Synthesis of Benzyltributylstannanes by the Reaction of N-Tosylhydrazones with Bu3SnH

Article abstract of DOI:10.1021/acs.joc.6b02639

An efficient stannylation process with N-tosylhydrazones or directly with carbonyl compounds has been developed. A series of functionalized benzyl- and alkyltributylstannanes can be synthesized in moderate to good yields under transition-metal-free conditions. Tandem transformations involving stannylation/Stille cross-coupling reaction have been carried out without purification of the benzyltributylstannane intermediates to afford a series of diarylmethane derivatives.

Full text of DOI:10.1021/acs.joc.6b02639

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Article
Synthesis of Benzyltributylstannanes by the
Reaction of N-Tosylhydrazones with Bu3SnH
Di Qiu, Shuai Wang, He Meng, Shengbo Tang, Yan Zhang, and Jianbo Wang
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.6b02639 • Publication Date (Web): 14 Dec 2016
Downloaded from http://pubs.acs.org on December 15, 2016
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Synthesis of Benzyltributylstannanes by the Reaction of
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N-Tosylhydrazones with Bu3SnH
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Di Qiu,†,‡ Shuai Wang,† He Meng,† Shengbo Tang,†Yan Zhang† and Jianbo Wang*,†
†Beijing National Laboratory of Molecular Sciences (BNLMS), Key Laboratory of Bioorganic
Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking
University, Beijing 100871, China
‡College of Chemistry, Tianjin Key Laboratory of Structure and Performance for Functional
Molecules, Tianjin Normal University, Tianjin 300387, China
RECEIVED DATE (to be automatically inserted after your manuscript is accepted if
required according to the journal that you are submitting your paper to)
ABSTRACT. An efficient stannylation process with N-tosylhydrazones or directly with carbonyl
compounds has been developed. A series of functionalized benzyl- and alkyltributylstannanes can
be synthesized in moderate to good yields under transition-metal-free conditions. Tandem
transformations involving stannylation/Stille cross-coupling reaction have been carried out without
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purification of the benzyltributylstannane intermediates to afford a series of diarylmethane
derivatives.
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INTRODUCTION
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Organotin reagents have found many applications in various fields.1 In particular, organotin
reagents have been widely applied in cross-coupling reactions (Stille coupling).2 In addition to the
commonly used arylstannane reagents, the corresponding alkylstannane reagents (in particular the
benzylstannane reagents), have also been extensively explored as important building blocks for
C-C bond formations.2b,3 Due to their importance, the development of synthetic methods for
alkylstannane reagents has attracted attentions over the years, however, the methods for accessing
these reagents are still limited.
Scheme 1. Synthetic Methods for Alkylstannanes
The general method for synthesizing alkylstannanes involves the reaction between alkyl
Grignard reagents, lithium or zinc reagents with trialkyltin chloride (Scheme 1a).4 Although widely
applied, this traditional strategy needs rigorous reaction conditions, and thus functional group
tolerance is poor. More recently, palladium-catalyzed stannylation of benzyl or alkyl halides with
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distannanes (R3SnSnR3) has been developed (Scheme 1b).5 Direct substitution reaction of alkyl
halides with trialkyl stannyl anion represents a straightforward approach (Scheme 1c).6 Besides, it
was reported that the reaction of diazo compounds with Bu3SnH gave alkylstannane products
through carbene insertion, but the studies were mainly focused on mechanistic aspects of the
reaction.7 Tributyltin radical addition to alkenes has also been reported.8 Although various
stannylation methods have been established, it is still highly desirable to develop efficient
alternative methods for the synthesis of alkylstannane reagents.
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N-tosylhydrazones, which can be conveniently prepared from the corresponding ketones and
aldehydes, have played an important role as versatile intermediates in organic synthesis. In
particular, non-stabilized diazo compounds, which do not bear electron-withdrawing substituents
on the diazo carbon, can be generated in situ from N-tosylhydrazones in the presence of base
(Bamford-Stevens reaction).9 The in situ generated diazo compounds can undergo various
transformations, particularly the transition-metal-catalyzed carbene transfer reactions and
cross-coupling reactions.10 Besides, transition-metal-free transformations of N-tosylhydrazones
have also been explored in recent studies to form C-C,11 C-O,12 C-N13 and C-S14 bonds. We have
previously reported the transition-metal-free formation of C-B bond from N-tosylhydrazones.15 In
connection to our interests on the transformations of N-tosylhydrazones, we report herein the
conversion of N-tosylhydrazones into benzylstannanes. The reaction represents a new general
access to alkylstannane reagents (Scheme 1d).
RESULTS AND DISCUSSIONS
At the outset, the commercially available tributyltin hydride was chosen as the stannylating reagent
and N-tosylhydrazone 1a as the substrate. The initial reaction in the presence of tBuOLi in toluene
at 90 oC afforded the desired benzyltributylstannane 2a in 29% yield (Table 1, entry 1). We noted
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that the major by-products were Bu3Sn-SnBu3 and diphenylethene. When the reaction was carried
out at 60 oC, the reaction gave only trace amount of the product 2a (entry 3). Switch the solvent to
MeCN also resulted in only trace amount of the product (entry 2). Subsequently, we proceeded to
screen the effect of base. With MeONa or K2CO3 as the base, the reaction gave diminished yields
(entries 4 and 5). Gratifyingly, with NaH as the base, the reaction afforded improved result (entry
6).
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In our previous studies, we noted that the phase transfer catalyst (PTC) could enhance the
solubility and thus significantly accelerate the transformation of N-tosylhydrazones to the diazo
intermediates. We have thus examined a series of cationic PTC in the current reaction system
(entries 7-13). Indeed the yield of 2a was enhanced significantly when adding 10%
tetrabutylammonium bromide (TBAB) or benzyltributylammonium chloride (BTBAC) (entries 7
and 8). With TBAB as the additive, increasing the loading of NaH resulted in diminished yields
(entries 9 and 10). After subsequent examining the reaction conditions, we found that
tetrabutylammonium chloride (TBAC) could provide the optimal result (entry 11). The yield could
be further improved by increasing the reaction temperature and the TBAC loading (entries 12 and
13).
Table 1. Optimization of Reaction Conditionsa
entry
solvent
toluene
MeCN
T(oC)
90
base (equiv)
tBuOLi (1.1)
tBuOLi (1.1)
additive (mol%)
3, yield (%)b
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--
--
90
trace
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tBuOLi (1.1)
MeONa (1.1)
K2CO3 (1.1)
NaH (1.1)
NaH (1.1)
NaH (1.1)
NaH (1.5)
NaH (2.0)
NaH (1.1)
NaH (1.1)
NaH (1.1)
n
trace
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toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
toluene
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--
90
90
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90
90
110
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<10
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TBAB (10)
BTBAC (10)
TBAB (10)
TBAB (10)
TBAC (10)
TBAC (20)
TBAC (20)
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aReaction conditions: N-tosylhydrazone (0.2 mmol), Bu3SnH (0.2 mmol), solvent (3 mL), 6 h.
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bYields refer to the purified products by silica gel column chromatography. TBAB:
tetrabutylammonium bromide; BTBAC:
tetrabutylammonium chloride.
benzyltributylammonium
chloride; TBAC:
With the optimized reaction conditions, we proceeded to examine the scope of this
transformation. First, a series of N-tosylhydrazones derived from the corresponding aldehydes
were examined (Scheme 2). The reaction all proceeded smoothly and a series of benzyl and alkyl
tributylstannanes could be obtained in moderate yields. For the N-tosylhydrazones derived from
the benzaldehydes bearing various substituents on the aromatic ring, this strategy has shown good
functional tolerance for both electron-withdrawing and electron-donating substituents, which
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include alkyl (2b, c), phenyl (2j), halogen (2d, e, f, l, q, r), methoxy (2g, s), acetoxy (2h),
trifluoromethyl (2i), nitro (2m) and N,N-dimethylamino groups (2k).
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For ortho-substituted N-tosylhydrazones, the reaction afforded diminished yields (2n and 2p),
presumably due to steric hindrance. With the N-tosylhydrazones derived from piperonal (2t),
naphthyl (2u) or pyridinyl (2v) aldehydes, the corresponding stannylation products were isolated in
moderate yields. Furthermore, the reactions with N-tosylhydrazones derived from alkyl aldehydes
were examined. The corresponding alkyltributylstannanes could also be obtained under the same
reaction conditions, but the yields were diminished (2w-z).
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Scheme 2. Scope of N-Tosylhydrazones Derived from Aldehydesa
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aReaction conditions: N-tosylhydrazone 1a-z (0.2 mmol), Bu3SnH (0.2 mmol), NaH (50 wt%,
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0.22 mmol), TBAC (0.04 mmol), toluene (3 mL), 110 C, 6 h. Yield of product with silica gel
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column chromatography. bThe product was decomposed on silica gel column chromatography. The
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yield in brackets was determined by H NMR spectroscopy with mesitylene as the internal
c
standard. The product was contaminated by Bu3SnSnBu3, which could be removed by silica gel
column chromatography. The yield was determined by 1H NMR spectroscopy.
To demonstrate the practical usefulness of this transformation, the reaction has been carried out
with 10 mmol of N-tosylhydrazone 1b. As shown in eq 1, 2.89 gram of the corresponding
tolyltributylstannane 2b could be isolated (73% yield).
(1)
Subsequently, we studied the reaction with N-tosylhydrazone derived from acetophenone (Table
2). To our disappointment, we could only get low yield of the product 4a (entry 1). The
by-products formed from N-tosylhydrazones via [1,2]-H shift and dimerization were observed. It
becomes apparent that the N-tosylhydrazones of ketones has low reactivity toward Bu3SnH. To
improve the reaction, the modification of the previous conditions was then carried out. It was
found that changing the loading of PTC could not improve the reaction (entries 2 and 3). Then the
ratio of two reactants and base was adjusted (entries 4-6). We found that with increased loading of
N-tosylhydrazone the reaction could afford slightly improved result (entry 4).
Table 2. Optimization of the Reaction with N-Tosylhydrazone Derived from Acetophenonea,b
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entry 3a : Bu3SnH : NaH
TBAC (mol%) yield (%)
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1 : 1 : 1.1
1 : 1 : 1.1
1 : 1 : 1.1
1.2 : 1 : 1.3
1.5 : 1 : 1.6
1 : 1.5 : 1.1
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aReaction conditions: substrates in 0.2 mmol scale, toluene (3 mL), 110 C, 12 h. Yields refer to
o
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the products purified by silica gel column chromatography. TBAC: tetrabutylammonium chloride.
With the adjusted reaction conditions, a series of N-tosylhydrazones derived from the
corresponding ketones were then examined (Scheme 3). The N-tosylhydrazones bearing various
substituents on the aromatic ring, such as methyl (3b), halogen (3c-e, 3h), methoxy and acetoxy
(3f, g), pyridinyl (3i) and naphthyl (3j) ketone derivatives were subjected to this transformation.
The reaction afforded the stannylation products in low to moderate yields. When the R group is
methyl, this reaction gave the secondary alkyl tributylstannanes in moderate yields in most cases.
However, when testing N-tosylhydrazones bearing steric bulky groups, the corresponding reaction
gave diminished yields (4k, l, m). In the case of 4n, the lower yield was attributed to the formation
of indene as the side-product. In general, the low yields are partially attributed to the fact that the
stannylation products have low stability on silica gel column chromatography due to the easy
protonation. However, it is worth mentioning that most of these products are difficult to synthesize
with traditional methods.
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Scheme 3. Scope of N-Tosylhydrazones Derived from Ketonesa
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aReaction conditions: N-tosylhydrazone (0.24 mmol), Bu3SnH (0.2 mmol), NaH (50 wt%, 0.26
o
b
mmol), TBAC (0.04 mmol), toluene (3 mL), 110 C, 12 h. All the yields refer to the products
purified by silica gel column chromatography.
Since N-tosylhydrazones are generated with high efficiency from the reaction of
N-tosylhydrazine (TsNHNH2) with the corresponding aldehydes or ketones, we then proceeded to
carry out the one-pot synthesis of benzyl tributylstannanes from the carbonyl compounds without
purification of the N-tosylhydrazones intermediates. To our delight, the one-pot transformation of
both aldehydes and ketones afforded the stannylation products in good yields (eq 2 and eq 3). The
little amount of water generated from the reaction between carbonyl compounds and TsNHNH2 did
not have negative affect on this transformation.
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(2)
(3)
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Encouraged by the results, a series of carbonyl substrates were then subjected to the one-pot
transformation in 0.5 g scale (Scheme 4). In most cases, the carbonyl substrates could be
transformed to the corresponding benzylstannanes in moderate yields. For the reaction with ketone
substrates, longer reaction time is required both for the formation of N-tosylhydrazones and the
stannylation process.
Scheme 4. One-pot Synthesis of Benzyltributylstannanes from Aldehydes or Ketonesa
aReaction conditions for 2a-t: First step: aldehydes (2 mmol), TsNHNH2 (2 mmol), toluene (10
o
n
mL), 80 C, 1 h. Second step: Bu3SnH (2 mmol), NaH (50 wt%, 2.2 mmol), TBAC (0.4 mmol),
o
toluene (15 mL), 110 C, 6 h; Reaction conditions for 4a and 4j: First step: ketones (2.4 mmol),
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o
n
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TsNHNH2 (2.4 mmol), toluene (10 mL), 80 C, 4 h. Second step: Bu3SnH (2 mmol), NaH (50
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o
wt%, 2.6 mmol), TBAC (0.4 mmol), toluene (15 mL), 110 C, 12 h; Yields refer to the products
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purified by silica gel column chromatography. bTBAC (0.6 mmol).
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Since the purification of tin reagents is tedious and the stannylation products are generally not
stable on silica gel, we then explored the tandem transformation of direct Pd-catalyzed
cross-coupling of the benzyltributylstannane products without purification. Namely, the
stannylation and Pd-catalyzed Stille reaction with aryl bromides is carried out in tandem manner.
As shown in Scheme 5, upon complement of the stannylation of N-tosylhydrazone, the reaction
mixture was filtered to remove the precipitates, followed by the removal of solvents under reduced
pressure. Subsequently, the crude benzyltributylstannane product was subjected to Pd-catalyzed
Stille reaction to afford the diarylmethane product. A series of diarylmethanes can be accessed in
moderately high yields with this two-step tandem transformation.
Scheme 5. Tandem Stannylation and Pd-Catalyzed Stille Cross-Coupling Reactions for the
Synthesis of Diarylmethanesa
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aReaction conditions: first step: N-tosylhydrazone (0.2 mmol), nBu3SnH (0.2 mmol), NaH (50 wt%,
o
0.22 mmol), TBAC (0.04 mmol), toluene (3 mL), 110 C, 6 h. second step: Ar'Br (0.2 mmol),
Pd(PPh3)4 (0.01 mmol), DMF (3 mL), 90 oC, 18 h. bAll the yields refer to the products purified by
silica gel column chromatography. cAr'Br (0.22 mmol).
The reaction mechanism is proposed in the Scheme 6. The diazo intermediate A is first
generated in situ from N-tosylhydrazone in the presence of base. The nucleophilic diazo carbon
atom interacts with tributyltin hydride to form the tin anion complex B, followed by [1,2]-H
migration to afford the product with the extrusion of nitrogen gas. An alternative pathway involves
formation of carbene intermediate C, followed by the formation of zwitterionic intermediate D and
[1,2]-H migration to complete the formal carbene insertion into Sn-H bond.7,16 With the currently
available experimental evidence it is not possible to distinguish these two mechanisms. To gain
insights into the mechanistic details of this stannylation process, the reaction of 1b was carried out
in the presence of 10 equivalent of 1-methoxy-4-vinylbenzene in order to test whether a free
carbene intermediate was involved. Under such conditions, the stannylation process was almost
blocked completely, and the corresponding cyclopropane product was obtained in 75% yield as a
mixture of cis- and trans- isomers (Scheme 7). The result indicates that an in situ generated free
carbene intermediate is most likely to be involved in the stannylation transformation.
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Scheme 6. Proposed Reaction Mechanism
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Scheme 7. Stannylation Reaction in Presence of Styrene
CONCLUSION
In summary, we have developed a transition-metal-free conversion of N-tosylhydrazones to
benzyl- or alkyltributylstannanes, which are an important type of organometallic reagents widely
utilized in cross-coupling reactions. We have also demonstrated a tandem transformation to
convert the N-tosylhydrazones to diarylmethanes without purification of the stannylation products.
The reaction further expands the synthetic applications of N-tosylhydrazones, which are easily
available from the corresponding aldehydes or ketones.
EXPERIMENTAL SECTION
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General Methods. Toluene was distilled from calcium hydride. For chromatography, 200-300
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mesh silica gel was employed. Chemical shifts for H NMR (400 MHz) and C{1H} NMR (100
MHz) are reported relative to the chemical shift of tetramethylsilane (TMS): chemical shifts (δ)
were reported in ppm, and coupling constants (J) are in Hertz (Hz). IR spectra are reported in wave
numbers, cm−1. For HRMS measurements, the mass analyzer is FT-ICR. Starting materials were
obtained from commercial suppliers and were used without further purification.
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Typical Procedure for the Stannylation of N-Tosylhydrazones Derived from Aldehydes
(Scheme 2). Under nitrogen atmosphere, N-tosylhydrazone of benzaldehyde (0.2 mmol, 55 mg),
NaH (1.1 equiv, 0.22 mmol, 50 wt%, 11 mg) and TBAC (20% equiv, 0.04 mmol, 11 mg) were
weighed in a 10 mL Schlenk tube. Toluene (3 mL) was then added. The solution was stirred at
room temperature for 10 min. Then nBu3SnH (1 equiv, 0.2 mmol, 58 mg, 54 μL) was added to the
o
reaction system through a syringe. The resulting reaction solution was stirred at 110 C for 6 h.
The reaction mixture was then filtered through silica gel with petroleum ether as eluent. The
combined filtrate was concentrated on a rotary evaporator under reduced pressure to leave a crude
residue, which was purified by flash chromatography with silica gel (eluted with petroleum ether).
Benzyltributylstannane 2a was obtained as colorless liquid (60 mg, 79%).
Benzyltributylstannane 2a.17 Flash chromatography (silica gel, petroleum ether) afforded 1a (70
mg, 79%); colorless liquid. 1H NMR (400 MHz, CDCl3) 7.16 (t, J = 7.6 Hz, 2H), 6.99-6.95 (m,
3H), 2.30 (s, 2H), 1.44-1.39 (m, 6H), 1.28-1.22 (m, 6H), 0.86 (t, J = 7.3 Hz, 9H), 0.80 (t, J = 7.4
Hz, 6H); 13C{1H} NMR (100 MHz, CDCl3) 143.7, 128.2, 126.9, 122.8, 29.0, 27.3, 18.1, 13.7,
9.3.
Tributyl(4-methylbenzyl)stannane 2b.17 Flash chromatography (silica gel, petroleum ether)
afforded 2b (67 mg, 85%); colorless liquid. 1H NMR (400 MHz, CDCl3) 6.97 (d, J = 7.8 Hz, 2H),
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6.87 (d, J = 7.8 Hz, 2H), 2.26 (s, 3H), 2.25 (s, 2H), 1.46-1.38 (m, 6H), 1.28-1.22 (m, 6H), 0.86 (t, J
= 7.3 Hz, 9H), 0.79 (t, J = 7.4 Hz, 6H); 13C{1H} NMR (100 MHz, CDCl3) 140.3, 132.0, 128.9,
126.9, 29.0, 27.3, 20.8, 17.5, 13.7, 9.2.
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Tributyl(4-tert-butylbenzyl)stannane 2c. Flash chromatography (silica gel, petroleum ether)
afforded 2c (52 mg, 60%); colorless liquid. 1H NMR (400 MHz, CDCl3) 7.17 (d, J = 8.1 Hz, 2H),
6.91 (d, J = 8.1 Hz, 2H), 2.27 (s, 2H), 1.41-1.36 (m, 6H), 1.31-1.21 (m, 15H), 0.85 (t, J = 7.3 Hz,
9H), 0.80 (t, J = 7.3 Hz, 6H); 13C{1H} NMR (100 MHz, CDCl3) 145.6, 140.3, 126.6, 125.1, 34.1,
31.4, 29.0, 27.3, 17.4, 13.7, 9.3; IR (film): 2957, 2929, 2872, 1506, 1464, 1215, 1191, 907,829,
734 cm-1. EI-MS (m/z, relative intensity): 438 (M+, 5), 381 (16), 291 (89), 267 (57), 235 (100), 179
(95), 147 (60). HRMS (EI) calcd for C19H33120Sn[M-C4H9]+ 381.1599, found 381.1632.
Tributyl(4-fluorobenzyl)stannane 2d.18 Flash chromatography (silica gel, petroleum ether)
afforded 2d (51 mg, 64%); colorless liquid. 1H NMR (400 MHz, CDCl3) 6.93-6.83 (m, 4H), 2.26
(s, 2H), 1.43-1.37 (m, 6H), 1.28-1.22 (m, 6H), 0.86 (t, J = 7.3 Hz, 9H), 0.80 (t, J = 7.3 Hz, 6H);
13C{1H} NMR (100 MHz, CDCl3) 159.5 (d, J = 240 Hz), 139.2 (d, J = 2.9 Hz), 127.9 (d, J = 7.4
Hz), 114.9 (d, J = 20.9 Hz), 29.0, 27.3, 17.1, 13.7, 9.2.
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Tributyl(4-chlorobenzyl)stannane 2e.18 Flash chromatography (silica gel, petroleum ether)
afforded 2e (60 mg, 72%); colorless liquid. 1H NMR (400 MHz, CDCl3) 7.12 (d, J = 8.4 Hz, 2H),
6.90 (d, J = 8.4 Hz, 2H), 2.26 (s, 2H), 1.43-1.38 (m, 6H), 1.28-1.22 (m, 6H), 0.87 (t, J = 7.3 Hz,
9H), 0.80 (t, J = 7.3 Hz, 6H); 13C{1H} NMR (100 MHz, CDCl3) 142.4, 128.2, 128.1, 29.0, 27.3,
17.6, 13.6, 9.3.
(4-Bromobenzyl)tributylstannanes 2f.17 Flash chromatography (silica gel, petroleum ether)
afforded 2f (61 mg, 66%); colorless liquid. 1H NMR (400 MHz, CDCl3) 7.26 (d, J = 8.3 Hz, 2H),
6.85 (d, J = 8.4 Hz, 2H), 2.24 (s, 2H), 1.43-1.39 (m, 6H), 1.29-1.22 (m, 6H), 0.87 (t, J = 7.3 Hz,
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9H), 0.80 (t, J = 7.3 Hz, 6H); 13C{1H} NMR (100 MHz, CDCl3) 142.9, 131.1, 128.6, 115.9, 29.0,
27.3, 17.7, 13.7, 9.3.
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Tributyl(4-methoxybenzyl)stannane 2g.19 Flash chromatography (silica gel, petroleum ether)
afforded 2g (58 mg, 71%); colorless liquid. 1H NMR (400 MHz, CDCl3) 6.90 (d, J = 8.5 Hz, 2H),
6.73 (d, J = 8.5 Hz, 2H), 3.76 (s, 3H), 2.24 (s, 2H), 1.44-1.38 (m, 6H), 1.28-1.22 (m, 6H), 0.86 (t, J
= 7.3 Hz, 9H), 0.79 (t, J = 7.3 Hz, 6H); 13C{1H} NMR (100 MHz, CDCl3) 155.8, 135.5, 127.8,
113.8, 55.3, 29.0, 27.3, 16.8, 13.7, 9.2.
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4-((Tributylstannyl)methyl)phenyl acetate 2h. Flash chromatography (silica gel, petroleum
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ether:ethyl acetate = 100:1, then 50:1) afforded 2h (42 mg, 48%); colorless liquid. H NMR (400
MHz, CDCl3) 6.96 (d, J = 8.2 Hz, 2H), 6.88 (d, J = 8.3 Hz, 2H), 2.28 (s, 2H), 2.26 (s, 3H),
1.44-1.38 (m, 6H), 1.28-1.23 (m, 6H), 0.87 (t, J = 7.3 Hz, 9H), 0.81 (t, J = 7.3 Hz, 6H); 13C{1H}
NMR (100 MHz, CDCl3) 169.7, 146.6, 141.3, 127.6, 121.1, 29.0, 27.3, 21.1, 17.5, 13.6, 9.3; IR
(film): 2957, 2924, 1763, 1503, 1369, 1219, 1195, 908, 733 cm-1. EI-MS (m/z, relative
intensity):440 (M+, 7), 383 (6), 291 (40), 235 (59), 179 (89), 107 (100). HRMS (EI) calcd for
C21H36O2120Sn[M]+ 440.1732, found 440.1751.
Tributyl(4-(trifluoromethyl)benzyl)stannane 2i. Flash chromatography (silica gel, petroleum
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ether) afforded 2i (64 mg, 71%); colorless liquid. H NMR (400 MHz, CDCl3) 7.40 (d, J = 8.1
Hz, 2H), 7.05 (d, J = 8.1 Hz, 2H), 2.35 (s, 2H), 1.44-1.38 (m, 6H), 1.28-1.22 (m, 6H), 0.88-0.80
(m, 15H); 13C{1H} NMR (100 MHz, CDCl3) 148.6, 126.8, 125.2 (q, J = 3.7 Hz), 124.7 (q, J =
270 Hz), 29.0, 27.3, 18.7, 13.6, 9.4; IR (film): 2957, 2925, 2854, 1612, 1324, 1162, 1121, 1067
cm-1. EI-MS (m/z, relative intensity): 393 ([M-57]+, 11), 337 (6), 291 (74), 235 (75), 177 (100),
140 (58). HRMS (EI) calcd for C16H24F3120Sn[M-C4H9]+ 393.0847, found 393.0825.
(Biphenyl-4-ylmethyl)tributylstannanes 2j. Flash chromatography (silica gel, petroleum ether)
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afforded 2j (55 mg, 60%); colorless liquid. 1H NMR (400 MHz, CDCl3) 7.56 (d, J = 7.8 Hz, 2H),
7.42-7.38 (m, 4H), 7.30-7.26 (m, 1H), 7.05 (d, J = 7.8 Hz, 2H), 2.34 (s, 2H), 1.47-1.40 (m, 6H),
1.29-1.24 (m, 6H), 0.88-0.81 (m, 15H); 13C{1H} NMR (100 MHz, CDCl3) 143.0, 141.3, 135.7,
128.6, 127.3, 126.9, 126.7, 126.5, 29.0, 27.3, 17.9, 13.7, 9.4; IR (film): 2956, 2921, 2854, 1609,
1486, 1212, 1075, 907, 732 cm-1. EI-MS (m/z, relative intensity): 458 (M+, 2), 401 (9), 291 (51),
235 (43), 179 (48), 167 (100), 121 (15). HRMS (EI) calcd for C25H38120Sn[M]+ 458.1990, found
458.1991.
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N,N-Dimethyl-4-((tributylstannyl)methyl)aniline 2k. Decomposed on silica gel chromatography.
The yield was estimated by1H NMR spectroscopy with mesitylene (0.2 mmol) as internal standard
(mixture with toluene and Bu3SnSnBu3). 1H NMR (400 MHz, CDCl3) 6.87 (d, J = 8.5 Hz, 2H),
6.63 (d, J = 8.5 Hz, 2H), 2.84 (s, 6H), 2.22 (s, 2H), 1.44-1.38 (m, 6H), 1.29-1.24 (m, 6H),
0.88-0.81 (m, 15H); 13C{1H} NMR (100 MHz, CDCl3) 147.3, 131.9, 127.6, 113.8, 41.3, 29.0,
27.3, 16.4, 13.6, 9.2. EI-MS (m/z, relative intensity): 425 (M+, 8), 291 (3), 135 (6), 179 (8), 134
(100), 118 (9), 91 (3). HRMS (EI) calcd for C21H39N120Sn[M]+ 425.2099, found 425.2120.
(3-Bromobenzyl)tributylstannanes 2l. Flash chromatography (silica gel, petroleum ether)
afforded 2l (65 mg, 71%); colorless liquid. 1H NMR (400 MHz, CDCl3) 7.13 (s, 1H), 7.09 (d, J =
7.9 Hz, 1H), 7.01 (t, J = 7.7 Hz, 1H), 6.88 (d, J = 7.7 Hz, 1H), 2.26 (s, 2H), 1.45-1.38 (m, 6H),
1.29-1.23 (m, 6H), 0.87 (t, J = 7.3 Hz, 9H), 0.82 (t, J = 7.3 Hz, 6H); 13C{1H} NMR (100 MHz,
CDCl3) 146.5, 129.7, 125.8, 125.4, 122.4, 29.0, 27.3, 18.1, 13.7, 9.4; IR (film): 2957, 2922, 2849,
1593, 1414, 1208, 1070, 734 cm-1. EI-MS (m/z, relative intensity): 403[(M-57)+, 10], 347 (5), 291
(100), 235 (89), 177 (93), 121 (26). HRMS (EI) calcd for C15H2479Br120Sn[M-C4H9]+ 403.0078,
found 403.0079.
Tributyl(3-nitrobenzyl)stannane 2m.19 Flash chromatography (silica gel, petroleum ether:ethyl
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acetate = 100:1) afforded 2m (37 mg, 44%); yellow liquid. H NMR (400 MHz, CDCl3)
7.83-7.81 (m, 2H), 7.34-7.26 (m, 2H), 2.40 (s, 2H), 1.44-1.38 (m, 6H), 1.28-1.23 (m, 6H),
0.88-0.82 (m, 15H); 13C{1H} NMR (100 MHz, CDCl3) 148.4, 146.5, 132.9, 129.0, 121.2, 117.9,
28.9, 27.2, 18.5, 13.6, 9.5.
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Tributyl(2-methylbenzyl)stannane 2n.17 Flash chromatography (silica gel, petroleum ether)
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afforded 2n (46 mg, 58%); colorless liquid. H NMR (400 MHz, CDCl3) 7.06-7.00 (m, 2H),
6.96-6.95 (m, 1H), 6.89 (dt, J = 1.2, 7.3 Hz, 1H), 2.27 (s, 2H),2.19 (s, 3H), 1.44-1.37 (m, 6H),
1.29-1.22 (m, 6H), 0.85 (t, J = 7.3 Hz, 9H), 0.81-0.77 (m, 6H); 13C{1H} NMR (100 MHz, CDCl3)
142.1, 133.2, 129.8, 127.4, 125.9, 123.1, 29.0, 27.3, 20.2, 16.1, 13.6, 9.7.
Tributyl(2-phenoxybenzyl)stannane 2o. Flash chromatography (silica gel, petroleum ether, then
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petroleum ether:ethyl acetate = 200:1) afforded 2o (61 mg, 64%); colorless liquid. H NMR (400
MHz, CDCl3) 7.29 (t, J = 7.9 Hz, 2H), 7.10-7.08 (m, 1H), 7.03 (t, J = 7.3 Hz, 1H), 6.98-6.94 (m,
2H), 6.91 (d, J = 8.3 Hz, 2H), 6.82-6.80 (m, 1H), 2.23 (s, 2H), 1.44-1.38 (m, 6H), 1.26-1.20 (m,
6H), 0.85-0.78 (m, 15H); 13C{1H} NMR (100 MHz, CDCl3) 157.7, 152.4, 135.8, 129.6, 129.2,
124.2, 123.8, 122.2, 119.1, 117.5, 29.0, 27.3, 13.7, 12.7, 9.8; IR (film): 2955, 2924, 2871, 1589,
1485, 1237, 907, 879, 734 cm-1. EI-MS (m/z, relative intensity): 417 ([M-57]+, 100), 361 (6), 303
(11), 235 (14), 179 (23), 155 (9). HRMS (EI) calcd for C21H29O120Sn[M-C4H9]+4 17.1235, found
417.1245.
Tributyl(2,6-dimethylbenzyl)stannane 2p. Flash chromatography (silica gel, petroleum ether)
afforded 2p (32 mg, 39%); colorless liquid. 1H NMR (400 MHz, CDCl3) 6.93 (d, J = 7.4 Hz, 2H),
6.82 (t, J = 7.4 Hz, 1H), 2.25 (s, 2H),2.20 (s, 6H), 1.42-1.34 (m, 6H), 1.28-1.22 (m, 6H), 0.84 (t, J
= 7.1 Hz, 9H), 0.80-0.76 (m, 6H); 13C{1H} NMR (100 MHz, CDCl3) 140.5, 133.2, 127.6, 122.7,
29.0, 27.3, 20.9, 13.6, 13.4, 10.4; IR (film): 2957, 2927, 2871, 1464, 1477, 1096, 907, 733 cm-1.
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EI-MS (m/z, relative intensity): 353[(M-57)+, 4], 291 (32), 235 (48), 177 (52), 119 (100), 91 (19).
HRMS (EI) calcd for C17H29120Sn[M-C4H9]+ 353.1286, found 353.1306.
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(2-Bromo-4-chlorobenzyl)tributylstannanes 2q. Flash chromatography (silica gel, petroleum
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ether) afforded 2q (61 mg, 62%); colorless liquid. H NMR (400 MHz, CDCl3) 7.46 (d, J = 2.1
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Hz, 1H), 7.09 (dd, J = 2.1, 8.3 Hz, 1H), 6.98 (d, J = 8.3 Hz, 1H), 2.41 (s, 2H), 1.46-1.38 (m, 6H),
1.30-1.23 (m, 6H), 0.88-0.82 (m, 15H); 13C{1H} NMR (100 MHz, CDCl3) 142.8, 131.7, 128.9,
128.6, 127.4, 122.4, 28.9, 27.3, 19.7, 13.6, 10.2; IR (film): 2956, 2928, 2853, 1466, 1376, 1260,
1108, 1033, 907, 733 cm-1. EI-MS (m/z, relative intensity): 437[(M-57)+, 72], 381 (21), 323 (17),
291 (86), 235 (93), 177 (100). HRMS (EI) calcd for C15H2335Cl79Br120Sn[M-C4H9]+ 436.9688,
found 436.9656.
Tributyl(3,4-dichlorobenzyl)stannane 2r.20 Flash chromatography (silica gel, petroleum ether)
afforded 2r (59 mg, 65%); colorless liquid. 1H NMR (400 MHz, CDCl3) 7.20 (d, J = 8.3 Hz, 1H),
7.06 (d, J = 2.0 Hz, 1H), 6.79 (dd, J = 2.0, 8.3 Hz, 1H), 2.23 (s, 2H), 1.44-1.38 (m, 6H), 1.29-1.23
(m, 6H), 0.87 (t, J = 7.3 Hz, 9H), 0.84-0.80 (m, 6H); 13C{1H} NMR (100 MHz, CDCl3) 144.6,
131.9, 130.0, 128.4, 126.3, 29.0, 27.3, 17.7, 13.6, 9.4.
Tributyl(3,5-dimethoxybenzyl)stannane 2s.21 Flash chromatography (silica gel, petroleum
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ether:ethyl acetate = 100:1) afforded 2s (50 mg, 57%); pale yellow liquid. H NMR (400 MHz,
CDCl3) 6.16 (d, J = 2.0 Hz, 2H), 6.12 (d, J = 2.0 Hz, 1H), 3.74 (s, 6H), 2.25 (s, 2H), 1.46-1.38
(m, 6H), 1.29-1.24 (m, 6H), 0.87 (t, J = 7.3 Hz, 9H), 0.84-0.80 (m, 6H); 13C{1H} NMR (100 MHz,
CDCl3) 160.8, 146.2, 105.0, 95.4, 55.1, 29.1, 27.4, 18.8, 13.7, 9.5.
(Benzo[d][1,3]dioxol-5-ylmethyl)tributylstannanes 2t.22 Flash chromatography (silica gel,
petroleum ether , then petroleum ether:ethyl acetate = 100:1) afforded 2t (55 mg, 65%); colorless
liquid. 1H NMR (400 MHz, CDCl3) 6.64 (d, J = 7.9 Hz, 1H), 6.49 (d, J = 1.5 Hz, 1H), 6.43 (dd, J
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= 1.5, 7.9 Hz, 1H), 5.87 (s, 2H), 2.23 (s, 2H), 1.46-1.38 (m, 6H), 1.29-1.24 (m, 6H), 0.87 (t, J = 7.3
Hz, 9H), 0.83-0.79 (m, 6H); 13C{1H} NMR (100 MHz, CDCl3) 147.4, 143.4, 137.4, 119.1, 108.1,
107.6, 100.4, 29.0, 27.3, 17.8, 13.7, 9.2.
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Tributyl(naphthalen-2-ylmethyl)stannane 2u.17 Flash chromatography (silica gel, petroleum
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ether) afforded 2u (57 mg, 66%); colorless liquid. H NMR (400 MHz, CDCl3) 7.72 (d, J = 8.0
Hz, 1H), 7.65 (d, J = 8.2 Hz, 2H), 7.38-7.37 (m, 2H), 7.31 (d, J = 7.9 Hz, 1H), 7.14 (d, J = 8.4 Hz,
1H), 2.46 (s, 2H), 1.44-1.39 (m, 6H), 1.28-1.22 (m, 6H), 0.86-0.79 (m, 15H); 13C{1H} NMR (100
MHz, CDCl3) 141.5, 134.0, 130.5, 127.6, 127.5, 127.2, 126.7, 125.7, 123.8, 123.5, 29.0, 27.3,
18.7, 13.6, 9.4.
3-((Tributylstannyl)methyl)pyridine 2v.23 Flash chromatography (silica gel, petroleum ether:ethyl
acetate = 50:1, then 20:1) afforded 2v (37 mg, 49%); colorless liquid. 1H NMR (400 MHz, CDCl3)
8.30 (s, 1H), 8.23 (s, 1H), 7.28-7.26 (m, 1H), 7.09-7.06 (m, 1H), 2.24 (s, 2H), 1.44-1.38 (m, 6H),
1.29-1.23 (m, 6H), 0.89-0.81 (m, 15H); 13C{1H} NMR (100 MHz, CDCl3) 148.4, 144.4, 139.6,
133.8, 123.0, 28.9, 27.2, 14.8, 13.6, 9.4.
Tributyl(3-phenylpropyl)stannane 2w.24 Flash chromatography (silica gel, petroleum ether)
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afforded 2w (35 mg, 43%); colorless liquid. H NMR (400 MHz, CDCl3) 7.29-7.25 (m, 2H),
7.19-7.16 (m, 3H), 2.60 (t, J = 7.6 Hz, 2H), 1.83- 1.77 (m, 2H), 1.48-1.44 (m, 6H), 1.32-1.26 (m,
6H), 0.90-0.80 (m, 17H); 13C{1H} NMR (100 MHz, CDCl3) 142.6, 128.4, 128.2, 125.6, 40.8,
29.25, 29.20, 27.4, 13.7, 8.84, 8.76.
Methyl 4-(3-(tributylstannyl)propyl)benzoate 2x. Flash chromatography (silica gel, petroleum
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ether:ethyl acetate = 100:1) afforded 2x (39 mg, 42%); pale yellow liquid. H NMR (400 MHz,
CDCl3) 7.95 (d, J = 8.1 Hz, 2H), 7.23 (d, J = 8.1 Hz, 2H), 3.90 (s, 3H), 2.66 (t, J = 7.6 Hz, 2H),
1.83- 1.79 (m, 2H), 1.49-1.42 (m, 6H), 1.32-1.26 (m, 6H), 0.90-0.80 (m, 17H); 13C{1H} NMR (100
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MHz, CDCl3) 167.2, 148.1, 129.6, 128.5, 127.6, 51.9, 40.8, 29.2, 28.9, 27.4, 13.7, 8.8, 8.7; IR
(film): 2956, 2926, 2853, 1724, 1610, 1437, 1279, 1111, 908 cm-1. EI-MS (m/z, relative intensity):
411 ([M-57]+, 100), 355 (14), 295 (12), 235 (11), 177 (24), 145 (32), 118 (16). HRMS (ESI) calcd
for C23H40NaO2120Sn[M+Na]+ 491.1946, found 491.1956.
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Tributyl(3-(5-methylfuran-2-yl)butyl)stannane 2y. Flash chromatography (silica gel, petroleum
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ether) afforded 2y (31 mg, 37%); colorless liquid. H NMR (400 MHz, CDCl3) 5.84-5.82 (m,
2H), 2.66-2.60 (m, 1H), 2.25 (s, 3H), 1.84-1.80 (m, 1H), 1.65-1.60 (m, 1H), 1.48-1.42 (m, 6H),
1.32-1.26 (m, 6H), 1.20 (d, J = 6.9 Hz, 3H), 0.90-0.78 (m, 17H); 13C{1H} NMR (100 MHz, CDCl3)
159.0, 149.9, 105.5, 104.0, 37.0, 33.0, 29.2, 27.4, 18.4, 13.7, 13.5, 8.6, 5.9; IR (film):2956, 2924,
2870, 1463, 1222, 1019, 908, 735 cm-1. EI-MS (m/z, relative intensity): 371 ([M-57]+, 100), 291
(17), 235 (16), 177 (35), 121 (17), 109 (50). HRMS (EI) calcd for C17H31O120Sn[M-C4H9]+
371.1391, found 371.1411.
Tributyl(cyclohexylmethyl)stannane 2z. Flash chromatography (silica gel, petroleum ether)
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afforded 2z (50 mg, 2z:Bu3SnSnBu3= 1:0.3; 45% yield estimated by H NMR); colorless liquid.
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The representative H NMR chemicals shifts: H NMR (400 MHz, CDCl3) 0.86 (t, J = 7.3 Hz,
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9H), 0.80 (t, J = 7.4 Hz, 6H); C{1H} NMR (100 MHz, CDCl3)  37.6, 29.7, 29.3, 27.4, 26.7,
26.2, 18.9, 13.7, 9.4. Bu3SnSnBu3:13C NMR (100 MHz, CDCl3) HRMS
(EI) calcd for C15H31120Sn[M-C4H9]+ 331.1442; found 331.1453.
Typical Procedure for the Stannylation of N-Tosylhydrazones Derived from Ketones
(Scheme 3). The reaction was carried out with nBu3SnH (0.2 mmol), N-tosylhydrazones (1.2 equiv)
and NaH (1.3 equiv). The reaction solution was stirred at 110 oC for 12 h. The workup procedures
were the same as the typical procedure described previously for Scheme 2.
Tributyl(1-phenylethyl)stannane 4a.25 Flash chromatography (silica gel, petroleum ether)
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afforded 4a (45 mg, 57%); colorless liquid. 1H NMR (400 MHz, CDCl3) 7.20 (t, J = 7.6 Hz, 2H),
7.04-6.97 (m, 3H), 2.70 (q, J = 7.5 Hz, 1H), 1.57 (d, J = 7.5 Hz, 3H), 1.42-1.34 (m, 6H), 1.28-1.21
(m, 6H), 0.85 (t, J = 7.2 Hz, 9H), 0.79-0.75 (m, 6H); 13C{1H} NMR (100 MHz, CDCl3) 149.0,
128.2, 125.5, 123.2, 29.0, 27.4, 26.8, 17.3, 13.6, 8.7.
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Tributyl(1-p-tolylethyl)stannane 4b. Flash chromatography (silica gel, petroleum ether) afforded
4b (36 mg, 44%); colorless liquid. 1H NMR (400 MHz, CDCl3) 7.02 (d, J = 7.9 Hz, 2H), 6.92(d,
J = 7.9 Hz, 2H), 2.65 (q, J = 7.6 Hz, 1H), 2.28 (s, 3H), 1.55 (d, J = 7.6 Hz, 3H), 1.40-1.34 (m, 6H),
1.29-1.22 (m, 6H), 0.85 (t, J = 7.3 Hz, 9H), 0.78-0.74 (m, 6H); 13C{1H} NMR (100 MHz, CDCl3)
145.8, 132.4, 128.8, 125.5, 29.1, 27.5, 26.3, 20.8, 17.6, 13.7, 8.7; IR (film):2956, 2924, 2855,
1510, 1463, 1376, 907, 734 cm-1. EI-MS (m/z, relative intensity): 410 (M+, 1), 353 ([M-57]+, 5),
291 (46), 235 (55), 179 (67), 119 (100), 91 (22). HRMS (EI) calcd for C17H29120Sn[M-C4H9]+
353.1286; found 353.1294.
Tributyl(1-(4-fluorophenyl)ethyl)stannane 4c. Flash chromatography (silica gel, petroleum ether)
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afforded 4c (42 mg, 51%); colorless liquid. H NMR (400 MHz, CDCl3) 6.98-6.94 (m, 2H),
6.92-6.88 (m, 2H), 2.66 (q, J = 7.6 Hz, 1H), 1.54 (d, J = 7.6 Hz, 3H), 1.41-1.35 (m, 6H), 1.28-1.22
(m, 6H), 0.86 (t, J = 7.3 Hz, 9H), 0.79-0.75 (m, 6H); 13C{1H} NMR (100 MHz, CDCl3) 159.7 (d,
J = 241 Hz), 144.6 (d, J = 2.9 Hz), 126.5 (d, J = 7.5 Hz), 114.8 (d, J = 20.8 Hz), 29.0, 27.4, 25.8,
17.7, 13.6, 8.7; IR (film):2956, 2927, 2871, 1505, 1463, 1228, 907, 831, 733 cm-1. EI-MS (m/z,
relative intensity): 357[(M-57)+, 7], 291 (53), 235 (66), 179 (100) ,123 (89), 103 (30). HRMS (EI)
calcd for C16H26F120Sn[M-C4H9]+ 357.1035, found 357.1057.
Tributyl(1-(4-chlorophenyl)ethyl)stannane 4d. Flash chromatography (silica gel, petroleum ether)
afforded 4d (43 mg, 50%); colorless liquid. 1H NMR (400 MHz, CDCl3) 7.17 (d, J = 8.4 Hz, 2H),
6.95(d, J = 8.4 Hz, 2H), 2.66 (q, J =7.5 Hz, 1H), 1.54 (d, J = 7.5 Hz, 3H), 1.40-1.34 (m, 6H),
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1.28-1.22 (m, 6H), 0.86 (t, J = 7.3 Hz, 9H), 0.79-0.75 (m, 6H); 13C{1H} NMR (100 MHz, CDCl3)
147.6, 128.2, 126.7, 29.0, 27.4, 26.2, 17.3, 13.6, 8.7; IR (film): 2955, 2922, 2872, 1488, 1459,
1091, 1010, 907, 826, 734 cm-1. EI-MS (m/z, relative intensity): 373 ([M-57]+, 9), 291 (65), 235
(76), 179 (100), 139 (43), 103 (35). HRMS (EI) calcd for C16H2635Cl120Sn[M-C4H9]+ 373.0740,
found 373.0760.
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(1-(4-Bromophenyl)ethyl)tributylstannanes 4e. Flash chromatography (silica gel, petroleum
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ether) afforded 4e (48 mg, 50%); colorless liquid. H NMR (400 MHz, CDCl3) 7.31 (d, J = 8.4
Hz, 2H), 6.89 (d, J = 8.4 Hz, 2H), 2.65 (q, J = 7.6 Hz, 1H), 1.53 (d, J = 7.6 Hz, 3H), 1.40-1.34 (m,
6H), 1.27-1.21 (m, 6H), 0.86 (t, J = 7.3 Hz, 9H), 0.80-0.75 (m, 6H); 13C{1H} NMR (100 MHz,
CDCl3) 148.2, 131.1, 127.2, 116.3, 29.0, 27.4, 26.3, 17.2, 13.6, 8.8; IR (film): 2956, 2930, 2853,
1488, 1463, 1007, 908, 822, 734 cm-1. EI-MS (m/z, relative intensity): 417 [(M-57)+,8], 291 (88),
235 (86), 179 (100), 121 (26), 104 (54). HRMS (EI) calcd for C16H2679Br120Sn[M-C4H9]+ 417.0234,
found 417.0247.
Tributyl(1-(4-methoxyphenyl)ethyl)stannane 4f. Flash chromatography (silica gel, petroleum
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ether) afforded 4f (41 mg, 48%); colorless liquid. H NMR (500 MHz, CDCl3) 6.95 (d, J = 8.6
Hz, 2H), 6.78(d, J = 8.6 Hz, 2H), 3.78 (s, 3H), 2.63 (q, J = 7.6 Hz, 1H), 1.54 (d, J = 7.6 Hz, 3H),
1.41-1.37 (m, 6H), 1.27-1.23 (m, 6H), 0.86 (t, J = 7.3 Hz, 9H), 0.78-0.75 (m, 6H); 13C{1H} NMR
(125 MHz, CDCl3) 156.1, 141.1, 126.4, 113.8, 55.3, 29.1, 27.4, 25.7, 17.9, 13.6, 8.7; IR
(film):2954, 2927, 2852, 1508, 1464, 1244, 1042, 908, 734 cm-1. EI-MS (m/z, relative intensity):
426 (M+, 6), 369[(M-57)+, 5], 291 (44), 235 (51), 179 (52), 135 (100). HRMS (EI) calcd for
C17H29O120Sn[M-C4H9]+ 369.1235, found 369.1236.
4-(1-(Tributylstannyl)ethyl)phenyl acetate 4g. Flash chromatography (silica gel, petroleum
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ether:ethyl acetate = 100:1, then 50:1) afforded 4g (41 mg, 45%); pale yellow liquid. H NMR
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(400 MHz, CDCl3) 7.01 (d, J = 8.5 Hz, 2H), 6.92 (d, J = 8.5 Hz, 2H), 2.69 (q, J = 7.5 Hz, 1H),
2.27 (s, 3H), 1.55 (d, J = 7.5 Hz, 3H), 1.41-1.34 (m, 6H), 1.27-1.22 (m, 6H), 0.86 (t, J = 7.3 Hz,
9H), 0.80-0.75 (m, 6H); 13C{1H} NMR (100 MHz, CDCl3) 169.7, 146.8, 146.6, 126.1, 121.0,
29.0, 27.4, 26.1, 21.1, 17.5, 13.6, 8.7; IR (film):2957, 2917, 2850, 1766, 1506, 1191, 908, 733 cm-1.
EI-MS (m/z, relative intensity): 454 (M+, 22), 397 [(M-57)+, 9], 291 (43), 235 (64),179 (64), 121
(100). HRMS (EI) calcd for C22H38O2120Sn[M]+ 454.1888, found 454.1887.
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(1-(3-Bromophenyl)ethyl)tributylstannanes 4h. Flash chromatography (silica gel, petroleum
ether) afforded 4h (61 mg, 64%); colorless liquid. 1H NMR (400 MHz, CDCl3) 7.17 (s, 1H), 7.11
(d, J = 8.1 Hz, 1H), 7.06 (t, J = 7.7 Hz, 1H), 6.93 (d, J = 7.5 Hz, 1H), 2.66 (q, J = 7.5 Hz, 1H),
1.54 (d, J = 7.5 Hz,3H), 1.40-1.34 (m, 6H), 1.28-1.22 (m, 6H), 0.86 (t, J = 7.3 Hz, 9H), 0.81-0.76
(m, 6H); 13C{1H} NMR (100 MHz, CDCl3) 151.7, 129.6, 128.3, 126.1, 124.1, 122.5, 29.0, 27.4,
26.7, 17.1, 13.6, 8.9; IR (film): 2956, 2926, 2870, 1589, 1464, 1072, 907, 733 cm-1. EI-MS (m/z,
relative intensity): 417[(M-57)+, 6], 291 (82), 235 (86), 179 (100), 120 (29), 104 (45). HRMS (EI)
calcd for C16H2679Br120Sn[M-C4H9]+ 417.0234, found 417.0257.
3-(1-(Tributylstannyl)ethyl)pyridine 4i. Flash chromatography (silica gel, petroleum ether:ethyl
acetate = 50:1, then 20:1) afforded 4i (43 mg, 55%); colorless liquid. 1H NMR (400 MHz, CDCl3)
8.33 (d, J = 1.6 Hz, 1H), 8.25 (d, J = 4.4 Hz, 1H), 7.32 (d, J = 7.6 Hz, 1H), 7.13 (dd, J = 4.8, 7.6
Hz, 1H), 2.67 (q, J = 7.5 Hz, 1H), 1.58 (d, J = 7.5 Hz, 3H), 1.41-1.35 (m, 6H), 1.28-1.22 (m, 6H),
0.86 (t, J = 7.3 Hz, 9H), 0.83-0.79 (m, 6H); 13C{1H} NMR (100 MHz, CDCl3) 147.7, 144.7,
144.5, 132.2, 123.0, 29.0, 27.4, 23.7, 16.9, 13.6, 8.9; IR (film): 2956, 2925, 2871, 1463, 1418,
1377, 998, 908, 733 cm-1. EI-MS (m/z, relative intensity): 397 (M+, 41), 340 [(M-57)+, 9], 291 (22),
235 (74), 179 (100), 121 (26). HRMS (EI) calcd for C19H35N120Sn[M]+ 397.1786, found 397.1809.
Tributyl(1-(naphthalen-2-yl)ethyl)stannane 4j. Flash chromatography (silica gel, petroleum ether)
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afforded 4j (44 mg, 50%); colorless liquid. H NMR (400 MHz, CDCl3) 7.75-7.66 (m, 3H),
7.41-7.39 (m, 2H), 7.34-7.32 (m, 1H), 7.20-7.18 (m, 1H), 2.86 (q, J = 7.5 Hz, 1H), 1.67(d, J = 7.5
Hz, 3H), 1.41-1.33 (m, 6H), 1.26-1.20 (m, 6H), 0.84-0.77 (m, 15H); 13C{1H} NMR (100 MHz,
CDCl3) 146.7, 134.0, 130.8, 127.5, 127.4, 127.0, 126.3, 125.7, 124.0, 121.7, 29.1, 27.4, 27.3,
17.3, 13.6, 8.9; IR (film): 2956, 2923, 2856, 1628, 1598, 1463, 1170, 907, 733 cm-1. EI-MS (m/z,
relative intensity): 446 (M+, 1), 389 [(M-57)+, 2], 291 (33), 235 (38), 179 (49), 155 (100), 121 (17).
HRMS (EI) calcd for C24H38120Sn[M]+ 446.1990, found 446.2018.
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Tributyl(1-phenylbutyl)stannane 4k. Flash chromatography (silica gel, petroleum ether) afforded
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4k (41 mg, 48%); colorless liquid. H NMR (400 MHz, CDCl3) 7.18 (t, J = 7.6 Hz, 2H),
7.01-6.95 (m, 3H), 2.60 (dd, J = 6.2, 10.1 Hz, 1H), 2.09-2.00 (m, 1H), 1.87-1.78 (m, 1H),
1.38-1.32 (m, 6H), 1.28-1.21 (m, 8H), 0.89-0.83 (m, 12H), 0.77-0.73 (m, 6H); 13C{1H} NMR (100
MHz, CDCl3) 147.1, 128.2, 126.3, 123.2, 34.6, 34.1, 29.0, 27.4, 23.0, 13.9, 13.6, 9.0; IR
(film):2956, 2925, 2871, 1599, 1491, 1463, 1377, 908, 734 cm-1. EI-MS (m/z, relative intensity):
424 (M+,1), 367[(M-57)+, 17], 291 (100), 235 (97), 179 (76), 91 (75). HRMS (EI) calcd for
C18H31120Sn[M-C4H9]+ 367.1442, found 367.1466.
(1-(Benzo[d][1,3]dioxol-5-yl)butyl)tributylstannanes 4l. Flash chromatography (silica gel,
petroleum ether, then petroleum ether to ethyl acetate = 100:1) afforded 4l (33 mg, 35%); colorless
liquid. 1H NMR (400 MHz, CDCl3) 6.66 (d, J = 7.9 Hz, 1H), 6.53 (d, J = 1.0 Hz, 1H), 6.45 (dd, J
= 1.0, 7.9 Hz, 1H), 5.88 (s, 2H), 2.52 (dd, J = 6.1, 10.1 Hz, 1H), 2.00-1.90 (m, 1H), 1.81-1.72 (m,
1H), 1.40-1.36 (m, 6H), 1.28-1.22 (m, 8H), 0.90-0.84 (m, 12H), 0.78-0.74 (m, 6H); 13C{1H} NMR
(100 MHz, CDCl3) 147.5, 143.6, 141.3, 118.8, 108.0, 106.9, 100.4, 35.1, 33.8, 29.1, 27.4, 22.9,
13.9, 13.6, 9.0; IR (film): 2956, 2926, 2870, 1485, 1243, 1181, 1042, 942, 908, 733 cm-1. EI-MS
(m/z, relative intensity): 468 (M+, 9), 411 [(M-57)+, 12], 291 (62), 235 (71), 177 (78), 135 (100).
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HRMS (EI) calcd for C23H40O2120Sn[M]+ 468.2045, found 468.2065.
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Tributyl(2-methyl-1-phenylpropyl)stannane 4m. Flash chromatography (silica gel, petroleum
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ether) afforded 4m (22 mg, 26%); colorless liquid. H NMR (400 MHz, CDCl3) 7.18 (t, J = 7.6
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Hz, 2H), 7.00-6.96 (m, 3H), 2.37-2.28 (m, 1H), 2.24-2.15 (m, 1H), 1.37-1.31 (m, 6H), 1.25-1.20
(m, 6H), 1.06 (d, J = 6.4 Hz, 3H), 0.86-0.82 (m, 12H), 0.74-0.70 (m, 6H); 13C{1H} NMR (100
MHz, CDCl3) 146.9, 128.2, 127.2, 123.4, 45.8, 31.4, 29.1, 27.5, 24.8, 23.3, 13.6, 10.0; IR
(film):2955, 2925, 2871, 1593, 1493, 1463, 908, 734 cm-1. EI-MS (m/z, relative intensity): 367
[(M-57)+, 17], 291 (79), 235 (94), 179 (96), 120 (31), 91 (100). HRMS (EI) calcd for
C18H31120Sn[M-C4H9]+ 367.1442, found 367.1435.
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Tributyl(2,3-dihydro-1H-inden-1-yl)stannane 4n. Flash chromatography (silica gel, petroleum
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ether) afforded 4n (28 mg, 33%); colorless liquid. H NMR (400 MHz, CDCl3) 7.16 (d, J = 7.3
Hz, 1H), 7.07-7.03 (m, 1H), 7.01-6.99 (m, 1H), 6.97-6.93 (m, 1H), 3.01-2.99 (m, 1H), 2.93-2.90
(m, 1H), 2.81-2.72 (m, 1H), 2.40-2.32 (m, 1H), 2.18-2.16 (m, 1H), 1.44-1.38 (m, 6H), 1.28-1.23
(m, 6H), 0.85 (t, J = 7.3 Hz, 9H), 0.82-0.78 (m, 6H); 13C{1H} NMR (100 MHz, CDCl3) 149.7,
141.7, 126.1, 124.1, 123.6, 121.9, 33.1, 32.1, 30.4, 29.1, 27.4, 13.6, 9.3; IR (film): 2955, 2925,
2852, 1473, 1457, 1079, 908, 734 cm-1. EI-MS (m/z, relative intensity): 408 (M+, 1), 351 [(M-57)+,
5], 291 (49), 235 (70), 179 (79), 117 (100), 91 (16). HRMS (EI) calcd for C17H27120Sn[M-C4H9]+
351.1129; found 351.1151.
Typical Procedure for the Stannylation of Aldehydes or Ketones (Scheme 4). Under
nitrogen atmosphere, TsNHNH2 (2 mmol, 372 mg), toluene (10 mL) and benzaldehyde (2 mmol,
212 mg) were weighed in a 100 mL Schlenk tube. The solution was sealed and heated at 80 oC for
1 h. After the reaction was cooled down to room temperature, NaH (1.1 equiv, 2.2 mmol, 50 wt%,
106 mg), TBAC (20% equiv, 0.4 mmol, 111 mg) and toluene (15 mL) were added. The reaction
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n
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mixture was stirred at room temperature for 10 min. Then Bu3SnH (1 equiv, 2 mmol, 582 mg)
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was added to the reaction system through a syringe. The resulting reaction solution was stirred at
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110 C for 6 h. The reaction mixture was then filtered through silica gel with petroleum ether as
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eluent. The combined filtrate was then concentrated on a rotary evaporator under reduced pressure
to leave a crude residue, which was purified by flash chromatography with silica gel (eluted with
petroleum ether). Benzyltributylstannane 2a was obtained as colorless liquid (556 mg, 73%).
Typical Procedure of Tandem Stannylation/Stille Cross-Coupling Reactions (Scheme 5).
Under nitrogen atmosphere, N-tosylhydrazone 1a (0.2 mmol, 55 mg), NaH (1.1 equiv, 0.22 mmol,
50 wt%, 11 mg) and TBAC (20% equiv, 0.04 mmol, 11 mg) were weighed in a 10 mL Schlenk
tube. Toluene (3 mL) was then added in succession. The solution was stirred at room temperature
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for 10 min. Bu3SnH (1 equiv, 0.2 mmol, 58 mg, 54 μL) was added into this system through
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syringe. The resulting reaction solution was stirred at 110 C for 6 h. The reaction mixture was
filtered through silica gel to remove the insoluble precipitate. The combined filtrate was then
concentrated on a rotary evaporator under reduced pressure to leave a crude product. Then under
nitrogen atmosphere, Pd(PPh3)4 (5 mol%, 12 mg), methyl 4-bromobenzoate (1 equiv, 43 mg) and
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DMF (3 mL) were added, andthe solution was stirred at 90 C for 18 h. The solution was
concentrated on a rotary evaporator under reduced pressure to leave a crude residue, which was
purified by silica gel column chromatography (eluted first with petroleum ether, then with
petroleum ether:EtOAc = 100:1) to afford methyl 4-benzylbenzoate 3a as pale yellow solid (32 mg,
70%).
Methyl 4-benzylbenzoate 5a.26 Flash chromatography (silica gel, petroleum ether:ethyl acetate =
200:1, then 100:1) afforded 5a (32 mg, 70%); yellow liquid. 1H NMR (400 MHz, CDCl3) 7.95 (d,
J = 8.3 Hz, 2H), 7.31-7.21 (m, 5H), 7.17 (d, J = 8.3 Hz, 2H), 4.02 (s, 2H), 3.88 (s, 3H); 13C{1H}
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NMR (100 MHz, CDCl3) 167.0, 146.5, 140.1, 129.8, 128.9, 128.6, 128.1, 126.3, 51.9, 41.9.
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Diphenylmethane 5b.26 Flash chromatography (silica gel, petroleum ether) afforded 5b (22 mg,
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66%); colorless liquid. H NMR (400 MHz, CDCl3) 7.29-7.26 (m, 4H), 7.20-7.17 (m, 6H), 3.98
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(s, 2H); 13C{1H} NMR (100 MHz, CDCl3) 141.1, 128.9, 128.4, 126.0, 41.9.
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1-Benzyl-4-nitrobenzene 5c.27 Flash chromatography (silica gel, petroleum ether to ethyl acetate
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= 100:1) afforded 5c (32 mg, 75%); yellow liquid. H NMR (400 MHz, CDCl3) 8.13 (d, J = 8.5
Hz, 2H), 7.34-7.30 (m, 4H), 7.26-7.24 (m, 1H), 7.17 (d, J = 7.4 Hz, 2H), 4.07 (s, 2H); 13C{1H}
NMR (100 MHz, CDCl3) 148.8, 146.5, 139.2, 129.6, 128.9, 128.8, 126.7, 123.7, 41.7.
1-Benzyl-3-methoxybenzene 5d.26 Flash chromatography (silica gel, petroleum ether, then
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petroleum ether:ethyl acetate = 100:1) afforded 5d (22 mg, 56%); colorless liquid. H NMR (400
MHz, CDCl3) 7.30-7.26 (m, 2H), 7.22-7.18 (m, 4H), 6.98 (d, J =7.5 Hz, 1H), 6.75-6.73 (m, 2H),
3.95 (s, 2H), 3.77 (s, 3H); 13C{1H} NMR (100 MHz, CDCl3) 159.7, 142.7, 140.9, 129.4, 128.9,
128.4, 126.1, 121.4, 114.8, 111.3, 55.1, 42.0.
3-Benzylpyridine 5e.28 Flash chromatography (silica gel, petroleum ether:ethyl acetate = 20:1,
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then 5:1) afforded 5e (24 mg, 71%); yellow liquid. H NMR (400 MHz, CDCl3) 8.51 (s, 1H),
8.45 (d, J = 4.1 Hz, 1H), 7.46 (d, J = 7.6 Hz, 1H), 7.32-7.28 (m, 2H), 7.24-7.16 (m, 4H), 3.97 (s,
2H); 13C{1H} NMR (100 MHz, CDCl3) 150.1, 147.6, 139.7, 136.3, 128.8, 128.7, 126.4, 123.4,
39.0.
Methyl 4-(4-methylbenzyl)benzoate 5f.29 Flash chromatography (silica gel, petroleum ether:ethyl
acetate = 200:1) afforded 5f (37 mg, 77%); yellow liquid. 1H NMR (500 MHz, CDCl3) 7.94 (d, J
= 8.5 Hz, 2H), 7.24 (d, J = 8.5 Hz, 2H), 7.10 (d, J = 8.0 Hz, 2H), 7.05 (d, J = 8.0 Hz, 2H), 3.98 (s,
2H), 3.88 (s, 3H), 2.31 (s, 3H); 13C{1H} NMR (125 MHz, CDCl3) 167.0, 146.8, 137.0, 135.8,
129.8, 129.2, 128.8, 128.8, 128.0, 51.9, 41.5, 21.0.
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Methyl 4-(3,4-dichlorobenzyl)benzoate 5g. Flash chromatography (silica gel, petroleum
ether:ethyl acetate = 200:1) afforded 5g (31 mg, 53%); yellow liquid. 1H NMR (400 MHz, CDCl3)
7.98 (d, J = 8.1 Hz, 2H), 7.35 (d, J = 8.2 Hz, 1H), 7.26-7.22 (m, 3H), 7.00 (dd, J = 1.2, 8.0 Hz,
1H), 3.97 (s, 2H), 3.91 (s, 3H); 13C{1H} NMR (100 MHz, CDCl3) 166.8, 145.0, 140.3, 132.5,
130.8, 130.5, 130.0, 128.9, 128.6, 128.3, 52.1, 40.9; IR (film): 1721, 1611, 1471, 1435, 1281, 1071,
1032, 907 cm-1. EI-MS (m/z, relative intensity): 296 (55), 294 (M+,77), 263 (63), 235 (63), 207
(46), 165 (100). HRMS (ESI) calcd for C15H1335Cl2O2[M+H]+ 295.02871, found 295.02894.
Methyl 4-(4-methoxybenzyl)benzoate 5h.30 Flash chromatography (silica gel, petroleum
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ether:ethyl acetate = 200:1, then 100:1) afforded 5h (30 mg, 59%); yellow liquid. H NMR (400
MHz, CDCl3) 7.95 (d, J = 8.2 Hz, 2H), 7.23 (d, J = 8.2 Hz, 2H), 7.08 (d, J = 8.6 Hz, 2H), 6.83 (d,
J = 8.6 Hz, 2H), 3.96 (s, 2H), 3.89 (s, 3H), 3.78 (s, 3H); 13C{1H} NMR (100 MHz, CDCl3) 167.0,
158.1, 147.0, 132.2, 129.9, 129.8, 128.8, 128.0, 114.0, 55.2, 52.0, 41.0.
Methyl 4-(biphenyl-4-ylmethyl)benzoate 5i. Flash chromatography (silica gel, petroleum
ether:ethyl acetate = 300:1, then 200:1) afforded 5i (38 mg, 63%); yellow solid, mp = 96-97 oC. 1H
NMR (400 MHz, CDCl3) 7.97 (d, J = 8.2 Hz, 2H), 7.56 (d, J = 7.4 Hz, 2H), 7.52 (d, J = 8.1 Hz,
2H), 7.41 (t, J = 7.6 Hz, 2H), 7.34-7.32 (m, 1H), 7.28 (d, J = 8.2 Hz, 2H), 7.23 (d, J = 8.0 Hz, 2H),
4.06 (s, 2H), 3.89 (s, 3H); 13C{1H} NMR (100 MHz, CDCl3) 167.0, 146.4, 140.8, 139.3, 139.2,
129.8, 129.3, 128.9, 128.7, 128.1, 127.3, 127.1, 127.0, 52.0, 41.5; IR (film): 1721, 1609, 1487,
1435, 1280, 1110, 909, 732 cm-1. EI-MS (m/z, relative intensity): 302 (M+, 100), 271 (16), 243 (51),
228 (10), 207 (10), 165 (46). HRMS (ESI) calcd for C21H19O2[M+H]+ 303.1380; found 303.1381.
Methyl 4-(benzo[d][1,3]dioxol-5-ylmethyl)benzoate 5j. Flash chromatography (silica gel,
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petroleum ether:ethyl acetate = 200:1) afforded 5j (30 mg, 56%); white solid, mp = 70-71 C. H
NMR (400 MHz, CDCl3) 7.95 (d, J = 8.1 Hz, 2H), 7.23 (d, J = 8.1 Hz, 2H), 6.74 (d, J = 7.6 Hz,
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