BF3-OEt2-mediated rearrangement of (4-phenylpiperidin-4-yl)-arylmethanols

Article abstract of DOI:10.1002/jccs.200800070

Synthesis of several 4-benzhydrylidenepiperidine analogs has been established starting from different (4-phenylpiperidin-4-yl)-arylmethanols via boron trifluoride etherate mediated rearrangement. The possible rearranged mechanism was proposed. Boron trifluoride etherate-mediated rearrangement of the related derivatives was also examined. It presents a novel rearrangement reaction catalyzed by boron trifluoride etherate and broadens the scope of application.

Full text of DOI:10.1002/jccs.200800070

468
Journal of the Chinese Chemical Society, 2008, 55, 468-473
BF3-OEt2-mediated Rearrangement of (4-Phenylpiperidin-4-yl)-
arylmethanols
Meng-Yang Changa* (
), Tsun-Cheng Wua (
) and Shiang-Tsern Linb (
)
aDepartment of Applied Chemistry, National University of Kaohsiung, Kaohsiung 811, Taiwan, R.O.C.
bDepartment of Nutrition, Chung-Ho Memorial Hospital, Kaohsiung Medical University,
Kaohsiung 807, Taiwan, R.O.C.
Synthesis of several 4-benzhydrylidenepiperidine analogs has been established starting from differ-
ent (4-phenylpiperidin-4-yl)-arylmethanols via boron trifluoride etherate mediated rearrangement. The
possible rearranged mechanism was proposed. Boron trifluoride etherate-mediated rearrangement of the
related derivatives was also examined. It presents a novel rearrangement reaction catalyzed by boron tri-
fluoride etherate and broadens the scope of application.
Keywords: Boron trifluoride etherate; 4-Benzhydrylidenepiperidine; Rearrangement; Ritanserin.
Scheme I
1. INTRODUCTION
Recently, we explored some interesting reactions by
boron trifluoride etherate for synthesizing different five,
six and seven-membered structural frameworks (pyrroli-
dine, piperidine and azepane), such as isomerization reac-
tion, ring-contraction and ring-expansion.1-5 As shown in
Scheme I, the relative position of nitrogen atom and oxy-
gen atom is an important factor in the boron trifluoride
etherate-mediated process. Boron trifluoride etherate has
been reviewed for reactions involving carbon-carbon or
carbon-heteroatom bond formations. Representative exam-
ples include dehydration, rearrangement, isomerization,
ring-contraction, ring-expansion, etc.6-10 Due to the numer-
ous advantages associated with this eco-friendly com-
pound, it has been explored as a powerful reagent for dif-
ferent reactions. Many research groups successfully devel-
oped various useful transformations by application of this
reagent.
4-phenylpiperidinyl-4-carboxylic acid as the starting mate-
rial in good yields.
2. RESULTS AND DISCUSSION
Continuing further investigation on the application of
rearrangement, treatment of structural skeletons having ni-
trogen and oxygen atoms with 1,6-position by boron tri-
fluoride etherate was next examined (Scheme II). Herein, a
concise and high-yield methodology for synthesizing the
related derivatives of 4-benzhydrylidenepiperidine A, 4-
(1-arylvinyl)-4-phenylpiperidine B, and 4-triphenylmeth-
yl-1,2,5,6-tetrahydropyridine C was described from the
The structural framework A (e.g. cyproheptadine,11
loratidine,12 ketotifen13 and ritanserin14) and B with various
important biological activities have been interestingly re-
ported from the literature.15-24 The structural characteristics
of framework C possessed a 4-triarylmethyl substitutent.
This synthesis of framework C with a tri-aryl group at a
quaternary carbon center has not usually been reported in
* Corresponding author. Tel: +(886)-7-5919464; Fax: +(886)-7-5919348; E-mail: mychang@nuk.edu.tw

Rearrangement of (4-Phenylpiperidin-4-yl)-arylmethanols
J. Chin. Chem. Soc., Vol. 55, No. 2, 2008 469
Scheme III
Scheme II
the literature. Accordingly, an easy and straightforward
synthesis of 4-substituted piperidine ring systems A, B and
C was achieved by boron trifluoride etherate-mediated
rearrangement.
For investigating the boron trifluoride etherate-medi-
ated rearrangement, the structural framework A was easily
yielded from commercially available 4-phenylpiperidinyl-
4-carboxylic acid (1) by the five-step standard reaction
protocol. First, two compounds 2a (R=Ms) and 2b (R=Ts)
were synthesized via N-tosylation of compound 1 and re-
duction of the corresponding ester with lithium aluminum
hydride in 79% and 82% yields, respectively. Further, alco-
hols 2a and 2b were converted into compounds 3a1~3a3
and 3b1~3b5 by PCC-mediated oxidation, Grignard addi-
tion (R1=Ph, 2-MePh, 3-MeOPh, 4-MeOPh, 4-FPh, and
2,6-Me2Ph), and followed by subsequent boron trifluoride
etherate-mediated rearrangement in 75~88% yields. These
experimental results are summarized in Table 1. The possi-
ble mechanism was also shown in Scheme III. Compounds
3a1~3a3 and 3b1~3b5 were obtained as the single isomer via
phenyl group 1,2-shift rearrangement and followed by pro-
ton abstract. The characteristic structure of compound 3b5
was determined by single-crystal X-ray analysis as shown
in Fig. 1.25
and 6b4 with structural framework C were obtained in 90%
and 81% yields, respectively, via phenyl group 1,2-shift re-
arrangement and followed by proton abstraction. Herein a
new synthetic route toward preparation of different aryl
groups on a quaternary carbon was also developed. The
Table 1. Synthesis of 4-benzhydrylidenepiperidine analogs
3a1~3a3 and 3b1~3b5 has been established starting from
compounds 2a and 2b via the three-step transformationa
R1
Ph
OH
Ph
1) PCC
2) R1MgBr
3) BF3
N
N
R
R
2a, R=Ms
2b, R=Ts
3
Entry
Substrate
R1
Product
Yield (%)b
1
2
3
4
5
6
7
8
2a
2a
2a
2b
2b
2b
2b
2b
3-MeOC6H4
4-FC6H4
3a1
3a2
3a3
3b1
3b2
3b3
3b4
3b5
82
79
75
88
80
79
80
78
As shown in Scheme IV, treatment of alcohols 4b1
(R1=Ph) or 4b4 (4-MeOPh) yielded compounds 5b1 or 5b4
as the sole product with structural framework B via the
above reaction sequence (PCC oxidation, Grignard addi-
tion with methylmagnesium bromide, and boron trifluoride
etherate-mediated reaction). During the process, the ex-
pected structural framework A was not observed. Next,
when the aliphatic methyl group was changed to aromatic
phenyl group for compounds 4b1 and 4b4, compounds 6b1
4-MeOC6H4
C6H5
2-MeC6H4
3-MeOC6H4
4-MeOC6H4
2,6-Me2C6H3
a The product was adjusted based on isolated products.
b All yields of compounds 3a1~3a3 and 3b1~3b5 were based on
compounds 2a and 2b confirmed.

470 J. Chin. Chem. Soc., Vol. 55, No. 2, 2008
Chang et al.
results, the aryl group is an important substitutent for pro-
viding a stable benzylic cation in the overall process. We
envisioned that the reason was the formed complex mixture
was derived from E/Z-configuration and the possible com-
petition between boron trifluoride etherate-mediated rear-
Scheme IV
characteristic structures of compounds 5b1 and 6b1 was de-
termined by single-crystal X-ray analysis as shown in Figs.
2 and 3.25 The synthetic procedure could be monitored by
TLC plate until the reaction was complete.
Fig. 2.
When vinylmagnesium bromide was chosen as Grig-
nard reagent, the complex products were afforded in the
following treatment of the resulting tertiary alcohol with
boron trifluoride etherate. On the other hand, the same re-
action with allyl or benzylmagnesium bromides was exam-
ined. But, the desired product still was not obtained. Some
attempts toward the rearrangement were unsuccessful un-
der a variety of conditions (prolonged reaction time, ele-
vated temperature, and different Lewis acid). Based on the
Fig. 3.
Fig. 1.

Rearrangement of (4-Phenylpiperidin-4-yl)-arylmethanols
rangement and dehydration of the formed tertiary alcohol.
J. Chin. Chem. Soc., Vol. 55, No. 2, 2008 471
with ethyl acetate (3 ´ 20 mL). The combined organic lay-
ers were washed with brine, dried, filtered and evaporated
to yield crude product. Purification on silica gel (hex-
ane/ethyl acetate = 4/1~2/1) afforded pure compounds.
4.2.1. 4-[1-(3-Methoxyphenyl)-benzylidene]-1-(4-meth-
ylsulfonyl)-piperidine (3a1)
Viscous gum; HRMS (ESI, M++1) calcd for C20H24NO3S
358.1477, found 358.1479; 1H NMR (300 MHz, CDCl3) d
7.32-7.19 (m, 4H), 7.13-7.09 (m, 2H), 6.80-6.76 (m, 1H),
6.71 (d, J = 7.5 Hz, 1H), 6.65-6.64 (m, 1H), 3.77 (s, 3H),
3.27 (t, J = 5.7 Hz, 4H), 2.79 (s, 3H), 2.51-2.46 (m, 4H); 13C
NMR (75 MHz, CDCl3) d 159.62, 143.36, 141.70, 138.56,
132.59, 129.64 (2x), 129.46, 128.46 (2x), 127.07, 122.19,
115.77, 111.99, 55.42, 47.79, 47.76, 30.97, 31.41, 31.30.
4.2.2. 4-[1-(4-Fluorophenyl)-benzylidene]-1-(4-methyl-
sulfonyl)-piperidine (3a2)
3. CONCLUSION
In summary, we developed an easy and high-yield
methodology for synthesizing three kinds of structural
frameworks A, B and C by boron trifluoride etherate-medi-
ated rearrangement. It is worth noting that products 3a1~
3a3 and 3b1~3b5 are analogs with biological activities skel-
etons and could be applied in the preparation of structural
framework A. Further novel application of this methodol-
ogy with rearrangement formation of new carbon-carbon
bonds is now underway.
4. EXPERIMENTAL SECTION
4.1. General
Tetrahydrofuran (THF) was distilled prior to use. All
other reagents and solvents were obtained from commer-
cial sources and used without further purification. Reac-
tions were routinely carried out under an atmosphere of dry
nitrogen with magnetic stirring. Products in organic sol-
vents were dried with anhydrous magnesium sulfate before
concentration in vacuo.
Mp 166-167 °C; HRMS (ESI, M++1) calcd for
1
C19H21FNO2S 346.1277, found 346.1278; H NMR (300
MHz, CDCl3) d 7.34-7.24 (m, 3H), 7.11-6.96 (m, 6H), 3.28
(t, J = 5.1 Hz, 4H), 2.80 (s, 3H), 2.48 (t, J = 5.1 Hz, 4H); 13C
NMR (75 MHz, CDCl3) d 163.53, 160.27, 141.78, 137.71,
132.92, 131.43, 131.33, 129.73 (2x), 128.54 (2x), 127.20,
115.54, 115.26, 47.73, 47.69, 35.03, 31.40, 31.37; Anal.
Calcd for C19H20FNO2S: C, 66.06; H, 5.84; N, 4.05. Found:
C, 66.45; H, 5.63; N, 4.32.
4.2. A representative procedure for compounds 3a1~
3a3, 3b1~3b5, 5b1, 5b4 and 6b1, 6b4 is as follows
A solution of primary or secondary alcohol (1.0
mmol) in dichloromethane (5 mL) was added to a mixture
of pyridinium chlorochromate (431 mg, 2.0 mmol) and
Celite (1.0 g) in dichloromethane (20 mL). After being
stirred at rt for 6 h, the mixture was filtered through a short
silica gel column. The filtrate was dried, filtered and evap-
orated to yield crude compound. Without further purifica-
tion, a solution of methylmagnesium bromide or different
arylmagnesium bromide reagents (1.0 M in THF, 1.5 mL,
1.5 mmol) was added to a stirred solution of the resulting
aldehyde or ketone in tetrahydrofuran (20 mL) at -78 °C.
The reaction mixture was stirred at -78 °C for 5 h. The total
procedure was monitored by TLC until the reaction was
completed. Boron trifluoride etherate (1 mL) was added to
a stirred solution of the resultant reaction mixture at 0 °C.
The reaction mixture was stirred at 0 °C for 30 min. Satu-
rated sodium bicarbonate solution (10 mL) was added to
the reaction mixture and the solvent was concentrated un-
der reduced pressure. Water (5 mL) and ethyl acetate (20
mL) were added to the residue and the mixture was filtered
through a short plug of Celite. The filtrate was concen-
trated under reduced pressure. The residue was extracted
4.2.3. 4-[1-(4-Methoxyphenyl)-benzylidene]-1-(4-meth-
ylsulfonyl)-piperidine (3a3)
Viscous gum; HRMS (ESI, M++1) calcd for C20H24NO3S
358.1477, found 358.1477; 1H NMR (300 MHz, CDCl3) d
7.33-7.21 (m, 3H), 7.11-7.07 (m, 2H), 7.02 (d, J = 8.7 Hz,
2H), 6.83 (d, J = 8.7 Hz, 2H), 3.79 (s, 3H), 3.29-3.24 (m,
4H), 2.79 (s, 3H), 2.53-2.43 (m, 4H); 13C NMR (75 MHz,
CDCl3) d 158.61, 142.28, 138.29, 134.34, 131.98, 130.95
(2x), 129.79 (2x), 128.41 (2x), 126.97, 113.78 (2x), 55.46,
47.83, 47.80, 34.94, 31.43, 31.39.
4.2.4. 4-Benzhydrylidene-1-(4-methylphenylsulfonyl)-
piperidine (3b1)
Mp 75-77 °C; HRMS (ESI, M++1) calcd for C25H26NO2S
404.1684, found 404.1685; 1H NMR (300 MHz, CDCl3) d
7.64 (d, J = 8.1 Hz, 2H), 7.35-7.18 (m, 8H), 7.05-7.01 (m,
4H), 3.06 (t, J = 6.0 Hz, 4H), 2.45 (s, 3H), 2.44 (t, J = 6.0
Hz, 4H); 13C NMR (75 MHz, CDCl3) d 143.76, 141.94
(2x), 138.31, 133.46, 132.57, 129.94 (2x), 129.76 (4x),
128.35 (4x), 127.94 (2x), 126.94 (2x), 47.96 (2x), 31.12
(2x), 21.81; Anal. Calcd for C25H25NO2S: C, 74.41; H,
6.24; N, 3.47. Found: C, 74.80; H, 6.52; N, 3.65.

472 J. Chin. Chem. Soc., Vol. 55, No. 2, 2008
Chang et al.
4.2.5. 4-[1-(2-Methylphenyl)-benzylidene]-1-(4-methyl-
phenylsulfonyl)-piperidine (3b2)
5.5 Hz, 2H), 2.10 (s, 6H); 13C NMR (125 MHz, CDCl3) d
143.48, 140.90, 139.15, 135.74 (2x), 134.87, 133.44,
132.27, 129.64 (2x), 129.53 (2x), 127.83 (2x), 127.62 (2x),
127.60 (2x), 126.86, 126.58, 47.46, 46.94, 31.02, 30.01,
21.55, 20.37 (2x); Anal. Calcd for C27H29NO2S: C, 75.14;
H, 6.77; N, 3.25. Found: C, 75.38; H, 6.89; N, 3.41. Sin-
gle-crystal X-ray diagram: crystal of compound 3b5 was
grown by slow diffusion of ethyl acetate into a solution of
compound 3b5 in dichloromethane to yield colorless prisms.
The compound crystallizes in the monoclinic crystal sys-
tem. Space group P2(1)/n, a = 10.2967(15) Å, b = 7.6056(11)
Å, c = 29.784(4) Å, V = 2330.2(6) Å3, Z = 4, dcalcd = 1.230
mg/m3, absorption coefficient 0.162 mm-1, F(000) = 920, R
indices (all data) R1 = 0.0971, wR2 = 0.1001, 2q range
(1.37~28.30°).
Mp 147-149 °C; HRMS (ESI, M++1) calcd for
1
C26H28NO2S 418.1841, found 418.1842; H NMR (500
MHz, CDCl3) d 7.64 (d, J = 8.0 Hz, 2H), 7.33 (d, J = 8.0 Hz,
2H), 7.26-7.01 (m, 9H), 3.33-3.28 (m, 1H), 3.25-3.20 (m,
1H), 2.88-2.78 (m, 2H), 2.58-2.55 (m, 2H), 2.46 (s, 3H),
2.25-2.19 (m, 2H), 2.06 (s, 3H); 13C NMR (125 MHz,
CDCl3) d 143.43, 141.18, 140.20, 136.95, 135.90, 133.30,
132.48, 130.21, 129.62 (2x), 129.55, 129.36 (2x), 127.89
(2x), 127.61 (2x), 127.02, 126.52, 125.56, 47.58, 47.39,
30.98, 30.10, 21.52, 19.82; Anal. Calcd for C26H27NO2S:
C, 74.79; H, 6.52; N, 3.35. Found: C, 74.96; H, 6.38; N,
3.67.
4.2.6. 4-[1-(3-Methoxyphenyl)-benzylidene]-1-(4-meth-
ylphenylsulfonyl)-piperidine (3b3)
Mp 128-129 °C; HRMS (ESI, M++1) calcd for
4.2.9. 1-(4-Methylphenylsulfonyl)-4-phenyl-4-(1-phen-
ylvinyl)-piperidine (5b1)
Mp 136-138 °C; HRMS (ESI, M++1) calcd for
1
C26H28NO3S 434.1790, found 434.1790; H NMR (500
1
MHz, CDCl3) d 7.64 (d, J = 8.0 Hz, 2H), 7.34 (d, J = 8.0 Hz,
2H), 7.27-7.16 (m, 4H), 7.03 (d, J = 7.5 Hz, 2H), 6.75 (dd, J
= 2.5, 8.0 Hz, 1H), 6.62 (d, J = 7.0 Hz, 1H), 6.57 (br s, 1H),
3.74 (s, 3H), 3.05 (t, J = 5.5 Hz, 4H), 2.46-2.43 (m, 4H),
2.45 (s, 3H); 13C NMR (125 MHz, CDCl3) d 159.28,
143.49, 143.12, 141.44, 137.84, 133.25, 132.42, 129.68
(2x), 129.38 (2x), 129.10, 128.10 (2x), 127.69 (2x), 126.70,
121.95, 115.56, 111.57, 55.14, 47.70, 47.68, 30.92, 30.81,
21.56; Anal. Calcd for C26H27NO3S: C, 72.03; H, 6.28; N,
3.23. Found: C, 72.39; H, 6.34; N, 3.62.
C26H28NO2S 418.1841, found 418.1842; H NMR (500
MHz, CDCl3) d 7.65 (d, J = 8.0 Hz, 2H), 7.35-7.33 (m, 6H),
7.28-7.23 (m, 1H), 7.18-7.15 (m, 1H), 7.10-7.07 (m, 2H),
6.55 (d, J = 8.0 Hz, 2H), 5.31 (s, 1H), 5.22 (s, 1H), 3.32-
3.27 (m, 2H), 2.94 (td, J = 3.0, 9.0 Hz, 2H), 2.46 (s, 3H),
2.21-2.13 (m, 4H); 13C NMR (125 MHz, CDCl3) d 152.74,
144.58, 143.28, 141.61, 133.41, 129.47 (2x), 128.43 (2x),
128.14 (2x), 127.52 (2x), 127.49 (2x), 126.92, 126.85 (2x),
126.47, 116.68, 44.95, 42.74 (2x), 34.20 (2x), 21.46; Anal.
Calcd for C26H27NO2S: C, 74.79; H, 6.52; N, 3.35. Found:
C, 74.91; H, 6.70; N, 3.24. Single-crystal X-ray diagram:
crystal of compound 5b1 was grown by slow diffusion of
ethyl acetate into a solution of compound 5b1 in dichloro-
methane to yield colorless prisms. The compound crystal-
lizes in the monoclinic crystal system. Space group P2(1)/
c, a = 12.6685(19) Å, b = 7.0554(8) Å, c = 24.878(4) Å, V =
2167.8(5) Å3, Z = 4, dcalcd = 1.279 mg/m3, absorption coef-
ficient 0.172 mm-1, F(000) = 888, R indices (all data) R1 =
0.0716, wR2 = 0.1507, 2q range (1.65~22.72°).
4.2.7. 4-[1-(4-Methoxyphenyl)-benzylidene]-1-(4-meth-
ylphenylsulfonyl)-piperidine (3b4)
Viscous gum; HRMS (ESI, M++1) calcd for C26H28NO3S
434.1790, found 434.1791; 1H NMR (500 MHz, CDCl3) d
7.65 (d, J = 8.0 Hz, 2H), 7.34 (d, J = 8.0 Hz, 2H), 7.25-7.16
(m, 3H), 7.02-7.00 (m, 2H), 6.94 (d, J = 9.0 Hz, 2H), 6.81-
6.78 (m, 2H), 3.78 (s, 3H), 3.05 (dd, J = 5.5, 11.5 Hz, 4H),
2.49-2.43 (m, 4H), 2.45 (s, 3H); 13C NMR (125 MHz,
CDCl3) d 158.28, 143.47, 142.02, 137.59, 134.10, 133.25,
131.83, 130.69 (2x), 129.66 (2x), 129.52 (2x), 128.05 (2x),
127.69 (2x), 126.61, 113.44 (2x), 55.19, 47.75, 47.72,
30.95, 30.91, 21.56.
4.2.10. 1-(4-Methylphenylsulfonyl)-4-phenyl-4-[1-(4-
methoxyphenyl)vinyl]-piperidine (5b4)
Viscous gum; HRMS (ESI, M++1) calcd for C27H30NO3S
448.1946, found 448.1947; 1H NMR (300 MHz, CDCl3) d
7.62 (d, J = 8.1 Hz, 2H), 7.32-7.21 (m, 7H), 6.60 (d, J = 8.7
Hz, 2H), 6.45 (d, J = 8.7 Hz, 2H), 5.24 (s, 1H), 5.18 (s, 1H),
3.72 (s, 3H), 3.32-3.25 (m, 2H), 2.92-2.84 (m, 2H), 2.45 (s,
3H), 2.21-2.04 (m, 4H); 13C NMR (75 MHz, CDCl3) d
158.83, 152.44, 145.15, 143.56, 134.35, 133.88, 129.77
(2x), 129.54 (2x), 128.76 (2x), 127.87 (2x), 127.17 (2x),
4.2.8. 4-[1-(2,6-Dimethylphenyl)-benzylidene]-1-(4-
methylphenylsulfonyl)-piperidine (3b5)
Mp 172-173 °C; HRMS (ESI, M++1) calcd for
1
C27H30NO2S 432.1997, found 432.1998; H NMR (500
MHz, CDCl3) d 7.64 (d, J = 8.0 Hz, 2H), 7.33 (d, J = 8.0 Hz,
2H), 7.25-6.98 (m, 8H), 3.14 (t, J = 5.5 Hz, 2H), 3.03 (t, J =
5.5 Hz, 2H), 2.70 (t, J = 5.5 Hz, 2H), 2.45 (s, 3H), 2.14 (d =

Rearrangement of (4-Phenylpiperidin-4-yl)-arylmethanols
J. Chin. Chem. Soc., Vol. 55, No. 2, 2008 473
2005, 46, 653.
126.77, 116.59, 113.20 (2x), 55.36, 45.40, 43.07 (2x),
34.59 (2x), 21.80.
8. Terentev, A. O.; Kutkin, A. V.; Platonov, M. M.; Ogibin, Y.
N.; Nikishin, G. I. Tetrahedron Lett. 2003, 39, 7359.
9. Kuhnert, N.; Clifford, M. N.; Radenac, A.-G. Tetrahedron
Lett. 2001, 42, 9261.
4.2.11. 1-(4-Methylphenylsulfonyl)-4-trityl-1,2,3,6-
tetrahydropyridine (6b1)
Mp 241-243 °C; HRMS (ESI, M++1) calcd for
10. Stephan, E.; Olaru, A.; Jaouen, G. Tetrahedron Lett. 1999,
40, 8571.
1
C31H30NO2S 480.1997, found 480.1998; H NMR (500
MHz, CDCl3) d 7.66 (d, J = 8.0 Hz, 2H), 7.34 (d, J = 8.0 Hz,
2H), 7.25-7.14 (m, 15H), 5.71 (t, J = 3.5 Hz, 1H), 3.73 (d, J
= 3.0 Hz, 2H), 3.13 (t, J = 5.5 Hz, 2H), 2.47 (s, 3H), 1.94 (br
s, 2H); 13C NMR (125 MHz, CDCl3) d 143.94 (3x), 143.48,
141.01, 133.28, 130.71 (6x), 129.69 (2x), 127.69 (2x),
127.65 (6x), 126.08 (3x), 121.88, 64.97, 45.22, 43.20,
28.80, 21.57; Anal. Calcd for C31H29NO2S: C, 77.63; H,
6.09; N, 2.92. Found: C, 77.82; H, 5.95; N, 3.11. Single-
crystal X-ray diagram: crystal of compound 6b1 was grown
by slow diffusion of ethyl acetate into a solution of com-
pound 6b1 in dichloromethane to yield colorless prisms.
The compound crystallizes in the monoclinic crystal sys-
tem. Space group P2(1)/c, a = 12.7011(4) Å, b = 10.5663(3)
11. Hoyer, D.; Clarke, D. E.; Fozard, J. R.; Hartig, P. R.; Martin,
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Å, c = 18.8754(5) Å, V = 2485.05(12) Å3, Z = 4, dcalcd
=
1.282 mg/m3, absorption coefficient 0.160 mm-1, F(000) =
1016, R indices (all data) R1 = 0.0861, wR2 = 0.1773, 2q
range (1.63~25.82°).
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ACKNOWLEDGMENTS
The authors would like to thank the National Science
Council (NSC-95-2113-M-390-003-MY2) of the Republic
of China for financial support.
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Ther. 1997, 283, 463.
Received September 11, 2007.
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