y.;
Marks, T. J. Organometallics 1996, 15, 3370-3372. (d) Li, Y.; Marks, T. J.
J. Am. Chem. Soc. 1996, 118, 707-708.
(4) (a) Arredondo, V. A.; Tian, S.; McDonald, F. M.; Marks, T. J. J. Am.
Chem. Soc. 1999, 121, 3633-3639. (b) Arredondo, V. A.; McDonald, F. M.;
Marks, T. J. Organometallics 1999, 18, 1949-1960. (c) Arredondo, V. A.;
McDonald, F. M.; Marks, T. J. J. Am. Chem. Soc. 1998, 120, 4871-4872.
(5) Bond enthalpy data: (a) Nolan, S. P.; Stern, D.; Hedden, D.; Marks,
T. J. ACS Symp. Ser. 1990, 428, 159-174. (b) Nolan, S. P.; Stern, D.; Marks,
T. J. J. Am. Chem. Soc. 1989, 111, 7844-7853.
(6) AM-1 level calculations indicate that addition of methyl phosphine to
ethylene is exothermic by ∼-15 kcal/mol, while addition to acetylene is
exothermic by ∼-38 kcal/mol. We thank Dr. Albert Israel for these
calculations.
Anaerobic cyclization of primary and secondary alkynyl and
alkenyl phosphines mediated by Cp′2LnCH(TMS)2 precatalysts
(Cp′ ) η5-Me5C5; Ln ) La, Sm, Y; TMS ) Me3Si) is general in
scope (Table 1).13 Secondary phosphinoalkenes undergo cycliza-
tion to yield reasonably stable tertiary phospholanes (entries 2-4),
albeit somewhat sluggishly, presumably due to the phenyl group
bulk. A notable competing side reaction is noncatalytic intramo-
(7) (a) Laurenco, C.; Villien, L.; Kaufmann, G. Tetrahedron 1984, 40,
2731-2740. (b) MacDiarmid, J. E.; Quin. L. D. J. Org. Chem. 1981, 46,
1451-1456. (c) Chen, C. H.; Brighty, K. E.; Michaels, F. M. J. Org. Chem.
1981, 46, 361-367. (d) Awerbouch, O.; Kashman, Y. Tetrahedron 1975, 31,
33-43. (e) Collins, D. J.; Rowley, L. E.; Swan, J. M. Aust. J. Chem. 1974,
27, 815-830.
(11) Syntheses of primary and secondary phosphines: (a) Guillemin, J.
C.; Savignac, P.; Denis, J. M. Inorg. Chem. 1991, 30, 2170-2173. (b) Cabioch,
J. L.; Denis, J. M. J. Organomet. Chem. 1989, 377, 227-233. (c) Wolfsberger,
W. Chem. Zeitung 1988, 112, 379-381. (d) Kosolapoff, G. M.; Maeir, L.
Organic Phosphorus Compounds; Wiley-Interscience: New York, 1972; Vol.
1, pp 1-287.
(8) (a) Burk, M. J.; Gross, M. F.; Martinez, J. P. J. Am. Chem. Soc. 1995,
117, 9375-9376. (b) Burk, M. J.; Harper, G. P.; Kalberg, C. S. J. Am. Chem.
Soc. 1995, 117, 4423-4424. (c) Burk, M. J.; Feaster, J. E.; Nugent, W. A.;
Harlow, R. L. J. Am. Chem. Soc. 1993, 115, 10125-10138.
(12) (a) Na/NH3: ref 11c. (b) Li/THF: Chou, T.-S.; Yuan, J.-J.; Tsao, C.-
H. J. Chem. Res. (S), 1985, 18-19. (c) Li and Na cleavage methods:
Budzelaar, P. H. M.; Doorn, J. A.; Meijboom, N. Recl. TraV. Chim. Pays-
Bas 1991, 110, 420-432.
(9) Preliminary observations: Giardello, M. A.; King, W. A.; Nolan, S.
P.; Porchia, M.; Sishta, C.; Marks, T. J. In Energetics of Organometallic
Species; Marthinho Simoes, J. A., Ed.; Kluwer: Dordrecht, 1992; pp 35-51.
(10) Douglass, M. R.; Marks, T. J. Communicated in part at the 217th
National Meeting of the American Chemical Society, Anaheim, CA, March
1999; abstract INOR 375.
(13) Details of the synthetic and catalytic procedures, as well as charac-
terization data, can be found in the Supporting Information.
(14) Ashby, E. C.; Prather, J. J. Am. Chem. Soc. 1966, 88, 729-733. (b)
Reference 11a.
(15) (a) Delamarche, I.; Mosset, P. J. Org. Chem. 1994, 59, 5453-5457.
(b) Bhattacharya, A. K.; Thyagarajan, G. Chem. ReV. 1981, 81, 415-430.
10.1021/ja993633q CCC: $19.00 © 2000 American Chemical Society
Published on Web 02/09/2000

Communications to the Editor
J. Am. Chem. Soc., Vol. 122, No. 8, 2000 1825
Table 1. Results for the Organolanthanide-Catalyzed
Hydrophosphination/Cyclization of Phosphinoalkenes and
Phosphinoalkynesa
responding roughly to dimers; however, NMR data indicate
several products that could not be completely characterized.
Phosphine 14 is inferred but never observed by NMR; products
with molecular weights of dimers are observed, and thus
presumably the unstable secondary phospholane formed undergoes
rapid conversion to a dimer.
In principle, four stereoisomers can result from alkenyl
phosphine cyclizations, because inversion at phosphorus is slow.18
For 1 f 2, the 31P NMR exhibits two product resonances in a
∼2:1 ratio, while for 3 f 4, the product exhibits two resonances
in varying ratios depending on the catalyst. Transformations 5
f 619 and 7 f 8 exhibit two product 31P signals of equal
1
magnitude regardless of the catalyst. Complex H spectra for 6
are consistent with mixtures of cis-(R,S) and trans-(R,R or S,S)
methyl dispositions.
Kinetic studies of the hydrophosphination/cyclization by H
1
NMR (integration of olefinic or P-H resonances vs that of CH2-
TMS2 formed in catalyst initiation; 30-150:1 substrate:catalyst)
reveal linear dependence of [substrate] on reaction time, consistent
with zero-order rate dependence on [substrate]. The data thus
implicate the same turnover-limiting catalytic step observed for
organolanthanide-mediated hydroamination,2-4 that is, insertion
of the carbon-carbon unsaturation into the Ln-heteroatom bond.
However, for analogous substrates and catalysts, hydrophosphi-
nation is ∼5-10 times slower than the corresponding hydroami-
nation process.2,3 Another deviation from the hydroamination
pathway is the protolytic initiating step of the catalytic cycle. As
judged by NMR, cleavage of the Ln-CH(TMS)2 bond by
phosphine is not immediate upon mixing precatalyst and substrate.
The corresponding organolanthanide hydrides,20 however, effect
immediate catalytic initiation (presumably evolving H2),5 with
appropriate color changes. Transformation 9 f 10 exhibits the
highest turnover frequencies, with declining Nt values on proceed-
ing from the largest eight-coordinate lanthanide ionic radius La3+
(1.160 Å) to smaller Sm3+ (1.079 Å) and Y3+ (1.019 Å),21
analogous to the trend for aminoalkenes,2 and opposite of that
for aminoalkynes.3 Opening the lanthanide coordination sphere
(with constant metal) using the Me2Si(Me4C5)(tBuN) ancillary
ligand22 leads to enhanced rates, from 2 h-1 at 40 °C to 13 h-1 at
22 °C (entry 4).
a Turnover frequencies measured in C6D6 with 2-3 mg, precatalyst.
1
Conversion is >95% by H and 31P NMR spectroscopy. b Cp′2LaCH-
(TMS)2 as precatalyst. c Cp′2SmCH(TMS)2 as precatalyst. d Cp′2YCH-
(TMS)2 as precatalyst. e Me2Si(Me4C5)(tBuN)SmNTMS2 as precatalyst.
lecular 1,2 P-H addition16 to afford a six-membered phospho-
rinane (eq 3). Control experiments reveal that this pathway can
These results demonstrate that lanthanocenes are competent
catalysts for the hydrophosphination/cyclization of primary and
secondary alkenyl and alkynyl phosphines and that both parallels
and distinct differences are observed versus the corresponding
hydroamination processes. Further explorations of the scope,
selectivity, and mechanism of catalytic hydrophosphination are
in progress.
be significantly suppressed by carrying out cyclizations at
relatively low temperatures with exclusion of light. Final product
mixtures for entries 1-4 contain exclusively the desired phos-
pholane, contaminated with ∼5-20% of the phosphorinane.17
Primary phosphinoalkenes undergo more rapid cyclization (entry
1), as do phosphinoalkynes (entries 5-7). Although products 2-8
are stable and can be isolated, secondary phospholanes resulting
from alkynyl phosphine cyclization (products 10-14) are some-
what unstable and could only be characterized in situ by NMR.
The ultimate products exhibit molecular weights (GC/MS) cor-
Acknowledgment. Financial support by NSF (CHE-9618589) is
gratefully acknowledged. We thank Dr. S. Tian for a sample of Me2Si-
(Me4C5)(tBuN)SmNTMS2 and Dr. M. A. Giardello for helpful comments.
Supporting Information Available: Detailed synthetic procedures
and analytical data for compounds 1-14 (PDF). This material is available
free of charge via the Internet at http://pubs.acs.org.
(16) Examples of P-H addition to olefins to form phospolanes and
phosphorinanes: (a) Hackney, M. L.; Schubert, D. M.; Brandt, P. F.;
Haltiwanger, R. C.; Norman, A. D. Inorg. Chem. 1997, 36, 1867-1872. (b)
Brandt, P. F.; Schubert, D. M.; Norman, A. D. Inorg. Chem. 1997, 36, 1728-
1731. (c) Field, L. D.; Thomas, I. P. Inorg. Chem. 1996, 35, 2546-2548. (d)
Davies, J. H.; Downer, J. D.; Kirby, P. J. Chem. Soc., C 1966, 245-247.
(17) Substrates undergo ∼10-15% conversion to the corresponding
phosphorinanes during drying procedures, i.e., before the catalytic reaction is
initiated; the percentage of the final product mixture can be as high as ∼10-
30% phosphorinane. Phospholanes and phosphorinanes are reported to be
separable by fractional distillation.16a Although it seems unlikely that endocy-
clic rings are catalytic products,2-4 this possibility cannot be rigorously
excluded at present.
JA993633Q
(18) (a) Baechler, R. D.; Mislow, K. J. Am. Chem. Soc. 1970, 92, 3090-
3093. (b) Rauk, A.; Allen, L. C.; Mislow, K. Angew. Chem., Int. Ed. Engl.
1970, 9, 400-414.
(19) The δ 10.4 ppm signal corresponds to the (R,R) or (S,S) isomer,
prepared by an alternative route: Burk, M. J.; Feaster, J. E.; Harlow, R. L.
Tetrahedron: Asymmetry 1991, 2(7), 569-592.
(20) Jeske, G.; Lauke, H.; Mauermann, H.; Swepston, P. N.; Schumann,
H.; Marks, T. J. J. Am. Chem. Soc. 1985, 107, 8091-8103.
(21) Shannon, R. D. Acta Crystallogr. 1976, A32, 751-767.
(22) Tian, S.; Arredondo, V. A.; Stern, C. L.; Marks, T. J. Organometallics
1999, 18, 2568-2570.