Synthesis of diheteroarylamine ligands by palladium-catalyzed mono- and diamination of dichloroheteroarenes with heteroarenamines

Article abstract of DOI:10.1002/hlca.201000148

The syntheses of bidentate (see 6 and 12), bis-bidentate (7, 10, and 13) up to oligo-bidentate (see 11 and 14) diheteroarylamine-based N,N-ligands are reported (Tables 2, 4, and 5). In the course of investigations on heteroaromatic (C-N)-bond formations,

Full text of DOI:10.1002/hlca.201000148

46
Helvetica Chimica Acta – Vol. 94 (2011)
Synthesis of Diheteroarylamine Ligands by Palladium-Catalyzed Mono- and
Diamination of Dichloroheteroarenes with Heteroarenamines
by Daniel Samson and Ewald Daltrozzo*
Fachbereich Chemie, Universitꢀt Konstanz, Universitꢀtsstrasse 10, DE-78464 Konstanz
(fax: þ 497531883043; e-mail: ewald.daltrozzo@uni-konstanz.de)
The syntheses of bidentate (see 6 and 12), bis-bidentate (7, 10, and 13) up to oligo-bidentate (see 11
and 14) diheteroarylamine-based N,N-ligands are reported (Tables 2, 4, and 5). In the course of
investigations on heteroaromatic (CꢀN)-bond formations, a protocol for the Pd-catalyzed mono- and
diamination of 2,6-dichloropyridine (1) and 4,6-dichloropyrimidines 5 with heteroaren-2-amines 2 and
pyrimidine-4,6-diamines 8 is developed. The results are applied to the syntheses of the ꢁpentamersꢂ 11a –
11d and the ꢁheptamerꢂ 14 based on 4,6-disubstituted 2-alkylpyrimidines 5 and 8, respectively.
Introduction. – Over the last decades, a central topic of our research activities have
been correlations between molecular structure and fluorescence [1 – 3]. In addition to
the synthesis and investigation of boron chelates II of bidentate heteroaromatic N,N-
ligands I, one field of interest has been the investigation of bis- and oligo-BR2
complexes of oligo-bidentate heteroaromatic N,N-ligands. Aside from the potential
pharmacological activity of the title compounds, our interest in an easy and convenient
availability of a great variety of amines I originates from the fact that the complexation
of I with boron reagents results in dyes II that generally show high room-temperature
fluorescence quantum yields [3]. Apart from their interesting spectroscopic features,
we recommend dyes of type II as efficient laser dyes and attractively active emitters in
OLEDs (organic light-emitting diodes) for a long time. In this context, we compared C-
bridged 6-membered-ring ligand systems (i.e., diheteroarylacetonitriles [4][5], X ¼
CꢀCN in Fig. 1) with N-bridged 6-membered-ring ligand systems (i.e., diheteroaryl-
amines [6], X ¼ N in Fig. 1). However, the access to the latter is very limited due to
synthetic difficulties [7].
Fig. 1. General formulas of diheteroarylamine ligands I and boron chelates II thereof
The basic condensation of heteroaren-2-amines with leaving-group-substituted
heteroaromatics resulting in diheteroarylamines I is well-known for A, B ¼ pyridin-2-yl
or quinolin-2-yl; however, the yields are unsatisfactory and the reaction does not work
at all for many other combinations of heteroaromatic reactants. To overcome the
ꢃ 2011 Verlag Helvetica Chimica Acta AG, Zꢄrich

Helvetica Chimica Acta – Vol. 94 (2011)
47
problems known from established syntheses of I, we studied the applicability of the
Buchwald – Hartwig procedure with heteroaromatic substrates. In addition to the
syntheses of a great variety of compounds I, the use of dichloro- and/or diamino-
substituted heteroarenes as bi-functionalized reactants with the possibility of multiple
combinations were taken into consideration from the very beginning of our studies. In
contrast to a few reported Pd-catalyzed aminations of chloroheteroarenes with
heteroarenamines [8 – 11], to the best of our knowledge, no reliable amination protocol
for both the mono- and the diamination of dichloroheteroarenes has been established
so far, with exception of the syntheses of oligo-pyridin-2-amines based on 2,6-
dibromopyridines as precursors [12 – 17]. Furthermore, Dommisse and co-workers did
not observe any formation of the diaminated products when reacting dichloropyridines
even with a large excess of pyridin-2-amine for 40 h under Buchwald – Hartwig
conditions. Hence, they reported the selectivity of the mild Pd-catalyzed monoamina-
tion on dichloropyridines with heteroarenamines [8]. Caused by the straightforward
and low-cost access to chloroheteroarenes compared to bromo- and iodoheteroarenes
or heteroaryl triflates, we investigated the Pd-catalyzed mono- and diamination of
dichloroheteroarenes, namel, 2,6-dichloropyridine (1), 4,6-dichloropyrimidine (5a),
and several 2-alkylated 4,6-dichloropyrimidines 5b – 5d, accepting the comparatively
disadvantageous chloride leaving group (cf. Tables 1, 2, 4, and 5) to obtain bidentate
(see 6 and 12), bis-bidentate (see 7, 10, and 13) up to oligo-bidentate (see 11 and 14)
diheteroarylamine-based N,N-ligands. Also the reversed reactant functionalities
regarding the amino function and leaving group were taken into consideration for
the syntheses of bidentate (see 6’) and bis-bidentate (see 7’) ligands (cf. Table 3). The
results were applied for the syntheses of the ꢁpentamersꢂ 11a – 11d (cf. Table 4) and the
ꢁheptamerꢂ 14 (cf. Table 5) based on 4,6-disubstituted 2-alkylpyrimidines 5 and 8,
respectively.
Results and Discussion. – When reacting 2,6-dichloropyridine (1) with the
pyrimidin-2-amines 2a or 2b (Table 1) by using 17 equiv. of K2CO3 as base and
[Pd(OAc)2]/BINAP (¼1,1’-[1,1’-binaphthalene]-2,2’-diylbis[1,1-diphenylphosphine])
as catalyst in toluene (reaction condition a) in Table 1), we obtained mixtures of
mono- and diaminated products and unreacted starting materials nearly independent of
the chosen reactant stoichiometry. No constitutional selectivity in favor of either mono-
or diamination was observed. However, when using the Pd0 source [Pd(dba)2] (dba ¼
dibenzylideneacetone ¼ 1,5-diphenylpenta-1,4-dien-3-one) and 2.2 equiv. of tBuONa as
base, the yield of the diamination product increased significantly while the mono-
amination product was only observed as an intermediate during the reaction (reaction
condition b) in Table 1). We interprete this as a major result of the increased ꢁeffectiveꢂ
catalytic amount of the Pd0 catalyst complex, which is able to cleave the remaining
second CꢀCl bond by insertion within the oxidative addition step and, therefore, to
promote the second amination, assisted by the higher basicity of the alkoxide compared
to that of the carbonate. When using a PdII source, the in situ reduction to the efficient
Pd0 catalyst resting state has to take place before the catalyst complex can enter the
catalytic cycle with the oxidative addition step [18]. Hence, it is not necessary to use a
more electron-rich chelating phosphine coligand other than common BINAP when a
Pd0 source is used for the diamination of dichloroheteroarenes. We transferred these

48
Helvetica Chimica Acta – Vol. 94 (2011)
Table 1. Mono- vs. Diamination of 2,6-Dichloropyridine (1) with Pyrimidin-2-amines 2a and 2b: Reaction
Conditions and Yields of Mono- and Diaminated Products 3 and 4, respectively
Reactants
Approx. ratio
Reaction conditiona)
Pd Source
Yield [%] of 3
Yield [%] of 4
1/2a
1/2a
1/2b
1/2b
1 : 1
1 : 2
1 : 1
1 : 2
a)
b)
a)
b)
PdII
Pd0
PdII
Pd0
10 (3a)
not det. (3a)
73 (3b)
3 (4a)
58 (4a)
5 (4b)
not det. (3b)
90 (4b)
a) Reaction conditions: a) > 9 equiv. of carbonate, PdII salt, chelating phosphine, toluene (reflux). b) 1 –
3 equiv. of alkoxide, Pd0 complex, chelating phosphine, toluene (reflux).
findings to the mono- and diamination of 4,6-dichloropyrimidines 5a – 5d with several
heteroaren-2-amines 2a – 2f (Table 2) to obtain the 4,6-disubstituted pyrimidines 7a –
7i. The used catalyst loadings were typically between 2 and 6 mol-%. Higher loadings
were only applied when necessary for completion of the individual reaction. The
phosphine/Pd ratio was chosen to be 1.5 or higher to increase the amount of the
BINAP-stabilized catalytically active Pd0 complex, to compensate partial phosphine
oxidation, and to inhibit complexation of Pd by reactants and products, which is the
most critical issue.
At elevated temperatures, the pyrimidine moiety is sensitive to strong bases such as
the alkoxides, which are commonly used in the standard Buchwald – Hartwig-amination
protocols. Therefore, it was necessary to decrease the amount of base or substitute
alkoxides by the milder carbonates for both the mono- and the desirable diamination.
In general, the monoamination products 6 were obtained in moderate to good yields
when using PdII sources for the catalyst and equimolar reactant ratios, whereas the
diamination products 7 for many combinations of substrates required Pd0 sources
(Table 2). In some cases, the diaminated products could also be isolated in moderate
to good yields by using PdII sources; however, higher catalyst loadings were necessary
in these reactions. With Pd0 sources, the diaminated products were also obtained in
a mixture with the monoaminated products when the amine reactants were used
in substoichiometric amounts1). Thus, the diaminated products could be obtained
1
)
The yields of the (2:1)-condensation products given in Tables 1 – 3 are calculated on the basis of the
amount of the limiting reactant when the reactantsꢂ ratio was 1:1. Thus, the effective yields of the
diaminated products are always significantly higher (up to a factor of 2, when no monoaminated
product is formed at all).

Helvetica Chimica Acta – Vol. 94 (2011)
49
Table 2. Mono- vs. Diamination of 4,6-Dichloropyrimidines 5a – 5d with Heteroaren-2-amines 2a – 2f:
Reaction Conditions and Yields of Mono- and Diaminated Products 6 and 7, respectively
Reactantsa) Approx. ratio Reaction conditionsb) Pd Source Yield [%] of 6 Yield [%] of 7
5a/2a
5a/2a
5a/2b
5a/2b
5b/2b
5b/2b
5a/2c
5a/2c
6d/2c
5a/2d
5a/2d
5d/2e
5a/2f
5b/2f
5c/2f
1 : 1
1 : 2
1 : 1
1 : 2
1 : 0.8
1 : 2
1 : 1
1 : 2
1 : 1
1 : 2
1 : 2
1 : 2
1 : 2
1 : 1
1 : 2
a)
a)
a)
a)
b)
c)
d)
e)
e)
d)
f)
Pd0
Pd0
Pd0
Pd0
Pd0
PdII
PdII
Pd0
Pd0
PdII
Pd0
Pd0
PdII
PdII
PdII
69 (6a)
not det. (6a)
75 (6b)
not det. (6b)
29 (6c)
not det. (6c)
41 (6d)
not det. (6d)
n/a (6d)
38 (6e)
not det. (6e)
not det. (6f)
not det. (6g)
30 (6h)
not det. (7a)
31 (7a)
not det. (7b)
66 (7b)
36 (7c)
75 (7c)
not det. (7d)
82 (7d)
52 (7d)
not det. (7e)
81 (7e)
86 (7f)
a)
c)
c)
d)
77 (7g)
10 (7h)
27 (7i)
67 (6i)
b
a) For the formulas of 2a and 2b, see Table 1. ) Reaction conditions: a) > 9 equiv. of carbonate, Pd0
complex, chelating phosphine, toluene (reflux). b) 2 – 6 equiv. of carbonate, Pd0 complex, chelating
phosphine, dioxane (reflux). c) 2 – 6 equiv. of carbonate, PdII salt, chelating phosphine, dioxane (reflux).
d) 1 – 5 equiv. of carbonate, PdII salt, chelating phosphine, toluene (reflux). e) > 9 equiv. of carbonate,
PdII salt, chelating phosphine, toluene (reflux). c) 1 – 3 equiv. of alkoxide, PdII salt, chelating phosphine,
toluene (reflux).
in reasonably high yields by using Pd0 sources and excess of amine reactants and
base.
When reversing the reactant functionality by conducting the 1:1 and 2 :1
condensation of the pyrimidine-4,6-diamines 8a – 8c with the 2-chloroheteroarenes 9a

50
Helvetica Chimica Acta – Vol. 94 (2011)
and 9b, different results regarding the yields of mono- vs. diaminated products were
obtained (Table 3). In these cases, the monoaminated products were only observed as
intermediates during reaction when using Pd0 sources or in a mixture with the
diaminated products when using PdII sources. This fact was nearly independent of the
excess of the chlorinated reactants 9. We interprete this as a consequence of the
reactivity of the heteroarenediamines 8, which is not decreased after monoamination.
Hence, it is not necessary to activate a second CꢀCl bond in the pyrimidine moiety for
further reaction as it is in case of the nonreversed reactant functionality as described
above.
Table 3. Reversed Reactant Functionality: Reaction Conditions and Yields of Mono- and Diaminated
Products 6’ and 7’, respectively
Reactants Approx. ratio
Reaction conditionsa) Pd Source Yield [%] of 6’
Yield [%] of 7’
8a/9a
8a/9a
8b/9a
8c/9a
8a/9b
8c/9b
1 : 1
1.2 : 1
1 : 1
1 : 2
1 : 1
1 : 2
a)
b)
c)
b)
c)
c)
PdII
Pd0
PdII
Pd0
PdII
PdII
18 (6’k)
41 (7’k)
53 (7’k)
44 (7’l)
83 (7’m^)
12 (7’n¼7i)
9 (7’o)
not det. (6’k)
not det. (6’l)
not det. (6’m)
17b) (6’n)
22 (6’o)
a) Reaction conditions: a) 1 – 5 equiv. of carbonate, PdII salt, chelating phosphine, toluene (reflux). b)
> 9 equiv. of carbonate, Pd0 complex, chelating phosphine, toluene (reflux). c) > 9 equiv. of carbonate,
PdII salt, chelating phosphine, toluene (reflux). b) Compound 6’n was also obtained, in 56% yield, by
reacting the bifunctional 6-chloropyrimidin-4-amine with 2f (1 : 1 ratio) under condition c).
The results of the reversed reactant functionality were applied for the syntheses of
the ꢁpentamersꢂ 11a – 11d (Table 4) by using a Pd0 source and excess of the
dichloroheteroarene reactants 6b, 6e, and 6i.
For the stepwise syntheses of the ꢁheptamerꢂ 14 (Table 5), a comparatively
inefficient PdII source (instead of a Pd0 source as discussed above) was used to avoid

Helvetica Chimica Acta – Vol. 94 (2011)
51
Table 4. Amination of the Chlorinated Diheteroarylamines 6b, 6e, and 6i with Pyrimidine-4,6-diamines 8a
and 8b or Triazine-2,4-diamine 8c: Reaction Conditions and Yields of Mono- and Diaminated Products 10
and 11, respectively
Reactants Approx. ratio Reaction conditionsb) Pd Source Yield [%] of 10 Yield [%] of 11
8a/6b
8b/6e
8b/6i
8c/6b
1 : 2
1 : 1.7
1 : 2
a)
a)
a)
a) or b)
Pd0
Pd0
Pd0
Pd0
47 (10a)
30 (10b)
not det. (10c)
5 (10d)
33 (11a)
48 (11b)
46 (11c)
23 (11d)
1 : 2
b
a) For the formulas of 8a – 8c, see Table 3. ) Reaction conditions: a) > 9 equiv. of carbonate, Pd0
complex, chelating phosphine, toluene (reflux). b) 1 – 3 equiv. of alkoxide, Pd0 complex, chelating
phosphine, toluene (reflux).
side reactions or uncontrolled oligomerization. For the synthesis of 14, Ph3P was added
to the catalyst mixture to avoid partial BINAP oxidation.
The solubilities of the ꢁoligomersꢂ 11 and 14 were increased by using the 2-alkylated
pyrimidine reactants 5b – 5d, 6i, and 8a – 8c. The crude product mixtures were washed
carefully with H2O before drying and subsequent purification because of the adsorption
of the products on the heterogeneous base. To our surprise, the wastage of the Pd
catalyst by the formation of Pd chelates with the ligands described in this work was not
a problem. In contrast to this finding, we isolated and characterized Pd complexes
containing a 2 :1 ratio of the bidentate diheteroarylamine ligands and the metal from
Pd-catalyzed syntheses with quinolin-2-amines [6].
For all reported products 3, 4, 6, 7, and 10 – 14, the temperature- and solvent-
dependent tautomer equilibria in neutral solution preferably exist on the side of the

52
Helvetica Chimica Acta – Vol. 94 (2011)
Table 5. Amination of 5b with 8b and Synthesis of the ꢀ Heptamerꢁ 14: Reaction Conditions and Yields of
Mono- and Diaminated Products 12 and 13 or 14, respectively
Reactants Approx. ratio Reaction conditionsa) Pd Source Yield [%] of 12 Yield [%] of 13 or 14
5b/8b
13/8b
2 : 1
2 : 1
a)
a)
PdII
PdII
23 (12)
not det.
48 (13)
88 (14)
a) Reaction conditions: a) > 9 equiv. of carbonate, PdII salt, chelating phosphine, toluene (reflux).
tautomers containing central NH bridges. Due to the electron-withdrawing forces of
the connected azaaromatics and dependent on the solvent, always minor parts of the
systems exist on the side of Ib (X ¼ N, Fig. 1), as evidenced by a longer-wavelength
absorption (Scheme).
Scheme. Tautomers Ia and Ib in Neutral Solution
Monoprotonation of diheteroarylamines results in the formation of the H-chelate
structures IIIa and not of the azacyanine-type structures IIIb as it results from
alkylation (Fig. 2). This structural assignment clearly follows from the UV/VIS spectra
of the derivatives III with A ¼ B, showing the characteristic differences for the S0 ! S1
transition which are typical for C2v and Cs symmetry of the chromophoric systems,
respectively [3]. Spectra/structure correlations and a detailed discussion of the
tautomeric species occurring by protonation of oligo-bidentate compounds will be
presented elsewhere [19].

Helvetica Chimica Acta – Vol. 94 (2011)
53
Fig. 2. Comparison of the protonated species IIIa with the corresponding N,N’-dialkylated azacyanine-
type species IIIb
Summary. – When conducting Pd-catalyzed aminations of dichloropyridines or
dichloropyrimidines with heteroarenamines, the (1:1)-condensation products were
preferably formed when using PdII sources, nearly independent of the reactant ratio.
However, the (2 :1)-condensation products could be obtained in reasonably high yields
by using Pd0 sources. When reversing the reactant functionality, the monoamination
products were only observed as intermediates during reaction when using Pd0 sources
or in a mixture with the diamination products when using PdII sources.
Experimental Part
General. All catalysts were purchased from commercial sources and used without further
purification. Toluene was distilled on sodium/benzophenone before use. Flash chromatography (FC):
Merck silica gel 60 (63 – 200 mm), if not otherwise noted. UV/VIS Spectra: Varian-Cary-50 spectrometer;
1
lmax in nm. H-NMR Spectra: Jeol-GX-400 spectrometer; residual solvent peaks as internal reference;
chemical shifts d rel. to Me4Si in ppm (CHCl3 in CDCl3 at d 7.26, (D5)DMSO in (D6)DMSO at d 2.49),
coupling constants J in Hz. MS: Finnigan-MAT-312 instrument for EI; Bruker-Biflex-III instrument for
MALDI TOF, with a-cyano-4-hydroxycinnamic acid (CHCA) as the matrix; in m/z (rel. %). Elemental
analyses: Elemental CHN analyzer Vario EL.
Reactants. Compounds 1, 2a – 2c, 2f, and 8c were purchased from commercial sources. The other
compounds were synthesized as follows: 2d and 2e by a modified protocol [20][21] as described in detail
in [6], 5a as described in [4][6][22], 5b – 5d by optimized procedures as described in [4][23], and 8a – 8d
and 9b as described in [24 – 26].
4-Phenylquinolin-2-amine (2d). NaH (6.2 g, 0.26 mol) was added to pyridine (400 ml) at r.t. under
N2, then MeCN (21.1 g, 0.52 mol) was added dropwise followed by 2-aminobenzophenone (¼(2-
aminophenyl)phenylmethanone; 34.1 g, 0.17 mol). The mixture was stirred and heated to 1008 for 20 h.
After quenching with ice water, the precipitate was washed with dist. H2O, digested with MeOH, and
dried in vacuo: 33.5 g (88%) of 2d. UV/VIS (MeOH): 340. 1H-NMR (CDCl3, 258): 7.73 (dd, J ¼ 8.3, 1.2,
HꢀC(8)); 7.66 (dd, J ¼ 8.3, 1.2, HꢀC(5)); 7.56 (dt, J ¼ 8.3, 1.5, HꢀC(7)); 7.21 (dt, J ¼ 8.3, 1.5, HꢀC(6)); 6.67
(s, HꢀC(3)); 4.80 (br. s, NH2ꢀC(2)). EI-MS (1008): 220.0 (100). Anal. calc. for C15H12N2: C 81.79, H 5.49,
N 12.72; found: C 81.84, H 5.67, N 12.79.
6-Chloro-3,4-diphenylquinolin-2-amine (2e). As described for 2d, with NaH (5.9 g, 0.25 mol),
pyridine (300 ml), phenylacetonitrile (83.8 g, 0.49 mol), and 2-amino-6-chlorobenzophenone (¼(2-
amino-6-chlorophenyl)phenylmethanone; 37.7 g, 0.16 mol): 36.2 g of crude 2d. Purification by vacuum
1
sublimation gave 18.1 g (35%) of 2e. UV/VIS (MeOH): 345. H-NMR (CDCl3, 258): 7.65 (d, J ¼ 9.0,
HꢀC(8)); 7.48 (dd, J ¼ 8.9, 2.2, HꢀC(7)); 7.29 (d, J ¼ 2.4, HꢀC(5)); 7.28 – 7.18 (m, 6 arom. H (Hm and Hp

54
Helvetica Chimica Acta – Vol. 94 (2011)
of 2 Ph); 7.15 – 7.06 (m, 4 arom. H (Ho of 2 Ph)); 4.86 (br. s, NH2ꢀC(2)). EI-MS (1208): 330.2 (100). Anal.
calc. for C21H15ClN2: C 76.24, H 4.57, N 8.47; found: C 76.28, H 4.55, N 8.50.
2-Chloro-4-phenylquinoline (9a). This compound was obtained by chlorination of 4-phenylquino-
line-2(1H)-one (28.1 g, 0.12 mol) with PCl5 (29.8 g, 0.15 mol) in PhCl (100 ml) for 60 min at 1208: 21.1 g
(70%) of 9a. UV/VIS (MeOH): 295. 1H-NMR (CDCl3, 258): 8.09 (dd, J ¼ 8.6, 0.5, HꢀC(8)); 7.88 (dd, J ¼
8.6, 1.0, HꢀC(5)); 7.74 (dt, J ¼ 7.8, 1.5, HꢀC(7)); 7.47 – 7.57 (m, HꢀC(6), Ph); 7.35 (s, HꢀC(3)). EI-MS
(608): 241.0 (41). Anal. calc. for C15H10ClN: C 75.16, H 4.21, N 5.84; found: C 75.15, H 4.20, N 5.91.
Ligands. Typical procedure for the Pd-catalyzed amination of dichloroheteroarenes with hetero-
arenamines and for the amination of chloroheteroarenes with heteroarenediamines; for conditions, see
Tables 1 – 5: The reactants, base, palladium source, and chelating phosphine were refluxed (if not
otherwise noted) in toluene or in dioxane, resp. (Tables 1 – 5). After cooling, the precipitate was filtered
off, dried under reduced pressure, and washed properly with H2O to remove inorganic components. The
combined dried org. phase was concentrated and the residue purified by FC, recrystallization, digestion,
or vaccum sublimation as noted.
N2-(6-Chloropyridin-2-yl)pyrimidin-2-amine (3a). Condition a), Table 1: 1 (5.96 g, 40 mmol), 2a
(4.22 g, 45 mmol), K2CO3 (92 g, 0.67 mol), [Pd(OAc)2] (0.15 g, 0.67 mmol, 1.7 mol-%), and BINAP
(0.62 g, 0.99 mmol, 2.5 mol-%). Purification by vacuum sublimation yielded 0.84 g (10%) of 3a2). UV/
VIS (MeCN): 302. 1H-NMR (CDCl3, 258): 9.01 (br. s, NHꢀC(2)); 8.60 (d, J ¼ 4.9, HꢀC(4), HꢀC(6)); 8.35
(d, J ¼ 8.3, HꢀC(3’)); 7.66 (dd, J ¼ 8.3, 7.8, HꢀC(4’)); 6.99 (d, J ¼ 7.8, HꢀC(5’)); 6.92 (t, J ¼ 4.9, HꢀC(5)).
N2,N6-Dipyrimidin-2-ylpyridine-2,6-diamine (4a). Condition b), Table 1: 1 (2.5 g, 17 mmol), 2a
t
(3.54 g, 38 mmol), BuONa (3.57 g, 38 mmol), [Pd(dba)2] (0.26 g, 0.9 mmol, 5.2 mol-%), and BINAP
(0.73 g, 1.4 mmol, 8.2 mol-%). Purification by recrystallization from 1,2-dichlorobenzene yielded 2.60 g
(58%) of 4a. UV/VIS (MeOH): 307. 1H-NMR (CDCl3, 258): 9.82 (br. s, NHꢀC(2), NHꢀC(6)); 8.53 (d,
J ¼ 4.9, 4 H, HꢀC(4’), HꢀC(6’)); 7.95 (d, J ¼ 8.3, HꢀC(3), HꢀC(5)); 7.66 (t, J ¼ 8.3, HꢀC(4)); 6.79 (t, J ¼
4.9, 2 H, HꢀC(5’)). EI-MS (1508): 265.0 (100). Anal. calc. for C13H11N7 · 0.2 1,2-dichlorobenzene: C 57.88,
H 4.04, N 33.27; found: C 56.99, H 4.33, N 33.50.
N2-(6-Chloropyridin-2-yl)-4,6-dimethylpyrimidin-2-amine (3b). Condition a), Table 1: 1 (5.96 g,
40 mmol), 2b (5.41 g, 44 mmol), K2CO3 (92 g, 0.66 mol), [Pd(OAc)2] (0.15 g, 0.67 mmol, 1.7 mol-%),
and BINAP (0.62 g, 0.99 mmol, 2.5 mol-%). Purification by vacuum sublimation yielded 6.73 g (73%) of
3b3). EI-MS (808): 233.8 (100). UV/VIS (MeOH): 292. 1H-NMR (CDCl3, 258): 8.44 (d, J ¼ 8.3,
HꢀC(3’)); 7.77 (br. s, NHꢀC(2)); 7.61 (dd, J ¼ 8.3, 7.8, HꢀC(4’)); 6.91 (d, J ¼ 7.8, HꢀC(5’)); 6.59 (s,
HꢀC(5)); 2.39 (s, MeꢀC(4), MeꢀC(6)). Anal. calc. for C11H11ClN4: C 56.30, H 4.72, N 23.87; found: C
56.49, H 4.98, N 24.00.
N2,N6-Bis(4,6-dimethylpyrimidin-2-yl)pyridine-2,6-diamine (4b). Condition b), Table 1: 1 (5 g,
t
34 mmol), 2b (9.54 g, 74 mmol), BuONa (7.14 g, 74 mmol), [Pd(dba)2] (0.56 g, 1 mmol, 3 mol-%),
and BINAP (1.47 g, 2.4 mmol, 7.2 mol-%). Purification by recrystallization from toluene yielded 9.80 g
(90%) of 4b. UV/VIS (MeCN): 316. 1H-NMR (CDCl3, 258): 8.17 (br. s, NHꢀC(2), NHꢀC(6)); 8.07 (d,
J ¼ 8.1, HꢀC(3), HꢀC(5)); 7.67 (t, J ¼ 8.1, HꢀC(4)); 6.53 (s, 2 H, HꢀC(5’)); 2.39 (s, 12 H, MeꢀC(4’),
MeꢀC(6’)). EI-MS (1608): 321.1 (100). Anal. calc. for C17H19N7: C 63.53, H 5.96, N 30.51; found: C 63.53,
H 6.26, N 30.46.
N2-(6-Chloropyrimidin-4-yl)pyrimidin-2-amine (6a). Condition a), Table 2: 5a (0.5 g, 3.35 mmol), 2a
(0.32 g, 3.35 mmol), K2CO3 (4.6 g, 33.5 mmol), [Pd(dba)2] (0.038 g, 0.066 mmol, 2 mol-%), and BINAP
(0.063 g, 0.1 mmol, 3 mol-%). Purification by FC (CHCl3) and subsequent recrystallization from toluene
yielded 0.48 g (69%) of 6a. UV/VIS (MeCN): 270. 1H-NMR (CDCl3, 258): 9.29 (br. s, NHꢀC(2)); 8.71 (s,
HꢀC(2’)); 8.66 (d, J ¼ 4.9, HꢀC(4), HꢀC(6)); 8.56 (s, HꢀC(5’)); 7.00 (t, J ¼ 4.9, HꢀC(5)). EI-MS (1008):
206.6 (100).
N4,N6-Dipyrimidin-2-ylpyrimidine-4,6-diamine (7a). Condition a), Table 2: 5a (0.5 g, 3.38 mmol), 2a
(0.64 g, 6.7 mmol), K2CO3 (9.3 g, 68 mmol), [Pd(dba)2] (0.038 g, 0.06 mmol, 1.8 mol-%), and BINAP
(0.063 g, 0.1 mmol, 2.9 mol-%). Purification by vacuum sublimation yielded 0.28 g (31%) of 7a. UV/VIS
(MeCN): 263. 1H-NMR (CDCl3, 258): 9.39 (d, J ¼ 1.0, HꢀC(5)); 8.58 (d, J ¼ 4.9, 4 H, HꢀC(4’), HꢀC(6’));
2
)
)
Additionally, 0.30 g (3%) of the diaminated product 4a was obtained.
Additionally, 0.58 g (5%) of the diaminated product 4b was obtained.
3

Helvetica Chimica Acta – Vol. 94 (2011)
55
8.53 (d, J ¼ 1.0, HꢀC(2)); 8.13 (br. s, NHꢀC(4), NHꢀC(6)); 6.90 (t, J ¼ 4.9, 2 H, HꢀC(5’)). EI-MS (2008):
265.8 (100). Anal. calc. for C12H10N8: C 54.13, H 3.79, N 42.08; found: C 53.03, H 3.77, N 40.11.
N2-(6-Chloropyrimidin-4-yl)-4,6-dimethylpyrimidin-2-amine (6b). Condition a), Table 2: 5a (2.5 g,
15 mmol), 2b (1.9 g, 15 mmol), K2CO3 (23 g, 0.17 mmol), [Pd(dba)2] (0.24 g, 0.45 mmol, 3 mol-%), and
BINAP (0.73 g, 1.18 mmol, 7.8 mol-%). Purification by FC (CHCl3) yielded 2.63 g (75%) of 6b. UV/VIS
(MeCN): 270. 1H-NMR (CDCl3, 258): 8.84 (br. s, NHꢀC(2)); 8.73 (d, J ¼ 1.0, HꢀC(2’)); 8.59 (d, J ¼ 1.0,
HꢀC(5’)); 6.70 (s, HꢀC(5)); 2.46 (s, MeꢀC(4), MeꢀC(6)). EI-MS (808): 234.7 (100). Anal. calc. for
C10H10ClN5: C 50.96, H 4.28, N 29.72; found: C 50.89, H 4.25, N 29.65.
N4,N6-Bis(4,6-dimethylpyrimidin-2-yl)pyrimidine-4,6-diamine (7b). Condition a), Table 2: 5a (5 g,
33.8 mmol), 2b (9.3 g, 74.4 mmol), K2CO3 (93 g, 0.68 mol), [Pd(dba)2] (0.48 g, 0.9 mmol, 2.6 mol-%),
and BINAP (1.47 g, 2.36 mmol, 6.9 mol-%). Purification by recrystallization from 1,2-dichlorobenzene
yielded 7.2 g (66%) of 7b. UV/VIS (MeCN): 267. 1H-NMR ((D6)DMSO, 308): 9.68 (s, NHꢀC(4),
NHꢀC(6)); 9.01 (d, J ¼ 1.0, HꢀC(5)); 8.35 (d, J ¼ 1.0, HꢀC(2)); 6.81 (s, 2 H, HꢀC(5’)); 2.35 (s, 12 H,
MeꢀC(4’), MeꢀC(6’)). EI-MS (1808): 322.1 (40). Anal. calc. for C16H18N8: C 59.61, H 5.63, N 34.76;
found: C 59.56, H 5.67, N 34.66.
N2-(6-Chloro-2-methylpyrimidin-4-yl)-4,6-dimethylpyrimidin-2-amine (6c). Condition b), Table 2:
5b (2.5 g, 15 mmol), 2b (1.57 g, 12.5 mmol), Na2CO3 (2.67 g, 25 mmol), [Pd(dba)2] (0.28 g, 0.4 mmol,
3.2 mol-%), and BINAP (0.9 g, 1.4 mmol, 11 mol-%). Purification by repeated FC (CHCl3) yielded
0.91 g (29%) of 6c4). UV/VIS (MeCN): 272. 1H-NMR (CDCl3, 258): 8.37 (s, HꢀC(5’)); 7.96 (br. s,
NHꢀC(2)); 6.68 (s, HꢀC(5)); 2.57 (s, MeꢀC(2’)); 2.44 (s, MeꢀC(4), MeꢀC(6)). EI-MS (808): 248.7 (100).
Anal. calc. for C11H12ClN5: C 52.91, H 4.84, N 28.05; found: C 52.88, H 4.82, N 27.72.
N4,N6-Bis(4,6-dimethylpyrimidin-2-yl)-2-methylpyrimidine-4,6-diamine (7c). Condition c), Table 2:
5b (2.5 g, 15 mmol), 2b (4.5 g, 36.5 mmol), Na2CO3 (8.16 g, 85 mmol), [Pd(OAc)2] (0.27 g, 1.2 mmol,
8 mol-%), and BINAP (1.14 g, 2.2 mmol, 14 mol-%). Purification by recrystallization from toluene and
subsequent vacuum sublimation yielded 3.78 g (75%) of 7c. UV/VIS (MeCN): 265. 1H-NMR
((D6)DMSO, 308): 9.48 (s, NHꢀC(4), NHꢀC(6)); 8.89 (s, HꢀC(5)); 6.79 (s, 2 HꢀC(5’)); 2.35 (s,
MeꢀC(2)); 2.34 (s, 12 H, MeꢀC(4’), MeꢀC(6’)). EI-MS (1408): 336.7 (61). Anal. calc. for C17H20N8: C
60.70, H 5.99, N 33.31; found: C 61.72, H 5.81, N 29.26.
6-Chloro-N4-pyridin-2-ylpyrimidin-4-amine (6d). Condition d), Table 2: 5a (2.0 g, 13.5 mmol), 2c
(1.27 g, 13.5 mmol), Na2CO3 (2.0 g, 53 mmol), [Pd(OAc)2] (0.12 g, 0.53 mmol, 3.9 mol-%), and BINAP
(0.50 g, 0.8 mmol, 5.9 mol-%). Purification by FC (CHCl3) yielded 1.13 g (41%) of 6d. UV/VIS (MeCN):
1
300. H-NMR (CDCl3, 258): 8.57 (d, J ¼ 1.0, HꢀC(2)); 8.36 (ddd, J ¼ 4.9, 2.0, 1.0, HꢀC(6’)); 7.94 (br. s,
NHꢀC(4)); 7.91 (d, J ¼ 1.0, HꢀC(5)); 7.68 (dq, J ¼ 8.3, 7.3, 2.0, HꢀC(4’)); 7.31 (br. d, J ¼ 8.3, HꢀC(3’));
7.01 (ddd, J ¼ 7.3, 4.9, 1.0, HꢀC(5’)). EI-MS (1508): 207.8 (20). Anal. calc. for C9H7ClN4: C 52.31, H 3.41, N
27.11; found: C 52.46, H 3.36, N 26.82.
N4,N6-Dipyridin-2-ylpyrimidine-4,6-diamine (7d). This compound could be obtained 1) by direct
Pd0-catalyzed diamination of 5a with 2c or 2) by stepwise Pd0-catalyzed amination of the isolated
monoamination product 6d with 2c.
1) Condition e), Table 2: 5a (1 g, 6.75 mmol), 2c (1.4 g, 14.9 mmol), K2CO3 (18.6 g, 134 mmol),
[Pd(dba)2] (0.116 g, 0.2 mmol, 3 mol-%), and BINAP (0.25 g, 0.4 mmol, 6 mol-%). Purification by
digestion with MeOH yielded 1.48 g (82%) of 7d.
2) Condition e), Table 2: 6d (1 g, 4.84 mmol), 2c (0.54 g, 5.8 mmol), K2CO3 (13.3 g, 96 mmol),
[Pd(dba)2] (0.08 g, 0.14 mmol, 2.9 mol-%), and BINAP (0.18 g, 0.29 mmol, 6 mol-%). Purification by
digestion with MeOH yielded 0.67 g (52%) of 7d. UV/VIS (MeCN): 312. 1H-NMR ((D6)DMSO, 308):
9.84 (s, NHꢀC(4), NHꢀC(6)); 8.35 (s, HꢀC(5)); 8.26 (d, J ¼ 5.0, 2 H, HꢀC(6’)); 8.18 (s, HꢀC(2)); 7.67 (dd,
J ¼ 8.3, 6.8, 2 H, HꢀC(4’)); 7.62 (d, J ¼ 8.3, 2 H, HꢀC(3’)); 6.92 (dd, J ¼ 6.8, 5.0, 2 H, HꢀC(5’)). EI-MS
(1608): 263.9 (100). Anal. calc. for C14H12N6: C 63.62, H 4.58, N 31.80; found: C 63.07, H 4.48, N 31.48.
N2-(6-Chloropyrimidin-4-yl)-4-phenylquinolin-2-amine (6e). Condition d), Table 2: 2d (7.13 g,
32 mmol), 5a (2.4 g, 16 mmol), Na2CO3 (5.4 g, 51 mmol), [Pd(OAc)2] (0.28 g, 1.2 mmol, 7.5 mol-%),
and DPEPhos (¼ bis[2-(diphenylphosphino)phenyl] ether; 0.88 g, 1.6 mmol, 10 mol-%). Purification by
digestion with EtOH and subsequent FC (CHCl3) yielded 2.0 g (38%) of 6e. UV/VIS (MeCN): 345.
4
)
Additionally, 1.52 g (36%) of the diaminated product 7c was obtained.

56
Helvetica Chimica Acta – Vol. 94 (2011)
1H-NMR (CDCl3, 258): 8.68 (s, NHꢀC(2)); 8.60 (d, J ¼ 0.7, HꢀC(2’)); 8.03 (br. d, J ¼ 8.3, HꢀC(8)); 7.89
(d, J ¼ 0.7, HꢀC(5’)); 7.80 (br. d, J ¼ 8.3, HꢀC(5)); 7.71 (ddd, J ¼ 8.3, 7.1, 1.5, HꢀC(7)); 7.57 – 7.48 (m,
PhꢀC(4)); 7.40 (ddd, J ¼ 8.3, 7.1, 1.2, HꢀC(6)); 7.09 (s, HꢀC(3)). EI-MS (1808): 332.1 (100). Anal. calc. for
C19H13ClN4: C 68.57, H 3.94, N 16.84; found: C 68.47, H 4.19, N 16.54.
N4,N6-Bis(4-phenylquinolin-2-yl)pyrimidine-4,6-diamine (7e). Condition f), Table 2: 2d (3.8 g,
t
17 mmol), 5a (1.3 g, 8.7 mmol), BuONa (2.3 g, 24 mmol), [Pd(dba)2] (0.28 g, 0.49 mmol, 5.7 mol-%),
and BINAP (0.32 g, 0.5 mmol, 5.9 mol-%). Purification by FC (CHCl3) and subsequent vacuum
1
sublimation yielded 3.58 g (81%) of 7e. UV/VIS (MeCN): 352. H-NMR ((D6)DMSO, 308): 10.40 (s,
NHꢀC(4), NHꢀC(6)); 9.42 (d, J ¼ 0.7, HꢀC(5)); 8.45 (d, J ¼ 0.7, HꢀC(2)); 7.94 (br. d, J ¼ 8.5, 2 H,
HꢀC(8’)); 7.69 (br. d, J ¼ 8.5, 2 H, HꢀC(5’)); 7.65 (s, 2 H, HꢀC(3’)); 7.65 (ddd, J ¼ 8.5, 7.1, 1.0, 2 H,
HꢀC(7’)); 7.6 – 7.5 (m, 10 H, PhꢀC(4’)); 7.40 (ddd, J ¼ 8.5, 7.1, 1.0, 2 H, HꢀC(6’)). EI-MS (2808): 516.1
(70). Anal. calc. for C34H24N6: C 79.05, H 4.68, N 16.27; found: C 79.09, H 4.76, N 15.44.
N4,N6-Bis(6-chloro-3,4-diphenylquinolin-2-yl)-2-isopropylpyrimidine-4,6-diamine (7f). Condition
a), Table 2: 2e (4.82 g, 14.6 mmol), 5d (1.35 g, 7.1 mmol), K2CO3 (9.3 g, 67 mmol), [Pd(dba)2] (0.27 g,
0.47 mmol, 6.6 mol-%), and BINAP (0.33 g, 0.53 mmol, 7.4 mol-%). Purification by digestion with
toluene and subsequent recrystallization from 1,2-dichlorobenzene yielded 4.83 g (86%) of 7f. UV/VIS
(MeCN): 359. 1H-NMR ((D6)DMSO, 508): 9.82 (s, HꢀC(5)); 7.90 (d, J ¼ 9.0, 2 H, HꢀC(8’)); 7.75 (dd, J ¼
8.8, 2.4, 2 H, HꢀC(7’)); 7.40 – 7.22 (m, 24 H, NHꢀC(4), NHꢀC(6), HꢀC(5’), PhꢀC(3’), PhꢀC(4’)); 2.67
(sept., J ¼ 6.8, Me2CH); 1.01 (d, J ¼ 6.8, Me2CH). MALDI-MS: 778.9 (100).
N4,N6-Bis(benzothiazol-2-yl)pyrimidine-4,6-diamine (7g). Condition c), Table 2 : 5a (2.0 g,
13.5 mmol), 2f (4.04 g, 27 mmol), Na2CO3 (5.4 g, 50 mmol), [Pd(OAc)2] (0.24 g, 1 mmol, 7.9 mol-%),
and BINAP (1.06 g, 1.7 mmol, 12.6 mol-%). Purification by recrystallization from 1,2-dichlorobenzene
1
yielded 3.91 g (77%) of 7g. UV/VIS (MeOH): 328. H-NMR ((D6)DMSO, 308): 11.87 (s, NHꢀC(4),
NHꢀC(6)); 8.69 (d, J ¼ 0.7, HꢀC(2)); 7.92 (d, J ¼ 7.6, 2 H, HꢀC(4’)); 7.67 (d, J ¼ 8.1, 2 H, HꢀC(7’)); 7.40
(ddd, J ¼ 8.1, 7.1, 1.2, 2 H, HꢀC(6’)); 7.24 (ddd, J ¼ 7.6, 7.1, 1.0, 2 H, HꢀC(5’)); 7.08 (br. s, HꢀC(5)). EI-MS
(3208): 376.1 (100). Anal. calc. for C18H12N6S2: C 57.43, H 3.21, N 22.32; found: C 57.04, H 3.30, N 22.02.
N2-(6-Chloro-2-methylpyrimidin-4-yl)benzothiazol-2-amine (6h) and N4,N6-Bis(benzothiazol-2-yl)-
2-methylpyrimidine-4,6-diamine (7h). Condition c), Table 2: 5b (2.5 g, 15 mmol), 2f (2.2 g, 15 mmol),
Na2CO3 (5.45 g, 51 mmol), [Pd(OAc)2] (0.14 g, 0.6 mmol, 4 mol-%), and BINAP (0.57 g, 0.9 mmol,
6 mol-%). Separation by FC (CHCl3) yielded 1.36 g (30%) of 6h and 0.60 g (10%) of 7h.
Data of 6h: UV/VIS (MeCN): 311. 1H-NMR ((D6)DMSO, 308): 12.10 (br. s, NHꢀC(2)); 7.96 (d, J ¼
7.6, HꢀC(4)); 7.70 (d, J ¼ 8.1, HꢀC(7)); 7.41 (ddd, J ¼ 8.1, 7.3, 1.2, HꢀC(6)); 7.26 (ddd, J ¼ 8.1, 7.3, 1.2,
HꢀC(5)); 7.05 (s, HꢀC(5’)); 2.59 (s, MeꢀC(2’)). EI-MS (1508): 275.8 (100). Anal. calc. for C12H9ClN4S: C
52.08, H 3.28, N 20.24; found: C 51.58, H 3.47, N 19.76.
Data of 7h: UV/VIS (MeCN): 326. 1H-NMR ((D6)DMSO, 308): 11.78 (br. s, NHꢀC(4), NHꢀC(6));
7.92 (d, J ¼ 7.8, 2 H, HꢀC(4’)); 7.66 (d, J ¼ 8.1, 2 H, HꢀC(7’)); 7.38 (ddd, J ¼ 8.3, 8.1, 1.0, 2 H, HꢀC(6’));
7.22 (dd, J ¼ 8.3, 7.8, 2 H, HꢀC(5’)); 6.82 (s, HꢀC(5)); 2.62 (s, MeꢀC(2)). EI-MS (3008): 390.3 (100).
Anal. calc. for C19H14N6S2 · 0.2 CHCl3: C 55.65, H 3.45, N 20.28; found: C 56.32, H 3.75, N 20.91.
N2-(6-Chloro-2-propylpyrimidi^n-4-yl)benzothiazol-2-amine (6i) and N4,N6-Bis(benzothiazol-2-yl)-2-
propylpyrimidine-4,6-diamine (7i¼7’n). Condition d), Table 2: 5c (1.93 g, 10 mmol), 2f (3.04 g,
20 mmol), Na2CO3 (4.15 g, 39 mmol), [Pd(OAc)2] (0.18 g, 0.8 mmol, 8 mol-%), and BINAP (0.75 g,
1.2 mmol, 12 mol-%) After FC (CHCl3), purification by recrystallization from 1,2-dichlorobenzene
yielded 2.05 g (67%) of 6i and 1.14 g (27%) of 7i.
Data of 6i: UV/VIS (MeCN): 310. 1H-NMR ((D6)DMSO, 308): 12.11 (br. s, NHꢀC(2)); 7.97 (d, J ¼
7.8, HꢀC(4)); 7.71 (d, J ¼ 8.1, HꢀC(7)); 7.41 (ddd, J ¼ 8.1, 7.1, 1.0, HꢀC(6)); 7.27 (ddd, J ¼ 7.8, 7.1, 1.2,
HꢀC(5)); 7.03 (s, HꢀC(5’)); 2.83 (t, J ¼ 7.3, MeCH2CH2); 1.88 (sext., J ¼ 7.3, MeCH2CH2); 0.97 (t, J ¼ 7.3,
MeCH2CH2). EI-MS (1508): 303.9 (100). Anal. calc. for C14H13ClN4S: C 55.17, H 4.30, N 18.38; found: C
55.51, H 4.36, N 18.21.
Data of 7i: MALDI-MS: 419.0 (100). UV/VIS (MeCN): 327. 1H-NMR ((D6)DMSO, 808): 11.57 (br.
s, NHꢀC(4), NHꢀC(6)); 7.90 (d, J ¼ 7.6, 2 H, HꢀC(4’)); 7.66 (d, J ¼ 8.1, 2 H, HꢀC(7’)); 7.38 (ddd, J ¼ 8.1,
7.3, 1.2, 2 H, HꢀC(6’)); 7.22 (ddd, J ¼ 8.1, 7.3, 1.2, 2 H, HꢀC(5’)); 6.88 (s, HꢀC(5)); 2.90 (t, J ¼ 7.3,
MeCH2CH2); 2.03 (sext., J ¼ 7.3, MeCH2CH2); 1.05 (t, J ¼ 7.3, MeCH2CH2). EI-MS (3008): 418.2 (100).
Anal. calc. for C21H18N6S2: C 60.26, H 4.33, N 20.08; found: C 61.03, H 5.05, N 19.40.

Helvetica Chimica Acta – Vol. 94 (2011)
57
N4-(4-Phenylquinolin-2-yl)-2-propylpyrimidine-4,6-diamine (6’k). Condition a), Table 3: 9a (0.66 g,
2.75 mmol), 8a (0.50 g, 3.28 mmol), K2CO3 (1.05 g, 7.6 mmol), [Pd(OAc)2] (0.017 g, 0.07 mmol, 2.5 mol-
%), and BINAP (0.10 g, 0.01 mmol, 5.8 mol-%). Purification by recrystallization from toluene yielded
0.175 g (18%) of 6’k5). UV/VIS (MeCN): 348. 1H-NMR ((D6)DMSO, 808): 9.58 (br. s, NHꢀC(4)); 7.88
(dd, J ¼ 8.7, 1.2, HꢀC(8’)); 7.64 (ddd, J ¼ 8.7, 7.5, 1.5, HꢀC(7’)); 7.64 (dd, J ¼ 8.2, 1.7, HꢀC(5’)); 7.59 – 7.48
(m, HꢀC(5), PhꢀC(4’)); 7.32 (ddd, J ¼ 7.8, 7.5, 1.5, 1.2, HꢀC(6’)); 6.25 (s, NH2ꢀC(6)); 2.49 (t, J ¼ 7.1,
MeCH2CH2); 1.71 (sext., J ¼ 7.3, MeCH2CH2); 0.89 (t, J ¼ 7.3, MeCH2CH2). EI-MS (1608): 355.3 (100).
N4,N6-Bis(4-phenylquinolin-2-yl)-2-propylpyrimidine-4,6-diamine (7’k). Condition b), Table 3: 9a
(5.0 g, 20.8 mmol), 8a (2.65 g, 17 mmol), K2CO3 (47 g, 340 mmol), [Pd(dba)2] (0.39 g, 0.68 mmol, 4 mol-
%), and BINAP (0.63 g, 1 mmol, 5.9 mol-%). Purification by digestion with MeOH yielded 5.12 g (53%)
of 7’k. EI-MS (2508): 558.6 (23). UV/VIS (MeCN): 352. 1H-NMR ((D6)DMSO, 808): 10.06 (br. s,
NHꢀC(4), NHꢀC(6)); 9.09 (s, HꢀC(5)); 7.94 (d, J ¼ 8.3, 2 H, HꢀC(8’)); 7.76 (s, 2 H, HꢀC(3’)); 7.69 (dd,
J ¼ 8.3, 1.2, 2 H, HꢀC(5’)); 7.63 (ddd, J ¼ 8.3, 7.6, 1.5, 2 H, HꢀC(7’)); 7.6 – 7.5 (m, 10 H, PhꢀC(4’)); 7.37
(ddd, J ¼ 8.3, 7.6, 1.5, 2 H, HꢀC(6’)); 2.67 (t, J ¼ 7.3, MeCH2CH2); 1.82 (sext., J ¼ 7.3, MeCH2CH2); 0.94 (t,
J ¼ 7.3, MeCH2CH2). Anal. calc. for C37H30N6: C 79.54, H 5.41, N 15.04; found: C 79.61, H 5.46, N 14.99.
2-Butyl-N4,N6-bis(4-phenylquinolin-2-yl)pyrimidine-4,6-diamine (7’l). Condition c), Table 3: 9a
(2.5 g, 10.4 mmol), 8b (1.75 g, 10.5 mmol), K2CO3 (28.2 g, 200 mmol), [Pd(OAc)2] (0.09 g, 0.4 mmol,
3.8 mol-%), and BINAP (0.38 g, 0.6 mmol, 5.7 mol-%). Purification by digestion with MeOH and
subsequent recrystallization from toluene yielded 2.67 g (44%) of 7’l. UV/VIS (CH2Cl2): 352. 1H-NMR
((D6)DMSO, 808): 10.08 (br. s, NHꢀC(4), NHꢀC(6)); 9.04 (s, HꢀC(5)); 7.94 (d, J ¼ 8.3, 2 H, HꢀC(8’));
7.77 (s, 2 H, HꢀC(3’)); 7.75 (d, J ¼ 7.8, 2 H, HꢀC(5’)); 7.63 (dd, J ¼ 8.3, 7.3, 2 H, HꢀC(7’)); 7.6 – 7.5 (m,
10 H, PhꢀC(4’)); 7.36 (dd, J ¼ 7.8, 7.3, 2 H, HꢀC(6’)); 2.67 (t, J ¼ 7.4, MeCH2CH2CH2); 1.74 (quint., J ¼ 7.4,
MeCH2CH2CH2); 1.35 (sext., J ¼ 7.4, MeCH2CH2CH2); 0.86 (t, J ¼ 7.4, MeCH2CH2CH2). MALDI-MS:
573.1 (100).
N4,N6-Bis(4-phenylquinolin-2-yl)-6-isopropyl-1,3,5-triazine-2,4-diamine (7’m). Condition b), Table 3 :
9a (3.94 g, 16 mmol), 8c (1.20 g, 7.8 mmol), K2CO3 (21 g, 150 mmol), [Pd(dba)2] (0.09 g, 0.16 mmol,
2.1 mol-%), and BINAP (0.29 g, 0.47 mmol, 6 mol-%). Purification by digestion with toluene and
subsequent recrystallization from 1,2-dichlorobenzene yielded 3.66 g (83%) of 7’m. UV/VIS (MeCN):
340. 1H-NMR ((D6)DMSO, 308): 10.4 (s, NHꢀC(2), NHꢀC(4)); 8.30 (s, 2 H, HꢀC(3’)); 7.88 (d, J ¼ 8.1,
2 H, HꢀC(8’)); 7.7 (m, 4 H, HꢀC(5’), HꢀC(6’)); 7.45 – 7.35 (m, 12 H, HꢀC(7’), PhꢀC(4’)); 2.82 (sept., J ¼
6.8, Me2CH); 1.24 (d, J ¼ 6.8, Me2CH). EI-MS (2508): 559.6 (27). Anal. calc. for C36H29N7: C 77.26, H
5.22, N 17.52; found: C 77.13, H 5.28, N 17.54.
N4-(Benzothiazol-2-yl)-2-propylpyrimidine-4,6-diamine (6’n). 1) Condition c), Table 3: 9b (2.53 g,
15 mmol), 8a (2.5 g, 16 mmol), K2CO3 (41 g, 290 mmol), [Pd(OAc)2] (0.13 g, 0.44 mmol, 2.9 mol-%),
and BINAP (0.55 g, 0.88 mmol, 5.9 mol-%). Purification by FC (CHCl3) and subsequent vacuum
sublimation yielded 0.71 g (17%) of 6’n6).
2) Same condition as in 1), with 6-chloropyrimidin-4-amine (1.98 g, 11.5 mmol), 2f (1.90 g,
12.6 mmol), K2CO3 (31 g, 220 mmol), PdCl2 (0.06 g, 0.35 mmol, 3 mol-%), and DPEPhos (0.25 g,
0.46 mmol, 4 mol-%). Purification by FC (AcOEt/MeOH 95 :5, basic Al2O3) yielded 1.84 g (56%) of 6’n.
1
UV/VIS (MeCN): 307. H-NMR ((D6)DMSO, 308): 11.25 (s, NHꢀC(4)); 7.86 (d, J ¼ 7.8, HꢀC(4’)); 7.56
(d, J ¼ 7.8, HꢀC(7’)); 7.30 (ddd, J ¼ 7.8, 7.3, 1.0, HꢀC(6’)); 7.15 (ddd, J ¼ 7.8, 7.3, 1.0, HꢀC(5’)); 6.57 (s,
NH2ꢀC(6)); 5.91 (s, HꢀC(5)); 2.55 (t, J ¼ 7.3, MeCH2CH2); 1.80 (sext., J ¼ 7.3, MeCH2CH2); 0.93 (t, J ¼
7.3, MeCH2CH2). EI-MS (1708): 284.9 (100). Anal. calc. for C14H15N5S: C 58.92, H 5.30, N 24.54; found:
C 59.03, H 5.30, N 24.46.
N2-(Benzothiazol-2-yl)-6-isopropyl-1,3,5-triazine-2,4-diamine (6’o) and N2,N4-Bis(benzothiazol-2-
yl)-6-isopropyl-1,3,5-triazine-2,4-diamine (7’o). Condition c), Table 3: 9b (2.79 g, 16.5 mmol), 8c (1.2 g,
7.8 mmol), K2CO3 (21.5 g, 156 mmol), [Pd(OAc)2] (0.09 g, 0.4 mmol, 5.1 mol-%), and BINAP (0.29 g,
0.47 mmol, 6 mol-%). After fractionated recrystallization from CHCl3, purification by vacuum
1
sublimation yielded 0.48 g (22%) of 6’o. UV/VIS (CH2Cl2): 301. H-NMR ((D6)DMSO, 808): 11.29 (s,
5
)
Additionally, 0.71 g of a mixture of the monoaminated product 6’k and the diaminated product 7’k
was obtained from the filtrate.
Additionally, 0.75 g (12%) of the diaminated product 7’n (¼7i) was obtained.
^
6
)

58
Helvetica Chimica Acta – Vol. 94 (2011)
NHꢀC(2)); 7.86 (d, J ¼ 7.8, HꢀC(4’)); 7.65 (d, J ¼ 8.1, HꢀC(7’)); 7.36 (dd, J ¼ 8.1, 7.3, HꢀC(6’)); 7.22 (dd,
J ¼ 7.8, 7.3, HꢀC(5’)); 7.07 (s, NH2ꢀC(4)); 2.80 (sept., J ¼ 6.8, Me2CH); 1.41 (d, J ¼ 6.8, Me2CH). EI-MS
(1808): 286.0 (100). Anal. calc. for C13H14N6S: C 54.53, H 4.93, N 29.35; found: C 54.43, H 4.94, N 29.26.
After fractionated crystallization from CHCl3, purification by vacuum sublimation and subsequent
1
digestion with MeOH yielded 0.30 g (9%) of 7’o. UV/VIS (CH2Cl2): 307. H-NMR ((D6)DMSO, 808):
11.48 (br. s, NHꢀC(2), NHꢀC(4)); 7.80 (d, J ¼ 8.3, 2 H, HꢀC(4’)); 7.59 (d, J ¼ 8.1, 2 H, HꢀC(7’)); 7.30 (dd,
J ¼ 8.1, 7.3, 2 H, HꢀC(6’)); 7.12 (dd, J ¼ 8.3, 7.3, 2 H, HꢀC(5’)); 2.92 (sept., J ¼ 7.1, Me2CH); 1.41 (d, J ¼
7.1, Me2CH). EI-MS (3008): 419.2 (100).
N4-(6-Amino-2-propylpyrimidin-4-yl)-N6-(4,6-dimethylpyrimidin-2-yl)pyrimidine-4,6-diamine (10a)
and N4,N6-Bis{6-[(4,6-dimethylpyrimidin-2-yl)amino]pyrimidin-4-yl}-2-propylpyrimidine-4,6-diamine
(11a). Condition a), Table 4: 6b (2.0 g, 8.5 mmol), 8a (0.65 g, 4.2 mmol), K2CO3 (11.7 g, 85 mmol),
[Pd(dba)2] (0.07 g, 0.13 mmol, 3 mol-%), and BINAP (0.16 g, 0.25 mmol, 6 mol-%). Purification by
fractionated crystallization from DMF yielded 0.69 g (47%) of 10a and 0.76 g (33%) of 11a.
Data of 10a: UV/VIS (CH2Cl2): 312. EI-MS (1508): 351.5 (100).
Data of 11a: UV/VIS (CH2Cl2): 312. 1H-NMR ((D6)DMSO, 808): 9.85 (br. s, 2 H, NHꢀC(6’)); 9.04 (s,
NHꢀC(4), NHꢀC(6)); 8.40 (s, 4 H, HꢀC(2’), HꢀC(5’)); 6.79 (s, 2 H, HꢀC(5’’)); 2.68 (br. t, J ¼ 6 – 7,
MeCH2CH2); 2.40 (s, 12 H, MeꢀC(4’’), MeꢀC(6’’)); 1.76 (sext., J ¼ 6.8, MeCH2CH2); 0.90 (t, J ¼ 6.8,
MeCH2CH2). MALDI-MS: 551.0 (100).
N4-(6-Amino-2-butylpyrimidin-4-yl)-N6-(4-phenylquinolin-2-yl)pyrimidine-4,6-diamine (10b) and 2-
Butyl-N4,N6-bis{6-[(4-phenylquinolin-2-yl)amino]pyrimidin-4-yl}pyrimidine-4,6-diamine (11b). Condi-
tion a), Table 4: 6e (0.77 g, 2.3 mmol), 8b (0.23 g, 1.38 mmol), K2CO3 (4.3 g, 31 mmol), [Pd(dba)2]
(0.024 g, 0.04 mmol, 2.9 mol-%), and BINAP (0.07 g, 0.11 mmol, 7.9 mol-%). Purification by fractionated
crystallization from DMF yielded 0.19 g (30%) of 10b and 0.51 g (48%) of 11b.
Data of 10b: UV/VIS (CH2Cl2): 349. MALDI-MS: 463.9 (100).
1
Data of 11b: UV/VIS (CH2Cl2): 349. H-NMR ((D6)DMSO, 308): 10.33 (s, NHꢀC(6’)); 10.30 (s,
NHꢀC(4), NHꢀC(6)); 8.81 (s, 2 H, HꢀC(2’)); 8.50 (s, 3 H, HꢀC(5), HꢀC(5’)); 8.04 (d, J ¼ 8.1, 2 H,
HꢀC(8’’)); 7.68 (ddd, J ¼ 8.1, 7.1, 1.0, 2 H, HꢀC(7’’)); 7.66 (d, J ¼ 8.3, 2 H, HꢀC(5’’)); 7.44 (s, 2 H,
HꢀC(3’’)); 7.37 (ddd, J ¼ 8.3, 7.1, 1.0, 2 H, HꢀC(6’’)); 2.72 (t, J ¼ 7.3, MeCH2CH2CH2); 1.69 (tt, J ¼ 7.8, 7.6,
MeCH2CH2CH2); 1.17 (sext., J ¼ 7.3, MeCH2CH2CH2); 0.70 (t, J ¼ 7.3, MeCH2CH2CH2). MALDI-MS:
759.3 (100).
N4,N6-Bis[6-(benzothiazol-2-ylamino)-2-propylpyrimidin-4-yl)-2-butylpyrimidine-4,6-diamine (11c).
Condition a), Table 4: 6i (0.91 g, 3 mmol), 8b (0.21 g, 1.3 mmol), K2CO3 (3.9 g, 28 mmol), [Pd(dba)2]
(0.026 g, 0.024 mmol, 1.5 mol-%), and BINAP (0.15 g, 0.24 mmol, 15 mol-%). Purification by digestion
with toluene yielded 0.41 g (46%) of 11c. UV/VIS (CH2Cl2): 325. 1H-NMR ((D6)DMSO, 808): 11.59 (br.
s, 2 H, NHꢀC(6’)); 9.97 (br. s, NHꢀC(4), NHꢀC(6)); 7.89 (d, J ¼ 7.8, 2 H, HꢀC(4’’)); 7.63 (d, J ¼ 7.8, 2 H,
HꢀC(7’’)); 7.61 (s, HꢀC(5)); 7.56 (s, 2 H, HꢀC(5’)); 7.34 (dd, J ¼ 7.8, 7.6, 2 H, HꢀC(6’’)); 7.19 (dd, J ¼ 7.8,
7.6, 2 H, HꢀC(5’’)); 2.89 (t, J ¼ 7.3, MeCH2CH2CH2); 2.81 (t, J ¼ 7.3, MeCH2CH2); 1.95 (sext., J ¼ 7.3,
MeCH2CH2); 1.48 (sext., J ¼ 7.3, MeCH2CH2CH2); 1.41 (sext., J ¼ 7.3, MeCH2CH2CH2); 1.02 (t, J ¼ 7.3,
MeCH2CH2); 0.95 (t, J ¼ 7.3, MeCH2CH2CH2). EI-MS (3008): 701.4 (100).
N2-{6-[(4,6-Dimethylpyrimidin-2-yl)amino]pyrimidin-4-yl}-6-isopropyl-1,3,5-triazine-2,4-diamine
(10d) and N4,N6-Bis{6-[(4,6-dimethylpyrimidin-2-yl)amino]pyrimidin-4-yl}-6-isopropyl-1,3,5-triazine-
2,4-diamine (11d). 1) Condition a), Table 4: 6b (2.0 g, 8.5 mmol), 8c (0.62 g, 4.05 mmol), K2CO3
(11.7 g, 85 mmol), [Pd(dba)2] (0.15 g, 0.25 mmol, 5.9 mol-%), and BINAP (0.37 g, 0.51 mmol,
t
12.6 mol-%). 2) Condition b), Table 4: 6b (2.36 g, 10 mmol), 8c (0.77 g, 5 mmol), BuONa (1.06 g,
11 mmol), [Pd(dba)2] (0.12 g, 0.2 mmol, 4 mol-%), and BINAP (0.19 g, 0.51 mmol, 6 mol-%). The crude
material of both syntheses was combined for workup (1.88 g). Purification by fractionated crystallization
from DMF yielded 0.15 g (5%) of 10d and 1.16 g (23%) of 11d.
Data of 10d: UV/VIS (CH2Cl2): 265. EI-MS (1508): 352.3 (13).
Data of 11d: UV/VIS (CH2Cl2): 264. 1H-NMR ((D6)DMSO, 808): 9.65 (br. s, NHꢀC(6’)); 8.93 (s, 4 H,
NHꢀC(2), NHꢀC(4), HꢀC(2’)); 8.35 (s, 2 H, HꢀC(5’)); 6.65 (s, 2 H, HꢀC(5’’)); 2.89 (sept., J ¼ 6.8,
Me2CH); 2.22 (s, 12 H, MeꢀC(4’’), MeꢀC(6’’)); 1.26 (d, J ¼ 6.8, Me2CH). MALDI-MS: 552.3 (100). EI-
MS (2008): 551.6 (100). Anal. calc. for C26H29N15: C 56.61, H 5.30, N 38.09; found: C 56.47, H 5.33, N 38.05.

Helvetica Chimica Acta – Vol. 94 (2011)
59
2-Butyl-N4-(6-chloro-2-methylpyrimidin-4-yl)pyrimidine-4,6-diamine (12). Condition b) at 1058,
Table 5: 5b (4.92 g, 30 mmol), 8b (2.5 g, 15 mmol), K2CO3 (14.5 g, 104 mmol), and [PdCl2(dppf)] ·
CH2Cl2 (0.25 g, 0.3 mmol, 2 mol-%; dppf ¼ 1,1’-bis(diphenylphosphino)ferrocene). Purification by FC
(petroleum ether/AcOEt 2 :1) yielded 1.01 g (23%) of 127). UV/VIS (MeCN): 294. 1H-NMR
((D6)DMSO, 308): 10.1 (br. s, NHꢀC(4)); 7.78 (s, HꢀC(5’)); 6.59 (s, NH2ꢀC(6)); 6.47 (s, HꢀC(5));
2.48 (t, J ¼ 7.6, MeCH2CH2CH2); 2.46 (s, MeꢀC(2’)); 1.64 (quint., J ¼ 7.6, MeCH2CH2CH2); 1.28 (sext.,
J ¼ 7.6, MeCH2CH2CH2); 0.87 (t, J ¼ 7.4, MeCH2CH2CH2). EI-MS (1508): 292.1 (10). Anal. calc. for
C13H17ClN6: C 53.33, H 5.85, N 28.71; found: C 53.08, H 5.87, N 28.71.
2-Butyl-N4,N6-bis(6-chloro-2-methylpyrimidin-4-yl)pyrimidine-4,6-diamine (13). Condition a) at
1058, Table 5 : 5b (5.28 g, 32 mmol), 8b (2.5 g, 15 mmol), K2CO3 (14.5 g, 104 mmol), and
[PdCl2(dppf)] · CH2Cl2] (0.33 g, 0.4 mmol, 2.6 mol-%). Purification by digestion with petroleum ether
and subsequent FC (petroleum ether/AcOEt 2 :1) yielded 3.02 g (48%) of 13. UV/VIS (MeCN): 309.
1H-NMR ((D6)DMSO, 308): 10.7 (s, NHꢀC(4), NHꢀC(6)); 7.90 (s, HꢀC(5)); 7.75 (s, 2 H, HꢀC(5’)); 2.75
(t, J ¼ 7.6, MeCH2CH2CH2); 2.48 (s, 6 H, MeꢀC(2’)); 1.76 (quint., J ¼ 7.6, MeCH2CH2CH2); 1.37 (sext.,
J ¼ 7.6, MeCH2CH2CH2); 0.92 (t, J ¼ 7.6, MeCH2CH2CH2). EI-MS (1508): 420.6 (11). Anal. calc. for
C18H20Cl2N8: C 51.56, H 4.81, N 26.72; found: C 51.40, H 4.85, N 26.66.
2-Butyl-N4,N6-bis{6-{{2-butyl-6-[(6-chloro-2-methylpyrimidin-4-yl)amino]pyrimidin-4-yl}amino}-2-
methylpyrimidin-4-yl}pyrimidine-4,6-diamine (14). Condition a) at 1058, Table 5: 13 (3.02 g, 7.2 mmol),
8b (0.53 g, 3.28 mmol), K2CO3 (9.05 g, 65 mmol), Pd(OAc)2 (0.04 g, 0.17 mmol, 5.1 mol-%), BINAP
(0.08 g, 0.12 mmol, 4 mol-%), and PPh3 (0.018 g, 0.06 mmol, 2 mol-%). Purification by recrystallization
from 1,2-dichlorobenzene yielded 2.67 (88%) of 14. UV/VIS (MeCN): 319. 1H-NMR ((D5)pyridine,
808): 11.2 – 10.4 (3 br. s, 6 NH); 8.50 (s, HꢀC(5)); 8.24 – 8.20 (3s, 6 H, HꢀC(5’), HꢀC(5’’), HꢀC(5’’’));
2.9 – 2.8 (br. m, 3 MeCH2CH2CH2); 2.55, 2.53 (2s, 4 Me); 2.0 – 1.7 (br. m, MeCH2CH2CH2); 1.5 – 1.3 (br.
m, MeCH2CH2CH2); 1.0 – 0.8 (br. m, MeCH2CH2CH2). MALDI-MS: 931.8 (100). Anal. calc. for
C44H52Cl2N20: C 56.71, H 5.62, N 30.06; found: C 56.83, H 5.68, N 30.12.
REFERENCES
[1] G. Scheibe, E. Daltrozzo, O. Wçrz, J. Heiss, Z. Phys. Chem. 1969, 64, 97.
[2] E. Daltrozzo, W. Sulger, ꢁ9th International Colour Symposiumꢂ, Abstracts p. 26, Engelberg, 1985.
[3] E. Daltrozzo, ꢁProc. XX. Coll. Spectros. Intern., Invited Lectures IIꢂ, Prague, 1977, pp. 151 – 174.
[4] W. Sulger, Ph.D. Thesis, University of Konstanz, 1981.
[5] T. F. Schlatterer, Ph.D. Thesis, University of Konstanz, 2000, Hartung-Gorre Verlag Konstanz, ISBN
3-89649-658-1.
[6] D. Samson, Ph.D. Thesis, University of Konstanz, 2009, Hartung-Gorre Verlag Konstanz, ISBN 3-
86628-255-9.
[7] W. Achberger, Ph.D. Thesis, University of Konstanz, 1997.
`
[8] T. H. M. Jonckers, B. U. W. Maes, G. L. F. Lemiere, R. Dommisse, Tetrahedron 2001, 57, 7027.
[9] J. Yin, M. M. Zhao, M. A. Huffman, J. M. McNamara, Org. Lett. 2002, 4, 3481.
[10] J. P. Stambuli, R. Kuwano, J. F. Hartwig, Angew. Chem. 2002, 114, 4940.
[11] A. F. Littke, G. C. Fu, Angew. Chem. 2002, 114, 4350.
[12] Y. Miyazaki, T. Kanbara, T. Yamamoto, Tetrahedron Lett. 2002, 43, 7945.
[13] C.-Y. Yeh, Y.-L. Chiang, G.-H. Lee, S.-M. Peng, Inorg. Chem. 2002, 41, 4096.
[14] C.-Y. Yeh, C.-H. Chou, K.-C. Pan, C.-C. Wang, G.-H. Lee, Y. O. Su, S.-M. Peng, J. Chem. Soc., Dalton
Trans. 2002, 2670.
[15] M.-K. Leung, A. B. Mandal, C.-C. Wang, G.-H. Lee, S.-M. Peng, H.-L. Cheng, G.-R. Her, I. Chao, H.-
F. Lu, Y.-C. Sun, M.-Y. Shiao, P.-T. Chou, J. Am. Chem. Soc. 2002, 124, 4287.
[16] H. Hasanov, U.-K. Tan, R.-R. Wang, G. H. Lee, S.-M. Peng, Tetrahedron Lett. 2004, 45, 7765.
[17] H.-Y. Gong, Q.-Y. Zheng, X.-H. Zhang, D.-X. Wang, M.-X. Wang, Org. Lett. 2006, 8, 4895.
7
)
Additionally, 1.61 g (25%) of the diaminated product 13 was obtained.

60
Helvetica Chimica Acta – Vol. 94 (2011)
[18] S. Shekhar, P. Ryberg, J. F. Hartwig, J. S. Mathew, D. G. Blackmond, E. R. Strieter, S. L. Buchwald, J.
Am. Chem. Soc. 2006, 128, 3584.
[19] D. Samson, E. Daltrozzo, in preparation.
[20] S. Kwon, S. Tanaka, K. Isagawa, Yuki Gosei Kagaku Kyokaishi 1973, 31, 328.
[21] S. Kwon, K. Isagawa, Yuki Gosei Kagaku Kyokaishi, 1973, 31, 313.
[22] R. Hull, J. Chem. Soc. 1951, 2214.
[23] A. Opitz, E. Daltrozzo, in preparation.
[24] A. Pinner, Chem. Ber. 1885, 18, 759.
[25] A. Pinner, Chem. Ber. 1885, 18, 2845.
[26] A. Pinner, Chem. Ber. 1887, 20, 2361.
Received April 9, 2010