Thiyl radical-mediated cyclization of ω-alkynyl O-tert-butyldiphenylsilyloximes

Article abstract of DOI:10.1039/c7ob00279c

ω-Alkynyl O-tert-butyldiphenylsilyloximes, upon treatment with odorless 4-tert-butylbenzenethiol in the presence of azobisisobutyronitrile (AIBN) in refluxing benzene, underwent addition of a thiyl radical to the alkynyl group followed by radical cyclizat

Full text of DOI:10.1039/c7ob00279c

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Takeharu Haino et al.
Solvent-induced emission of organogels based on tris(phenylisoxazolyl)
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Thiyl radical‐mediated cyclization of ‐alkynyl O‐tert‐
butyldiphenylsilyloximes
Received 00th January 20xx,
Accepted 00th January 20xx
Nina Shibata, Takashisa Tsuchiya, Yoshimitsu Hashimoto, Nobuyoshi Morita, Shintaro Ban and
Osamu Tamura*
DOI: 10.1039/x0xx00000x
‐Alkynyl O‐tert‐butyldiphenylsilyloximes, upon treatment with odorless 4‐tert‐butylbenzenethiol in the presence of
azobisisobutyronitrile (AIBN) in refluxing benzene, underwent addition of thiyl radical to the alkynyl group followed by
radical cyclization of the corresponding vinyl radical onto the O‐silyloxime moiety to give cyclic O‐silylhydroxylamines in
good yields. The reactivity of O‐silyloximes in radical cyclization was similar to or even higher than that of O‐benzyloximes.
Facile removal of the silyl group of the cyclization products leading to hydroxylamines and nitrone formation of the
hydroxylamines were also demonstrated.
www.rsc.org/
Introduction
1a: R =H
1b: R = SO2R'
N
OR
Oxime derivatives 1, which can be classified into oximes 1a, O‐
sulfonyl oximes 1b, O‐acyl oximes 1c, O‐alkyl oximes 1d, and O‐silyl
oximes 1e, exhibit various reactivities and have been widely utilized
in organic synthesis, especially for the synthesis of heterocycles.1
Among these oximes derivatives, the reactivity of O‐silyl oximes 1e
has not been extensively investigated, except for O‐protected
oximes,2 reduction to amines,3 precursors of nitroso alkenes,4 and
hetero Diels‐Alder reaction as 1‐siloxyazadienes.5 In addition, we
have reported synthesis of cyclic nitrones6,7 and both intra‐ and
intermolecular cycloaddition of N‐boranonitrones.8 In these
reactions, however, O‐silyl oximes 1e served only as starting
materials for generation of reactive nitrone intermediates. This
prompted us to consider the reactivity of O‐silyl oximes themselves,
especially in carbon‐carbon bond formation. Taking into account
the good radical‐accepting ability of O‐alkyl oximes 1d, owing to
stabilization of the radical intermediate by the electron‐donating
oxygen atom (eq 1, A),9‐12 we anticipated that O‐silyl oximes could
also be used in radical reactions, because silyloxy groups are also
strongly electron‐donating. To our knowledge, however, there is
only one report on radical addition onto O‐silyl oximes.13 Therefore,
in order to investigate the radical‐accepting ability of O‐silyl oximes,
we focused on radical cyclization of ‐alkynyl oximes induced by
addition of thiyl radical.14‐16 We have found that the reactivity of O‐
silyl oximes in radical cyclization is equal to or even higher than that
of O‐alkyl oximes (eq 2). We also describe facile removal of silyl
1c: R = acyl
1d: R = alkyl
1e: R = SiR'3
1
N
N
N
OR'
OR'
OR'
(1)
R
R
R
A
HS
N
OTBDPS
R1
AIBN
NHOTBDPS
R1
NHOTBDPS
(2)
R1
and/or
SAr
SAr
Scheme 1
groups from the cyclization products and formation of nitrone.
1. Preparation of the starting oximes
O‐Benzyl and O‐silyl oximes 2 and 3 were prepared as depicted in
Scheme 2. O‐Benzyloximes 2 for comparison with O‐silyloxime 3
were synthesized from the corresponding aldehydes by treatment
with O‐benzylhydroxylamine hydrochloride and sodium bicarbonate
in EtOH‐H2O (Scheme 2, conditions i). O‐tert‐Butyldiphenylsilyl
oximes 3 (O‐TBDPS oximes) were also prepared from aldehydes.
Showa Pharmaceutical University, 3‐3165, Higashi‐Tamagawagakuen, Machida,
Tokyo, Japan. E‐mail: tamura@ac.shoyaku.ac.jp
Electronic Supplementary Information (ESI) available: [details of any
supplementary information available should be included here]. See
DOI: 10.1039/x0xx00000x
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Thus, on treatment of aldehydes with O‐TBDPS hydroxylamine17 in explained in terms of the thermodynamic stabilities of products 6
the presence of MgSO4 in CH2Cl2 (conditions ii), dehydration and 7. Under radical conditions, vinyl sulfides undergo further
occurred smoothly to give O‐TBDPS oximes
Information).
3
(Supporting radical addition with thiyl radical, resulting in geometrical
isomerization.23 In this case, E type products may isomerize to
thermodynamically morestable
elimination of thiyl radical C via radical F.
G type products by addition‐
O
N–Y
R2
H2N–Y
i) or ii)
R2
X
X
R1
R1
2: Y = OBn
3: Y = OTBDPS
X = CH2, O, TsN
Table 1. Thiyl radical‐induced cyclization of oximes 2 and 3 having
terminal alkyne moieties.
i) H2NOBn•HCl, NaHCO3, EtOH-H2O
ii) H2NOTBDPS, CH2Cl2, MgSO4
HS
tBu
Scheme 2
NHOR
SAr
NOR
X
(5, 2.2 equiv)
X
AIBN (4, 0.55 equiv)
benzene, reflux
2-4 h
2: R = Bn
3: R = TBDPS
6: R = Bn
2. Radical cyclization of oximes 2 and 3 with 4‐
7: R = TBDPS
tert‐butylbenzenethiol
products (yield)
entry
oxime
Our investigation of radical cyclization began with a comparison of
the reactivity of O‐benzyl oximes 2 with O‐silyl oximes 3 in thiyl
radical‐induced radical cyclization. 4‐tert‐Butylbenzenethiol (5)18
was employed as a thiyl radical precursor in place of conventional
benzenethiol (PhSH), because thiol 5 exhibits only a faint smell
compared to the offensive odor of PhSH, which makes it
undesirable for practical use in radical cyclization. To our
knowledge, this is the first report of the use of thiol 5 for radical
cyclization as an odorless alternative to PhSH. Heating O‐benzyl
oxime 2a with 2.2 equiv of 4‐tert‐butylbenzenethiol (5) in the
presence of 0.55 equiv of azobisisobutyronitrile (AIBN) (4) in
refluxing benzene induced radical reaction to afford cyclization
product 6a in 54% yield (Table 1, entry 1).19 Similar treatment of O‐
TBDPS oxime 3a under the same conditions gave O‐TBDPS
cyclization product 7a in a similar yield (55%) (entry 2). In contrast,
oxime itself (2a, R = H) did not react under similar conditions,
probably because thiyl radical abstracted oxime hydrogen to give
the stable iminoxyl radical (‐CH=N‐O•), interfering with the radical
chain process.20 A difference in reactivity was observed between 2b
and 3b as oxygen‐tethered starting materials. Radical reaction of O‐
silyl oxime 3b furnished a much higher yield of cyclization product
(81% yield of 7b) than did the reaction of O‐benzyl oxime 2b (44%
yield of 6b) (entries 3 and 4). Radical reaction of nitrogen‐tethered
O‐silyl oxime 3c afforded a good yield (63%) of cyclization product
7c as a 4:1 mixture of geometrical isomers (entry 5).21 The data in
Table 1 indicate that the reactivity of O‐silyl oximes 2 is similar to or
greater than that of the O‐benzyl counterparts 3.
NOR
NHOR
H
SAr
1
2
2a: R = Bn
3a: R = TBDPS
6a: R = Bn (54%)
7a: R = TBDPS (55%)
NOR
NHOR
O
O
SAr
6b: R = Bn (44%)
E : Z= 16:84
7b: R = TBDPS (81%)
E : Z= 11:89
3
4
2b: R = Bn
3b: R = TBDPS
NHOTBDPS
TsN
NOTBDPS
TsN
SAr
5
3c
7c (63%)
E : Z= 20:80
NHOR
X
SAr
B
We next examined radical cyclization of O‐silyl oximes 3 having an
internal alkyne moiety (Table 2). Heating oxygen‐tethered O‐benzyl
oxime 3d bearing a methyl group at the alkyne terminus with thiol 5
in the presence of AIBN (4) gave six‐membered cyclization product
8d (69%), along with a small amount of five‐membered ring product
7d (7%) (entry 1). In a similar manner, nitrogen‐tethered O‐TBDPS
oxime 3e underwent radical cyclization with thiol 5 to give
All the reactions in Table 1 resulted in exclusive formation of five‐
membered ring products 6 and 7 without any six‐membered
products B. This radical process may involve several equilibriums
(Scheme 3).16a Reversible addition of thiyl radical C to the alkyne
moiety22 provides vinyl radical D, which undergoes cyclization to
give 6 and 7. Predominance of (Z)‐geometry (X = TsN or O) of the
vinyl sulfide group in cyclization products 6 and 7 may be
2 | J. Name., 2012, 00, 1‐3
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Scheme 3
ARTICLE
Table 2. Thiyl radical‐induced cyclization of oximes 2 and 3 having
an internal alkyne moiety.
NOR
SAr
C
6 and 7
tBu
2 and 3
X
HS
NOTBDPS
SAr
C
(5, 2.2 equiv)
D
X


ArS
R1
AIBN (4, 0.55 equiv)
benzene, reflux
2-4 h
3
NHOR
SAr
NHOR
SAr
SAr
NHOTBDPS
NHOTBDPS
C
X
X
X
R1
X
R1
SAr
E
SAr
F
C
SAr
SAr
7
8
(Z): X = CH2
(E): X = O, TsN
products (yield)
NHOTBDPS
oxime
SAr
SAr
entry
C
C
NHOTBDPS
NOTBDPS
NHOR
X
X
Me
Me
SAr
X
X
Me
SAr
ArS
more stable
1
2
3d: X = O
3e: X = TsN
7d (7%)
7e (11%)
8d (69%)
8e (63%)
G
(E): X = CH2
NHOTBDPS
(Z): X = O, TsN
NOTBDPS
X
Ph
X
Ph
SAr
3
4
3f: X = O
8f (78%)
8g (73%)
8e and 7e in 63% and 11% yields, respectively (entry 2). Radical
reaction of phenyl‐substituted oxime 3f exhibited clear regio‐
selectivity and exclusively afforded six‐membered cyclization
product 8f in 78% yield (entry 3). Nitrogen‐tethered O‐silyl oxime 3g
also gave 8g as a sole product in 73% yield (entry 4). Table 2 shows
that radical cyclization of oximes 3 having substituents at the alkyne
terminus tends to afford six‐membered products.
3g: X = TsN
Figure 1
‡
‡
NOR
NOR
R'
SAr
NOR
Ph
X
Although the origin of the regio‐selectivity remains unclear, one
possibility might involve steric interaction in the transition states
(Figure 1). Transition state H derived from attack at the‐position
of 3 by thiyl radical suffers steric interaction between the oxime
group and substituent at the terminal of the alkene moiety,
whereas transition state I exhibits less steric repulsion. Thus, six‐
membered cyclization products 8 would be formed predominantly
via I. In the case of phenyl‐substituted substrates, radical
R'
SAr
H
X
X
SAr
I
J
tethers, however, afforded thiyl radical‐addition product 11j in 63%
yield in place of seven‐membered cyclic compound (entry 4).
intermediate J may be strongly stabilized by conjugation with the Conformational effects on the present cyclization were also
phenyl group, and hence the reaction would tend to occur via J
followed by I (R’ = Ph), resulting in the exclusive formation of six‐ under our usual conditions did not give cyclization product 7k at all,
examined (Table 4). Treatment of carbon‐tethered ketoxime 3k
membered products.
although the corresponding aldoxime 3a afforded a moderate yield
of cyclization product 7a (Table 4, entry 1 vs Table 1, entry 2).
Cyclization ability could be recovered by utilizing conformational
effects. Thus, tosylamide‐tethered ketoxime 3l underwent thiyl
radical addition followed by cyclization to furnish 7l in 56% yield
(entry 2). The tosylamide tether was also effective for phenyl
ketoxime 3m, giving rise to 7m in 57% yield. Gem‐disubstitution
effect (Thope‐Ingold effect)24 was found to improve the yield of
cyclization product (entries 4 and 5). Malonate‐derived aldoxime 3n
afforded the cyclized product in 73% yield, whereas the straight‐
chain aldoxime 3a gave only a moderate yield of cyclization product
We next examined radical cyclization of homologated substrates
(Table 3). O‐Benzyl oxime 2h, on treatment with thiol 5 in the
presence of AIBN (4) in refluxing benzene, underwent radical
addition of thiyl radical followed by cyclization to give 9h in 59%
yield (entry 1). Reaction of O‐silyl counterpart 3h under the same
conditions afforded cyclization product 10h in a slightly better yield
(62%) (entry 2). Radical reaction of nitrogen‐tethered O‐TBDPS
oxime 3i furnished six‐membered cyclization product 10i in a
moderate yield (49%) (entry 3). Oxime 3j having further elongated
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Table 3. Thiyl radical‐induced cyclization of homologated oximes 2
and 3.
Table 4. Conformational effect in thiyl radical‐induced cyclization of
O‐silyl oximes 3.
HS
tBu
NOTBDPS
HS
tBu
(5,2.2 equiv)
NOR
NHOR
)
X
R
(5,2.2 equiv)
R1
AIBN (4, 0.55 equiv)
benzene, reflux
2-4 h
X
X
AIBN (4, 0.55 equiv)
benzene, reflux
2-4 h
(
(
)
SAr
n
3
n
NHOTBDPS
NHOTBDPS
2: R = Bn
3: R = TBDPS
n = 1, 2
9: R = Bn
10: R = TBDPS
R
R
X
R1
R1
X
SAr
or
entry
oxime
NOR
SAr
product (yield)
NHOR
7
8
entry
oxime
product
O
O
SAr
NHOTBDPS
Me
NOTBDPS
Me
1
2
2h: R = Bn
3h: R = TBDPS
9h (59%)
10h (62%)
X
X
NOTBDPS
NHOTBDPS
SAr
SAr
3k: X = CH2
3l: X = TsN
7k: X = CH2 (0%)
7l: X = TsN (56%)
1
2
TsN
3
4
TsN
3i
10i (49%)
NHOTBDPS
Ph
NOTBDPS
Ph
NOTBDPS
SAr
NOTBDPS
TsN
3
4
TsN
O
O
SAr
7m (57%)
3m
3j
11j (63%)
NHOTBDPS
NOTBDPS
MeO2C
MeO2C
MeO2C
MeO2C
SAr
7n (73%, E: Z = 90:10)
3n
7a (Table 4, entry 4 vs Table 1, entry 2). The yield of cyclization
product 8o from gem‐dimethylated substrate 3o reached 91%
(Table 4, entry 5 vs Table 2, entry 3).
Me
Me
O
NHOTBDPS
Me
NOTBDPS
Ph
Me
Ph
5
O
SAr
3o
8o (91%)
3. Radical cyclization of related substrates
Another kind of radical, such as tin radical, can be used in place of
thiyl radical for radical cyclization.25 Thus, on treatment with
Bu3SnH in the presence of AIBN in refluxing benzene, oxime 3g
having a phenyl group at the alkyne‐terminus underwent addition
of tributyltin radical followed by radical cyclization of the resulting
vinyl radical onto silyl oxime, giving rise to yield six‐membered
product 12 bearing a vinyl stannyl group in 49%. Since vinyl stannyl
compounds are known to be good substrates for Stille coupling, this
reaction would be useful in organic synthesis. The present thiyl
radical‐induced cyclization can be applied to ‐alkenyl O‐silyl oxime
13. When oxime 13 was exposed to thiol 5 in the presence of AIBN
in refluxing benzene for 3 h, cis‐cyclized product cis‐14 and trans‐
product trans‐14 were obtained in 31% and 35% yields, respectively
(Scheme 4).
Scheme 4
NOTBDPS
NHOTBDPS
Bu3SnH
(2.2 equiv)
TsN
TsN
Ph
AIBN
(4, 0.55 equiv)
benzene
Ph
SnBu3
12 (49%)
3g
reflux, 3 h
HS
tBu
NOTBDPS
(5,2.2 equiv)
TsN
AIBN (4, 0.55 equiv)
benzene, reflux, 3 h
13
NHOTBDPS
NHOTBDPS
SAr
TsN
TsN
31%
35%
trans-14
SAr
cis-14
4 | J. Name., 2012, 00, 1‐3
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4. Desilylation of the products
Experimental
Facile cleavage of the oxygen‐silicon bond is a characteristic Melting points were determined with a Yanagimoto micro melting
reaction of O‐silyl compounds, whereas the corresponding cleavage point apparatus and are uncorrected. Infrared spectra (IR) were
is unavailable with O‐alkyl compounds. Thus, desilylation of the recorded with a Shimadzu FTIR–8200A. 1H NMR and 13C NMR
cyclized products 7a, 8d and 10h was next examined (Scheme 5). spectra spectra were recorded on a JEOL JNM–AL300 (300 MHz)
When O‐TBDPS hydroxylamine 7a was treated with TBAF‐AcOH spectrometer. Measurements of mass spectra (MS) and high‐
(1:4) in THF at
0 °C, clean desilylation occurred to give resolution MS (HRMS) were performed with a JEOL JMS‐HX110
hydroxylamine 15a in 74% yield. Compounds 8d and 10h were also mass spectrometer or a JEOL JMS‐T100LP. Column chromatography
exposed to TBAF‐AcOH to afford hydroxylamines 15d and 15h in was carried out on silica gel (Silica Gel 60 N, Kanto Chemical Co.,
80% and 81% yields, respectively. Since alkyl hydroxylamines are Inc. or Silica Gel BW‐127ZH, Fuji Silysia Chemical, ltd). Merck
representative precursors for nitrones, which are very useful 1,3‐ precoated thin layer chromatography (TLC) plates (silica gel 60
dipolar compounds, nitrone formation was demonstrated by using F254, 0.25 mm, Art 5715) were used for the TLC analysis.
hydroxylamine 15a. Thus, hydroxylamine 15a was condensed with
General procedure: To a boiling solution of an oxime 2 or 3 (1
equiv) in benzene (40 mL/ 1 mmol of an oxime) was added
dropwise a solution of 5 (2.2 equiv) and AIBN (0.55 equiv) in
benzene (5 mL/1 mmol of 5) via syringe‐pump over 2‐4 hrs. The
mixture was concentrated under reduced pressure, and the residue
was chromatographed on silica gel to afford product(s).
benzaldehyde in the presence of MgSO4 in (CH2Cl)2 to afford nitrone
16 in 88% yield.
Scheme 5
NHOR
Me
NHOR
SAr
(E)‐O‐Benzyl‐N‐{2‐[(4‐tert‐
O
butylphenylthio)methylene]cyclopentyl}hydroxylamine (6a) (Table
1, entry 1). Following General Procedure, 6a (35.0 mg, 54%) was
obtained from 2a (35.6 mg, 0.177 mol), 5 (67.1 L, 0.389 mmol),
SAr
7a: R = TBDPS
8d: R = TBDPS
a
a
and
4 (16.0 mg, 97.0 mol) after purification by column
15a: R = H (74%)
15d: R = H (80%)
chromatography on silica gel (hexane‐AcOEt, 10/1). IR (KBr) 3030,
2963, 2868 cm‐1; H‐NMR (300 MHz, DMSO)  1.25 (s, 9H), 1.53‐
NHOR
1
1.67 (m, 2H), 1.75‐1.83 (m, 2H), 2.15‐2.26 (m, 2H), 3.79‐3.89 (m,
1H), 6.34‐6.36 (m, 1H), 6.65 (d, J = 5.9 Hz, 1H), 7.21‐7.33 (m, 9H);
13C‐NMR (75 MHz, DMSO)  22.6, 30.0, 30.8, 31.0, 34.1, 64.4, 75.5,
116.0, 126.0, 127.4, 127.9, 128.1, 132.3, 138.3, 144.8, 148.8 (one
signal overlapped); HRMS (EI) m/z calcd for C23H29NOS 367.1970,
found 367.1955.
O
SAr
10h: R = TBDPS
15h: R = H (81%)
a
O–
N+ Ph
b
15a
(E)‐N‐{2‐[(4‐tert‐Butylphenylthio)methylene]cyclopentyl}‐O‐(tert‐
butyldiphenylsilyl)hydroxylamine (7a) (Table 1, entry 2). Following
General Procedure, 7a (45.5 mg, 55%) was obtained from 2a (60.9
mg, 0.174 mol), 5 (66.1 L, 0.383 mmol), and 4 (14.9 mg, 90.5 mol)
after purification by column chromatography on silica gel (hexane‐
SAr 16
Conditions: a) TBAF, AcOH, THF, 0 °C; b) PhCHO,
MgSO4, (CH2Cl)2, r.t., 88%
1
AcOEt, 25/1). IR (KBr) 3072, 2963, 2858 cm‐1; H‐NMR (300 MHz,
Conclusions
CDCl3)  1.09 (s, 9H), 1.31 (s, 9H), 1.62‐2.23 (m, 6H), 3.80 (s, 1H),
4.98 (d, J = 7.0 Hz, 1H), 6.29 (s, 1H), 7.20‐7.70 (m, 14H); 13C‐NMR
(75 MHz, CDCl3)  19.2, 23.0, 27.1, 27.4, 30.2, 31.3, 31.4, 34.4, 67.0,
118.4, 126.0, 127.4, 127.5, 128.6, 129.5, 132.9, 134.0, 135.5, 135.8,
135.9, 144.0, 149.3; HRMS (EI) m/z calcd for C32H41NOSSi 515.2678,
found 515.2687.
We have demonstrated good radical‐accepting ability of O‐
silyloximes by utilizing them for odorless thiol‐derived thiyl radical‐
induced cyclization of ‐alkynyl O‐tert‐butyldiphenyloximes.
Removal of silyl groups from the cyclization products was readily
accomplished to give hydroxylamines. We also showed that one of
the hydroxylamines was readily converted to a nitrone. Synthetic
applications of the present cyclization and other radical reactions of
O‐silyloximes are under investigation.
O‐Benzyl‐N‐{4‐[(4‐tert‐
butylphenylthio)methylene]tetrahydrofuran‐3‐yl}hydroxylamine
(6b) (Table 1, entry 3). Following General Procedure, 6b (28.0 mg,
44%, E/Z = 16/84) was obtained from 2b (33.7 mg, 0.166 mol), 5
(63.0 L, 0.365 mmol), and 4 (14.9 mg, 90.5 mol) after purification
by column chromatography on silica gel (hexane‐AcOEt, 5/1). IR
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(KBr) 3030, 2962, 2866, 1716 cm‐1; 1H‐NMR (300 MHz, CDCl3) 1.24
(s, 9H), 3.78‐3.83 (m, 1H), 3.90‐3.95 (m, 1H), 4.01‐4.07(m, 1H), 4.18‐
4.25 (m, 1H), 4.35‐4.42 (m, 1H), 4.67 (s, 2H x 0.16), 4.71 (br s, 2H x
0.84), 6.19‐6.21 (m, 1H x 0.16), 6.33‐6.35 (m, 1H x 0.84), 7.19‐7.27
(m, 9H); 13C‐NMR (75 MHz, CDCl3)  31.0, 34.3, 64.1, 69.5, 71.9,
76.3, 119.0, 126.0, 127.7, 128.21, 128.28, 128.3, 129.2, 137.3,
138.6, 150.1 (several signals overlapped); HRMS (FAB) m/z calcd for
C21H26NO2Si [M+H]+ 370.1762, found 370.1782.
0.365 mmol), and 4 (14.9 mg, 91.3 μmol) after purification by
column chromatography on silica gel (hexane‐AcOEt, 10/1).
7d: IR (KBr) 3072, 2962, 2858 cm‐1; 1H‐NMR (300 MHz, CDCl3)  1.08
(s, 9H), 1.29 (s, 9H), 1.56 (s, 3H), 3.66 (dd, J = 9.9 and 3.9 Hz, 1H),
3.90 (br, 1H), 4.21 (dd, J = 14.1 and 2.1 Hz, 1H), 4.44‐4.55 (m, 2H),
5.15 (br, 1H), 7.13‐7.70 (m, 14H); 13C‐NMR (75 MHz, CDCl3)  19.1,
20.3, 27.3, 31.2, 34.5, 64.7, 70.8, 71.1, 125.9, 127.4, 127.5, 129.4,
129.5, 131.3, 133.9, 135.70, 135.73, 150.4 (several signals
overlapped); HRMS (EI) m/z calcd for C32H42NO2SSi531.2627, found
531.2608
N‐{4‐[(4‐tert‐Butylphenylthio)methylene]tetrahydrofuran‐3‐yl}‐O‐
(tert‐butyldiphenylsilyl)hydroxylamine (7b). (Table 1, entry 4).
Following General Procedure, 7b (67.0 mg, 81%, E/Z = 11/89) was
obtained from 2b (57.5 mg, 0.159 mol), 5 (60.4 L, 0.350 mmol),
8d: IR (KBr) 3072, 2961, 2856 cm‐1; 1H‐NMR (300 MHz, CDCl3)  1.10
(s, 9H), 12.8 (s, 9H), 1.65 (s, 3H), 3.06 (d, J = 9.3 Hz, 1H), 3.39 (dd, J =
11.4 and 2.1 Hz, 1H), 3.91 (s, 1H), 4.50 (d, J = 11.4 Hz, 1H), 5.49 (d, J
= 10.2 Hz, 1H), 7.09‐7.76 (m, 14H); 13C‐NMR (75 MHz, CDCl3)  18.7,
19.2, 27.4, 31.2, 34.4, 61.0, 64.2, 68.7, 126.1, 127.4, 127.5, 128.5,
129.46, 129.49, 129.6, 130.1, 133.9, 135.2, 135.4, 135.7, 135.9,
149.8; HRMS (FAB) m/z calcd for C32H40NO2SSi [M+H]+ 532.2706,
found 532.2656
and
4 (13.0 mg, 79.5 mol) after purification by column
chromatography on silica gel (hexane‐AcOEt, 25/1). All data were
described without distinction of the two diastereomers. IR (KBr)
1
3072, 2961, 2932, 2856 cm‐1; H‐NMR (300 MHz, CDCl3)  1.10 (s,
9H x 0.89), 1.12 (s, 9H x 0.11), 1.30 (s, 9H x 0.11), 1.31 (s, 9H x 0.89),
3.73‐3.81 (m, 1H + 2H x 0.89), 4.05‐4.40 (m, 2H x 0.11 + 2H x 0.89 +
2H x 0.11), 5.17 (br, 1H x 0.89), 5.48 (br, 1H x 0.11), 6.24 (s, 1H x
0.11), 6.29 (s, 1H x 0.89), 7.21‐7.41 (m, 14H); 13C‐NMR (75 MHz,
CDCl3)  19.0, 19.2, 26.6, 27.4, 29.7, 31.3, 34.5, 64.5, 65.8, 69.7,
71.2, 71.4, 71.6, 119.2, 119.4, 126.1, 127.5, 127.7, 129.1, 129.2,
129.6, 131.8, 133.7, 135.7, 135.9, 138.5, 150.1; HRMS (FAB) m/z
calcd for C31H39NO2SSi [M+H]+ 517.2471, found 517.2567.
N‐{4‐[(E)‐1‐(4‐tert‐Buthylphenylthio)ethylidene]‐1‐tosylpyrrolidin‐
3‐yl}‐O‐(tert‐buthyldiphenylsilyl)hydroxylamine (7e) and
N‐[5‐(4‐tert‐Butylphenylthio)‐4‐methyl‐1‐tosyl‐1,2,3,6‐
tetrahydropyridin‐3‐yl]‐O‐(tert‐butyldiphenylsilyl)hydroxylamine
(8e) (Table 2, entry 2).
N‐{4‐[(4‐tert‐Butylphenylthio)methylene]‐1‐tosylpyrrolidin‐3‐yl}‐
O‐(tert‐butyldiphenylsilyl)hydroxylamine (7c) (Table 1, entry 5).
Following General Procedure, 7c (70.3 mg, 63%, E/Z = 20/80) was
obtained from 3c (84.4 mg, 0.167 mol), 5 (63.5 L, 0.368 mmol),
and 4 (46.6 mg, 0.284 mmol) after purification by column
chromatography on silica gel (hexane‐CH2Cl2, 1/2 then hexane‐
Following General Procedure, 7e (12.7 mg, 11%) and 8e (70.4 mg,
63%) were obtained from 3e (84.5 mg, 0.163 mmol), 5 (61.8 μL,
0.358 mmol), and 4 (14.7 mg, 89.5 μmol) after purification by
column chromatography on silica gel (hexane‐CH2Cl2, 1/2 then
hexane‐AcOEt, 5/1).
1
AcOEt, 25/1). IR (KBr) 2963, 2858, 2349 cm‐1; H‐NMR (300 MHz,
CDCl3) 1.04 (s, 9H x 0.2), 1.06 (s, 9H x 0.8), 1.29 (s, 9H x 0.2), 1.31
(s, 9H x 0.8), 2.41 (s, 3H x 0.2), 2.43 (s, 3H x 0.8), 3.12‐3.28 (m, 1H x
0.8, 1H x 0.2), 3.56‐3.88 (m, 1H x 0.8 x 3, 1H x 0.2 x 3, 1H x 0.8), 4.16
(br, 1H x 0.2), 5.00 (d, J = 10.9 Hz, 1H x 0.8), 5.33 (d, J = 8.1 Hz, 1H x
0.2), 6.12 (s, 1H x 0.8), 6.29 (s, 1H x 0.2), 7.13‐7.72 (m, 18H); 13C‐
NMR (75 MHz, CDCl3) 19.1, 21.5, 27.2, 27.3, 31.2, 34.5, 50.2, 50.9,
51.5, 52.4, 63.1, 64.5, 122.4, 122.7, 126.1, 126.2, 127.5, 127.6,
127.7, 127.9, 129.3, 129.6, 129.7, 131.1, 131.7, 132.2, 133.2, 133.4,
133.5, 134.9, 135.4, 135.7, 135.9, 143.7, 143.8, 150.3, 150.4; HRMS
(EI) m/z calcd for C38H46N2O3S2Si 670.2719, found 670.2711.
1
7e: IR (KBr) 2961, 2858 cm‐1; H‐NMR (300 MHz, CDCl3)  1.07 (s,
9H), 1.29 (s, 9H, 3H), 2.44 (s, 3H), 2.90 (dd, J = 5.1 and 10.3 Hz, 1H),
3.58 (d, J = 14.7 Hz, 1H), 3.80 (br, 1H), 4.05 (d, J = 14.7 Hz, 1H), 4.22
(d, J = 10.3 Hz, 1H), 4.96 (br, 1H), 7.08‐7.77 (m, 18H); 13C‐NMR (75
MHz, CDCl3)  19.2, 19.4, 21.6, 27.0, 27.3, 31.2, 50.9, 51.4, 63.4,
126.0, 127.5, 127.6, 127.7, 128.1, 128.6, 129.6, 129.7, 131.8, 132.1,
133.4, 134.8, 135.5, 135.7, 135.8, 143.7 (several signals
overlapped); HRMS (EI) m/z calcd for C39H48N2O3S2Si 684.2876,
found 684.2875.
N‐{4‐[1‐(4‐tert‐Butylphenylthio)ethylidene]tetrahydrofuran‐3‐yl}‐
O‐(tert‐butyldiphenylsilyl)hydroxylamine (7d) and
1
8e: IR (KBr) 2961, 2856, cm‐1; H‐NMR (300 MHz, CDCl3)  1.12 (s,
9H), 1.29 (s, 9H), 1.60 (s, 3H), 2.39 (s, 3H), 2.41 (d, J = 11.0 Hz, 1H),
3.10 (d, J = 16.1 Hz, 1H), 3.25 (d, J = 9.5 Hz, 1H), 3.86 (d, J = 16.1 Hz,
1H), 4.39 (d, J = 11.7 Hz, 1H), 5.35 (d, J = 10.6 Hz, 1H), 7.03‐7.77 (m,
18H); 13C‐NMR (75 MHz, CDCl3)  18.9, 19.2, 21.5, 27.3, 31.2, 34.5,
43.5, 48.9, 61.9, 126.0, 126.2, 127.4, 127.6, 127.7, 129.4, 129.6,
133.5, 133.6, 133.7, 135.7, 135.9, 136.0, 143.7, 150.0; HRMS (EI)
m/z calcd for C39H48N2O3S2Si 684.2876, found 684.2890.
N‐[5‐(4‐tert‐Butylphenylthio)‐4‐methyl‐3,6‐dihydro‐2H‐pyran‐3‐
yl]‐O‐(tert‐butyldiphenylsilyl)hydroxylamine (8d) (Table 2, entry
1).
Following General Procedure, 7d (6.3 mg, 7%) and 8d (61.0 mg,
69%) were obtained from 3d (60.7 mg, 0.166 mmol), 5 (63.0 μL,
6 | J. Name., 2012, 00, 1‐3
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DOI: 10.1039/C7OB00279C
ARTICLE
N‐[5‐(4‐tert‐Butylphenylthio)‐4‐phenyl‐3,6‐dihydro‐2H‐pyran‐3‐yl]‐
O‐(tert‐butyldiphenylsilyl)hydroxylamine (8f) (Table 2, entry 3).
(14.9 mg, 91.3 μmol) after purification by column chromatography
on silica gel (hexane‐AcOEt, 15/1). IR (KBr) 3072, 2962, 2856 cm‐1;
1H‐NMR (300 MHz, CDCl3) 1.10 (s, 9H), 1.31 (s, 9H), 2.31‐2.41 (m,
1H), 2.48‐2.54 (m, 1H), 3.41 (td, J = 10.8 and 3.3 Hz, 1H), 3.50 (dd, J
= 12.0 and 3.0 Hz, 1H), 3.86‐3.93 (m, 1H), 3.97‐4.01 (m, 1H), 5.60
(br, 1H), 5.98 (s, 1H), 7.22‐7.72 (m, 14H); 13C‐NMR (75 MHz, CDCl3) 
19.2, 27.1, 27.4, 27.9, 31.3, 34.4, 64.1, 68.1, 69.3, 120.8, 126.0,
127.5, 127.7, 128.8, 129.5, 132.4, 133.8, 135.3, 135.8, 135.9, 136.1,
149.5; HRMS (FAB) m/z calcd for C32H42NO2SSi [M+H]+ 532.2706,
found 532.2711.
Following General Procedure, 8f (76.9 mg, 78%) was obtained
from 3f (70.9 mg, 0.166 mmol), 5 (63.0 μL, 0.365 mmol), and 4 (14.9
mg, 91.3 μmol) after purification by column chromatography on
1
silica gel (hexane‐AcOEt, 20/1). IR (KBr) 2962, 2856 cm‐1; H‐NMR
(300 MHz, CDCl3)  1.00 (s, 9H), 1.29 (s, 9H), 3.57‐3.64 (m, 2H), 4.01
(dd, J = 16.2 and 1.8 Hz, 1H) 4.11 (d, J = 16.5 Hz, 1H), 4.56 (d, J = 9.6
Hz, 1H), 5.50 (br, 1H), 7.16‐7.58 (m, 19H); 13C‐NMR (75 MHz, CDCl3)
 19.1, 27.2, 31.1, 34.4, 60.9, 64.8, 68.5, 126.0, 127.2, 127.27,
127.33, 127.7, 127.8, 128.5, 129.3, 131.0, 132.3, 133.6, 133.7,
135.3, 135.55, 135.61, 136.9, 138.8, 150.4; HRMS (FAB) m/z calcd
for C37H44NO2SSi [M+H]+ 594.2862, found.594.2876
N‐{4‐[(E)‐(4‐tert‐Butylphenylthio)methylene]‐1‐tosylpiperidin‐3‐
yl}‐O‐(tert‐butyldiphenylsilyl)hydroxylamine (10i) (Table 3, entry
3).
Following General Procedure, 10i (59.7 mg, 49%) was obtained
from 3i (92.3 mg, 0.178 mmol), 5 (67.5 μL, 0.391 mmol), and 4 (16.1
N‐[5‐(4‐tert‐Butylphenylthio)‐4‐phenyl‐1‐tosyl‐1,2,3,6‐
tetrahydropyridin‐3‐yl]‐O‐(tert‐butyldiphenylsilyl)hydroxylamine
(8g) (Table 2, entry 4).
mg, 97.9 μmol) after purification by column chromatography on
silica gel (hexane‐AcOEt, 5/1). IR (KBr) 2963, 2858 cm‐1; 1H‐NMR
(300 MHz, CDCl3)1.10 (s, 9H), 1.30 (s, 9H), 2.25‐2.36 (m, 1H), 2.40
(s, 3H), 2.47‐2.55 (m, 2H) 2.66 (dd, J = 8.4 and 3.3 Hz, 1H), 3.27 (d, J
= 10.3 Hz, 1H), 3.49‐3.53 (m, 1H), 3.69 (d, J = 11.0 Hz, 1H), 5.51 (d, J
= 10.6 Hz, 1H), 5.86 (s, 1H), 7.14‐7.71 (m, 18H); 13C‐NMR (75 MHz,
CDCl3)  19.2, 21.5, 26.5, 27.4, 31.2, 34.5, 46.2, 48.4, 62.9, 122.6,
126.0, 127.5, 127.7, 129.1, 129.6, 129.7, 131.8, 133.3, 133.7, 133.9,
135.8, 135.9, 143.6, 149.9 (several signals overlapped); HRMS (EI)
m/z calcd for C39H48N2O3S2Si 684.2876 found 684.2891.
Following General Procedure, 8g (87.2 mg, 73%) was obtained
from 3g (92.5 mg, 0.159 mmol), 5 (60.4 L, 0.350 mmol), and 4
(14.4 mg, 87.5 mol) after purification by column chromatography
on silica gel (hexane‐AcOEt, 6/1). IR (KBr) 2963, 2858 cm‐1; 1H‐NMR
(300 MHz, CDCl3)  0.98 (s, 9H), 1.31 (s, 9H), 2.42 (s, 3H), 2.69 (d, J =
11.7 Hz, 1H), 3.23 (d, J = 16.5 Hz, 1H), 3.77 (d, J = 9.9 Hz, 1H), 3.89
(d, J = 16.5 Hz, 1H), 4.32 (d, J = 11.7 Hz, 1H), 5.40 (d, J = 10.3 Hz, 1H),
7.01‐7.61 (m, 23H); 13C‐NMR (75 MHz, CDCl3)  19.2, 21.5, 27.2,
31.2, 34.6, 44.1, 48.8, 62.0, 126.2, 127.4, 127.5, 127.8, 127.9, 128.6,
128.8, 129.4, 129.7, 129.9, 131.3, 133.3, 133.5, 133.6, 135.6, 135.7,
137.7, 138.8, 143.8, 150.9 (several signals overlapped); HRMS (EI)
m/z calcd for C44H50N2O3S2Si 746.3032, found 746.3101.
2‐[5‐(4‐tert‐Butylphenylthio)pentyloxy]acetaldehyde
O‐(tert‐
butyldiphenylsilyl)oxime (11j) (Table 3, entry 4).
Following General Procedure, 11j (58.6 mg, 63%, E/Z = 1:1) was
obtained from 3j (63.0 mg, 0.166 mmol), 5 (63.0 μL, 0.365 mmol),
O‐Benzyl‐N‐{4‐[(E)‐(4‐tert‐butylphenylthio)methylene]tetrahydro‐
2H‐pyran‐3‐yl}hydroxylamine (9h) (Table 3, entry 1).
and
4 (14.9 mg, 91.3 μ mol) after purification by column
Following General Procedure, 9h (40.3 mg, 59%) was obtained
from 2h (36.1 mg, 0.166 mmol), 5 (63.0 μL, 0.365 mmol), and 4
chromatography on silica gel (hexane‐AcOEt, 20/1). All data were
described without distinction of the diastereomers.
(14.9 mg, 91.3 μmol) after purification by column chromatography
IR (KBr) 3072, 2960, 2858 cm‐1; 1H‐NMR (300 MHz, CDCl3) 1.10 (s,
9H) 1.30 (s, 9H), 1.64‐1.74 (m, 2H), 2.15‐2.33 (m, 2H), 3.37‐3.57 (m,
2H), 4.06‐4.09 (m, 1H), 4.50‐4.53 (m, 1H), 5.68‐5.80 (m, 1H x 0.5),
5.84‐5.97, (m, 1H x 0.5), 6.10‐6.23 (m, 1H), 7.13‐7.16 (m, 1H x 0.5),
7.66‐7.69 (m, 1H x 0.5), 7.25‐7.41 (m, 14H); 13C‐NMR (75 MHz,
CDCl3) 19.2, 25.7, 27.0, 28.9, 29.5, 31.3, 67.4, 69.7, 122.5, 124.4,
126.0, 127.6, 129.0, 129.6, 131.2, 133.3, 134.7, 135.5, 153.3
(several signals overlapped); HRMS (FAB) m/z calcd for C33H44NO2SSi
[M+H]+ 546.2862, found 546.2812.
on silica gel (hexane‐AcOEt, 10/1). IR (KBr) 2962, 2904 cm‐1; 1H‐
NMR (300 MHz, CDCl3) 1.30 (s, 9H), 2.52‐2.55 (m, 2H), 3.44‐3.53
(m, 3H), 3.63 (dd, J = 11.7 and 3.0 Hz, 1H), 3.90‐3.98 (m, 2H), 4.70
(d, J = 11.4 Hz, 1H), 4.76 (d, J = 11.4 Hz, 1H), 5.50‐5.90 (very br, 1H),
6.19 (s, 1H), 7.23‐7.65 (m, 9H); 13C‐NMR (75 MHz, CDCl3)  28.1,
31.2, 34.5, 62.8, 68.1, 69.8, 76.5 120.8, 126.1, 127.8, 128.3, 128.5,
129.0, 132.3, 136.2, 137.6, 149.7; HRMS (FAB) m/z calcd for
C23H30NO2S [M+H]+ 384.1997, found 384.1968.
N‐{4‐[(E)‐(4‐tert‐Butylphenylthio)methylene]tetrahydro‐2H‐pyran‐
3‐yl}‐O‐(tert‐butyldiphenylsilyl)hydroxylamine (10h) (Table 3,
entry 2).
N‐{4‐[(E)‐(4‐tert‐Butylphenylthio)methylene]‐3‐methyl‐1‐
tosylpyrrolidin‐3‐yl}‐O‐(tert‐butyldiphenylsilyl)hydroxylamine (7l)
(Table 4, entry 2).
Following General Procedure, 10h (56.4 mg, 62%) was obtained
from 3h (60.7 mg, 0.166 mmol), 5 (63.0 μL, 0.365 mmol), and 4
Following General Procedure, 7l (66.8 mg, 56%) was obtained
from 3l (92.2 mg, 0.178 mmol), 5 (67.4 μL, 0.391 mmol), and 4 (16.0
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J. Name., 2013, 00, 1‐3 | 7
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ARTICLE
Journal Name
N‐[5‐(4‐tert‐Butylphenylthio)‐2,2‐dimethyl‐4‐phenyl‐3,6‐dihydro‐
mg, 97.7 μmol) after purification by column chromatography on
2H‐pyran‐3‐yl]‐O‐(tert‐butyldiphenylsilyl)hydroxylamine
(8o)
silica gel (hexane‐CH2Cl2, 1/5, 1/3 then hexane‐AcOEt, 8/1).
(Table 4, entry 5).
IR (KBr) 3072, 2963, 2932, 2858 cm‐1; H‐NMR (300 MHz, CDCl3)
1
Following General Procedure, 8o (93.5 mg, 91%) was obtained
from 3o (75.6 mg, 0.166 mmol), 5 (63.0 μL, 0.365 mmol), and 4
1.05‐1.08 (m, 12H), 1.29 (s, 9H), 2.42 (s, 3H), 2.86 (d, J = 9.7 Hz, 1H),
3.65 (d, J = 9.7 Hz, 1H), 3.74 (dd, J = 12.6 and 2.0 Hz, 1H), 3.86 (dd, J
= 12.6 and 2.0 Hz, 1H), 5.06 (br s, 1H), 6.11 (br s, 1H), 7.15‐7.78 (m,
18H); 13C‐NMR (75 MHz, CDCl3)  19.2, 21.4, 21.5, 27.1, 27.2, 31.2,
34.5, 50.9, 56.4, 67.6, 120.1, 126.2, 127.5, 128.0, 129.3, 129.7,
131.4, 133.1, 133.3, 135.4, 135.8, 136.1, 138.6, 143.7, 150.3
(several signals overlapped); HRMS (EI) m/z calcd for C39H48N2O3S2Si
684.2876, found 684.2859.
(14.9 mg, 91.3 μmol) after purification by column chromatography
on silica gel (hexane‐AcOEt, 20/1).
IR (neat) 2962, 2858 cm‐1; 1H‐NMR (300 MHz, CDCl3)  0.92 (s, 9H),
1.27‐1.28 (m, 12H), 1.54 (s, 3H), 3.53 (d, J = 6.6 Hz, 1H), 3.96 (dd, J =
17.4 and 1.5 Hz, 1H), 4.07 (d, J = 17.4 Hz, 1H), 5.46 (br, 1H), 7.15‐
7.48 (m, 14H); 13C‐NMR (75 MHz, CDCl3) 18.6, 24.0, 25.4, 27.2,
31.20, 31.24, 34.5, 64.4, 67.9, 73.8, 126.0, 127.0, 127.3, 127.4,
127.8, 128.7, 129.1, 129.3, 129.4, 129.8, 130.8, 133.6, 133.7,
135.75, 135.84,139.6, 140.2, 150.3 (several signals overlapped);
HRMS (ESI) m/z calcd for C39H48NO2SSi 622.3175 [M+H]+, found
622.3166
N‐{4‐[(E)‐(4‐tert‐Butylphenylthio)methylene]‐3‐phenyl‐1‐
tosylpyrrolidin‐3‐yl}‐O‐(tert‐butyldiphenylsilyl)hydroxylamine
(7m) (Table 4, entry 3).
Following General Procedure, 7m (68.7 mg, 57%) was obtained
from 3m (93.2 mg, 0.160 mmol), 5 (60.9 μL, 0.353 mmol), and 4
O‐(tert‐Butyldiphenylsilyl)‐N‐{4‐phenyl‐1‐tosyl‐5‐(tributylstannyl)‐
1,2,3,6‐tetrahydropyridin‐3‐yl}hydroxylamine (12) (Scheme 4).
(14.5 mg, 88.3 μmol) after purification by column chromatography
on silica gel (hexane‐CH2Cl2, 1/5).
To a boiling solution of an oxime 3g (96.5 mg, 0.166 mmol) in
benzene (6.3 mL) was added dropwise a solution of Bu3SnH (95.8
1
IR (KBr) 2963, 2858 cm‐1; H‐NMR (300 MHz, CDCl3)  0.97 (s, 9H),
1.26 (s, 9H), 2.40 (s, 3H), 3.43 (d, J = 9.9 Hz, 1H), 3.62 (d, J = 9.9 Hz,
1H), 3.88 (d, J = 14.6 Hz, 1H), 4.04 (d, J = 14.6 Hz, 1H), 5.34 (s, 1H),
6.05 (s, 1H), 7.11‐7.65 (m, 23H); 13C‐NMR (75 MHz, CDCl3) 19.0,
21.4, 21.5, 27.1, 31.2, 34.4, 51.3, 56.7, 73.9, 121.4, 126.1, 127.2,
127.6, 127.8, 127.9, 128.2, 129.2, 129.7, 129.8, 129.9, 131.5, 132.6,
132.9, 135.8, 136.0, 137.8, 140.0, 143.6, 150.1. One signal was
orverlapped.; HRMS (EI) m/z calcd for C44H50N2O3S2Si 746.3032,
found 746.3033.
mL, 0.365 mmol) and AIBN (15.0 mg, 91.3μmol) in benzene (2.0 mL)
via syringe‐pump over 2 hrs and the resulting mixture was heated at
reflux further for 3 hrs. The mixture was concentrated under
reduced pressure, and the residue was chromatographed on silica
gel (K2CO3 10 w/w%, hexane‐AcOEt, 5/1) to afford 12 (71.6 mg,
49%) as a colorless oil.
1
IR (KBr) 2957, 2928, 2855 cm‐1; H‐NMR (300 MHz, CDCl3)  0.44‐
0.60 (m, 6H), 0.770‐0.87 (m, 9H), 0.96 (s, 9H), 1.01‐1.26 (m, 12H),
2.42 (s, 3H), 2.56 (d, J = 9.2 Hz, 1H), 3.35 (d, J = 16.8 Hz, 1H), 3.70 (d,
J = 10.6 Hz, 1H), 4.10 (d, J = 16.8 Hz, 1H), 4.42 (d, J = 10.6 Hz, 1H),
5.44 (d, J = 11.0 Hz, 1H), 6.88 (br d, J = 6.6 Hz, 2H), 7.10‐7.60 (m,
15H), 7.75 (d, J = 8.1 Hz, 2H); 13C‐NMR (75 MHz, CDCl3)  10.3, 13.5,
19.1, 21.5, 27.2, 28.9, 43.9, 51.1, 62.1, 127.1, 127.3, 127.4, 127.8,
127.9, 128.4, 129.2, 129.3, 129.6, 129.7, 133.5, 133.8, 133.9, 135.6,
135.7, 140.2, 143.6, 143.9, 147.9; HRMS (FAB) m/z calcd for
C46H64N2O3SSiSn [M+H]+ 872.3429, found 872.3519.
Dimethyl
3‐[(4‐tert‐butylphenylthio)methylene]‐4‐(tert‐
butyldiphenylsilyloxyamino)cyclopentane‐1,1‐dicarboxylate (7n)
(Table 4, entry 4).
Following General Procedure, 7n (72.6 mg, 73%, E/Z = 90/10) was
obtained from 3n (77.3 mg, 0.166 mmol), 5 (63.0 μL, 0.365 mmol),
and
4 (14.9 mg, 91.3 μ mol) after purification by column
chromatography on silica gel (hexane‐AcOEt, 8/1). All data were
described without distinction of the two diastereomers.
N‐[{3R*,3S*‐4‐(4‐tert‐Butylphenylthio)methyl}‐1‐tosylpyrrolidin‐3‐
yl]‐O‐(tert‐butyldiphenylsilyl)hydroxylamine (cis‐14) and its
(3R*,4R*)‐isomer (trans‐14) (Scheme 4).
IR (KBr) 2957, 2858, 1736 cm‐1; 1H‐NMR (300 MHz, CDCl3)  1.08 (s,
9H x 0.9), 1.10 (s, 9H x 0.1), 1.30 (s, 9H x 0.1), 1.31 (s, 9H x 0.9),
2.28‐2.34 (m, 1H), 2.53‐2.60 (m, 1H), 2.92‐2.97 (m, 1H), 3.61‐3.72
(m, 6H), 3.91‐3.95 (br, 1H), 5.23 (br, 1H), 6.22 (br s, 1H x 0.1), 6.23
(br s, 1H x 0.9), 7.18‐7.70 (m, 14H); 13C‐NMR (75 MHz, CDCl3)  19.2,
27.3, 31.3, 34.5, 37.9, 52.9, 58.1, 65.4, 76.6, 120.6, 126.0, 127.46,
127.53, 128.7, 129.5, 132.3, 133.7, 135.7, 135.8, 172.1 (several
signals overlapped); HRMS (EI) m/z calcd for C36H45NO5SSi
[M]+631.2788, found.631.2809
Following General Procedure, cis‐14 (33.4 mg, 31%) and trans‐14
(38.4 mg, 35%) were obtained from 13 (82.1 mg, 0.162 mmol), 5
(61.5 mmL, 0.356 mmol), and 4 (14.6 mg, 89.1 mmol) after
purification by column chromatography on silica gel (hexane‐CH2Cl2,
1/2 then hexane‐AcOEt, 5/1).
cis‐14: IR (KBr) 3854, 2856 cm‐1; 1H‐NMR (300 MHz, CDCl3)  1.04 (s,
9H), 1.29 (s, 9H), 2.16‐2.28 (m, 1H), 2.40‐2.49 (m, 4H), 2.80 (dd, J =
8 | J. Name., 2012, 00, 1‐3
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7.3 and 5.9 Hz, 1H), 2.99 (t, J = 9.5 Hz, 1H), 3.22 (dd, J = 10.6 and 5.5 (E)‐N‐{4‐[4‐(tert‐butylphenylthio)methylene]tetrahydro‐2H‐pyran‐
Hz, 1H), 3.30 (br, 1H), 3.47 (t, J = 9.5 Hz, 1H), 3.59 (d, J = 10.6 Hz, 3‐yl}hydroxylamine (15h) (Scheme 5).
1H), 4.87 (d, J = 9.2 Hz, 1H), 7.09‐7.71 (m, 18H); 13C‐NMR (75 MHz,
To a stirred solution of TBDPS ether 10h (36.4 mg, 0.0684 mmol) in
THF (0.7 mL) was added a solution of TBAF (ca. 0.10 mmol) and
126.0, 127.5, 127.6, 129.7, 129.8, 131.4, 133.2, 133.6, 135.6, 135.8,
CDCl3)  19.0, 21.5, 27.2, 31.2, 31.9, 34.4, 40.6, 50.7, 51.1, 62.8,
acetic acid (23 L, 0.40 mmol) in THF (0.8 mL) at 0 °C, and the
mixture was stirred at the same temperature for 2 h. After addition
of H2O, the same work‐up for 15a gave a crude material, which was
143.5, 149.8; HRMS (EI) m/z calcd for C38H48N2O3S2Si 672.2876,
found 672.2862.
trans‐14: IR (KBr) 3855, 3747, 3738, 3715, 3678, 3672, 3651, 2392, purified by PTLC (hexane‐AcOEt, 1/1) to afford 15h (16.3 mg, 81%)
1
2349 cm‐1; H‐NMR (300 MHz, CDCl3) 1.01 (s, 9H), 1.28 (s, 9H), as colorless oil. IR (neat) 3364, 3252, 2961 cm‐1; 1H‐NMR (300
2.13 (br, 1H), 2.40‐2.47 (m, 4H), 2.71‐2.77 (m, 1H), 2.85‐2.90 (m,
1H), 3.15‐3.26 (m, 4H), 4.97 (br, 1H), 7.11‐7.64 (m, 18H); 13C‐NMR
(75 MHz, CDCl3) 19.0, 21.5, 27.2, 31.2, 34.4, 36.4, 40.4, 50.5, 51.5, 11.7 and 1.8 Hz, 1H), 6.28 (s, 1H), 7.27‐7.38 (m, 4H); 13C‐NMR (75
MHz, CDCl3)  1.31 (s, 9H), 2.38‐2.63 (m, 2H), 3.48‐3.56 (m, 2H),
3.59 (dd, J = 11.7 and 2.7 Hz, 1H), 3.90‐4.08 (m, 1H), 4.15 (dd, J =
66.1, 126.0, 127.4, 127.5, 127.7, 129.6, 129.7, 131.3, 132.5, 133.1,
133.2, 135.6, 135.8, 143.5, 149.7; HRMS (EI) m/z calcd for
C38H48N2O3S2Si 672.2876, found 672.2872.
MHz, CDCl3)  28.0, 31.2, 34.5, 64.1, 68.0, 69.0, 122.6, 126.2, 129.4,
131.9, 134.5, 150.1; HRMS (EI) m/z calcd for C16H23NO2S 293.1449,
found 293.1447.
(E)‐N‐{2‐[4‐(tert‐
(Z)‐N‐[(E)‐2‐{4‐(tert‐butylphenylthio)methylene}cyclopentyl]‐1‐
butylphenylthio)methylene]cyclopentyl}hydroxylamine
(Scheme 5).
(15a)
phenylmethanimine oxide (16) (Scheme 5).
To a stirred suspension of hydroxylamine 15a (53.7 mg, 0.194
mmol) and MgSO4 (35.0 mg, 0.291 mmol) in 1,2‐dichloroethane
(0.19 mL) was added benzaldehyde (60 L, 0.59 mmol) at 0 °C, and
the mixture was stirred at room temperature for 30 min. The
resulting mixture was concentrated under reduced pressure. The
residue was purified by PTLC (hexane‐AcOEt, 1/1) to afford 16 (62.2
To a stirred solution of 7a (100 mg, 0.194 mmol) in THF (1.9 mL)
was added a solution of TBAF (ca. 0.29 mmol) and acetic acid (67
L, 1.2 mmol) in THF (2.2 mL) at 0 °C, and the mixture was stirred at
the same temperature for 2 h. After addition of H2O, the resulting
mixture was extracted with AcOEt (x 3). The organic layer was
washed with sat. NaHCO3 aq. (x 1), brine (x 1), dried (Na2SO4) and
concentrated under reduced pressure. The residue was
chromatographed on silica gel (hexane‐AcOEt, 2/1) and purified by
PTLC (hexane‐AcOEt, 1/1) to afford 15a (40.0 mg, 74%).
mg, 88%) as pale yellow oil. IR (neat) 2963, 1489 cm‐1; H‐NMR
1
(300 MHz, CDCl3)  1.29 (s, 9H), 1.76‐1.95 (m, 1H), 1.97‐2.23 (m,
2H), 2.41‐2.69 (m, 3H), 4.84 (dd, J = 6.3 and 4.5 Hz, 1H), 6.48 (dd, J =
3.6 and 2.4 Hz, 1H), 7.25‐7.35 (m, 4H), 7.37‐7.45 (m, 3H), 7.46 (s,
1H), 8.18‐8.32 (m, 2H); 13C‐NMR (75 MHz, CDCl3)  23.6, 30.4, 31.1,
32.3, 34.4, 79.9, 123.4, 126.1, 128.4, 128.6, 129.6, 130.2, 130.4,
131.6, 132.9, 139.3, 150.2; HRMS (FAB) m/z calcd for C23H27NOS
[M+H]+ 366.1881, found 366.1899.
IR (KBr) 2963, 2905, 2870 cm‐1; 1H‐NMR (300 MHz, CDCl3)  1.30 (s,
9H), 1.79‐2.37 (m, 6H), 3.90 (s, 1H), 4.81 (br, 1H), 6.34 (s, 1H) 7.26‐
7.31 (m, 4H); 13C‐NMR (75 MHz, CDCl3)  23.2, 30.2, 31.1, 31.3, 34.5,
66.8, 118.9, 126.1, 129.1, 132.6, 143.5, 149.7; HRMS (EI) m/z calcd
for C16H23NOS 277.1500, found 277.1488.
Acknowledgements
The acknowledgements come at the end of an article after the
conclusions and before the notes and references.
N‐[5‐(4‐tert‐butylphenylthio)‐4‐methyl‐3,6‐dihydro‐2H‐pyran‐3‐
yl]hydroxylamine (15d) (Scheme 5).
To a stirred solution of 8d (34.7 mg, 0.0652 mmol) in THF (0.65 mL)
was added a solution of TBAF (ca. 0.10 mmol) and acetic acid (22
L, 0.38 mmol) in THF (0.75 mL) at 0 °C, and the mixture was stirred
at the same temperature for 2.5 h. After addition of H2O, the same
Notes and references
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work‐up for 15a gave
a
crude material, which was
chromatographed on silica gel (hexane‐AcOEt, 2/1) followed by
(hexane‐AcOEt, 1/1) to afford 15d (15.2 mg, 80%) as colorless oil.
IR (neat) 3384, 3250, 2963 cm‐1; 1H‐NMR (300 MHz, CDCl3)  1.29 (s,
9H), 2.09 (t, J = 2.1 Hz, 3H), 3.36 (br s, 1H), 3.53 (dd, J = 11.7 and 2.4
Hz, 1H), 3.98 (br s, 2H), 4.32 (dd, J = 11.7 and 1.8 Hz, 1H), 6.20 (br s,
1H), 7.13‐7.23 (m, 2H), 7.23‐7.35 (m, 2H); 13C‐NMR (75 MHz, CDCl3)
 19.0, 31.2, 34.5, 61.4, 64.9, 68.7, 126.2, 129.5, 129.6, 129.9,
134.3, 150.0; HRMS (EI) m/z calcd for C16H23NO2S 293.1449, found
293.1439.
3. For examples, see: (a) R. D. Tillyer, C. Boudreau, D. Tschaen, U.‐H.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1‐3 | 9
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DOI: 10.1039/C7OB00279C
ARTICLE
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10 | J. Name., 2012, 00, 1‐3
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