Novel, efficient alkene-phosphinite hybrid ligand based on D-glucose

Article abstract of DOI:10.1021/ol901579g

A commercially available 2,3-unsaturated pyranoside, derived from D-glucose, was converted Into a new type of olefin phosphorus chelate ligand in only three steps. Application In rhodium catalyzed conjugate additions of phenylboronic acid to enones led to

Full text of DOI:10.1021/ol901579g

ORGANIC
LETTERS
2
009
Vol. 11, No. 18
212-4215
Novel, Efficient Alkene-Phosphinite
Hybrid Ligand Based on D-Glucose
4
Tobias Minuth and Mike M. K. Boysen*
Institute of Organic Chemistry, Gottfried Wilhelm Leibniz UniVersity of HannoVer,
Schneiderberg 1B, D-30167 HannoVer, Germany
mike.boysen@oci.uni-hannoVer.de
Received July 10, 2009
ABSTRACT
A commercially available 2,3-unsaturated pyranoside, derived from D-glucose, was converted into a new type of olefin phosphorus chelate
ligand in only three steps. Application in rhodium catalyzed conjugate additions of phenylboronic acid to enones led to excellent levels of
stereoinduction for several cyclic substrates. The easy preparation and the high efficiency of this ligand make it an interesting and promising
alternative to established systems.
2
During recent years, chiral olefins have emerged as novel
and exciting ligands for metal catalyzed asymmetric trans-
formations. While simple alkenes coordinate metals only
weakly, the enhanced stability of complexes with novel olefin
ligands stems from chelation of the metal by either two
alkene moieties as in chiral dienes or by an olefin in
combination with phosphorus or nitrogen donor centers.
Prominent examples of alkene-phosphorus hybrid ligands are
shown in Figure 1. The first reports on this type of ligand
1
3
by Gr u¨ tzmacher described 1, based on a 5H-dibenzo[a,d]-
cycloheptene backbone. Hayashi introduced norbornene-
4
based 2, which is one of the most successful alkene-
(
1) For reviews, see: (a) Glorius, F. Angew. Chem., Int. Ed. 2004, 43,
364. (b) Defieber, C.; Gr u¨ tzmacher, H.; Carreira, E. M. Angew. Chem.,
Int. Ed. 2008, 47, 4482.
2) For prominent examples, see: (a) Hayashi, T.; Ueyama, K.;
3
phosphorus ligands. Later Gr u¨ tzmacher published 3 as a
5
variant of 1. Ligands 4 and 5, containing a binaphthyl
(
6
7
scaffold were reported by Widhalm and Carreira, respec-
Tokunaga, N.; Yoshida, K. J. Am. Chem. Soc. 2003, 125, 11508. (b) Fischer,
C.; Defieber, C.; Suzuki, T.; Carreira, E. M. J. Am. Chem. Soc. 2004, 126,
628. (c) Defieber, C.; Paquin, J.-F.; Serna, S.; Carreira, E. M. Org. Lett.
004, 6, 3873. (d) Berthon-Gelloz, G.; Hayashi, T. J. Org. Chem. 2006,
1, 8957. (e) Helbig, S.; Sauer, S.; Cramer, N.; Laschat, S.; Baro, A.; Frey,
8
9
tively. Bolm and Stepnicka described several examples of
planar chiral hybrid ligands, among them 6 and 7.
These ligands have been employed in iridium catalyzed
hydrogenation of imines (1) and acrylic acid derivatives
(3), iridium catalyzed amination of allylic alcohols (5) and
1
2
7
W. AdV. Synth. Catal. 2007, 349, 2331. (f) Feng, C.-G.; Wang, Z.-Q.; Shao,
3b
C.; Xu, M.-H.; Lin, G.-Q. Org. Lett. 2008, 10, 4101.
5
7
(3) (a) Deblon, S.; Gr u¨ tzmacher, H.; Sch o¨ nberg, H. WO 03/048175 A1,
1
0
9b,11
2
003. (b) Maire, P.; Maire, P.; Deblon, S.; Breher, F.; Geier, J.; B o¨ hler, C.;
R u¨ egger, H.; Sch o¨ nberg, H.; Gr u¨ tzmacher, H. Chem.sEur. J. 2004, 10,
198.
4) Shintani, R.; Duan, W.-L.; Nagano, T.; Okada, A.; Hayashi, T.
Angew. Chem., Int. Ed. 2005, 44, 4611.
5) Piras, E.; L a¨ ng, F.; R u¨ egger, H.; Stein, D.; W o¨ rle, M.; Gr u¨ tzmacher,
H. Chem.sEur. J. 2006, 12, 5849.
6) Kas a´ k, P.; Arion, V. B.; Widhalm, M. Tetrahedron Asymmetry 2006,
7, 3084.
7) Defieber, C.; Ariger, M. A.; Moriel, P.; Carreira, E. M. Angew.
palladium catalyzed allylic substitutions (2 and 6).
Their most important application, however, is the rhodium
4
(
catalyzed conjugate addition of boronic acids to enones
12,13
(Hayashi-Miyaura reaction),
with Hayashi’s ligand 2
(
(
(10) For a review see: Trost, B. M.; van Vranken, D. L. Chem. ReV.
1
1996, 96, 395.
(
(11) Shintani, R.; Duan, W.-L.; Okamoto, K.; Hayashi, T. Tetrahedron
Chem., Int. Ed. 2007, 46, 3139.
Asymmetry 2005, 16, 3400
(12) Takaya, Y.; Ogasawara, M.; Hayashi, T.; Sakai, M.; Miyaura, N.
J. Am. Chem. Soc. 1998, 120, 5579
(13) For reviews see: (a) Hayashi, T.; Yamasaki, K. Chem. ReV. 2003,
103, 2829. (b) Hayashi, T. Pure Appl. Chem. 2004, 76, 465
.
(
(
8) Stemmler, R. T.; Bolm, C. Synlett 2007, 1365.
9) (a) Stepnicka, P.; Cisarova, I. Inorg. Chem. 2006, 45, 8785. (b)
.
Stepnicka, P.; Lamac, M.; Cisarova, I. J. Organomet. Chem. 2008, 693,
4
46.
.
10.1021/ol901579g CCC: $40.75
Published on Web 08/19/2009
 2009 American Chemical Society

2
3a,d
23b
tion
and imine alkynylation. We have now become
interested in the preparation of a novel type of alkene-
phosphinite hybrid ligand based on carbohydrates for two
reasons: as described above, phosphorus-based donor centers
can be easily introduced into a carbohydrate framework by
phosphinite formation, and a number of unsaturated carbo-
hydrate derivatives are accessible by well established syn-
thetic methods or even commercially available at reasonable
pricing.
Scheme 1. Preparation of a Novel Carbohydrate
Alkene-Phosphinite-Hybrid Ligand from Commercially
Available 2,3-Unsaturated Pyranose 9
Figure 1. Chiral alkene-phosphine hybrid ligands.
4
,14
giving excellent results.
Ligands 3, 4, 5 and 7 have also
5
,6,8,15
been successfully employed for this reaction.
Despite its high efficiency, ligand 2 suffers from the
drawback of a laborious preparative route which includes
4
,14
an enantiomeric resolution by preparative HPLC.
The
preparation of 1 and 3 is fraught with similar difficulties.
Only the synthesis of 4 and 5 makes use of enantiomerically
pure binaphthyl precursors and until today no example of
an alkene-phosphine ligand based on compounds from the
chiral pool has been reported.
6
,7
Our ligand synthesis (Scheme 1) started from ethyl-
,6-di-O-acetyl-2,3-dideoxy-R-D-erythro-hex-2-enopyra-
nose (9), which was purchased from Sigma-Aldrich
approximately 25 Euros/g, May 2009). This 2,3-unsatur-
4
(
Carbohydrates are attractive, if comparatively rarely used,
16
starting materials for the design of chiral complex ligands.
The first examples of this type were reported independently
(
16) For reviews see: (a) Hale, K. J. Second Supplement to the Second
Edition of Rodd’s Chemistry of Carbon Compounds, Vol. 1E/F/G; Sainsbury,
M., Ed.; Elsevier: Amsterdam, 1993; Chapter 23b, p 273. (b) Di e´ guez, M.;
P a` mies, O.; Claver, C. Chem. ReV. 2004, 104, 3189. (c) Di e´ guez, M.; Claver,
C.; P a` mies, O. Eur. J. Org. Chem. 2007, 4621. (d) Boysen, M. M. K.
Chem.sEur. J. 2007, 13, 8648.
1
7
18
19
20
by Cullen, Thompson, Selke, and Descotes who
prepared bidentate phosphinite ligands by the simple reaction
of carbohydrate diols with diphenyl chlorophosphine. Since
this pioneering work a large number of carbohydrate ligands,
featuring a wide range of donor atoms, have appeared in
the literature. Many of these ligands contain at least one
phosphorus-based donor center, as found in the more recent
(
(
17) Cullen, W. R.; Sugi, Y. Tetrahedron Lett. 1978, 19, 1635.
18) Jackson, R.; Thompson, D. J. J. Organomet. Chem. 1978, 159, C29.
(19) Selke, R. React. Kinet. Catal. Lett. 1979, 10, 135.
(
(
20) Sinou, D.; Descotes, G. React. Kinet. Catal. Lett. 1980, 14, 463.
21) (a) Casalnuovo, A. L.; RajanBabu, T. V.; Ayers, T. A.; Warren,
T. H. J. Am. Chem. Soc. 1994, 116, 9869. (b) RajanBabu, T. V.; Ayers,
T. A.; Halliday, G. A.; You, K. K.; Calabrese, J. C. J. Org. Chem. 1997,
62, 6012. (c) Clyne, D. S.; Mermet-Bouvier, Y. C.; Nomura, N.; RajanBabu,
T. V. J. Org. Chem. 1999, 64, 7601. (d) Park, H.; RajanBabu, T. V. J. Am.
Chem. Soc. 2002, 124, 734.
2
1
examples of phosphinite ligands reported by RajanBabu,
2
2
Uemura and Ohe.
In the course of our work, we have introduced new
bis(oxazolines) derived from D-glucosamine, which have
proven to be very efficient in asymmetric cyclopropana-
2
3
(22) (a) Yonehara, K.; Hashizume, T.; Mori, K.; Ohe, K.; Uemura, S.
J. Org. Chem. 1999, 64, 5593. (b) Yonehara, K.; Hashizume, T.; Mori, K.;
Ohe, K.; Uemura, S. J. Org. Chem. 1999, 64, 9374.
(
23) (a) Irmak, M.; Groschner, A.; Boysen, M. M. K. Chem. Commun.
(
14) Duan, W.-L.; Iwamura, H.; Shintani, R.; Hayashi, T. J. Am. Chem.
Soc. 2007, 129, 2130
15) Mariz, R.; Brice n˜ o, A.; Dorta, R.; Dorta, R. Organometallics 2008,
7, 6605
2007, 177. (b) Irmak, M.; Boysen, M. M. K. AdV. Synth. Catal. 2008, 350,
403. (c) Minuth, T.; Boysen, M. M. K. Synlett 2008, 1483. (d) Minuth, T.;
Irmak, M.; Groschner, A.; Lehnert, T.; Boysen, M. M. K. Eur. J. Org.
Chem. 2009, 997.
.
(
2
.
Org. Lett., Vol. 11, No. 18, 2009
4213

ated pyranose can also be prepared from D-glucose (8)
formed from [Rh(acac)(H
CDCl showed significant upfield shifts for the olefinic
pyranose protons [ H NMR (400 MHz, CDCl
ppm for H-2; δ ) 4.47 ppm for H-3] compared to free ligand
2
C)CH
2 2
) ] with 1 eq of 12 in
2
4
via D-glucal using a Ferrier rearrangement as the key
3
2
5
1
step. Basic deprotection of 9 with subsequent regiose-
3
): δ ) 3.34
2
6
lective tritylation led to alcohol 11. Reaction with
diphenyl chlorophosphine under conditions described
previously for the preparation of carbohydrate-based
1
12 [ H NMR (400 MHz, CDCl ): δ ) 5.75 ppm for H-2; δ
3
) 5.92 ppm for H-3]. The phosphinite resonance in com-
pexed gluco-enoPhos (12) experienced a downfield shift and
2
2
oxazoline-phosphinite hybrid ligands yielded the desired
hybrid ligand gluco-enoPhos (12), which was thus ob-
tained in only three steps and good overall yield.
3
1
103
31
was split up to a doublet due to P- Rh coupling [ P
1
NMR (161.9 MHz, CDCl
Hz] while free 12 gave a singlet further upfield [ P NMR
(161.9 MHz, CDCl ): δ ) 113.3 ppm, s]. These findings
correlate with those reported for olefin-phosphine ligands and
3
): δ ) 159.0 ppm, d, JP,Rh ) 193.7
3
1
Next we tested the new alkene-phosphinite hybrid ligand
in asymmetric conjugate additions of boronic acids to enones
3
1
2,13
(
Hayashi-Miyaura reaction).
of 2-cyclohexene-1-one (13a) with phenylboronic acid (14)
in the presence of 1.5 mol % [RhCl(H CdCH and 3.3
To our delight, the reaction
4
-6
their rhodium complexes.
gluco-enoPhos (12) was also employed in a palladium
catalyzed asymmetric allylic alkylation reaction.
2
2 2 2
) ]
2
7
10,28
mol % 12 under Hayashi’s conditions furnished the 1,4-
addition product 15a in good yield and excellent enantiose-
lectivity of 99% ee.
When
racemic 1,3-diphenyl-2-propenyl acetate (16) was treated
with dimethylmalonate (17) in the presence of a palladium
2
9
The same yield and excellent level of stereoinduction were
obtained for 2-cyclopentene-1-one 13b, while lactone 13c
was converted to 15c in moderate yield and 94% ee. Due to
its conformational flexibility and the absence of large
substituents at the termini, acyclic enone 13d represents a
challenging substrate for stereoselective conjugate addition.
With the new ligand 12, addition product 15d was obtained
in good yield and 52% ee which, for this substrate, is still
encouraging. The results of the conjugate additions are
summarized in Scheme 2.
complex of 12 under known conditions, the allylation
product was formed in good yield and 61% ee (Scheme 3).
Scheme 3
.
Application of gluco-enoPhos (12) in an Asymmetric
Allylic Alkylation Reaction
Scheme 2. Application of gluco-enoPhos (12) in Conjugate
Additions of Phenylboronic Acid to Enones
Although only a moderate level of stereoinduction was
achieved in this transformation, it clearly shows that the new
ligand 12 is able to exert asymmetric induction in combina-
tion with other metal centers in different reactions.
In conclusion, with gluco-enoPhos, we have introduced a
novel type of alkene-phosphinite hybrid ligand, accessible
in three simple steps from a commercially available unsatur-
ated pyranose derivative. As this precursor is derived from
D-glucose, time-consuming and laborious enantiomeric reso-
lution steps are not necessary for the preparation of this new
ligand. First applications in asymmetric catalysis led to
excellent levels of stereoselectivity in 1,4-additions of boronic
acids to enones and moderate selectivity in asymmetric allylic
(
24) Ferrier, R. J.; Overend, W. G.; Ryan, A. E. J. Chem. Soc. 1962,
667.
25) de Freita Filho, J. R.; Srivastava, R. M.; da Silva, W. J. P.; Cottier,
3
(
L.; Sinou, D. Carbohydr. Res. 2003, 338, 673.
(
(
(
26) Hotha, S.; Tripathi, A. J. Comb. Chem. 2005, 7, 968.
27) Okamoto, K.; Hayashi, T.; Rawal, V. H. Org. Lett. 2008, 10, 4387.
28) For selected application of carbohydrate-based ligands in this
reaction, see: (a) Gl a¨ ser, B.; Kunz, H. Synlett 1998, 53. (b) Reference 22a.
c) Khiar, N.; Ara u´ jo, C. S.; Su a´ rez, B.; Fern a´ ndez, I. Eur. J. Org. Chem.
(
Evidence for the bidentate coordination of gluco-enoPhos
12) to rhodium(I) through both the alkene and the phos-
phinite was obtained from NMR studies. The complex
2
006, 1685. (d) Mata, Y.; Di e´ guez, M.; P a` mies, O.; Claver, C. AdV. Synth.
(
Catal. 2005, 347, 1943.
(29) Sprinz, J.; Helmchen, G. Tetrahedron Lett. 1993, 34, 1769.
4214
Org. Lett., Vol. 11, No. 18, 2009

alkylations. These results together with the facile preparation
of the ligand make it a very attractive and promising
candidate for future applications in catalysis. Studies con-
cerning the scope of the new ligand and its optimization are
currently underway.
Groschner (Georg-August University of G o¨ ttingen, Germany)
for assistance with chiral HPLC experiments.
Supporting Information Available: Experimental details
and analytical data for all described compounds. This
material is available free of charge via the Internet at
http://pubs.acs.org.
Acknowledgment. We thank the DFG and the Volks-
wagenFoundation for generous financial support and Annika
OL901579G
Org. Lett., Vol. 11, No. 18, 2009
4215