N-Tosyl Hydrazone Precursor for Diazo Compounds as Intermediates in the Synthesis of Aluminum Complexes

Article abstract of DOI:10.1021/acs.organomet.8b00518

The one-pot reaction of LAlH₂ (1; L = HC(CMeNAr)₂, Ar = 2,6-iPr₂C₆H₃) with N-tosyl hydrazone as a precursor for preparing the diazo intermediate resulted in an aluminum compound with the composition L

Full text of DOI:10.1021/acs.organomet.8b00518

Article
pubs.acs.org/Organometallics
Cite This: Organometallics XXXX, XXX, XXX−XXX
N‑Tosyl Hydrazone Precursor for Diazo Compounds as
Intermediates in the Synthesis of Aluminum Complexes
Yashuai Liu,† Xiaoli Ma,*,† Yi Ding,† Zhi Yang,*,†,‡ and Herbert W. Roesky*,§
†School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 102488, People’s Republic of China
‡State Key Laboratory of Elemento-organic Chemistry, Nankai University, Nankai Qu 300071, People’s Republic of China
§
̈
̈
̈
Georg-August-Universitat Gottingen, Institute of Inorganic Chemistry, Tammannstrasse 4, D-37077 Gottingen, Germany
S
* Supporting Information
ABSTRACT: The one-pot reaction of LAlH2 (1; L = HC(CMeNAr)2, Ar = 2,6-iPr2C6H3) with N-tosyl hydrazone as a
precursor for preparing the diazo intermediate resulted in an aluminum compound with the composition LAl[OS(O)Ar]-
NHNCMePh, (Ar = 4-Me-phenyl (2); LAl(H)NHNCHR, R = 2-thienyl (3), 2-F-phenyl (4)). This is the first example of
utilizing N-tosyl hydrazone as precursor of diazo ligands for aluminum compounds. Compound 2 with Al−O−S(O)−C and the
Al−N(H)NC chains was obviously obtained via the reaction of LAlH2 (1) with the intermediates given in Scheme 2. In
contrast, compounds 3 and 4 exhibit only one Al−N(H)NC chain due to the different behavior of the substituents R. It is
worth mentioning that complex 5 with five-coordinate aluminum was obtained directly from the reaction of N-tosyl hydrazone
with LAlH2. In compound 5, the aluminum atom functions as the center of three heterocycles. LAl(H)NHAr (Ar = 2,6-
iPr2C6H3) (6) was obtained via the decomposition of the educts at 110 °C. Complexes 2−6 were characterized by NMR and
single-crystal X-ray diffraction studies. Additionally, the hydroboration of benzaldehyde catalyzed by 1−6, respectively, was
studied, affording the corresponding product in high yield.
hydrazones are stable in air and can be easily obtained through
the condensation of aldehydes or ketones with tosylhydrazides.
These reactions determine the extensive application of N-tosyl
hydrazones as precursors of diazo compounds in organic
synthesis. The first application of N-tosyl hydrazone for
preparing diazo compounds in a Pd-catalyzed cross-coupling
reaction was carried out by Barluenga et al. in 2007.17 Since
then, many cross-coupling reactions starting from N-tosyl
hydrazones have been reported catalyzed by transition
metals.18−28 Nevertheless, N-tosyl hydrazones are seldom
applied as precursors for diazo compounds in stoichiometric
transformations with energetic organometallic compounds.
The β-diketiminato aluminum dihydride LAlH2 (1; L =
HC(CMeNAr)2, Ar = 2,6-iPr2C6H3) can react with small
molecules,29,30 unsaturated species,13,31,32 amines,33−35 and
ionic compounds36 to generate interesting aluminum com-
INTRODUCTION
■
In recent years diazo compounds have emerged as an
important reagent in cross-coupling reactions catalyzed by
transition metals, leading to the formation of various C−X
bonds (e.g., X = C, N, O, Si, etc.).1−11 Furthermore, diazo
compounds are important starting materials to generate M−N
bonds via the stoichiometric transformation of energetic
organometallic compounds with diazo compounds.12,13 In
spite of the importance of diazo compounds, only a few stable
diazo compounds, such as trimethyldiazomethane and α-
diazocarbonyl derivatives, are usually applied in cross-coupling
reactions or stoichiometric transformations.14 Diazo com-
pounds without electron-withdrawing groups are normally
unstable and difficult to handle, significantly limiting the scope
of diazo compounds in cross-coupling reactions or stoichio-
metric transformations.
Diazo compounds can be obtained in situ from the
corresponding N-tosyl hydrazones via a Bamford−Stevens
reaction in the presence of a base.15,16 Morever, N-tosyl
Received: July 25, 2018
© XXXX American Chemical Society
A
DOI: 10.1021/acs.organomet.8b00518
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Organometallics
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Scheme 1. Optimized Synthetic Route for Compound 2
pounds. So far, only LAl(NHNCHSiMe3)2 has been
prepared via the end-on insertion of the diazo group of
N2CHSiMe3 into each Al−H bond of LAlH2 (1).13 Moreover,
the aluminum(I) compound LAlI was treated with 2 equiv of
diphenyldiazomethane to yield the unexpected diiminylalumi-
num derivative L1Al(NCPh2)2..12 Comparable diazo alumi-
num compounds have not been synthesized due to the
limitation of diazo precursors. Herein, we report on three
molecules bearing the Al−NH−NCR moiety by the reaction
of 1 with N-tosyl hydrazones in a one-pot reaction,
respectively, which diminished the limited application of
diazo compounds in stoichiometric reactions. Surprisingly,
compound 5 with three heterocycles arranged at one Al atom
was obtained when 1 was treated with a phenolic hydroxy-
containing N-tosyl hydrazone directly. The high-temperature
treatment of 1 with N-tosyl hydrazone in hexane resulted in
the decomposition of the educts and formation of LAl(H)-
NHAr (6; Ar = 2,6-iPr2C6H3).
but no crystals were obtained. Perhaps due to the excellent
solubility within the multicomponent mixture, no suitable
crystal formation was observed. Therefore, the toluene was
replaced by n-hexane after the reaction.
A suspension of N-tosyl hydrazone and NaH in n-hexane
was stirred at room temperature for 5 h, and then it was treated
with 1 equiv of LAlH2 (1) at 60 °C for 10 h, affording
aluminum compound 2 in 71% yield via insertion of NN
and SO bonds into both Al−H bonds of 1. The insertion of
a CO bond into the Al−H bond has been reported before,31
while the insertion of an SO bond into an Al−H bond has
been seldom explored. Compound 2 was isolated after growing
colorless crystals from a concentrated n-hexane solution. An X-
ray-quality single crystal of 2 was obtained in n-hexane solution
at low temperature. The molecular structure and selected bond
lengths and angles are given in Figure 1. The X-ray single-
crystal structure of 2 shows that 2 belongs to the triclinic space
RESULTS AND DISCUSSION
■
From the previous literature,24,37 diazo compounds can be
obtained in situ from the corresponding N-tosyl hydrazones.
Furthermore, they react with tin or germanium hydrides in the
presence of transition metals or a PTC (phase transfer
catalyst), leading to the formation of Sn−C or Ge−C bonds
with elimination of one molecule of N2. A similar synthesis of
LAlH2 (1) with N-tosyl hydrazones was investigated by our
group, resulting in the end-on insertion of the NN bond into
Al−H, rather than the formation of the expected Al−C bond.
The optimized synthetic route is shown in Scheme 1.
According to previous literature,24,37 a suspension of N-tosyl
hydrazone and NaH in toluene was stirred at room
temperature for 5 h, and then it was treated with 1 equiv of
LAlH2 (1) at 110 °C for 10 h, resulting in LAl(H)−NHAr (6;
Ar = 2,6-iPr2C6H3) with an Al−N−C chain. This compound
has already been obtained when a mixture of equal amounts of
LAlH2 (1) and 2,6-iPr2C6H3NH2 was treated in the absence of
solvent at 150 °C until H2 evolution ceased.40 It is proposed
that heating the precursors to 110 °C in toluene resulted in
decomposition and rearrangement to yield product 6. X-ray-
quality single crystals of 6 were obtained in toluene at low
temperature. A comparison between the crystallographic data
of 6 with those of LAl(H)NHAr (Ar = 2,6-iPr2C6H3)38
confirmed the present structure (see the Supporting
Information). To avoid the decomposition and rearrangement
of precursors, the reaction temperature was reduced to 60 °C,
Figure 1. X-ray single-crystal structure of 2. Thermal ellipsoids are
drawn at the 50% probability level. The hydrogen atoms are omitted
for clarity. Selected bond distances (Å) and angles (deg): Al−N(1)
1.8785(19), Al−N(2) 1.8801(19), Al−N(4), 1.8017(19), Al−O(3)
1.7610(16), S−O(1) 1.476(2), S−O(3) 1.5807(16); N(2)−Al−N(1)
97.78(9), N(4)−Al−O(3) 109.55(8), N(1)−Al−N(4) 116.01(9),
N(1)−Al−O(3) 110.37(8), N(2)−Al−O(3) 109.44(8), N(2)−Al−
N(4) 113.14(9).
B
DOI: 10.1021/acs.organomet.8b00518
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Organometallics
group P1
Article
̅
and exhibits an S−O−Al−N(H)−NC framework.
The Al(1)−O(3) bond length of 2 (average 1.761 Å) is close
to the normal Al−OH bond distance (average 1.705 Å) in
LAl(OH)2,39 and the S(1)−O(3) bond length (average 1.581
Å) is longer than the S(1)O(1) bond length (average 1.476
Å), suggesting the formation of Al−O and S−O bonds via the
insertion of an SO moiety into the Al−H bond. The Al(1)−
N(4) bond length (average 1.802 Å) is mostly close to the Al−
N bond length (Al−N 1.807 Å or Al−N 1.816 Å) in
LAl(NHNCHSiMe3)2 reported by Zhu et al. in 2010.13 This
implies that an NN bond inserts into the Al−H bond. In the
1H NMR spectrum of 2 three singlet resonances appear for
NCMe, CMe in L, and p-Me (δ 1.6 to 2.2 ppm with a ratio
of 1:2:1).
In addition, LAl(H)CH(Me)Ph was not obtained in the
absence of transition metals or a PTC, and at room
temperature no product was obtained in toluene or n-hexane
due to its low reactivity. Finally, the optimized reaction
conditions for the synthesis of aluminum compounds with Al−
NHNC chain structure were obtained: a suspension of N-
tosyl hydrazones and NaH in n-hexane was stirred at room
temperature for 5 h, and then it was treated with 1 equiv of
LAlH2 (1) at 60 °C for 10 h.
Figure 2. X-ray single-crystal structure of 3. Thermal ellipsoids are
drawn at the 50% probability level. The hydrogen atoms are omitted
for clarity, except for that of the Al−H bond. Selected bond distances
(Å) and angles (deg): Al−N(3) 1.884(3), Al−N(4) 1.889(3), Al−
N(1), 1.814(3), Al−H(2f) 1.5434; N(3)−Al−N(4) 97.08(12),
N(1)−Al−H(2f) 111.7, N(1)−Al−N(4) 110.04(13), N(4)−Al−
H(2f) 116.0, N(1)−Al−N(3) 110.10(13), N(3)−Al−H(2f) 111.0.
Under the optimized conditions, the reaction of N-tosyl
hydrazone with LAlH2 (1) gave the corresponding product
LAl(H)NHNCHR (R = 2-thienyl (3), 68% yield; R = 2-F-
phenyl (4), 83% yield) with the end-on insertion of the NN
bond into the Al−H bond. Obviously, the electronic properties
of the substituent in N-tosyl hydrazone prevents the insertion
of the SO bond into the adjacent comparatively stable Al−H
bond. X-ray-quality single crystals of 3 and 4 were obtained in
n-hexane solution at low temperature. 3 and 4 both crystallized
in the monoclinic space group P21/n and have as a common
characteristic an Al−NH−NC chain. The Al−N bond
lengths of 3 (average 1.814 Å) and 4 (average 1.814 Å) are
close to the Al−N bond length (Al−N 1.807 Å or Al−N 1.816
Å) of LAl(NHNCHSiMe3)2 reported by Zhu et al.13
suggesting that the Al−N bonds in both compounds 3 and 4
are covalent bonds. The molecular structures of 3 and 4 are
1
shown in Figures 2 and 3, respectively. The H NMR spectra
of 3 and 4 are in agreement with the single-crystal structure.
It is worth mentioning that compound 5 with three
heterocycles arranged at one Al atom was obtained in 57%
yield. Moreover, we found that N′-(2-hydroxybenzylidene)-4-
methylbenzenesulfonohydrazide did not transform into the
corresponding diazo compound via a Bamford−Stevens
reaction at room or higher temperature. The reaction could
proceed with insertion of the SO bond into LAlH2 (1) along
with the coordination of an N atom to the central Al atom,
resulting in the formation of compound 5. An X-ray-quality
single crystal of 5 was obtained in hexane solution at low
Figure 3. X-ray single-crystal structure of 4. Thermal ellipsoids are
drawn at the 50% probability level. The hydrogen atoms are omitted
for clarity, except for that of the Al−H bond. Selected bond distances
(Å) and angles (deg): Al−N(1) 1.8886(14), Al−N(2) 1.8883(14),
Al−N(3), 1.8140(17), Al−H(1e) 1.562(12); N(1)−Al−N(2)
97.11(6), N(3)−Al−H(1e) 110.2(5), N(1)−Al−N(3) 110.79(7),
N(1)−Al−H(1e) 115.1(5), N(2)−Al−N(3) 111.86(7), N(2)−Al−
H(1e) 111.2(5).
̅
temperature (triclinic space group P1). In compound 5, the
S(1)−O(2) bond (average 1.499 Å) is longer than the S(1)−
O(1) bond (average 1.429 Å). The Al−O(2) bond length
(average 1.901 Å) is close to the Al−O covalent bond (1.8929
or 1.9376 Å) in ref 40, suggesting that there is an insertion of
an SO bond into an Al(1)−H bond with transformation
from a double to a single bond. Another Al(1)−O(3) bond
length (average 1.795 Å) is close to the normal Al−OH bond
distance (average 1.705 Å) in LAl(OH)2,38 implying an Al−O
covalent bond. According to the Al(1)−N(3) bond length
(average 2.012 Å), it is obviously a coordinate bond in
comparison with the Al−N covalent bond (Al−N 1.807 Å or
Al−N 1.816 Å) of LAl(NHNCHSiMe3)2.13 The X-ray
single-crystal structure of 5 is shown in Figure 4.
Compounds 3−5 were obtained after growing crystals from
a concentrated n-hexane solution, and their synthetic route is
shown in Scheme 2.
C
DOI: 10.1021/acs.organomet.8b00518
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Scheme 3. Proposed Mechanism of the Synthesis of 2
1. As shown in Table 1, the yields changed from 71% to 99%
(Table 1, entries 2−7) and were obtained using compounds
Figure 4. X-ray single crystal structure of 5. Thermal ellipsoids are
drawn at the 50% probability level. The hydrogen atoms are omitted
for clarity. Selected bond distances (Å) and angles (deg): Al−N(1)
1.8967(14), Al−N(2) 1.9170(14), Al−N(3), 2.0119(15), Al−O(2)
1.9008(12), Al−O(3), 1.7952(13), S−O(1) 1.4292(13), S−O(2)
1.4993(12); N(1)−Al−N(2) 97.97(6), N(1)−Al−N(3) 116.17(6),
N(1)−Al−O(2) 100.25(6), N(1)−Al−O(3) 101.10(6), N(2)−Al−
N(3) 145.50(6), N(2)−Al−O(2) 90.05(6), N(2)−Al−O(3)
91.50(6), N(3)−Al−O(2) 79.64(6), N(3)−Al−O(3) 86.87(6),
O(2)−Al−O(3) 158.16(6).
Table 1. Hydroboration of Benzaldehyde Catalyzed by 1−
a
6
b
entry
cat.
loading (mol %)
t (h)
yield (%)
1
2
3
4
5
6
7
none
0
1
1
1
1
1
1
1
1
1
1
1
1
1
trace
99
75
87
78
1
2
3
4
5
6
From previous results and our recent work, a possible
mechanism for the synthesis of 2 is shown in Scheme 3. The
diazo compound along with the sodium salt A were obtained
via treatment of N-tosyl hydrazone with NaH as strong base at
room temperature.15,16 This was followed by the end-on
insertion of the diazo compound into the Al−H bond,
resulting in the intermediate B. This step is supported by the
similar insertion of an NN bond into an Al−H bond
reported by Zhu et al.13 Finally, B reacted with the sodium salt
A, affording the corresponding compound 2 via insertion of an
SO bond into the other Al−H bond with elimination of
NaH.
71
90
a
All reactions were carried out in C6D6 using 1 mmol of HBpin and 1
b
mmol of benzaldehyde at room temperature. Conversion was
determined by NMR spectroscopy on the basis of the consumption of
the benzaldehyde, and the identity of the product was confirmed by
the PhCH2OBpin signal in NMR spectra.
The pioneering work of hydroboration of aldehydes and
ketones catalyzed by aluminum hydride has been reported by
Yang et al.,41 and the catalytic activity of numerous aluminum
compounds and other p-block compounds in hydroboration
has been explored.42−48 Herein, we carried out the reaction of
HBpin (1 mmol) with benzaldehyde (1 mmol) by addition of
1−6 (1 mol %) in C6D6 (2 mL) at room temperature for 1 h.
The results of catalytic hydroboration are summarized in Table
1−6 as catalysts (Table 1). The yields of aluminum dihydride
1 (99%), aluminum monohydrides 3, 4, and 6 (87%, 78%,
90%), and 2 and 5 (75%, 71%) show a decrease in the catalytic
activity, in comparison with LAlH2 (1), due to the replacement
of one or both hydrogens by other substituents. Probably, the
steric hindrance of the substituents in complexes 3 and 4
results in lower yields of the corresponding products, although
the electronegative element N may increase the Lewis acidic
Scheme 2. Synthetic Route of Compounds 3−5
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27.65 (s), 25.93 (s), 23.93 (s), 23.34 (d, J = 11.4 Hz), 22.84 (s),
22.46 (s), 20.23 (s), 7.61 (s). Anal. Calcd for C44H57AlN4O2S
(732.40): C, 72.10; H, 7.84; N, 7.64. Found: C, 72.56; H, 7.61; N,
7.89.
character. The mechanism for the reaction of aldehydes and
ketones with HBpin was mentioned in previous literature.41 In
contrast, the catalytic cycle is not suitable for the hydro-
boration of CO2 according to a recent paper by Aldridge and
co-workers.51 They proposed that the Al−O/B−H σ-bond
metathesis is thermodynamically very unlikely without addi-
tional interaction of the strongly Lewis acidic borane in the
hyboration of CO2. Aluminum hydrides were applied to the
hydroboration of benzaldehyde mainly due to the Lewis acidic
character of the central aluminum and enhancement of the
negative hydrogen, which was verified by the results of
hydroboration. Furthermore, the yields of hydroborations
catalyzed by 2−6 could be improved to 99% by increasing the
reaction time or temperature (see the Supporting Informa-
tion).
Synthesis of LAl(H)NHNCH-2-thienyl (3). A suspension of 4-
methyl-N′-(thiophen-2-ylmethylene)benzenesulfonohydrazide (0.141
g, 0.5 mmol) with NaH (60% dispersion in mineral oil; 0.040 g, 1.0
mmol) in n-hexane (15 mL) was stirred at room temperature. After
the suspension was stirred for 5 h, LAlH2 (1; 0.224 g, 0.5 mmol) was
loaded under a nitrogen atmosphere. The mixture was stirred at 60 °C
for 10 h, and then the suspension was filtered. Red crystals of 3 were
obtained upon cooling to −7 °C. An additional crop of 3 was
obtained from the mother liquor. Total yield: 0.194 g (68%). Mp:
1
165−171 °C. H NMR (400 MHz, CDCl3, 298 K, TMS): δ 7.20−
7.09 (m, 7 H, ArH), 6.96−6.80 (m, 2 H, ArH), 5.70 (s, 1 H, NH),
5.25 (s, 1 H, γ-H), 3.18−3.05 (m, 4 H, CHMe2), 1.77 (s, 6 H, CMe),
1.22 (d, J = 6.9 Hz, 6 H,), 1.08 (d, J = 6.9 Hz, 6 H), 1.01 (m, 12 H).
13C NMR (100 MHz, CDCl3, 298 K, TMS): δ 169.31 (s, NC),
144.81 (s), 143.75 (s), 143.31 (s), 142.97 (s), 142.51 (s), 138.30 (s),
138.05 (s), 126.07 (s), 125.51 (d, J = 5.6 Hz), 123.78−123.17 (m),
122.99 (d, J = 12.2 Hz), 121.50 (s), 120.56 (d, J = 6.3 Hz), 96.35 (s,
γ-C), 27.67 (s), 27.34 (s), 26.01 (s), 25.45 (s), 23.46 (dd, J = 32.0,
13.6 Hz), 22.35 (s). Anal. Calcd for C34H47AlN4S (570.33): C, 71.54;
H, 8.30; N, 9.82. Found: C, 71.79; H, 8.53; N, 9.97.
CONCLUSION
■
The three compounds 2−4 with the chain structure Al−
NHNCR have been obtained via the reactions of N-tosyl
hydrazones as precursors for diazo compounds with LAlH2 (1)
through end-on insertion of the NN bond into an Al−H
bond, and this is the first example of utilizing N-tosyl
hydrazones as precursors for diazo compounds in aluminum
chemistry. We have developed an efficient method for the
formation of aluminum compounds with the chain structure
Al−NHNCR, diminishing the limited application of diazo
compounds in stoichiometric transformations, and the
insertion of an SO bond into an Al−H bond has been
explored successfully. Additionally, the five-coordinated
aluminum compound 5 with three heterocycles was obtained
by serendipity. The hydroboration of benzaldehyde catalyzed
by 1−6, respectively, was explored, affording the correspond-
ing product in moderate to high yield.
Synthesis of LAl(H)NHNCH-2-F-phenyl (4). A suspension of
N′-(2-fluorobenzylidene)-4-methylbenzenesulfonohydrazide (0.147 g,
0.5 mmol) with NaH (60% dispersion in mineral oil; 0.040 g, 1.0
mmol) in n-hexane (15 mL) was stirred at room temperature. After
the suspension was stirred for 5 h, LAlH2 (1; 0.224 g, 0.5 mmol) was
loaded under a nitrogen atmosphere. The mixture was stirred at 60 °C
for 10 h, and then the suspension was filtered. Colorless crystals of 4
were obtained upon cooling to −7 °C. An additional crop of 4 was
obtained from the mother liquor. Total yield: 0.242 g (83%). Mp:
1
160−164 °C. H NMR (400 MHz, CDCl3, 298 K, TMS): δ 7.27−
7.16 (m, 8 H, ArH), 7.03−6.87 (m, 2 H, ArH), 5.43 (s, 1 H, NH),
5.24 (s, 1 H, γ-H), 3.25−3.12 (m, 4 H, CHMe2), 1.84 (s, 6 H, CMe),
1.29 (d, J = 6.9 Hz, 6 H), 1.15 (d, J = 6.9 Hz, 6 H), 1.00 (m, 12 H).
13C NMR (100 MHz, CDCl3, 298 K, TMS): δ 169.77 (s), 169.37 (s,
EXPERIMENTAL SECTION
■
General Procedures. All manipulations were carried out under a
purified nitrogen atmosphere using Schlenk techniques or inside an
Etelux MB 200G glovebox. All solvents were refluxed over the
appropriate drying agent and distilled prior to use. Commercially
available chemicals were purchased from J&K chemical or VAS and
used as received. LH,49 LAlH2,50 and N-tosyl hydrazones17 were
prepared as described in the literature. Elemental analyses were
performed by the Analytical Instrumentation Center of the Beijing
Institute of Technology. NMR spectra were recorded on Bruker AM
400 spectrometers. Melting points were measured in sealed glass
tubes.
NC), 144.69 (s), 143.95−143.66 (m), 143.47 (d, J = 30.0 Hz),
142.51 (s), 138.26 (s), 138.05 (s), 126.11 (s), 123.63 (s), 123.44 (s),
123.43−122.45 (m), 114.16 (s), 113.95 (s), 96.34 (s, γ-C), 27.69 (s),
25.51 (s), 23.69 (s), 23.66−23.11 (m), 22.36 (s), 21.63 (s). Anal.
Calcd for C36H48AlFN4 (582.37): C, 74.19; H, 8.30; N, 9.61. Found:
C, 74.54; H, 8.11; N, 9.86.
Synthesis of LAl[(μ-O)(o-C6H4)][(μ-O)(H)S(O)(p-Me-C6H4)NH]-
(NCH) (5). A suspension of N′-(2-hydroxybenzylidene)-4-methyl-
benzenesulfonohydrazide (0.145 g, 0.5 mmol) with LAlH2 (1; 0.224
g, 0.5 mmol) in n-hexane (15 mL) was stirred at 60 °C for 10 h, and
then the suspension was filtered. Colorless crystals of 5 were obtained
upon cooling to −7 °C. An additional crop of 5 was obtained from the
Synthesis of LAl[OS(O)Ar]NHNC(Me)Ph (Ar = 4-Me-
phenyl) (2). A suspension of 4-methyl-N′-(1-phenylethylidene)-
benzenesulfonohydrazide (0.145 g, 0.5 mmol) with NaH (60%
dispersion in mineral oil; 0.040 g, 1.0 mmol) in n-hexane (15 mL) was
stirred at room temperature. After the suspension was stirred for 5 h,
LAlH2 (1; 0.224g, 0.5 mmol) was loaded under a nitrogen
atmosphere. The mixture was stirred at 60 °C for 10 h, and then
the suspension was filtered. Colorless crystals of 2 were obtained upon
cooling to −7 °C. An additional crop of 2 was obtained from the
1
mother liquor. Total yield: 0.209 g (57%). Mp: 198−206 °C. H
NMR (400 MHz, CDCl3, 298 K, TMS): δ 8.04 (s, 1 H, HC = N),
7.24−7.10 (m, 4 H, ArH), 7.01 (dd, J = 19.0, 8.1 Hz, 3 H, ArH), 6.81
(d, J = 8.3 Hz, 1 H, ArH), 6.67 (t, J = 8.0 Hz, 3 H, ArH), 6.55 (d, J =
7.8 Hz, 2 H, ArH), 5.29 (s, 1 H, γ-H), 3.64 (dt, J = 13.1, 6.7 Hz, 1 H,
CHMe2), 3.28 (tt, J = 13.7, 6.7 Hz, 2 H, CHMe2), 2.57−2.46 (m, 1
H, CHMe2), 2.15 (s, 3 H, p-ArMe), 1.81 (s, 3 H, CMe), 1.71 (s, 3 H,
CMe), 1.35 (d, J = 6.5 Hz, 3 H), 1.20 (s, 1 H, NH), 1.06 (t, J = 6.5
Hz, 12 H), 0.78 (d, J = 6.5 Hz, 3 H), 0.70 (d, J = 6.5 Hz, 3 H), 0.39
(d, J = 6.5 Hz, 3 H). 13C NMR (100 MHz, CDCl3, 298 K, TMS): δ
168.86 (d, J = 8.2 Hz, NC), 160.61 (s), 153.96 (s), 143.91 (d, J =
4.0 Hz), 143.23 (d, J = 10.5 Hz), 140.54 (d, J = 19.8 Hz), 139.27 (s),
137.48 (s), 124.40 (s), 123.92−123.79 (m), 123.56 (d, J = 25.1 Hz),
122.94 (d, J = 8.2 Hz), 119.36 (s), 117.63 (s), 116.10 (s), 97.59 (s, γ-
C), 27.29 (d, J = 6.6 Hz), 26.33 (s), 26.05 (s), 24.18−23.46 (m),
23.27 (d, J = 5.2 Hz), 22.96 (s), 22.75 (s), 20.26 (s). Anal. Calcd for
C43H54AlN4O3S (733.37): C, 70.37; H, 7.42; N, 7.63. Found: C,
70.86; H, 7.23; N, 7.86.
1
mother liquor. Total yield: 0.261 g (71%). Mp: 155−161 °C. H
NMR (400 MHz, CDCl3, 298 K, TMS): δ 7.55 (d, 2 H, ArH), 7.30−
7.16 (m, 9 H, ArH), 6.84 (d, 2 H, ArH), 6.71 (d, 2 H, ArH), 5.32 (s, 1
H, NH), 5.21 (s, 1 H, γ-H), 3.16−3.06 (sept, 2 H, CHMe2), 3.04−
2.95 (sept, 2 H, CHMe2), 2.18 (S, 3 H, p-ArMe), 1.81 (S, 6 H, CMe),
1.64 (S, 3 H, NCMe), 1.18 (d, JH−H = 6.4 Hz, 6 H), 1.04 (d, J = 6.4
Hz, 6 H), 0.89 (d, J = 6.4 Hz, 6 H), 0.73 (d, J = 6.4 Hz, 6 H). 13C
NMR (100 MHz, CDCl3, 298 K, TMS): δ 170.44 (s, NC), 148.39
(s), 144.49 (s), 142.85 (s), 140.30 (s), 139.03 (s), 137.44 (s), 136.45
(s), 128.10 (s), 127.26 (s), 126.75 (s), 126.25 (s), 124.52 (d, J = 10.8
Hz), 123.62 (s), 123.12 (s), 122.89 (s), 122.62 (s), 96.88 (s, γ-C),
E
DOI: 10.1021/acs.organomet.8b00518
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
(10) Tsoi, Y. T.; Zhou, Z.; Chan, A. S.; Yu, W. Y. Palladium-
Catalyzed Oxidative Cross-Coupling Reaction of Arylboronic Acids
with Diazoesters for Stereoselective Synthesis of (E)-α, β-Diary-
lacrylates. Org. Lett. 2010, 12, 4506−4509.
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.organo-
met.8b00518.
■
S
(11) Zhang, Y.; Wang, J. Recent Developments in Pd-Catalyzed
Reactions of Diazo Compounds. Eur. J. Org. Chem. 2011, 2011,
1015−1026.
Experimental details, analytical and crystallographic data
of 2−6, details of the crystal structure refinements, and
NMR spectra (PDF)
(12) Zhu, H.; Chai, J.; Stasch, A.; Roesky, H. W.; Blunck, T.;
Vidovic, D.; Magull, J.; Schmidt, H. G.; Noltemeyer, M. Reactions of
the Aluminum(I) Monomer LAl [L = HC{(CMe)(NAr)}2; Ar = 2,6-
iPr2C6H3] with Imidazol-2-ylidene and Diphenyldiazomethane. A
Hydrogen Transfer from the Ligand to the Central Aluminum Atom
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Azido Compounds: An Al-H Addition to End-on Nitrogen of
Substrates. Sci. China: Chem. 2010, 53, 1970−1977.
Accession Codes
CCDC 1836601−1836605 contain the supplementary crys-
tallographic data for this paper. These data can be obtained
free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by
emailing data_request@ccdc.cam.ac.uk, or by contacting The
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
(14) Zhang, Z.; Wang, J. Recent Studies on the Reactions of α-
Diazocarbonyl Compounds. Tetrahedron 2008, 64, 6577−6605.
(15) Bamford, W.; Stevens, T. The Decomposition of Toluene-p-
Sulphonylhydrazones by Alkali. J. Chem. Soc. 1952, 4735−4740.
(16) Fulton, J. R.; Aggarwal, V. K.; de Vicente, J. The Use of
Tosylhydrazone Salts as a Safe Alternative for Handling Diazo
Compounds and Their Applications in Organic Synthesis. Eur. J. Org.
Chem. 2005, 2005, 1479−1492.
AUTHOR INFORMATION
Corresponding Authors
*E-mail for X.M.: maxiaoli@bit.edu.cn.
*E-mail for Z.Y.: zhiyang@bit.edu.cn.
*E-mail for H.W.R.: hroesky@gwdg.de.
■
ORCID
́
(17) Barluenga, J.; Moriel, P.; Valdes, C.; Aznar, F. N-
Herbert W. Roesky: 0000-0003-4454-1434
Notes
The authors declare no competing financial interest.
Tosylhydrazones as Reagents for Cross-Coupling Reactions: A
Route to Polysubstituted Olefins. Angew. Chem., Int. Ed. 2007, 46,
5587−5590.
(18) Brachet, E.; Hamze, A.; Peyrat, J. F.; Brion, J. D.; Alami, M. Pd-
Catalyzed Reaction of Sterically Hindered Hydrazones with Aryl
Halides: Synthesis of Tetra-Substituted Olefins Related to Isocom-
bretastatin A4. Org. Lett. 2010, 12, 4042−4045.
ACKNOWLEDGMENTS
■
We gratefully acknowledge financial support of this work by
the National Nature Science Foundation of China (21671018)
and the Deutsche Forschungsgemeinschaft (RO 224/68-1).
(19) Ganapathy, D.; Sekar, G. Efficient Synthesis of Polysubstituted
Olefins Using Stable Palladium Nanocatalyst: Applications in
Synthesis of Tamoxifen and Isocombretastatin A4. Org. Lett. 2014,
16, 3856−3859.
̈
̈
Dedicated to Hansjorg Grutzmacher on the occasion of his
60th birthday.
́
(20) Treguier, B.; Hamze, A.; Provot, O.; Brion, J. D.; Alami, M.
Expeditious Synthesis of 1,1-Diarylethylenes Related to Isocombre-
tastatin A-4 (isoCA-4) via Palladium-Catalyzed Arylation of N-
Tosylhydrazones with Aryl Triflates. Tetrahedron Lett. 2009, 50,
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