Regioselective free radical phenylsulfenation of a non-activated δ-carbon atom by the photolysis of alkyl benzenesulfenate

Article abstract of DOI:10.1016/S0040-4020(02)01477-1

A regioselective free radical introduction of a phenylthio group onto a non-activated δ-carbon atom was achieved by photolysis of alkyl benzenesulfenates in the presence of hexabutylditin, and δ-phenylthio alcohols were obtained in 35-91% yields. δ-Phenyl

Full text of DOI:10.1016/S0040-4020(02)01477-1

Tetrahedron 59 (2003) 187–196
Regioselective free radical phenylsulfenation of a non-activated
d-carbon atom by the photolysis of alkyl benzenesulfenate
a,b
Goran Petrovic, Radomir N. Saicic and Zivorad Cekovic
a,b
,
ˇ ´a,b
´
ˇ
ˇ
*
´
aFaculty of Chemistry, University of Belgrade, Studentski trg 16, P.O. Box 158, 11000 Belgrade, Serbia, Yugoslavia
bCenter for Chemistry, Institute for Chemistry, Metallurgy and Technology, Njegoseva 12, 11000 Belgrade, Serbia, Yugoslavia
Received 18 April 2002; revised 28 October 2002; accepted 14 November 2002
Abstract—A regioselective free radical introduction of a phenylthio group onto a non-activated d-carbon atom was achieved by photolysis
of alkyl benzenesulfenates in the presence of hexabutylditin, and d-phenylthio alcohols were obtained in 35–91% yields.
d-Phenylsulfenylation of a non-activated carbon atom induced only by irradiation of alkyl benzenesulfenates (without initiation by
hexabutylditin) also occurs, however, slower reaction rates were observed and lower yields of d-phenylthio alcohols were obtained. q 2002
Published by Elsevier Science Ltd.
1. Introduction
The reactivity of the d-carbon radicals mainly depends on
the ROz precursors, the reagents used, as well as the reaction
conditions.2,4 The reactivity of the carbon radical is
determined by the rate of reaction with its radical
counterpart, or added reagents, and also depends on the
concentrations of the substrate and reagents used.2g,h,5 In
some of these reactions involving d-carbon radicals 2,
generated by 1,5-transposition of the radical center, the
carbon radical was intercepted by ligand2h or electron
transfer oxidants,2a,b,4d atom or group transfer (formal
substitution of the d-hydrogen by an atom or group),6
intermolecular addition,7 cyclization8 and reaction with
carbon monoxide (Scheme 1).9
The introduction of various functional groups onto a remote,
non-activated carbon atom is of great synthetic importance.1
The regioselective functionalization of a non-activated
d-carbon atom involves a free radical 1,5-hydrogen
migration from d-carbon atom to oxygen1a – e 1 or
nitrogen1f,h centered radicals and, thus, transposition of
the radical center to d-carbon atom 2 takes place. The
reaction products and the nature of the introduced functional
groups depend on the alkoxyl radical precursors and
reagents used (Scheme 1).2
The carbon radicals generated by this methodology at an
open chain, or fixed systems with suitable stereochemistry
are preferentially located at the d-position, although
stereochemical circumstances determine the position of
the hydrogen to be abstracted.1a–e,3
2. Results and discussion
Recently we found that d-carbon radical 5, formed by
Scheme 1.
Keywords: radicals and radical reactions; 1,5-hydrogen migration; intramolecular fuctionalization; sulfenic acids and derivatives; sulfides; d-phenylthio
alcohols.
*
Corresponding author. Address: Faculty of Chemistry, University of Belgrade, Studentski trg 16, P.O. Box 158, 11000 Belgrade, Serbia, Yugoslavia.
ˇ
´
Tel.: þ381-11-637-890; fax: þ381-11-636-061; e-mail: zcekovic@chem.bg.ac.yu (Z. Cekovic).
0040–4020/03/$ - see front matter q 2002 Published by Elsevier Science Ltd.
PII: S0040-4020(02)01477-1

´
G. Petrovic et al. / Tetrahedron 59 (2003) 187–196
188
Scheme 2.
Scheme 3.
Scheme 4.
1,5-hydrogen migration in alkoxyl radical 4 was intercepted
by radicophilic olefins, leading to Michael type alkylation of
the remote non-activated carbon atoms.7,9 d-Alkylation was
accomplished by the photolysis of alkyl nitrites 3a or alkyl
benzenesulfenates 3b with tributyltin hydride (TBTH), both
in the presence of an excess of electron deficient olefinic
compound (Scheme 2).10
Scheme 5.
When 10 M equiv. of radicophilic olefin were used, the
d-alkyl radical 5, generated by TBTH reduction of alkyl
benzenesulfenates, preferentially underwent intermolecular
addition (Kadd¼3£105 M21 s21), rather than hydrogen
transfer from TBTH (KH¼2£106 M21 s21).11
Table 1. Phenylsulfenylation of the non-activated d-carbon atom by the
photolysis of acyclic alkyl benzenesulfenates in the presence of
hexabutylditin
Alkyl
benzenesulfenatesa
d-Phenylthio alcohols
Yields
(%)b
In order to carry out allylation of the non-activated d-carbon
atom we envisioned to use allyltributyltin (ATBT) instead
of TBTH.12 Thus, in the reaction of n-pentyl benzene-
sulfenate 7 (0.02 M solution) with 3 M equiv. of allyl-
tributyltin, under irradiation conditions, a low yield of
unsaturated alcohol 9 was obtained as a product of the
allylation of the d-carbon atom (Scheme 3).
(a) n-Butyl
17
(b) 1-Pentyl
80c
In order to increase the yield of the d-allylated alcohol 9, the
concentration of n-pentyl benzenesulfenate was increased to
0.25 M solution, when only 10% of the d-allylated product 9
was obtained. However, we isolated d-phenylthio pentanol
10 as the main reaction product (Scheme 4).
(c) 3-Heptyl
91
47
SPh
OH
(d) 1-Octyl
14
Apparently, at this concentration, ATBT acted more as a
sulfenation propagating species (via Bu3Snz) than as an
allylating agent. Given the potential synthetic importance of
a
Prepared according to the procedure described in Ref. 24.
Isolated yields (GC yields are 10–20% higher).
A 64% yield was obtained in the absence of (Bu3Sn)2.
b
c

´
G. Petrovic et al. / Tetrahedron 59 (2003) 187–196
189
Table 2. Phenylsulfenylation of non-activated d-carbon atom by the photolysis of cyclic alkyl benzenesulfenates in the presence of hexabutylditin
Alkyl benzenesulfenatesa
d-Phenylthio alcohols
Yields (%)b
51c
35
64d
62
43e
40
40
45f
a
Prepared according to procedure described in Ref. 24.
Isolated yields (GC yields are 10–20% higher).
b
c
The ratio of trans/cis¼1:0.86.
d
Only the exo-isomer was obtained.
(2)-(1R,3R,4S,8S)-19a and (2)-(1R,3R,4S,8R)-Menthane-3-9-diol-19b were obtained in the ratio of 10.5:1.
The ratio of exo/endo¼2:1.
e
f
a new, general method for d-phenylsulfenylation we set out
Phenylsulfenylation of the non-activated d-carbon atom was
applied in various structurally related alcohols. The results
obtained using acyclic alkyl benzenesulfenates are pre-
sented in Table 1, while the phenylthio alcohols obtained
from cyclic alkyl benzenesulfenates are summarized in
Table 2.
to further optimize the reaction conditions for this
transformation. Substituting hexabutylditin for ATBT
resulted in a yield enhancement, and d-phenylthio pentanol
10 was obtained in 80% yield.13 However, although a tin-
less variant of the sulfenylation reaction would also be
conceivable, in the absence of hexabutylditin the reaction
proceeded at a lower rate (60 min), and gave a lower yield of
d-phenylthio pentanol (Scheme 5).
This type of free radical phenylthio group transfer
essentially represents a simple interchange of the positions

´
G. Petrovic et al. / Tetrahedron 59 (2003) 187–196
190
Scheme 6.
Scheme 7.
of hydrogen and phenylthio groups. The sequence of radical
reactions is initiated by the tributyltin radical and is based
on its thiophilic addition to the sulfur of alkyl benzene-
sulfenate. The formed alkoxyl radical 24 upon intra-
molecular 1,5-hydrogen migration, gives the d-carbon
radical 25 (Scheme 6).
trans-isomer 15a is more stable for steric reasons, its
formation, involving the intermediate 26 requires a non-
favorable equatorial approach of the cyclohexyl radical to
the starting compound. On the other hand, axial attack of the
cyclohexyl radical 29 onto the alkyl benzenesulfenate,
leading to an axial phenylthio group is more favorable,
although the less stable cis-isomer 15b is formed (Scheme
8).15 These two factors probably determine the distribution
of stereoisomers 15a and 15b. The ratio of cis- and trans-
isomers was determined by 1H NMR spectrum of the
mixture of 15a and 15b.16
In the absence of any other reactive species the carbon
radical 25 undergoes homolytic substitution at the sulfur in
the alkyl benzenesulfenate 23, involving the intermediary
hypervalent sulfuranyl radical 26. A substitution at sulfur
involves the S–O bond cleavage with formation of
d-phenylthio alcohol 12, as a final reaction product, and
generating the alkoxyl radical 24 as a transient radical which
continues the chain (Scheme 7).14
However, the d-phenylsulfenylation of endo-2-norbornyl-
methyl benzenesulfenate proceeds stereoselectively and
only exo-6-phenylthio-endo-2-norbornylmethanol 17 was
obtained. This result is in agreement with stereoselective
reaction of the norbornyl radical proceeding with an exo-
approach to the alkyl benzenesulfenate.17
Comparable results for d-phenylsulfenylation were obtained
when irradiation of n-pentyl benzenesulfenates was carried
out without hexabutylditin, when d-phenylthio pentanol was
obtained in 64% yield. This result indicates that the alkoxyl
radical 24 is generated by photo-induced homolytic
dissociation of alkyl benzenesulfenates6 and d-phenyl-
sulfenylation occurs as in the presence of tributyltin radical
as an initiator.
An interesting stereoselectivity of the d-phenylsulfenylation
reaction was achieved in the photolysis of (2)-menthyl
benzenesulfenate. It should be expected that the two non-
activated methyl groups to be attacked are equivalent for
introduction of the phenylthio group, since the rotational
barrier for the isopropyl group is relatively low. However, it
was found that this reaction proceeds stereoselectively and
two stereoisomers 19a (S)- and 19b (R)- were obtained in
the ratio 10.5:1 (Scheme 9). Two stereoisomers were
separated by chromatography. The formation of the
S-diastereoisomer 19a in a considerable excess may be
explained by the different stereochemical interactions in the
Remote phenylsulfenylation of the cyclohexane ring is not
stereoselective. Thus in the reaction of cyclohexylethyl
benzenesulfenate (27), phenylthio group transfer from the
side-chain onto the cyclohexane ring takes place and a
mixture of cis- and trans-2-phenylthiocyclohexyl ethanol
was obtained in the ratio of trans/cis¼1:0.86. Although the
Scheme 8.

´
G. Petrovic et al. / Tetrahedron 59 (2003) 187–196
191
Scheme 9.
Scheme 10.
transition states necessary for 1,5-hydrogen migration and
the generation of two diastereoisomeric carbon radicals. In
the six-membered transition state 29, leading to
S-diastereoisomer 19a, the non-reacting methyl group
(from the isopropyl group) is in a quasi-equatorial position,
while in the transition state 30, leading to the R-diastereo-
isomer 19b, the methyl group is in the less favorable quasi-
axial position.
stereomeric phenylthio alcohols 19a and 19b were sub-
jected to the following sequence of reactions: oxidation by
m-CPBA to the correspondig sulfoxides,19 Pummerer
rearrangement20 and reduction of isomeric a-acetoxy
sulfides with LiAlH4; thus the (2)-(1R,3R,4S,8S)-
menthane-3,9-diol 31a and (2)-(1R,3R,4S,8R)-menthane-
3,9-diol 31b were obtained (Scheme 10). Physical constants
and spectral evidence were in full agreement with the
corresponding stereoisomers independently prepared from
the (2)-isopulegol by the previously described procedure.18
The absolute configurations of 19a and 19b were confirmed
by their transformation to the corresponding diastereomeric
menthane-3,9-diols 31a and 31b the stereochemistry of
which was determined by Ohloff.18 The separated dia-
Introduction of the phenylthio group onto the non-activated
d-carbon atom of alcohols can have valuable synthetic
Scheme 11.

´
G. Petrovic et al. / Tetrahedron 59 (2003) 187–196
192
applications. For example, d-phenylthio alcohols derived
from radical 5 may be easily oxidized to the corresponding
d-sulfoxides 33 and d-sulfones21 with their versatile
reactivities, or they can be deprotonated by a strong base,
and convert the d-carbon atom to the nucleophilic species
32.22 Conversion of the activated d-carbon atom of the
d-phenylthio alcohols to the carbonyl group can be achieved
via halogenation (35)23 followed by subsequent hydrolysis
to the corresponding carbonyl compounds. In this way an
inversion of the reactivity of the d-carbon atom, may be
accomplished and it can react as an electron acceptor 34
(Scheme 11).
NMR (200 MHz) d: 0.86–0.93 (m, 3H), 1.26–1.38 (m, 4H),
1.60–1.70 (m, 2H), 3.81 (t, J¼6.6 Hz, 2H), 7.14–7.42 (m,
5H). 13C NMR (50 MHz) d: 140.82, 128.74, 126.11, 78.40,
29.92, 27.71, 22.23, 13.78.
3.1.3. 3-Heptyl benzenesulfenate. 78% Yield, yellow-
green oil, bp 86–898C/0.3 mm Hg. IR (neat, cm21): 3061,
2000–1600, 1584, 1477, 1465, 1439, 1113, 1068, 1024,
944, 916, 893, 811, 738, 690. 1H NMR (200 MHz) d: 0.88 (t,
J¼6.4 Hz, 6H), 1.20–1.37 (m, 4H), 1.53–1.72 (m, 4H),
3.52 (quint, J¼5.8 Hz, 1H), 7.14–7.36 (m, 5H). 13C NMR
(50 MHz) d: 141.38, 128.62, 126.38, 124.53, 88.67, 32.95,
27.07, 26.44, 22.61, 13.87, 9.15.
3.1.4. n-Octyl benzenesulfenate. 71% Yield, yellow-green
oil, bp 103–1058C/0.02 mm Hg. IR (neat, cm21): 3060,
2000–1600, 1583, 1478, 1440, 1378, 1148, 1068, 1024,
968, 894, 737, 690. 1H NMR (200 MHz) d: 0.88 (t,
J¼6.2 Hz, 3H), 1.20–1.40 (m, 10H), 1.58–1.73 (m, 2H),
3.80 (t, J¼6.6 Hz, 2H), 7.13–7.40 (m, 5H). 13C NMR
(50 MHz) d: 140.85, 128.87, 126.28, 123.57, 78.62, 31.70,
30.32, 29.12, 25.66, 22.56, 14.02.
3. Experimental
Solvents used in all of the experiments were purified by
distillation before use (benzene distilled over calcium
hydride and methylene chloride over phosphorous pent-
oxide). Petroleum ether refers to the fraction with distilla-
tion range 45–658C. Purification and separation of the
reaction products were carried out by distillation and
column chromatography using silica gel 100–200 mesh
(60 A) and by dry flash chromatography using silica gel
˚
(60 A). The reactions were monitored by TLC using silica
gel (TLC 60 A) or by GC (Varian 3400, column OV-101 1%
on Chromosorb W-AW). IR spectra (nmax in cm21) were
recorded on Perkin–Elmer 457 grating instrument. 1H NMR
spectra (ppm in d-values) were recorded (in CDCl3) at
200 MHz, using Varian Gemini 200. 13C NMR spectra were
recorded on the same instrument at 50 MHz. Mass spectra
were recorded on Finningan ITDS 700 instrument.
˚
3.1.5. 2-(Cyclohexyl)-ethyl benzenesulfenate. 84% Yield,
yellow-green oil, bp 110–1128C/0.05 mm Hg. IR (neat,
cm21): 3059, 2000–1600, 1583, 1477, 1448, 1440, 1378,
˚
1
1090, 1067, 1024, 998, 971, 891, 835, 737, 690. H NMR
(200 MHz) d: 0.80–0.94 (m, 2H), 1.10–1.45 (m, 4H), 1.53
(q, J¼6.6 Hz, 2H), 1.55–1.70 (m, 5H), 3.82 (t, J¼6.6 Hz,
2H), 7.10–7.35 (m, 5H). 13C NMR (50 MHz) d: 140.79,
128.76, 126.19, 123.55, 76.49, 37.67, 34.09, 33.07, 26.35,
26.06.
3.1.6. trans-3,3,5-Trimethylcyclohexyl benzenesulfenate.
77% Yield, yellow-green oil, bp 102–1048C/0.09 mm Hg.
IR (neat, cm21): 3060, 2000–1600, 1584, 1477, 1455, 1439,
1387, 1364, 1344, 1247, 1180, 1154, 1091, 1077, 1068,
1024, 988, 926, 911, 884, 834, 737, 690. 1H NMR
(200 MHz) d: 0.87 (d, J¼7.2 Hz, 3H), 0.89 (s, 3H), 1.08
(s, 3H),0.74–1.21(m, 3H), 1.37–1.55(m, 1H), 1.86–2.12(m,
3H), 3.86 (quint, J¼3.0 Hz, 1H), 7.09–7.39 (m, 5H). 13C
NMR (50 MHz) d: 141.50, 128.78, 125.75, 122.76, 83.30,
48.23, 41.63, 39.03, 33.91, 30.53, 27.51, 22.83, 22.41.
3.1. Synthesis of alkyl benzenesulfenates
General procedure.24 To the solution of alcohol (0.02 mol)
and triethylamine (0.05 mol) in methylene chloride
(150 mL), cooled to 2788C under an argon atmosphere,
benzenesulfenyl chloride (0.025 mL) was added during
10 min at 2788C and left to reach rt. The mixture was
diluted with 400 mL of methylene chloride and washed
successively with 50 mL of 2 M hydrochloric acid, 50 mL
of saturated aqueous sodium bicarbonate and water. The
solution was dried over sodium sulfate. Solvent was
removed by evaporation and residual oil distilled on a
short path under reduced pressure. Solid alkyl benzene-
sulfenates were purified by dry flash chromatography. Alkyl
benzenesulfenates were obtained in 65–87% yields.
3.1.7. Cyclooctyl benzenesulfenate. 77% Yield, yellow-
green oil, bp 120–1228C/0.3 mm Hg. IR (neat, cm21):
3059, 2000–1600, 1582, 1477, 1440, 1362, 1329, 1148,
1086, 1068, 1046, 1024, 940, 912, 884, 844, 771, 737, 690.
1H NMR (200 MHz) d: 1.30–2.10 (m, 14H), 3.60–3.75 (m,
1H), 7.05–7.40 (m, 5H). 13C NMR (50 MHz) d: 141.90,
128.77, 125.68, 122.02, 88.24, 31.94, 27.13, 25.19, 22.86.
3.1.1. n-Butyl benzenesulfenate. 65% Yield, yellow-green
liquid, bp 74–768C/0.22 mm Hg. IR (neat, cm21): 3059,
2000–1600, 1584, 1478, 1439, 1378, 1121, 1090, 1059,
1
3.1.8. endo-2-Norbornylmethyl benzenesulfenate. 84%
Yield, bp 1158C/0.04 mm Hg. IR (neat, cm21): 3059,
2000–1600, 1582, 1478, 1452, 1440, 1379, 1344, 1301,
1171, 1135, 1068, 1041, 1024, 974, 954, 929, 779, 738, 690.
1H NMR (200 MHz) d: 0.55–0.65 (m, 1H), 0.95–1.76 (m,
8H), 2.17–2.29 (m, 2H), 3.74–3.79 (m, 2H), 7.13–7.45 (m,
5H). 13C NMR (50 MHz) d: 140.87, 128.88, 126.36, 123.74,
80.85, 40.44, 39.64, 38.14, 36.55, 33.59, 29.76, 22.61.
1024, 995, 965, 943, 903, 860, 773, 738, 691. H NMR
(200 MHz) d: 0.90 (t, J¼7.4 Hz, 3H), 1.36 sext, J¼7.4 Hz,
2H), 1.57–1.71 (m, 2H), 3.80 (t, J¼6.8 Hz, 2H), 7.12–7.40
(m, 5H). 13C NMR (50 MHz) d: 140.83, 128.80, 126.19,
123.46, 78.20, 32.30, 18.83, 13.62.
3.1.2. n-Pentyl benzenesulfenate. 73% Yield, yellow-
green oil, bp 708C/0.1 mm Hg. Anal. calcd C11H16OS: C,
67.30; H, 8.22; S, 16.33. Found: C, 67.72; H, 8.23; S, 16.43.
IR (neat, cm21): 3060, 2000–1600, 1583, 1477, 1439, 1378,
1300, 1089, 1069, 1043, 1024, 970, 892, 807, 738, 691. 1H
3.1.9. (1R,2S,5R)-2-Isopropyl-5-methylcyclohexyl ben-
zenesulfenate [(2)-menthyl benzenesulfenate]. 87%

´
G. Petrovic et al. / Tetrahedron 59 (2003) 187–196
193
Yield, yellow-green oil, bp 108–1108C/0.07 mm Hg. Micro
analysis was not performed because the compound decom-
poses with explosion in the Pregl apparatus, [a]2D2¼2256.7
(c¼1, CHCl3) of 92% purity of compound (determined by
1H NMR spectrum). IR (neat, cm21): 3062, 2000–1600,
1583, 1477, 1455, 1440, 1387, 1370, 1345, 1097, 1024,
1004, 981, 959, 914, 851, 778, 738, 690. 1H NMR
(200 MHz) d: 0.62 (d, J¼7.0 Hz, 3H), 0.87 (d, J¼7.2 Hz,
3H), 0.88 (d, J¼7.2 Hz, 3H), 0.72–1.00 (m, 3H), 1.20–1.38
(m, 2H), 1.54–1.66 (m, 2H), 2.18–2.38 (m, 2H), 3.37 (td,
J1¼10.7 Hz, J2¼4.4 Hz, 1H), 7.10–7.40 (m, 5H). 13C NMR
(50 MHz) d: 141.29, 128.52, 126.65, 125.37, 87.01, 48.62,
40.88, 34.10, 31.50, 25.06, 22.93, 22.03, 20.87, 15.59.
15 min. Benzene was removed by evaporation and the
reaction products from an oily residue were separated by
chromatography on silica gel column using petrolether/
aceton 95:5 or 90:10.
3.2.1. 4-Phenylthio-1-butanol (12). A solution of of
n-butyl benzenesulfenate (0.091 g, 0.5 mmol) and hexa-
butylditin (0.040 g, 0.07 mmol) in benzene (2 mL) was
irradiated according to general procedure. 4-Phenylthio-1-
butanol was isolated by column chromatography in 17%
(15 mg) as a colorless oil. IR (neat, cm21): 3381, 2000–
1
1600, 1584, 1481, 1439, 1062, 1026, 739, 691. H NMR
(200 MHz) d: 1.67–1.76 (m, 4H), 2.96 (t, J¼7.0 Hz, 2H),
3.66 (t, J¼6.0 Hz, 2H) 7.10–7.40 (m, 5H). 13C NMR
(50 MHz) d: 136.57, 129.12, 128.88, 125.86, 62.34, 33.43,
31.67, 25.45. HRMS calcd for C10H14OS (Mþ): 182.0765.
Found: 182.0767.
3.1.10. N-Carbethoxy nortropine-3a-benzenesulfenate.
97% Yield, yellow-green crystals, mp 458C. Anal. calcd
C16H21NO3S: C, 62.54; H, 6.84; N, 4.56. Found: C, 62.68,
H, 7.05, N, 4.42. IR (KBr, cm21): 2000–1800, 1696, 1583,
1477, 1439, 1383, 1354, 1325, 1314, 1225, 1212, 1169,
1107, 1032. 1H NMR (200 MHz) d: 1.23 (t, J¼7.0 Hz, 3H),
1.89–2.13 (m, 8H), 3.74–3.82 (m, 1H), 4.11 (q, J¼7.0 Hz,
2H), 4.17–4.30 (m, 2H), 7.11–7.40 (m, 5H). 13C NMR
(50 MHz) d: 153.67, 140.05, 128.92, 126.43, 123.74, 80.00,
60.70, 52.15, 36.13, 35.53, 28.24, 27.61, 14.64. MS (CI):
308 (Mþþ1) 100%, 183 [(Mþþ1)–OSPh] 50%.
3.2.2. 4-Phenylthio-1-pentanol (10). Obtained from
n-pentyl benzenesulfenate in 80% yield, isolated as a
colorless liquid. IR (neat, cm21): 3385, 2000–1600, 1584,
1480, 1439, 1404, 1377, 1263, 1092, 1065, 1025, 910, 739,
693. 1H NMR (200 MHz) d: 1.29 (d, J¼6.8 Hz, 3H), 1.56–
1.78 (m, 5H), 3.25 (sext, J¼6.6 Hz, 1H), 3.64 (t, J¼6.2 Hz,
1H), 7.17–7.33 (m, 3H) 7.36–7.43 (m, 2H). 13C NMR
(50 MHz) d: 135.09, 132.00, 128.79, 126.75, 62.61, 43.14,
32.75, 30.04, 21.15. HRMS calcd for C11H16OS (Mþ):
196.0922. Found: 196.0924.By photolysis of n-pentyl
benzenesulfenate in benzene solution in the absence of
hexabutylditin for 1 h, 4-phenylthio-1-pentanol (10) was
obtained in 64% yield.
3.1.11. 3b-Acetoxy-5-pregnen-20b-yl benzenesulfenate.
48% Yield, pale yellow crystals, IR (KBr, cm21): 3074,
2000–1600, 1732, 1584, 1477, 1438, 1370, 1332, 1249,
1198, 1146, 1134, 1119, 1091, 1072, 1039, 1011, 959, 931,
902, 891, 881, 865, 803, 772, 731, 688. 1H NMR (200 MHz)
d: 0.59 (s, 3H), 1.02 (s, 3H), 1.16 (d, J¼6.2 Hz, 3H), 0.92–
1.32 (m, 7H), 1.37–1.67 (m, 8H), 1.69–1.91 (m, 2H), 2.03
(s, 3H), 2.08–2.15 (m, 1H), 2.29–2.34 (m, 2H), 3.69–3.80
(m, 1H), 4.58–4.63 (m, 1H), 5.36 (d, J¼4.4 Hz, 1H), 7.17–
7.46 (m, 5H). 13C NMR (50 MHz) d: 170.51, 141.20,
139.73, 128.61, 127.09, 126.59, 122.40, 86.36, 73.89, 56.58,
55.97, 49.94, 42.09, 39.09, 38.04, 36.90, 36.54, 31.80,
31.66, 27.66, 25.65, 24.30, 21.37, 20.77, 19.44, 19.26,
12.03.
3.2.3. 4-Phenylthio-1-octanol (14). The title compound
was isolated as a colorless oil in 47% yield. Anal. calcd
C14H22OS: C, 70.54; H, 9.30; S, 13.45. Found: C, 70.32; H,
9.46; S, 13.45. IR (neat, cm21): 3348, 2000–1600, 1584,
1479, 1467, 1455, 1439, 1379, 1306, 1091, 1065, 1026, 745,
693. 1H NMR (200 MHz) d: 0.88 (t, J¼7.1 Hz, 3H), 1.24–
1.84 (m, 10H), 3.10 (quin, J¼6.6 Hz, 1H), 3.58–3.68 (m,
2H), 7.20–7.45 (m, 5H). 13C NMR (50 MHz) d: 135.49,
131.86, 128.76, 126.59, 62.67, 48.90, 34.21, 30.61, 29.75,
28.86, 22.51, 13.92. MS (CI): 239 (Mþþ1) 100% (exact
mass: 238.14; mol. wt: 238.39).
3.1.12. 3b-Acetoxy-5-pregnen-20a-yl benzenesulfenate.
54% Yield, pale yellow crystals, IR (KBr, cm21): 3054,
2000–1600, 1731, 1581, 1472, 1441, 1372, 1330, 1245,
1195, 1146, 1132, 1114, 1102, 1070, 1030, 1010, 954, 929,
3.2.4. 2-Phenylthio-5-heptanol (13). In the photolysis of
3-heptyl benzenesulfenate (0.11 g, 0.5 mmol) in the
presence of hexabutylditin, the title compound was isolated
as a colorless oil (0.1 g, 91% yield) and a mixture of two
diastereoisomers (1:1) was obtained. Anal. calcd C13H20OS:
C, 69.59; H, 8.98; S, 14.29. Found: C, 69.44; H, 9.07; S,
14.33. IR (neat, cm21): 3413, 3075 2000–1600, 1585, 1480,
1457, 1439, 1377, 1303, 1263, 1217, 1093, 1069, 1026,
1
900, 865, 744, 691. H NMR (200 MHz) d: 0.59 (s, 3H),
0.99 (s, 3H), 1.30 (d, J¼6.0 Hz, 3H), 0.92–1.32 (m, 7H),
1.37–1.67 (m, 8H), 1.83–1.92 (m, 2H), 2.03 (s, 3H), 2.08–
2.15 (m, 1H), 2.29–2.34 (m, 2H), 3.50–3.64 (m, 1H), 4.50–
4.68 (m, 1H), 5.37 (d, J¼4.8 Hz, 1H), 7.17–7.49 (m, 5H).
13C NMR (50 MHz) d: 170.54, 141.51, 139.57, 128.65,
126.58, 125.09, 122.49, 87.85, 73.85, 56.82, 56.39, 49.79,
41.85, 38.63, 38.01, 36.90, 36.49, 31.75, 31.50, 27.66,
25.62, 24.12, 21.37, 20.65, 20.10, 19.22, 12.24.
1
1000, 971, 910, 759, 693. H NMR (200 MHz) d: 0.93 (t,
J¼7.4 Hz, 3H), 1.30 (d, J¼6.6 Hz, 3H), 1.40–1.80 (m, 6H),
3.13–3.30 (m, 1H), 3.45–3.57 (m, 1H), 7.20–7.35 (m, 3H),
7.36–7.46 (m, 2H). 13C NMR (50 MHz) d: 135.17, 131.10,
128.78, 126.66, 73.04, 72.95, 43.40, 43.29, 34.16, 33.91,
32.65, 32.43, 30.15, 30.07, 21.16, 9.77. MS (CI): 225
(Mþþ1) 100%, 207 [(Mþþ1)–H2O] 50% (exact mass:
224.12; mol. wt: 224.36).
3.2. Phenylsulfenylation of non-activated d-carbon atom
by photolysis of alkyl benzenesulfenates in the presence
of hexabutylditin
General procedure. A solution of 0.5 mmol of alkyl
benzenesulfenate and 0.07 mmol (40 mg) of hexabutylditin
in 2 mL of benzene was irradiated at rt, in an argon
atmosphere, by a 125 W high pressure mercury lamp during
3.2.5. cis- and trans-2-(2-Phenylthiocyclohexyl)-ethanol
(15). This compound was obtained in 51% yield from

´
G. Petrovic et al. / Tetrahedron 59 (2003) 187–196
194
2-(cyclohexyl)-ethyl benzenesulfenate. The title compound
was isolated as a colorless oil and contains cis- 15b and
trans-isomer 15a in ratio of 0.86:1. Anal. calcd C14H20OS:
C, 71.14; H, 8.53; S, 13.57. Found: C, 71.00; H, 8.70; S,
13.30. IR (neat, cm21): 3335, 2000–1600, 1584, 1479,
1439, 1350, 1271, 1088, 1068, 1048, 1026, 1008, 974, 901,
thiomenthol] (19a). The title compound was obtained as
a white crystalline compound, mp 498C, [a]2D1¼229.4
(c¼1, CHCl3), in 39% yield by photolysis of (2)-menthyl
benzenesulfenate according to the described procedure.
Anal. calcd C16H24OS: C, 72.67; H, 9.15; S, 12.13. Found:
C, 72.72; H, 9.33; S, 12.41. IR (neat, cm21): 3392, 2000–
1600, 1584, 1480, 1455, 1439, 1377, 1312, 1263, 1147,
1
749, 692. H NMR (200 MHz) d: 1.00–2.10 (m, 11.46H),
1
2.26 (dt, J1¼10.6 Hz, J2¼7.4 Hz, 0.54H), 2.84 (td, Jaa¼
10.1 Hz, Jae¼3.6 Hz, 0.54H), 3.50 (td, Jee¼4.4 Hz, Jae¼
3.4 Hz, 0.46H), 3.62–3.82 (m, 2H), 7.15–7, 48 (m, 5H). 13C
NMR (50 MHz) d: 136.30, 135.09, 132.22, 131.34, 128.81,
128.72, 126.68, 126.32, 60.67, 52.64, 51.65, 38.84, 37.29,
37.11, 35.76, 34.16, 32.10, 31.03, 28.62, 26.07, 25.24,
24.73, 21.91. MS (CI): 237 (Mþþ1) 100% (exact mass:
236.12; mol. wt: 236.37).
1091, 1049, 1026, 991, 965, 922, 885, 846, 737, 691. H
NMR (200 MHz) d: 0.91 (d, J¼6.2 Hz, 3H), 0.94 (d, J¼
6.4 Hz, 3H), 0.82–1.14 (m, 2H), 1.25–1.71 (m, 5H), 1.92–
2.03 (m, 1H), 2.34 (sext, J1¼7.4 Hz, J2¼2.8 Hz, 1H), 2.80–
2.95 (m, 2H), 3.40 (td, Jaa¼10.4 Hz, Jae¼4.2 Hz, 1H),
7.10–7.36 (m, 5H). 13C NMR (50 MHz) d: 137.24, 128.81,
125.61, 71.04, 47.58, 45.01, 39.36, 34.19, 31.52, 30.99,
23.18, 22.09, 13.88. MS (CI): 265 (Mþþ1) 60%, 247
[(Mþþ1)–H2O] 100%.
3.2.6. 4-Phenylthiocyclooctanol (16). The title compound
was obtained (from cyclooctyl benzenesulfenate, 0.12 g,
0.5 mmol) as a mixture of cis- and trans-isomers and
isolated (40 mg, 35% yield) as colorless oil. IR (neat,
cm21): 3353, 2000–1600, 1584, 1475, 1439, 1365, 1275,
1238, 1146, 1091, 1068, 1045, 1026, 1000, 910, 750, 737,
3.2.10. (2)-(1R,2S,5R,10R)-5-Methyl-2-(1-methyl-2-
phenylthio-ethyl)-cyclohexanol 19b. The title compound
was also isolated by repeated chromatography of the residue
after isolation of the isomer 19a using toluene/ethyl acetate
95:5 as an eluent. Stereoisomer 19b was isolated as a
viscous colorless oil (9.8 mg, 3.7% yield), [a]2D2¼244.0
(c¼1, CHCl3). Anal. calcd C16H24OS: C, 72.67; H, 9.15; S,
12.13. Found: C, 72.33; H, 9.15; S, 12.22. IR (neat, cm21):
3364, 2000–1600, 1583, 1476, 1449, 1376, 1304, 1258,
1
692. H NMR (200 MHz) d: 1.25–2.20 (m, 13H), 3.25–
3.45 (m, 1H), 3.80–3.95 (m, 1H), 7.20–7.45 (m, 5H). 13C
NMR (50 MHz) d: 135.59, 131.90, 131.75, 128.85, 126.73,
126.68, 71.77, 71.44, 48.13, 47.99, 34.13, 33.87, 32.81,
32.55, 30.40, 30.27, 27.66, 27.62, 25.28, 25.03, 22.71,
22.07. HRMS calcd for C14H20OS (Mþ): 236.1235. Found:
236.1239.
1
1223, 1170, 1090, 1022, 969, 922, 891, 847, 740, 694. H
NMR (200 MHz) d: 0.90 (d, J¼6.6 Hz, 3H), 1.07 (d, J¼
6.9 Hz, 3H), 0.81–1.14 (m, 3H), 1.26–1.45 (m, 2H), 1.57–
1.70 (m, 2H), 1.87–1.98 (m, 1H), 2.05–2.25 (m, 1H), 2.70
(dd, Jgem¼12.6 Hz, Jvic¼9.1 Hz, 1H), 3.15 (dd, Jgem¼12.6
Hz, Jvic¼4.9 Hz, 1H), 3.50 (td, Jaa¼10.4 Hz, Jae¼4.2 Hz,
1H), 7.10–7.38 (m, 5H). 13C NMR (50 MHz) d: 137.29,
128.80, 128.77, 125.60, 71.05, 49.19, 45.05, 37.56, 34.42,
33.02, 31.46, 25.77, 22.02, 17.09.
3.2.7. endo-2-Hydroxymethyl-exo-6-phenylthio-norbor-
nane (17). The title compound was obtained as colorless
oil in 64% yield, from endo-2-norbornyl benzenesulfenate
according to the general procedure. IR (neat, cm21): 3362,
2000–1600, 1585, 1483, 1439, 1353, 1326, 1305, 1285,
1268, 1094, 1068, 1044, 1017, 975, 898, 734, 693. 1H NMR
(200 MHz) d: 0.67 (ddd, J1¼12.4 Hz, J2¼5.3 Hz, J3¼
2.6 Hz, 1H), 1.25–1.38 (m, 2H), 1.43–1.59 (m, 1H), 1.68–
1.86 (m, 3H), 2.12–2.42 (m, 3H), 3.56 (ddd, J1¼8.4 Hz,
J2¼4.3 Hz, J3¼1.6 Hz, 1H), 3.60–3.78 (m, 2H), 7.10–7.40
(m, 5H). 13C NMR (50 MHz) d: 137.68, 128.79, 128, 40,
125.43, 63.93, 43.87, 42.34, 41.42, 38.88, 37.12, 36.73,
32.33. HRMS calcd for C14H18OS (Mþ): 234.1078. Found:
234.1082.
3.2.11. (2)-(1R,3R,4S,8S)-Menthane-3,9-diol (31a). The
title compound was prepared from 19a,19,20 white crystals,
mp 908C (lit. 908C),18 [a]D22¼248.6 (c¼1, CHCl3). IR (KBr,
cm21): 3256, 3223, 1487 1455, 1413, 1375, 1345, 1324,
1276, 1234, 1168, 1107, 1081, 1050, 1017, 1000, 954, 918,
1
883, 845, 744. H NMR (200 MHz) d: 0.85 (d, J¼7.1 Hz,
3H), 0.91 (d, J¼6.6 Hz, 3H), 0.71–1.12 (m, 3H), 1.25–1.55
(m, 2H), 1.58–1.68 (m, 2H), 1.93–2.11 (m, 2H), 5.39 (s,
broad, 2H), 3.43 (td, Jaa¼10.6 Hz, Jae¼4.2 Hz, 1H), 3.48
(dd, Jgem¼10.6 Hz, Jvic¼7.6 Hz, 1H), 3.58 (dd, Jgem¼10.6
Hz, Jvic¼5.6 Hz, 1H). 13C NMR (50 MHz) d: 71.59, 66.53,
45.50, 45.04, 35.52, 34.28, 31.48, 25.16, 22.12, 12.47.
3.2.8. endo-2-Acetoxymethyl-exo-6-phenylthio-norbor-
nane. This compound was prepared in order to confirm
the exo orientation of the phenylthio group in endo-2-
hydroxymethyl-6-phenylthio-norbornane. Colorless oil, IR
(neat, cm21): 2000–1600, 1749, 1586, 1464, 1378, 1301,
Spectral evidence and mp of diastereoizomer 31a indepen-
dently prepared from (2)-isopulegol are identical with the
same isomer prepared from 19a and has [a]2D2¼244.0 (c¼1,
CHCl3).
1
1235, 1122, 1040, 798, 736, 690. H NMR (200 MHz) d:
0.70 (ddd, J1¼12.2 Hz, J2¼5.2 Hz, J3¼2.6 Hz, 1H), 1.25–
1.38 (m, 2H), 1.70–1.87 (m, 3H), 1.99 (s, 3H), 2.21–2.35
(m, 3H), 3.50 (ddd, J1¼8.3 Hz, J2¼4.5 Hz, J3¼1.6 Hz, 1H),
3.92 (dd, Jgem¼11.0 Hz, Jvic¼10.6 Hz, 1H), 4.22 (dd,
Jgem¼11.0 Hz, Jvic¼6.6 Hz, 1H), 7.10–7.40 (m, 5H). 13C
NMR (50 Hz) d: 171.02, 137.40, 129.19, 128.76, 125.76,
65.05, 44.01, 41.83, 38.57, 38.46, 36.92, 36.67, 32.27,
20.86. HRMS calcd for C16H20O2S (Mþ): 276.1184. Found:
276.1187.
3.2.12. (2)-(1R,3R,4S,8R)-Menthane-3,9-diol (31b). The
title compound was prepared from 19b, white crystals, mp
1078C (lit. 1078C),18 [a]D22¼216.2 (c¼1, CHCl3). IR (KBr,
cm21): 3251, 1487, 1455, 1372, 1337, 1309, 1272, 1218,
1171, 1150, 1103, 1043, 1018, 993, 951, 846, 698. 1H NMR
(200 MHz) d: 0.92 (d, J¼6.9 Hz, 3H), 0.96 (d, J¼7.6 Hz,
3H), 0.77–1.05 (m, 2H), 1.12–1.48 (m, 3H), 1.50–1.69 (m,
2H), 1.76–2.03 (m, 2H), 3.28 (s, broad, 2H), 3.45 (td
Jaa¼10.4 Hz, Jae¼4.2 Hz, 1H), 3.58 (dd, Jgem¼10.6 Hz,
3.2.9. (2)-(1R,2S,5R,10S)-5-Methyl-2-(1-methyl-2-phenyl-
thio-ethyl)-cyclohexanol [(2)-(1R,3R,4S,8S)-9-phenyl-

´
G. Petrovic et al. / Tetrahedron 59 (2003) 187–196
195
Jvic¼3.5 Hz, 1H), 3.66 (dd, Jgem¼10.6 Hz, Jvic¼5.3 Hz,
1H). 13C NMR (50 MHz) d: 70.06, 67.07, 48.49, 44.50,
38.56, 34.54, 31.39, 29.49, 22.01, 11.85.
C16H21NO3S: C, 62.54; H, 6.84; N, 4.56. Found: C, 62.51;
H, 6.71; N, 4.44. IR (KBr, cm21): 3413, 2000–1600, 1661,
1483, 1431, 1384, 1330, 1162, 1114, 1097, 1046, 1011. H
1
NMR (200 MHz) d: 1.21–1.30 (m, 3H), 1.69–2.20 (m, 6H),
2.69–2.84 (m, 1H), 4.10–4.40 (m, 5H), 7.18–7.36 (m, 5H).
13C NMR (50 MHz) d: 154.59, 154.25, 136.86, 136.65,
129.92, 129.82, 128.90, 126.24, 64.54, 61.05, 59.55, 59.36,
53.02, 52.76, 47.88, 47.14, 38.29, 37.99, 37.69, 37.63,
36.92, 36.15. MS (CI): 308 (Mþþ1) 100%.
Stereoisomer 31b independently prepared from (2)-iso-
pulegol has identical spectral evidence and mp as the same
isomer prepared from 19b and [a]2D2¼215.6 (c¼1, CHCl3).
3.2.13. t-3,t-5-Dimethyl-c-3-phenylthiomethyl-r-cyclo-
hexanol (18). The title compound was isolated as a colorless
oil in 62% yield in the photolysis of trans-3,3,5-trimethyl-
cyclohexyl benzenesulfenate in the presence of hexabutyl-
ditin. Anal. calcd C15H22OS: C, 71.95; H, 8.86; S, 12.81.
Found: C, 71.72; H, 8.73; S, 12.69. IR (neat, cm21): 3410,
2000–1600, 1584, 1481, 1456, 1439, 1377, 1366, 1337,
1290, 1262, 1218, 1174, 1152, 1091, 1043, 1026, 1013, 949,
References
1. Leading references: (a) Heusler, K.; Kalvoda, J. Angew.
´
Chem., Int. Ed. Engl. 1964, 3, 525–538. (b) Mihailovic, M. Lj.;
1
ˇ
ˇ
909, 809, 756, 737, 691. H NMR (200 MHz) d: 0.85 (d,
´
Cekovic, Z. Synthesis 1970, 209–224. (c) Kalvoda, J.;
Heusler, K. Synthesis 1971, 501–526. (d) Barton, D. H. R.
Pure Appl. Chem. 1968, 16, 1. (e) Hesse, R. H. Adv. Free
Radical Chem. 1969, 3, 83. (f) Majetich, G.; Wheless, K.
Tetrahedron (Rep. No. 375) 1995, 51, 7095–7129.
(g) Robertson, J.; Pillai, J.; Lush, R. K. Chem. Soc. Rev.
2001, 30, 94–103. (h) Wolff, M. E. Chem. Rev. 1963, 63,
55–64.
J¼6.6 Hz, 3H), 1.00 (s, 3H), 0.82–2.02 (m, 8H), 3.31 (AB
q, DdAB¼0.28, J¼11.8 Hz, 2H), 4.15 (quint, J¼3.2 Hz, 1H),
7.09–7.29 (m, 3H), 7.34–7.40 (m, 2H). 13C NMR
(50 MHz) d: 137.99, 129.31, 128.77, 125.60, 67.69, 46.71,
44.95, 41.57, 41.09, 34.76, 30.48, 22.31, 22.24. MS (CI):
251 (Mþþ1) 100%, [Mþþ1)–H2O] 50% (exact mass:
250.14; mol. wt: 250.40).
2. (a) Barton, D. H. R.; Beaton, J. M.; Geller, L. E.; Pechet, M. M.
J. Am. Chem. Soc. 1960, 82, 2640–2641. (b) Barton, D. H. R.;
Beaton, J. M.; Geller, L. E.; Pechet, M. M. J. Am. Chem. Soc.
1961, 83, 4076–4083. (c) Walling, C.; Padwa, A. J. Am.
Chem. Soc. 1961, 83, 2207–2208. (d) Walling, C.; Padwa, A.
J. Am. Chem. Soc. 1963, 85, 1597–1601. (e) Cainelli, G.;
3.2.14. 3b-Acetoxy-20b-hydroxy-18-phenylthio-5-preg-
nene (20). The title compound was obtained in 40% yield
by photolysis of 3b-acetoxy-5-pregnen-20b-yl benzenesul-
fenate according to the general procedure. White crystalline
compound, mp 1498C. IR (KBr, cm21): 3464, 2000–1600,
1730, 1582, 1441, 1370, 1247, 1135, 1032, 943, 879, 735.
1H NMR (200 MHz) d: 0.92 (s, 3H), 1.14 (d, J¼6.2 Hz, 3H),
0.88–1.95 (m, 18H), 2.01 (s, 3H), 2.25–2.36 (m, 2H), 2.93
(AB q, DdAB¼0.46, J¼12.2 Hz, 2H), 3.76–3.94 (m, 1H),
4.52–4.68 (m, 1H), 5.36 (d, J¼4.8 Hz, 1H), 7.21–7.42 (m,
5H). 13C NMR (50 MHz) d: 170, 36, 139.69, 136.88,
129.94, 128.94, 126.46, 121.99, 73.67, 69.47, 58.65, 57.16,
49.60, 46.13, 37.91, 36.72, 36.38, 36.08, 34.05, 31.83,
31.57, 27.51, 25.48, 23.92, 22.15, 21.24, 19.13. HRMS
calcd for C29H40O3S (Mþ): 468.2703. Found: 468.2698.
´
Mihailovic, M. Lj.; Arigoni, D.; Jeger, O. Helv. Chim. Acta
ˇ
1959, 42, 1124–1127. (f) Mihailovic, M. Lj.; Cekovic, Z.;
ˇ
´
´ ´
Maksimovic, Z.; Jeremic, D.; Lorenc, Lj.; Mamuzic, R. I.
´
´
ˇ
Tetrahedron 1965, 21, 2799–2812. (g) Cekovic, Z.; Green,
ˇ
´
ˇ
M. M. J. Am. Chem. Soc. 1974, 96, 3000–3002. (h) Cekovic,
´
ˇ
Z.; Cvetkovic, M. Tetrahedron Lett. 1982, 23, 3791–3794.
´
3. (a) Dorigo, A. E.; Houk, K. N. J. Org. Chem. 1988, 53,
1650–1664. (b) Weavers, R. T. J. Org. Chem. 2001, 66,
6453–6461.
4. (a) Barton, D. H. R.; Beaton, J. M. J. Am. Chem. Soc. 1960, 82,
2641. (b) Barton, D. H. R.; Beaton, J. M. J. Am. Chem. Soc.
1961, 83, 4083–4089. (c) Barton, D. H. R.; Beaton, J. M.
J. Am. Chem. Soc. 1962, 84, 199–204. (d) Acott, B.;
Beckwith, A. L. J. Aust. J. Chem. 1964, 17, 1342–1353.
(e) Meystre, C.; Heusler, K.; Kalvoda, J.; Wieland, P.; Anner,
G.; Wettstein, A. Helv. Chim. Acta 1962, 45, 2161–2175.
3.2.15. 3b-Acetoxy-20a-hydroxy-18-phenylthio-5-preg-
nene (21). The title compound was obtained as a white
crystalline compound in 40% yield by photolysis of 3b-
acetoxy-5-pregnen-20a-yl benzenesulfenate as described
above. IR (KBr, cm21): 3451, 2000–1600, 1731, 1582,
1439, 1370, 1246, 1031, 955, 874, 739. 1H NMR (200 MHz)
d: 0.99 (s, 3H), 1.25 (d, J¼6.2 Hz, 3H), 0.95–1.98 (m, 18H),
2.03 (s, 3H), 2.26–2.37 (m, 2H), 2.32 (AB q, DdAB¼0.12,
J¼11.4 Hz, 2H), 4.16–4.27 (m, 1H), 4.54–4.67 (m, 1H),
5.38 (d, J¼4.4 Hz, 1H), 7.19–7.38 (m, 5H). 13C NMR
(50 MHz) d: 170.55, 139.79, 136.41, 129.74, 129.06,
126.49, 122.22, 73.80, 65.28, 57.88, 57.58, 49.97, 44.87,
38.00, 36.90, 36.63, 34.63, 34.21, 31.68, 27.64, 23.43,
21.35, 20.56, 19.23. HRMS calcd for C29H40O3S (Mþ):
468.2703. Found: 468.2698.
ˇ
(f) Cekovic, Z.; Dimitrijevic, Lj.; Djokic, G.; Srnic, T.
ˇ
´
´
´
´
Tetrahedron 1979, 35, 2021–2026.
5. (a) Akhtar, M.; Barton, D. H. R.; Sammes, P. G. J. Am. Chem.
Soc. 1965, 87, 4601–4607. (b) Allen, J.; Boar, R. B.; McGhie,
J. F.; Barton, D. H. R. J. Chem. Soc., Perkin Trans. 1 1973,
2402–2404. (c) Barton, D. H. R.; Day, M. J.; Hesse, R. H.;
Pechet, M. M. J. Chem. Soc., Perkin Trans. 1 1975,
2252–2256.
6. Pasto, D. J.; Gottard, F. Tetrahedron Lett. 1994, 35,
4303–4306.
ˇ
7. Petrovic, G.; Cekovic, Z. Tetrahedron Lett. 1997, 38,
ˇ
´
´
3.2.16. exo- and endo-6-Phenylthio-N-carbethoxy nor-
tropine (22). A solution of N-carbethoxy nortropine-3a-
benzenesulfenate (1.5 g, 4.88 mmol) and hexabutylditin
(0.44 g, 0.76 mmol) in benzene was irradiated for 1.5 h and
the title compound was isolated (2.7 g, 45%) yield) as a
white crystalline compound, mp 1198C. Anal. calcd
627–630.
ˇ
ˇ
´
8. Cekovic, Z.; Ilijev, D. Tetrahedron Lett. 1988, 29,
1441–1444.
9. Tsunoi, S.; Ryu, I.; Okuda, T.; Tanaka, M.; Komatsu, M.;
Sonoda, N. J. Am. Chem. Soc. 1998, 120, 8692–8701.
ˇ
10. Petrovic, G.; Cekovic, Z. Tetrahedron 1999, 55, 1377–1390.
ˇ
´
´

´
G. Petrovic et al. / Tetrahedron 59 (2003) 187–196
196
11. (a) Wagner, P. G.; Lindstom, M. J. J. Am. Chem. Soc. 1987,
109, 3057–3062. (b) Curran, D. P.; van Elbuty, P. E.; Giese,
B.; Gilges, S. Tetrahedron Lett. 1990, 31, 2861–2864.
12. (a) Keck, G. E.; Enholm, E. J.; Yates, J. B.; Wiley, M. R.
Tetrahedron 1985, 41, 4079–4094. (b) Keck, G. E.; Enholm,
E. J. Tetrahedron Lett. 1985, 26, 3311–3314. (c) Keck, G. E.;
Yates, J. B. J. Org. Chem. 1982, 47, 3590–3591.
17. (a) Giese, B.; Heuck, K.; Leuhardt, H.; Luning, U. Chem. Ber.
1984, 117, 2132–2139. (b) Biwala, R. M.; Vogel, P. J. Org.
Chem. 1992, 57, 2076–2083.
18. (a) Schulte-Elte, K. H.; Ohloff, G. Helv. Chim. Acta 1976, 50,
153–165. (b) Schmid, G.; Hofheinz, W. J. Am. Chem. Soc.
1983, 105, 624–625.
19. Trost, B. M.; Salymann, T. N. J.; Hiroi, K. J. Am. Chem. Soc.
1976, 98, 4887–4902.
ˇ
ˇ
´
ˇ ´
´
13. Petrovic, G.; Saicic, R. N.; Cekovic, Z. Tetrahedron Lett.
1997, 38, 7107–7110.
20. De Lucchi, O.; Miotti, U.; Modsena, G. Org. React. 1991, 40,
157–405, and references therein.
14. (a) Beckwith, A. L. J. J. Chem. Soc. Rev. 1993, 143–151.
(b) Franz, J. A.; Roberts, D. H.; Ferris, K. J. Org. Chem. 1987,
52, 2256–2262. (c) Perkins, C. W.; Martin, J. C.; Arduengo,
A. J.; Lau, W.; Alegria, A.; Kochi, J. K. J. Am. Chem. Soc.
1980, 102, 7753–7759.
21. (a) Uemura, S. Comprehensive Organic Synthesis; Trost,
B. M., Fleming, I., Eds.; Pergamon: Oxford, 1991; Vol. 7, pp
757–787 and references therein. (b) Kresze, G. Meth. Org.
Chem. (Houben Weyl) 1985, E 11, 669–886.
15. Damm, W.; Giese, B.; Hartung, J.; Hasskerl, T.; Houk, K. N.;
Huter, O.; Zipse, H. J. Am. Chem. Soc. 1992, 114, 4067–4079.
1
16. In the H NMR spectrum of the mixture of isomers 15 two
22. Ogura, K. Comprehensive Organic Synthesis; Trost, B. M.,
Fleming, I., Eds.; Pergamon: Oxford, 1991; Vol. 1, pp
505–539 and references therein.
signals were obtained for hydrogens next to the phenylthio
group, signals at d¼2.84 ppm belong to the trans-isomer 15a
and at d¼3.50 ppm are from the cis-isomer 15b and they
possess different coupling constants. This is in agreement
with described results. Eliel, E.; Wilen, S. H. Stereochemistry
of Organic Compounds; Wiley: New York, 1994, pp 712.
23. (a) Kennedy, M.; McKervey, M. A. Comprehensive Organic
Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon: Oxford,
1991; Vol. 7, pp 193–216 and references therein. (b) Dilworth,
B. M.; McKervey, M. A. Tetrahedron 1986, 42, 3731–3752.
24. (a) Hartung, J.; Gallou, F. J. Org. Chem. 1995, 60,
6706–6716. (b) Beckwith, A. L. J.; Hay, B. P.; Williams,
G. M. J. Chem. Soc., Chem. Commun. 1989, 1202–1203.