Chiral phosphite-type ligands based on ((4R,5R)-2,2-dimethyl-1,3-dioxolane-4,5-diyl)bis(diphenylmethanol) ((R,R)-TADDOL) with peripheral arylamino groups

Article abstract of DOI:10.1007/s11172-017-1883-8

New phosphite and amidophosphite inductors of chirality were obtained based on ((4R,5R)-2,2-dimethyl-1,3-dioxolane-4,5-diyl)bis(diphenylmethanol) ((R,R)-TADDOL) containing arylamino groups in the exocyclic substituents. Their use in the palladium-catalyze

Full text of DOI:10.1007/s11172-017-1883-8

Russian Chemical Bulletin, International Edition, Vol. 66, No. 7, pp. 1265—1268, July, 2017
1265
Chiral phosphiteꢀtype ligands based on
((4R,5R)ꢀ2,2ꢀdimethylꢀ1,3ꢀdioxolaneꢀ4,5ꢀdiyl)bis(diphenylmethanol)
((R,R)ꢀTADDOL) with peripheral arylamino groups
K. N. Gavrilov,a M. G. Maksimova,a I. V. Chuchelkin,a V. V. Lugovsky,a S. V. Zheglov,a
V. K. Gavrilov,a and A. M. Perepukhov b
aS. A. Esenin Ryazan State University,
46 ul. Svobody, 390000 Ryazan, Russian Federation.
Fax: +7 (491 2) 28 1435. Eꢀmail: k.gavrilov@rsu.edu.ru
bMoscow Institute of Physics and Technology,
9 Institutskii per. 9, 141700 Dolgoprudny, Moscow Region, Russian Federation.
Fax: +7 (495) 408 4257. Eꢀmail: aleksandrꢀiv@mail.ru
New phosphite and amidophosphite inductors of chirality were obtained based on
((4R,5R)ꢀ2,2ꢀdimethylꢀ1,3ꢀdioxolaneꢀ4,5ꢀdiyl)bis(diphenylmethanol) ((R,R)ꢀTADDOL)
containing arylamino groups in the exocyclic substituents. Their use in the palladiumꢀcataꢀ
lyzed enantioselective alkylation of (E)ꢀ1,3ꢀdiphenylallyl acetate with dimethyl malonate
gave the ee value up to 98%.
Key words: chiral phosphites, chiral amidophosphites, P,Nꢀligands, asymmetric alkylaꢀ
tion, palladium catalysts.
((4R,5R)ꢀ2,2ꢀDimethylꢀ1,3ꢀdioxolaneꢀ4,5ꢀdiyl)bisꢀ
(diphenylmethanol) ((R,R)ꢀTADDOL) (1) belongs to the
most available enantiomerically pure diols and is widely
used as highly efficient asymmetric inductor.1—4 Chiral
phosphorusꢀcontaining ligands on its basis showed good
properties in enantioselective metal complex catalysis.3,5
In particular, the corresponding phosphiteꢀtype P,Nꢀ
ligands are used in the Cuꢀcatalyzed processes of conjuꢀ
gate addition and allylic substitution, Rhꢀcatalyzed hydroꢀ
silylation, Irꢀcatalyzed hydroboration, as well as in the
Pdꢀcatalyzed reactions of methoxycarbonylation and
cyclization.6—15 P,NꢀPhosphites LA and amidophosphites
LB were used in the Pdꢀcatalyzed asymmetric allylic alkylꢀ
ation, first of all, of (E)ꢀ1,3ꢀdiphenylallyl acetate with
dimethyl malonate.16—18
This model reaction is widely used for the evaluation
of the efficiency of new inductors of chirality.19—23 Apart
from that, the products of alkylation with dimethyl malꢀ
onate are convenient precursors in the synthesis of esters
and amides of chiral unsaturated carboxylic acids.24
Earlier, we have reported the synthesis and involveꢀ
ment in the palladiumꢀ and copperꢀcatalyzed asymmetꢀ
ric conversions of phosphiteꢀtype P,Nꢀligands LC and LD
based on (Ra)ꢀ and (Sa)ꢀ1,1´ꢀbinaphthaleneꢀ2,2´ꢀdiol
((Ra)ꢀ and (Sa)ꢀBINOL) bearing the moieties of (Ra)ꢀ
and (Sa)ꢀ2´ꢀbenzylaminoꢀ1,1´ꢀbinaphthalenꢀ2ꢀol ((Ra)ꢀ
and (Sa)ꢀNꢀBnꢀNOBIN) or (S)ꢀ2ꢀ(phenylaminomethꢀ
yl)pyrrolidine ((S)ꢀPAMPY) as exocyclic substituents.25,26
In the present work, we describe the synthesis and
application in enantioselective catalysis of phosphiteꢀ and
amidophosphiteꢀtype P,Nꢀligands 2 and 3 with the same
exocyclic substituents and the fragment (R,R)ꢀTADDOL
in the dioxaphosphepine ring. A Pdꢀcatalyzed reacꢀ
tion of asymmetric allylic alkylation was chosen as
a catalytic process for their testing. We also compared
the enantidiscriminating activity of the ligands 2
and 3 between each other and with their known analogs
LA—LD.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1265—1268, July, 2017.
1066ꢀ5285/17/6607ꢀ1265 © 2017 Springer Science+Business Media, Inc.

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Russ. Chem. Bull., Int. Ed., Vol. 66, No. 7, July, 2017
Gavrilov et al.
Table 1. PdꢀCatalyzed alkylation of (E)ꢀ1,3ꢀdiphenylallyl acetꢀ
ate (4) with dimethyl malonatea
Entry Ligand
(L)
L : Pd
Solvent
Converꢀ
sion (%)
ee (%)b
1
2
3
4
5
6
7
8
1
1
1
1
2
2
2
2
1
2
1
2
1
2
1
2
THF
THF
CH2Cl2
CH2Cl2
THF
THF
CH2Cl2
CH2Cl2
110
115
155
144
115
113
100
100
80 (R)
75 (R)
98 (R)
97 (R)
76 (S)
76 (S)
87 (S)
79 (S)
a Reaction conditions: 2 mol. % of [Pd(allyl)Cl]2, 20 °C, 48 h.
b
Conversion of substrate 4 and enantiomeric excess of prodꢀ
uct 5 were determined by HPLC (Daicel Chiralcel OD—H,
C6H14—PriOH (99 : 1), 0.3 mL minꢀ1, 254 nm, t(R) = 28.0 min,
t(S) = 29.3 min).
Results and Discussion
high steric requirement, that follows from the high values
of their Tolman cone angles (θ) (215° and 197°, respecꢀ
tively) calculated using the semiempirical quantum chemꢀ
ical method AМ1 with full optimization of geometrical
parameters.33,34
Chiral inductors 2 and 3 were studied in the Pdꢀcataꢀ
lyzed asymmetric allylic alkylation of (E)ꢀ1,3ꢀdiphenylꢀ
allyl acetate (4) with dimethylmalonate, using [Pd(allyl)Cl]2
as a palladium source (Scheme 2, Table 1).
As it follows from the data given in Table 1, the values
of conversion and asymmetric induction strongly depend
on the ligand and the solvent nature, while the molar
ratio L : Pd does not exert significant influence on the
catalytic efficiency. Phosphite 2 shows an excellent enanꢀ
tioselectivity (up to 98% ee) and a predominant formaꢀ
tion of (R)ꢀenantiomer of the reaction product 5 (see
Table 1, entries 1—4). Considerably higher conversion
and asymmetric induction are observed in CH2Cl2. A simꢀ
ilar tendency is also characteristic of the catalytic experiꢀ
ments involving amidophosphite 3 (Table 1, entries 5—8).
Carrying out the reaction in CH2Cl2 can provide up to
87% ee with a quantitative conversion of the starting subꢀ
The new P,Nꢀligands 2 and 3 were synthesized by the
condensation of (R,R)ꢀTADDOL (1) with PCl3 catalyzed
by Nꢀmethylpyrrolidone (NMP) and the subsequent reꢀ
action with (Sa)ꢀNꢀBnꢀNOBIN or (S)ꢀPAMPY in toluꢀ
ene in the presence of an excess of Et3N as a base (Scheme 1).
The latter reactants were obtained from commercial
(Sa)ꢀBINOL27—30 and available (S)ꢀpyroglutamic acid
anilide,31,32 respectively. It is important that inexpensive
natural (R,R)ꢀtartaric and (S)ꢀglutamine acids were used
in the synthesis of (R,R)ꢀTADDOL and (S)ꢀPAMPY.
Like in the case of the synthesis of ligands LC and LD, the
phosphorylation of amino phenol (Sa)ꢀNꢀBnꢀNOBIN
exclusively involves the hydroxyl group and the pyrrolidine
amino group is involved in the diamine (S)ꢀPAMPY.
Compounds 2 and 3 are well soluble in common orꢀ
ganic solvents, they can be purified by flashꢀchromatoꢀ
graphy, are stable enough in air, and can be stored under
dry atmosphere for a long time. Their structure was conꢀ
firmed by H, 13C, and 31P NMR spectroscopy and eleꢀ
mental analysis. Ligands 2 and 3 are characterized by
1
Scheme 1
Reagents and conditions: i. PCl3, NMP; ii. (Sa)ꢀNꢀBnꢀNOBIN, Et3N, toluene; iii. (S)ꢀPAMPY, Et3N, toluene.

Chiral phosphiteꢀtype ligands
Russ. Chem. Bull., Int. Ed., Vol. 66, No. 7, July, 2017
1267
Scheme 2
suspension of (R,R)ꢀTADDOL (0.93 g, 2 mmol) in PCl3 (4 mL,
45.5 mmol), and the mixture was refluxed for 5 min until it
became homogeneous. Then, an excess of PCl3 was removed
in vacuo (40 Torr), the residue was dried in vacuo (30 min, 1 Torr)
to remove traces of PCl3 and dissolved in toluene (12 mL).
Triethylamine (0.56 mL, 4 mmol) and (Sa)ꢀNꢀBnꢀNOBIN or
(S)ꢀPAMPY (2 mmol) were added to the resulting solution
with vigorous stirring at 20 °C. The reaction mixture was stirred
for 24 h at 20 °C, then heated to 40 °C and stirred at this
temperature for 1 h. After cooling to 20 °C, the mixture was
filtered through a short column with SiO2/Al2O3. The filtrate
was concentrated in vacuo (40 Torr), the products 2 and 3 were
purified by column chromatographiy on silica gel (eluent toluꢀ
ene—hexane (2 : 1) and toluene—heptane (1 : 2), respectively).
(3aR,8aR)ꢀ6ꢀ[(Sa)ꢀ(2´ꢀBenzylaminoꢀ1,1´ꢀbinaphthalenꢀ2ꢀ
yl)oxy]ꢀ2,2ꢀdimethylꢀ4,4,8,8ꢀtetraphenyltetrahydro[1,3]diꢀ
oxolo[4,5ꢀe][1,3,2]dioxaphosphepine (2). The yield was 1.29 g
(74%), a white powder, m.p. 107—108 °C. Found (%): C, 80.32;
H, 5.62; N, 1.44. C58H48NO5P. Calculated (%): C, 80.07;
H, 5.56; N, 1.61. 31P NMR (CDCl3), δ: 134.2 (s). 13C NMR
(CDCl3), δ: 26.0 (s, Me); 26.9 (s, Me); 47.6 (s, CH2N); 79.6
(d, CHO, 3JC,P = 5.0 Hz); 82.0 (d, CHO, 3JC,P = 11.5 Hz); 83.5
(d, C(Ph2), 2JC,P = 4.3 Hz); 84.1 (s, C(Ph2)); 113.7 (s, C(Me2));
113.9 (s, CHAr); 121.4 (s, CHAr); 122.3 (d, CHAr, 3JC,P = 6.1 Hz);
123.9 (d, CAr, 3JC,P = 3.8 Hz); 124.3 (s, CHAr); 125.0 (s, CHAr);
126.0 (s, CHAr); 126.1 (s, CHAr); 126.5 (s, CHAr); 126.6
(s, CHAr); 126.7 (s, CHAr); 126.8 (s, CHAr); 126.9 (s, CHAr);
127.0 (s, CHAr); 127.1 (s, CHAr); 127.2 (s, CAr); 127.3 (s, CHAr);
127.5 (s, CHAr); 127.7 (s, CHAr); 127.8 (s, CHAr); 127.9
(s, CHAr); 128.0 (s, CHAr); 128.1 (s, CAr); 128.3 (s, CHAr);
128.4 (s, CHAr); 128.8 (s, CHAr); 128.9 (s, CAr); 129.4 (s, CHAr);
131.2 (s, CAr); 133.6 (s, CAr); 134.1 (s, CAr); 139.9 (s, CAr);
Reagents and conditions: i. CH2(CO2Me)2, Pdꢀcat, BSA,
AcOK, solvent.
strate. In all the cases, the (S)ꢀenantiomer of product 5
was predominant.
In conclusion, we have obtained new phosphiteꢀtype
P,Nꢀligands 2 and 3, successfully used them in the asymꢀ
metric Pdꢀcatalyzed allylic alkylation of (E)ꢀ1,3ꢀdipheꢀ
nylallyl acetate (4) with dimethylmalonate. The bulkier
ligand 2 provides higher enantioselectivity, but lower
conversion. Palladium catalysts based on the known
P,Nꢀligands LA—LD give 56—88% ee in this reaction.
Therefore, amidophosphite 3 demonstrated efficiency
comparable with that of these analogs, while phosphite 2
is a considerably better inductor of chirality. We plan to
continue our studies of the processes of asymmetric metal
complex catalysis involving ligands 2 and 3.
Experimental
31P, H, and 13C NMR spectra were recorded on Bruker
Avance 400 (161.98, 400.13, and 100.61 MHz) and Varian Inova
500 (202.33, 499.8, and 125.69 MHz) relative to 85% H3PO4 in
D2O and Me4Si, respectively. The signals in the 1H and 13C NMR
140.6 (s, CAr); 141.3 (s, CAr); 143.7 (s, CAr); 145.2 (d, CAr,
1
1
2JC,P = 4.2 Hz). H NMR (CDCl3), δ: 0.45 (s, 3 H, Me); 0.78
(s, 3 H, Me); 3.94 (br.s, 1 H, NH); 4.18 (d, 1 H, CH2N,
2J = 16.0 Hz); 4.30 (d, 1 H, CH2N, 2J = 16.0 Hz); 5.00 (d, 1 H,
CHO, 3J = 8.0 Hz); 5.38 (d, 1 H, CHO, 3J = 8.0 Hz); 6.89 (d, 1 H,
spectra were assigned using the APT, H—1H COSY, H—1H
NOESY, 1H—13C HSQC, 1H—13C HMBC experiments and
taking into account the data in the works.25,26,35,36 Enantioꢀ
meric analysis of the catalytic reaction products was carried out
on a Stayer HPL chromatograph. Elemental analysis was carꢀ
ried out on a Carlo Erba EA1108 CHNSꢀO microanalyzer.
All the reactions were carried out under dry argon in anhyꢀ
drous solvents. (R,R)ꢀTADDOL (1) was synthesized following
a known procedure.36 (Sa)ꢀNꢀBnꢀNOBIN and (S)ꢀPAMPY
were obtained from (Sa)ꢀBINOL (Aldrich) and available
(S)ꢀpyroglutamiс acid anilide (obtained, in turn, from (S)ꢀ
glutamiс acid (Aldrich) and aniline (Aldrich)) according to the
procedures described earlier.27—32 The reagents (E)ꢀ1,3ꢀdiꢀ
phenylallyl acetate (4) and [Pd(allyl)Cl]2 were obtained acꢀ
cording to the known procedures.37 The catalytic experiments
on asymmetric alkylation of substrate 4 with dimethyl malꢀ
onate, the determination of compound 4 conversion and enanꢀ
tiomeric excess of product 5 were carried out being guided by
the procedure published earlier.38
1
1
CHAr
(m, 6 H, CHAr); 7.16—7.23 (m, 15 H, CHAr); 7.24—7.30 (m, 5 H,
CHAr); 7.40—7.45 (m, 3 H, CHAr); 7.67 (d, 1 H, CHAr
3J = 8.1 Hz); 7.73 (d, 1 H, CHAr 3J = 8.9 Hz); 7.85 (d, 1 H,
CHAr, 3J = 8.9 Hz); 7.91 (d, 1 H, CHAr, 3J = 8.1 Hz).
,
3J = 8.6 Hz); 7.05—7.10 (m, 3 H, CHAr); 7.11—7.16
,
,
(3aR,8aR)ꢀ2,2ꢀDimethylꢀ4,4,8,8ꢀtetraphenyltetrahydroꢀ6ꢀ
[(S)ꢀ2ꢀ(phenylaminomethyl)pyrrolidnꢀ1ꢀyl]ꢀ[1,3]dioxolo[4,5ꢀe]ꢀ
[1,3,2]dioxaphosphepine (3). The yield was 1.10 g (82%), a white
powder, m.p. 112—113 °C. Found (%): C, 75.40; H, 6.54;
N, 4.29. C42H43N2O4P. Calculated (%): C, 75.20; H, 6.46;
N, 4.18. 31P NMR (CDCl3), δ: 139.6 (s). 13C NMR (CDCl3),
δ: 25.3 (s, Me); 25.4 (s, CH2); 27.7 (s, Me); 30.36 (s, CH2);
2
45.2 (d, CH2N, JC,P = 15.0 Hz); 48.6 (d, CH2N(Ph), 3JC,P
=
2
= 4.6 Hz); 56.9 (d, CHN, JC,P = 13.9 Hz); 81.9 (d, C(Ph2),
2JC,P = 9.3 Hz); 82.1 (s, C(Ph2)); 82.3 (d, CHO, 3JC,P = 20.8 Hz);
3
82.6 (d, CHO, JC,P = 3.8 Hz); 111.6 (s, C(Me2)); 112.8
(s, CHNPh); 116.9 (s, CHNPh); 127.0 (s, CHPh); 127.1 (s, CHPh);
127.2 (s, CHPh); 127.3 (s, CHPh); 127.4 (s, CHPh); 127.5
(s, CHPh); 127.7 (s, CHPh); 128.2 (s, CHPh); 128.3 (s, CHPh);
128.7 (s, CHPh); 128.8 (s, CHPh); 129.0 (s, CHNPh); 129.1
(s, CHPh); 141.5 (s, CPh); 142.3 (s, CPh); 146.6 (s, CPh); 146.9
Phosphorus trichloride, Nꢀmethylpyrrolidone (NMP), diꢀ
methyl malonate, bis(trimethylsilyl)acetamide (BSA), and triꢀ
ethylamine are commercially available agents from Fluka and
Aldrich.
1
(s, CPh); 148.6 (s, CNPh). H NMR (CDCl3), δ: 0.33 (s, 3 H,
Synthesis of ligands 2 and 3 (general procedure). NꢀMethylꢀ
pyrrolidone (0.01 g, 0.1 mmol) was added to a vigorously stirred
Me); 1.36 (s, 3 H, Me); 1.72—1.80 (m, 1 H, CH2); 1.87—1.99
(m, 2 H, CH2); 2.05—2.13 (m, 1 H, CH2); 3.08—3.16 (m, 2 H,

1268
Russ. Chem. Bull., Int. Ed., Vol. 66, No. 7, July, 2017
Gavrilov et al.
CH2N(Ph)); 3.21—3.28 (m, 1 H, CH2N); 3.72—3.79 (m, 1 H,
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CH2N); 4.13—4.20 (m, 1 H, CHN); 4.32 (br.t, 1 H, NH, J =
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= 5.6 Hz); 4.87 (d, 1 H, CHO, 3J = 8.6 Hz); 5.27 (dd, 1 H,
CHO, 3J = 8.6 Hz, 4J = 3.6 Hz); 6.44 (d, 2 H, CHNPh, 3J = 7.6 Hz);
6.66 (t, 1 H, CHNPh
= 7.6 Hz); 7.18—7.28 (m, 5 H, CHPh); 7.29—7.38 (m, 7 H,
, ,
3J = 7.6 Hz); 7.09 (t, 2 H, CHNPh 3J =
CHPh); 7.47—7.52 (m, 4 H, CHPh); 7.66 (d, 2 H, CHPh
3J = 7.4 Hz); 7.79 (d, 2 H, CHPh, 3J = 6.7 Hz).
,
Asymmetric alkylation of (E)ꢀ1,3ꢀdiphenylallyl acetate (4)
with dimethyl malonate. A solution of [Pd(allyl)Cl]2 (0.0037 g,
0.01 mmol) and the corresponding ligand (0.02 mmol or
0.04 mmol) in the corresponding solvent (5 mL) was stirred for
40 min. After addition of (E)ꢀ1,3ꢀdiphenylallyl acetate 4
(0.1 mL, 0.5 mmol), the solution was stirred for another
15 min, followed by the addition of dimethyl malonate (0.1 mL,
0.87 mmol), BSA (0.22 mL, 0.87 mmol), and potassium acetate
(0.002 g). The reaction mixture was stirred for 48 h, diluted
with hexane (5 mL) and filtered through Celite. The solvents
were removed at reduced pressure (40 Torr), the residue was
dried in vacuo (10 Torr). Conversion of substrate 4 and enantioꢀ
meric excess of product 5 were determined by HPLC on
a Daicel Chiralcel OD—H chiral stationary phase (eluent
C6H14—PriOH (99 : 1), 0.3 mL min–1, 254 nm, t(R) = 28.0 min,
t(S) = 29.3 min).
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This work was financially supported by the Ministry
of Education and Science of the Russian Federation
(NIR, State Assignment No. 4.9515.2017/BCh, ligand 2)
and the Russian Foundation for Basic Research (Project
No. 16ꢀ33ꢀ00237 molꢀa, ligand 3).
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2013, 18, 2788.
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Received March 1, 2017;
in revised form May 10, 2017