2-(Selenocyanatomethyl)-2-propenol-A convenient synthon for ligation via the deselenative allylic rearrangement of allyl selenosulfides: Preparation, functional group compatibility, and application

Article abstract of DOI:10.1139/v2012-056

The preparation and reactions of 2-(selenocyanatomethyl)-2-propenol are described and reveal the compatibility of the allylic selenocyanate group with a range of mild oxidizing and Lewis acidic conditions. 2-(Selenocyanatomethyl)-2- propenol and its derivatives are employed in the functionalization of simple and amino acid derived thiols in methanolic solution at room temperature to give 2-(hydroxymethyl)allyl sulfides in good to excellent yield.

Full text of DOI:10.1139/v2012-056

944
2-(Selenocyanatomethyl)-2-propenol — A
convenient synthon for ligation via the
deselenative allylic rearrangement of allyl
selenosulfides: preparation, functional group
compatibility, and application
David Lachkar, Caroline Boudet, Xavier Guinchard, and David Crich
Abstract: The preparation and reactions of 2-(selenocyanatomethyl)-2-propenol are described and reveal the compatibility
of the allylic selenocyanate group with a range of mild oxidizing and Lewis acidic conditions. 2-(Selenocyanatomethyl)-2-
propenol and its derivatives are employed in the functionalization of simple and amino acid derived thiols in methanolic
solution at room temperature to give 2-(hydroxymethyl)allyl sulfides in good to excellent yield.
Key words: selenocyanates, selenosulfides, selenosulfoxides, ligation.
Résumé : Nous décrivons la préparation et les réactions de dérivatisation du 2-(sélénocyanatométhyl)-prop-2-énol,
montrant ainsi la compatibilité fonctionnelle du groupement sélénocyanate allylique envers les réactions en conditions
oxydantes et en présence d’acides de Lewis. Cet alcool et ses dérivés fonctionnalisés ont été engagés dans des réactions
de fonctionnalisation de thiols a température ambiante dans des conditions douces pour conduire a des sulfures de
`
`
2-(hydroxyméthyl)allyle avec de bons rendements.
Mots-clés : sélénocyanates, sélénosulfures, sélénosulfoxydes, ligature.
but were foiled in many of our attempts to derivatize the
hydroxyl group by the relative sensitivity of the allylic disul-
fide functionality.5 For this reason, we turned to the allylic
selenocyanates6 with the expectation of greater stability to a
number of derivatization reactions.2b To avoid possible prob-
lems arising from facile 1,3-sigmatropic rearrangement of
disymmetric allylic selenocyanates, we targeted systems in
which such rearrangements would have a degenerate nature,
namely, those based on methallyl selenocyanate substituted at
the 2 postion as in 2.
Introduction
Organoselenium chemistry is a major component of the
organic chemist’s toolbox,1 and the organoselenocyanates are
some of the most readily available and versatile of the
chalcogenide-based reagents. For our part, we have developed
the use of allylic seleno Bunte salts and allylic selenocyanates
as convenient precursors to the allyl selenosulfides, substrates
for dechalcogenative rearrangement to allyl alkyl sulfides
(Scheme 1),2 and as our contribution to the burgeoning field3
of chemical ligation. In continuation of this program we re-
quired a minimal hydroxyl-substituted allylic selenocyanate to
serve as a handle for introduction of the allylic selenocyanate
group into a range substrates. We report here on the synthesis
of 2-(selenocyanatomethyl)allyl alcohol for this purpose, on
functional group compatibility of the selenocyanate moiety,
and on its incorporation into various substrates.
We focused on 2-(selenocyanatomethyl)-3-propenol (6), as
the smallest possible alcohol derived from methallyl selenocy-
anate. To this end, p-methoxybenzyl alcohol was alkylated
with methallyl chloride to give the ether7 3, which was con-
verted with sulfuryl chloride into the known8 methallyl chlo-
ride 4 in 29% yield (Scheme 2). Reaction with potassium
In earlier work on the desulfurative allylic rearrangement of allyl
alkyl disulfides, we developed 2-(2-pyridyldithio)-3-propenol (1) or
its analogs as precursors to the necessary allyl alkyl disulfides,2b,4
Received 13 January 2012. Accepted 3 July 2012. Published at www.nrcresearchpress.com/cjc on 22 October 2012.
D. Lachkar, C. Boudet, and X. Guinchard. Centre de Recherche de Gif, Institut de Chimie des Substances Naturelles, CNRS, 1
Avenue de la Terrasse, 91190 Gif-sur-Yvette, France.
D. Crich. Centre de Recherche de Gif, Institut de Chimie des Substances Naturelles, CNRS, 1 Avenue de la Terrasse, 91190 Gif-sur-
Yvette, France; Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI 48202, USA.
Corresponding author: David Crich (e-mail: dcrich@chem.wayne.edu).
This article is part of a Special Issue dedictated to Professor Derrick Clive. We dedicate this paper to Professor Derrick L. J. Clive, a pioneer
in the application of organoselenium chemistry to organic synthesis, and in honor of his many seminal contributions to organic chemistry.
Can. J. Chem. 90: 944–953 (2012)
doi:10.1139/v2012-056
Published by NRC Research Press

Lachkar et al.
945
Scheme 3. Formation of 2-(selenocyanatomethyl)allyl tetraacetyl-
Scheme 1. Dechalcogenative allylic selenosulfide and disulfide
rearrangements.
␣-D-glucopyranoside (9).
Scheme 2. Preparation of 2-(selenocyanatomethyl)-3-propenol.
Scheme 4. Formation of 2-(selenocyanatomethyl)allyl ␤-D-mannopy-
ranoside (12).
selenocyanate in DMF then afforded the selenocyanate 5 in
81%yield.Exposureto2,3-dichloro-5,6-dicyano-1,4-benzoqui-
none (DDQ) in wet dichloromethane finally gave the desired
alcohol 6 in 74% yield and demonstrated the stability of the
allylic selenocyanate functionality to the mild oxidative con-
ditions used for removal of the p-methoxybenzyl ether
(Scheme 2).
Scheme 5. Reaction of 6 with a phosphoramidite.
With 6 in hand we turned to its application as a glycosyl
acceptor. Activation of tetraacetyl-␣-glucopyranosyl trichlo-
roacetimidate9 (7) in the presence of 6 with BF3 etherate
afforded the desired ␤-glycoside 9 in 41% yield (Scheme 3)
typically accompanied by the orthoester products 10. Ortho-
esters of this general type are typical byproducts in neighbor-
ing group participation directed glycosylation reactions and
are particularly problematic when the acceptor is a primary
alcohol.10 When acetobromoglucose 8 was employed as donor
and indium trichloride11 as promotor the glycoside 9 was
obtained in 31% yield, but attempts at activation of 8 with
more typical silver-based reagents resulted only in the formation
of decomposition products. While the yields from these glycosy-
lations are only moderate, they are nevertheless instructive as
they demonstrate the stability of the allylic selenocyanate func-
tionality toward selected Lewis acidic conditions.
In a second glycosylation reaction, donor 11 was coupled to 6
using the 1-benzenesulfinylpiperidine (BSP) / trifluoromethanesul-
fonic anhydride conditions12 in the presence of the hindered base
2,4,6-tri-tert-butylpyrimidine (TTBP)13 (Scheme 4). Glyco-
side 12 was obtained as a single isomer in 49% yield.
Encouraged by these results, we investigated the compati-
bility of 6 with typical conditions for phosphitylation such as
would be necessary for incorporation into nucleotides.14 Thus,
6 was allowed to react with dibenzyl N,N-di(isopropyl)phos-
phoramidite in the presence of tetrazole as promoter, to give a
presumed intermediate phosphite 13, followed by exposure to
m-CPBA as oxidant (Scheme 5). Unfortunately, complex re-
action mixtures were obtained under all reaction conditions
investigated from which the anticipated phosphate 14 could
only be isolated in modest yield. A cyclic byproduct 16 was
obtained in varying quantities from all reaction mixtures and
affords a possible explanation for the complexity: Arbuzov-
type reaction initiated by intramolecular attack of the first
formed phosphite on the electron-deficient selenocyanate.
Finally, attention was turned to the ligation reaction. Thus,
selenocyanates 5, 6, 9, and 12 were allowed to react with a
variety of aliphatic thiols in methanol at room temperature
under an argon atmosphere. After stirring overnight, and fil-
tration to remove precipitated selenium, chromatography on
silica gel afforded the coupled products with the yields set out
in Table 1.
In an attempt to probe the mechanism of the ligation reac-
tion, we monitored the reaction of selenocyanate 6 with ben-
1
zylmercaptan in deuteriomethanol at room temperature by H
1
and 77Se NMR spectroscopy (Figs. 1 and 2). In the H NMR
spectrum a slight upfield shift of the signals attributed to 6 is
observed on addition of the thiol, followed by the formation of
a set of new signals assigned to the intermediate selenosulfide.
This substance is then transformed rapidly and cleanly into
the final product (18). The kinetics of the reaction are such
Published by NRC Research Press

946
Can. J. Chem. Vol. 90, 2012
Table 1. Ligation of 6 and its derivatives with assorted thiols.
Entry
Substrate
Thiol
Product, yield
1
2
3
4
5
6
7
8
9
Published by NRC Research Press

Lachkar et al.
947
Table 1 (concluded).
Entry
Substrate
Thiol
Product, yield
10
11
12
13
that the onset of the formation of 18 is seen before the
complete conversion of 6 to the selenosulfide intermediate.
A set of minor signals attributable neither to the selenosul-
fide nor to the final product, and which are lost by the end
of the reaction, may represent the selenosulfoxide interme-
diate, a functional group that to date has not been described
in the literature. To probe this possibility further, we turned
to 77Se NMR spectroscopy. The rapid transformation of 6 to
the selenosulfide is clearly seen, with its disappearance later
as the reaction proceeds to completion. A minor unidenti-
fied signal is formed over the course of the reaction at ␦ 500
but, as this signal persists at the end of the reaction, it
cannot be the selenosulfoxide intermediate and must repre-
sent a minor selenium-containing byproduct. Unfortunately,
selenosulfoxides, like their thiosulfoxide cousins,2 must
retain their status as hypothetical reaction intermediates for the
present.
alcohol moiety may be derivatized by glycosylation under
standard conditions without detriment to the selenium func-
tionality. Attempted derivation of 6 as a phosphite ester was,
however, mostly unsatisfactory because of the apparent in-
compatibility of the selenocyanate group with a strong intra-
molecular nucleophile. Alcohol 6 itself and its derivatives
react with a variety of thiols in methanolic solution at room
temperature to give the corresponding mixed dialkyl sulfides
with the corresponding loss of selenium. Finally, compatibility
of the selenocyanate functionality with oxidative removal of a
p-methoxybenzyl ether and Lewis and (or) Brønsted acidic
conditions of glycosylation reactions has been demonstrated.
Experimental
1H NMR (300 or 500 MHz), 13C NMR (75 MHz), and 77Se
NMR (95 MHz) spectra were recorded on Bruker spectrome-
1
ters. H and 13C NMR chemical shifts are given in ppm with
In conclusion, 2-(selenocyanatomethyl)-3-propenol (6) is a
readily prepared functionalized allylic selenocyanate whose
respect to tetramethylsilane, following referencing to the in-
Published by NRC Research Press

1
Fig. 1. Vinylic proton region of the H NMR spectra for the reaction of 6 with benzyl mercaptan. (a) 6; (b) 6 ϩ benzylmercaptan; (c) after 48 min with formation of selenosulfide;
(d) after 76 min; and (e) after 576 min.

Fig. 2. 77Se NMR spectra of the reaction of 6 with benzyl mercaptan. (a) 6; (b) 6 ϩ benzylmercaptan; (c) after 37 min with formation of selenosulfide; (d) after 150 min; and
(e) after 420 min.

950
Can. J. Chem. Vol. 90, 2012
ternal solvent signal. 77Se NMR chemical shifts are given in
ppm with respect to dimethylselenide with the aid of referenc-
ing to the internal solvent signal. Multiplicities are given as
follows: s (singlet), br s (broad singlet), d (doublet), t (triplet), q
(quadruplet), dd (doublet of doublet), dt (doublet of triplet), and m
(multiplet). Coupling constants (J) are given in Hz. Infrared spectra
were recorded on a PerkinElmer FT-IR instrument and the data are
reported in reciprocal centimetres (cm–1). Mass spectra were re-
corded on a Micromass LCT (ESI). Reactions were performed using
oven-dried MgSO4 glassware under an atmosphere of dry argon.
TLC plates (Merck 60 F254 aluminum sheets) were visualized by UV
and (or) spraying with vanillin (1%) ϩ sulfuric acid (5%) in EtOH
followed by heating. THF and CH2Cl2 were dried by standing over
molecular sieves under argon. Unless otherwise noted, all reagent-
grade chemicals and solvents were obtained from commercial sup-
pliers and were used as received. Specific rotations are expressed in
deg cm3 g–1 dm–1 and c is expressed in g/100 cm3.
(95.4 MHz, CDCl3) ␦: 251.8. HRMS (ESI) calcd for
C5H6NOSe: 176.9693; found: 175.9606 [M – H]–.
2-(Selenocyanatomethyl)allyl 2,3,4,6-tetra-O-acetyl-b-D-
glucopyranoside (9)
From trichloroacetimidate 7
A solution of 6 (0.28 mmol, 50 mg) in CH2Cl2 (1 mL) and
4 Å molecular sieves was stirred 30 min at room temperature
and then cooled at –78 °C. BF3.OEt2 (0.16 mmol, 20 ␮L) and
7 (0.71 mmol, 350 mg) were added and the solution was
stirred at 0 °C for 2 h 30 min. The reaction mixture was then
quenched with NEt3, filtered, and evaporated in vacuo. The
crude product was purified by chromatography on silica gel
(eluent, AcOEt/Hept 1:1) to give 9 (58.3 mg, 41%) as a
colorless oil.
From bromide 8
2-(Chloromethyl)allyl p-methoxybenzyl ether (4)
Compound 6 (0.28 mmol, 50 mg) was added to CH2Cl2 (2 mL)
and 4 Å molecular sieves. The solution was stirred for 30 min at
room temperature and the donor 8 was added (0.381 mmol,
140 mg). InCl3 (0.14 mmol, 31.4 mg) was then added and the
solution was stirred for 3 days at room temperature. The reaction
mixture was diluted in CH2Cl2 and filtered through a Celite pad.
The filtrate was evaporated in vacuo and the crude product was
purified by chromatography on silica gel (eluent, AcOEt/Hept
1:1) to give 14 (45.1 mg, 31%) as a colorless oil. [␣]D25 –15.4 (c
0.54, CHCl3). IR (neat, cm–1): 697, 907, 1367, 1431, 1744, 2153,
2940. 1H NMR (500 MHz, CDCl3) ␦: 1.98 (s, 3H), 2.00 (s, 3H),
2.03 (s, 3H), 2.07 (s, 3H), 3.64–3.77 (m, 3H), 4.13–4.23 (m, 3H),
4.41 (d, J ϭ 12.3 Hz, 1H), 4.53 (d, J ϭ 7.9 Hz), 4.98 (dd, J ϭ 7.9,
9.7 Hz, 1H), 5.06 (t, J ϭ 9.7 Hz, 1H), 5.18 (t, J ϭ 9.5 Hz, 1H),
5.23 (s, 1H), 5.29 (s, 1H). 13C NMR (75.5 MHz, CDCl3) ␦: 20.6
(2 CH3), 20.7 (CH3), 20.8 (CH3), 31.3 (CH2), 61.8 (CH2), 68.3
(CH), 71.2 (CH), 72.0 (CH), 72.7 (CH), 69.9 (CH2), 100.0 (CH),
101.6 (CN), 119.1 (CH2), 139.3 (Cq), 169.3 (CO), 169.4 (CO),
170.2 (CO), 170.6 (CO). 77Se NMR (95.4 MHz, CDCl3) ␦: 248.0.
HRMS (ESI) calcd for C19H29N2O10Se: 525.0982; found:
525.1033 [M ϩ NH4]ϩ.
p-Methoxybenzyl methallyl ether (3)7 (9.2 mmol, 1.77 g) in
CH2Cl2 (100 mL) was treated with LiClO4 (1.8 mmol, 0.2 g)
and pyridine (11. mmol, 0.89 mL) and cooled to –78 °C before
SO2Cl2 (11.0 mmol, 0.89 mL) was added. After 1 h at 0 °C,
the reaction mixture was quenched with saturated aqueous
NaHCO3, extracted with CH2Cl2, and washed with brine. The
combined organic layers were dried over MgSO4, filtered, and
evaporated in vacuo. The crude product was purified by chro-
matography over silica gel (eluent, MTBE/Hept 5:95) to give
4 (0.60 g, 29%) whose spectral data correspond to those
reported in the literature.8
2-(Selenocyanatomethyl)allyl p-methoxybenzyl ether (5)
KSeCN (11.8 mmol, 1.7 g) was added to a solution of 4
(5.9 mmol, 1.34 g) in DMF (24 mL) and the solution was stirred
at 40 °C for 3 h. Water was added and the solution was extracted
twice with MTBE. The combined organic layers were dried over
MgSO4, filtered and evaporated in vacuo. The crude product was
purified by chromatography on silica gel (eluent, AcOEt/Hept
1:3) to give 5 (1.41 g, 81%) as a yellow oil. IR (neat, cm–1): 817,
921, 1031, 1077, 1174, 1246, 1302, 1514, 1610, 2148, 2836. 1H
NMR (500 MHz, CDCl3) ␦: 3.78 (s, 2H), 3.83 (s, 3H), 4.12 (s,
2H), 4.46 (s, 2H), 5.27 (s, 1H), 5.33 (s, 1H), 6.91 (d, J ϭ 8.2 Hz,
2H), 7.28 (d, J ϭ 7.9 Hz, 2H). 13C NMR (75.5 MHz, CDCl3) ␦:
31.9 (CH2), 55.4 (CH3), 70.8 (CH2), 72.3 (CH2), 102.4 (CN),
114.1 (2 CH), 118.6 (CH2),3 129.7 (2 CH), 129.8 (Cq), 140.5
(Cq), 159.6 (Cq). HRMS (ESI) calcd for C13H19N2O2Se:
315.0606; found: 315.0634 [M ϩ NH4]ϩ.
4-Methylphenyl 2-O-benzyl-4,6-O-benzylidene-3-O-
(2-naphthalenylmethyl)-a-D-thiomannopyranoside (11)
A
mixture of (4-methylphenyl) 4,6-O-benzylidene-
␤-D-thiomannopyranoside (2.4 mmol, 900 mg) and n-Bu2SnO
(2.9 mmol, 722 mg), in dry toluene (25 mL), was refluxed
overnight. The resulting solution was cooled at room temper-
ature and then concentrated under reduced pressure. The res-
idue was dissolved in dry DMF (10 mL) and then CsF
(4.8 mmol, 730 mg) and NAPBr (3.6 mmol, 780 mg) were
added. The resulting mixture was stirred 6 h at room temper-
ature, diluted with CH2Cl2, and filtered through Celite. The
filtrate was concentrated under reduced pressure. The residue
was dissolved in dry DMF (10 mL), cooled at 0 °C, and NaH
(4.8 mmol, 231 mg) was added. After 10 min of stirring, BnBr
(4.8 mmol, 570 ␮L) was added. The resulting mixture was
stirred overnight at room temperature, quenched with an aque-
ous saturated NaHCO3 solution, and extracted twice with
CH2Cl2. The combined organic layer was brine, dried (MgSO4),
and concentrated under reduced pressure. The crude product was
purified by chromatography on silica gel (eluent, 10% t-BuOMe
2-(Selenocyanatomethyl)prop-2-en-1-ol (6)
Water (330 ␮L) and DDQ (1.1 mmol, 230 mg) were added
to a solution of 10 (0.68 mmol, 200 mg) in CH2Cl2 (6.6 mL)
and the resulting solution was stirred for 3 h. It was quenched
with an aqueous saturated solution of NaHCO3, extracted with
CH2Cl2, and washed with brine. The combined organic layers
were dried over MgSO4, filtered, and evaporated in vacuo. The
crude product was purified by chromatography on silica gel
(eluent, AcOEt/Hept 1:1) to give 6 (87.6 mg, 74%) as a yellow
oil. IR (neat, cm–1): 727, 915, 1022, 1054, 1197, 1366, 1426,
1
1646, 1738, 2150, 2923, 3394. H NMR (500 MHz, CDCl3)
␦: 2.6–2.8 (br s, OH), 3.79 (s, 2H), 4.25 (s, 2H), 5.26 (s, 1H),
5.27 (s, 1H). 13C NMR (75.5 MHz, CDCl3) ␦: 31.5 (CH2),
63.9 (CH2), 102.6 (CN), 117.1 (CH2), 142.8 (Cq). 77Se NMR
Published by NRC Research Press

Lachkar et al.
951
in heptane) to give 4-methylphenyl 2-O-benzyl-4,6-O-benzyli-
dene-3-O-(2-naphthalenylmethyl)-␣-D-thiomannopyranoside (11,
1.32 g, 91%) as a clear viscous oil. [␣]22D ϩ102.2 (c 1.0, CHCl3).
1H NMR (500 MHz, CDCl3) ␦: 2.32 (s, 3H), 3.89 (t, J ϭ 10.0 Hz,
1H), 4.02–4.07 (m, 2H), 4.23 (dd, J ϭ 10.0 Hz, J ϭ 4.5 Hz, 1H),
4.26–4.37 (m, 2H), 4.72 (d, J ϭ 13.5 Hz, 1H), 4.75 (d, J ϭ
13.5 Hz, 1H), 4.81 (d, J ϭ 12.5 Hz, 1H), 4.94 (d, J ϭ 12.5 Hz,
1H), 5.44 (s, 1H), 5.64 (s, 1H), 7.08 (d, J ϭ 7.5 Hz, 2H),
7.29–7.48 (m, 10H), 7.52–7.55 (m, 2H), 7.70–7.73 (m, 1H),
7.78–7.83 (m, 3H). 13C NMR (75 MHz, CDCl3) ␦: 65.4, 68.5,
72.9, 73.0, 76.2, 77.8, 79.0, 87.3, 101.5, 125.6, 125.8, 126.0,
126.1, 126.1, 126.2, 127.6, 127.8, 127.9, 128.0, 128.1, 128.4,
128.8, 129.8, 129.9, 132.2, 132.9, 133.6, 135.8, 137.6, 137.7,
137.9. HRMS (ESI) calcd for C38H36O5S: 622.2627; found:
622.2641 [M ϩ NH4]ϩ.
2-(Benzyloxy)-5-methylene-1,3,2-oxaselenaphosphinane
2-oxide (16)
This compound, a colorless oil, was obtained in varying
amounts from different preparations of 14. IR (neat, cm–1): 672,
1
697, 741, 789, 976, 1008, 1261, 1456. H NMR (500 MHz,
CDCl3) ␦: 3.30–3.38 (m, 1H), 3.54–3.60 (m, 1H), 4.68–4.78 (m,
2H), 5.11–5.22 (m, 4H), 7.32–7.44 (m, 5H). 13C NMR
(75.5 MHz, CDCl3) ␦: 24.9, 68.9, 74.6, 74.7, 117.8, 128.4, 128.9,
135.5, 136.9. 31P NMR (75.5 MHz, CDCl3) ␦: 8.07. 77Se NMR
(95.4 MHz, CDCl3) ␦: 208.8; 213.7. HRMS (ESI) calcd for
C11H14O3PSe: 304.9846; found: 304.9933 [M ϩ H]ϩ.
General procedure for ligation
To freshly prepared selenocyanate 5 or 6 (1 mmol) in
degassed MeOH (10 mL) under an argon atmosphere was
added a solution of thiol (1.2 mmol) in MeOH (5 mL). The
reaction mixture was stirred at room temperature overnight
and filtered through a Celite pad, which was further rinsed
with MeOH. The solvent was evaporated to dryness and the
residue was purified by column chromatography.
2-(Selenocyanatomethyl)allyl 2-O-benzyl-4,6-O-benzyli-
dene-3-O-(2-naphthylmethyl)-b-D-mannopyranoside (12)
A stirred solution of thioglycoside 11 (0.54 mmol, 330 mg),
TTBP (1.0 mmol, 248 mg), BSP (0.6 mmol, 119 mg) in
CH2Cl2 (10 mL) was cooled to –78 °C and treated with Tf2O
(0.6 mmol, 96 ␮L). The resulting solution was stirred for 1 h
before addition of a solution of 6 (0.63 mmol, 110 mg) in
CH2Cl2 (2 mL). After stirring for 1 h at –78 °C, the reaction
mixture was quenched with saturated aqueous NaHCO3,
warmed to room temperature and extracted twice with CH2Cl2.
The combined organic layers were dried over MgSO4, filtered,
and evaporated in vacuo and the residue was purified by chro-
matography on silica gel (eluent, XXXX 1:4) to give 12 (172 mg,
2-(Benzylthiomethyl)allyl p-methoxybenzyl ether (18)
Prepared according to the general procedure, by reaction of 5
(1.01 mmol, 300 mg) with benzylmercaptan 17 (1.21 mmol,
143 ␮L), affording 18 (241 mg, 76%) as a colorless oil. IR
(neat, cm–1): 702, 819, 910, 1034, 1087, 1302, 1453, 1512, 1612,
2835. 1H NMR (500 MHz, CDCl3) ␦: 3.11 (s, 2H), 3.63 (s, 2H),
3.80 (s, 3H), 4.07 (s, 2H), 4.43 (s, 2H), 5.05 (s, 1H), 5.19 (s, 1H),
6.86–6.90 (m, 2H), 7.24–7.30 (m, 7H). 13C NMR (75.5 MHz,
CDCl3) ␦: 34.3 (CH2), 35.6 (CH2), 55.5 (CH3), 71.1 (CH2), 72.1
(CH2), 114.0 (2 CH), 115.1 (CH2), 127.1, 128.7, 129.3 (5 CH),
129.5, 129.6 (2 CH), 130.5 (Cq), 138.4 (Cq), 141.9 (Cq), 159.4
(Cq). HRMS (ESI) calcd for C19H26NO2S: 332.1679; found:
332.1670 [M ϩ NH4]ϩ.
23
49%) as a colorless oil. [␣]D –31.2 (c 0.92, CHCl3). IR
1
(neat, cm–1): 1086, 1377, 1454, 2149, 2874, 3047. H NMR
(500 MHz, CDCl3) ␦: 3.34–3.42 (m, 1H), 3.60–3.75 (m, 3H),
3.94–4.02 (m, 2H), 4.2 (d, J ϭ 12.5 Hz, 1H), 4.29 (t, J ϭ 9.6 Hz,
1H), 4.34–4.38 (m, 1H), 4.51 (s, 2H), 4.81–4.86 (m, 1H), 4.90–
5.02 (m, 3H), 5.28 (s, 1H), 5.33 (s, 1H), 5.69 (s, 1H), 7.31–7.90
(m, 17H). 13C NMR (75.5 MHz, CDCl3) ␦: 31.7, 67.9, 68.7, 70.3,
72.8, 75.1, 76.2, 78.1, 78.8, 101.4, 101.8, 119.2, 125.8, 126.1, 126.3,
126.6, 127.9, 128.1, 128.3, 128.4, 128.8, 129.1, 133.2, 133.4, 135.9,
137.7, 138.5, 139.8. 77Se NMR (95.4 MHz, CDCl3) ␦: 247.4.
HRMS (ESI) calcd for C36H39N2O6Se: 675.1968; found: 675.1996
[M ϩ NH4]ϩ.
N-(tert-Butoxycarbonyl) S-(p-methoxybenzyloxymethyl)allyl
L-cysteine methyl ester (20)
Prepared according to the general procedure, by reaction of 5
(1.01 mmol, 300 mg) with the L-cysteine derivative 19
(1.26 mmol, 209 ␮L), affording 20 (356 mg, 83%) as a colorless
oil. [␣]D25 ϩ8.5 (c 0.66, CHCl3). IR (neat, cm–1): 819, 915, 1034,
1
1246, 1366, 1513, 1613, 1713, 1746, 2976, 3359. H NMR
(500 MHz, CDCl3) ␦: 1.45 (s, 9H), 2.78–2.93 (m, 2H), 3.16–3.26
(m, 2H), 3.75 (3H, CH3), 3.80 (3H, CH3), 4.05 (s, 2H), 4.44 (s,
2H, CH2), 4.51–4.54 (br s, 1H), 5.08 (s, 1H), 5.18 (s, 1H),
5.29–5.34 (br s, 1H), 6.88 (d, J ϭ 8.5 Hz, 2H), 7.26 (d, J ϭ 8.7 Hz,
2H). 13C NMR (75.5 MHz, CDCl3) ␦: 14.2 (CH3), 28.5 (3 CH3),
33.6 (CH2), 35.4 (CH2), 52.7 (CH), 55.5 (CH3), 70.6 (CH2), 72.1
(CH2), 114.0 (2 CH), 115.9 (CH2), 129.6 (2 CH), 130.4 (Cq), 141.6
(Cq), 159.4 (Cq), 171.8 (CO). HRMS (ESI) calcd for C21H34N2O6S:
425.1872; found: 426.1928 [M ϩ NH4]ϩ.
Dibenzyl 2-(selenocyanatomethyl)allyl phosphate (14)
A stirred solution of 6 (0.28 mmol, 50 mg) in CH3CN
(2.64 mL) was cooled to 0 °C and treated with 1H-tetrazole
(0.77 mmol, 53.6 mg). Dibenzyl-N,N-diisopropyl phos-
phoramidite (0.57 mmol, 187 ␮L) was then added and the
resulting solution was stirred for 1 h. m-CPBA (0.99 mmol,
171 mg) was then added and, after 10 min, the reaction
mixture was quenched with water. The solution was extracted
with CH2Cl2 and the combined organic layers were dried over
MgSO4, filtered, and evaporated in vacuo. The crude product
was purified by chromatography on silica gel (eluent, AcOEt/
Ethyl 2-(p-methoxybenzyloxymethyl)allylthioacetate (22)
Prepared according to the general procedure, by reaction of 5
(0.17 mmol, 50 mg) with ethyl thioglycolate (21, 0.20 mmol,
24.4 mg), affording 22 (48.3 mg, 92%) as a colorless oil. IR
(neat, cm–1): 818, 911, 1034, 1090, 1171, 1246, 1512, 1609,
1724, 2936. 1H NMR (500 MHz, CDCl3) ␦: 1.30 (t, J ϭ 7.0 Hz,
3H), 3.15 (s, 2H), 3.35 (s, 2H), 3.83 (s, 3H), 4.09 (s, 2H), 4.20 (q,
J ϭ 7.1 Hz, 2H), 4.46 (s, 2H), 5.13 (s, 1H), 5.23 (s, 1H), 6.90 (d,
J ϭ 8.6 Hz, 2H), 7.29 (d, J ϭ 8.2 Hz, 2H). 13C NMR (75.5 MHz,
1
Hept 1:1) to give 14 (35.5 mg, 29%) as a colorless oil. H
NMR (500 MHz, CDCl3) ␦: 3.56 (s, 2H), 4.52 (s, 1H), 4.53 (s,
1H), 4.99–5.09 (m, 4H), 5.20 (s, 1H), 5.27 (s, 1H), 7.32–7.35
(m, 8H). 13C NMR (75.5 MHz, CDCl3) ␦: 31.1, 67.7, 67.8,
69.8, 69.9, 120.5, 128.3, 128.9, 129.0, 129.7. 31P NMR
(75.5 MHz, CDCl3) ␦: –0.43. HRMS (ESI) calcd for
C19H24N2O4P77Se: 455.0633; Found: 455.0643 [M ϩ NH4]ϩ.
Published by NRC Research Press

952
Can. J. Chem. Vol. 90, 2012
CDCl3) ␦: ϭ 32.2, 34.9, 41.5, 55.3, 61.3, 61.7, 71.9, 113.8, 115.9,
129.1, 129.4, 130.3, 140.8, 159.2, 170.4. HRMS (ESI) calcd for
C16H26NO4S: 328.1577; found: 328.1557 [M ϩ NH4]ϩ.
Ethyl 2-(hydroxybenzyloxymethyl)allylthioacetate (29)
Prepared according to the general procedure, by reaction of 6
(0.57 mmol, 100 mg) with ethyl thioglycolate 21 (0.68 mmol,
75 ␮L), affording 29 (61.8 mg, 57%) as a colorless oil. IR
(neat, cm–1): 757, 908, 1125, 1155, 1271, 1367, 1410, 1650,
p-Methoxybenzyl 2-(2-hydroxyethyl)thiomethyl ether (24)
Prepared according to the general procedure, by reaction of 5
(0.14 mmol, 40 mg) with 2-mercaptoethanol (23, 0.16 mmol,
13.0 mg), affording 24 (23.1 mg, 57%) as a colorless oil. IR
(neat, cm–1): 712, 760, 818, 915, 1033, 1066, 1173, 1301, 1511,
1
1725, 2982, 3428. H NMR (500 MHz, CDCl3) ␦: 1.24 (t, J ϭ
7.1 Hz, 3H), 2.16 (br s, 1H), 3.11(s, 2H), 3.28 (s, 2H), 4.05–4.17
(m, 4H), 5.10 (s, 1H), 5.16 (s, 1H). 13C NMR (75.5 MHz, CDCl3)
␦: 14.3, 21.2, 32.4, 35.1, 60.6, 61.6, 64.2, 114.6, 143.5, 170.7.
HRMS (ESI) calcd for C8H18NO3S: 208.1002; found: 213.0549
[M ϩ NH4]ϩ.
1
1612, 1647, 2835, 2912, 3399. H NMR (500 MHz, CDCl3) ␦:
2.68 (t, J ϭ 5.8 Hz, 2H), 3.25 (s, 2H), 3.72 (t, J ϭ 5.8 Hz, 2H),
3.83 (s, 3H), 4.10 (s, 2H), 4.47 (s, 2H), 5.01 (s, 1H), 5.13 (s, 1H),
6.91 (d, J ϭ 8.5 Hz, 2H), 7.29 (d, J ϭ 8.2 Hz, 2H). 13C NMR
(75.5 MHz, CDCl3) ␦: 34.2, 34.3, 35.3, 60.1, 70.6, 71.9, 113.8,
115.4, 129.4, 144.8, 156.3. HRMS (ESI) calcd for C14H20O3S:
268.1133; found: 269.1215 [M ϩ H]ϩ.
2-(2-Hydroxyethylthiomethyl)prop-2-en-1-ol (30)
Prepared according to the general procedure, by reaction of 6
(0.13 mmol, 22 mg) with 2-mercaptoethanol 23 (0.14 mmol,
10.7 mg), affording 30 (16.8 mg, 91%) as a colorless oil. IR
(neat, cm–1): 695, 820, 1062, 1104, 1254, 1314, 1520, 1605,
3420. 1H NMR (500 MHz, MeOD) ␦: 2.70 (t, J ϭ 6.0 Hz, 2H),
3.27 (s, 2H), 3.75 (t, J ϭ 5.9 Hz, 2H), 4.26 (s, 2H), 5.07 (s, 1H),
5.18 (s, 1H). 13C NMR (75.5 MHz, CDCl3) ␦: 34.1, 34.3, 60.3,
64.3, 114.1, 145.6.
N-(tert-Butoxycarbonyl) S-(p-methoxybenzyloxymethyl)allyl
glutathione dimethyl ester (26)
Prepared according to the general procedure, by reaction of 5
(0.10 mmol, 30 mg) with the glutathione derivative 25
(0.12 mmol, 59.7 mg), affording 26 (40.6 mg, 64%) as a colorless
N-(tert-Butoxycarbonyl) S-(hydroxymethyl)allyl
glutathione dimethyl ester (31)
oil. [␣]D ϩ0.5 (c 0.98, CHCl3). IR (neat, cm–1): 735, 1031,
25
1169, 1207, 1246, 1512, 1646, 1706, 1742, 2952, 3301. 1H NMR
(500 MHz, CDCl3) ␦: 1.45 (s, 9H), 1.98 (m, 1H), 2.15 (m, 1H),
2.87 (m, 2H), 3.29 (s, 2H), 3.75 (s, 3H), 3.76 (s, 3H), 3.82 (s, 3H),
4.07 (s, 2H), 4.14 (s, 2H), 4.45 (s, 1H), 5.21 (m, 1H), 5.37 (m,
1H), 6.89 (d, J ϭ 8.5 Hz, 2H), 7.28 (d, J ϭ 8.5 Hz, 2H). 13C NMR
(75.5 MHz, CDCl3) ␦: 28.3 (3 CH3), 28.7 (CH2), 32.9 (CH2), 34.9
(CH2), 41.3 (CH2), 52.4, 55.3, 70.7 (CH2), 71.9 (CH2), 113.8, 116.2
(2 CH), 129.5 (2 CH), 141.5 (Cq), 154.2 (Cq), 155.5 (Cq), 170.1
(Cq), 172.2 (Cq), 173.0 (Cq). HRMS (ESI) calcd for C29H44N3O10S:
626.2669; found: 626.2769 [M ϩ H]ϩ.
Prepared according to the general procedure, by reaction of
6 (0.28 mmol, 50 mg) with the glutathione derivative 25
(0.35 mmol, 154.7 mg), affording 31 (115.1 mg, 80%) as a
colorless oil. [␣]D ϩ2.4 (c 0.92, CHCl3). IR (neat, cm–1):
24
733, 1028, 1052, 1207, 1365, 1435, 1516, 1645, 1688, 1742,
2980, 3293. 1H NMR (500 MHz, CDCl3) ␦: 1.44 (s, 9H), 1.98
(m, 1H), 2.18 (m, 1H), 2.38 (m, 2H), 2.88 (m, 1H), 2.93 (m,
2H), 3.33 (dd, J ϭ 13.7 Hz, J ϭ 20.2 Hz, 2H), 3.76 (s, 6H),
4.23 (s, 2H), 4.40 (s large, 1H), 4.68 (q, J ϭ 6.9 Hz, 1H), 5.15
(s, 1H), 5.22 (s, 1H). 13C NMR (75.5 MHz, CDCl3) ␦: 25.6
(CH2), 28.5 (3 CH3), 32.3 (CH2), 34.4 (CH2), 41.3 (CH2), 52.4
(2 CH3), 53.0 (CH), 64.0 (CH), 68.0 (CH2), 80.3 (Cq), 114.3
(CH2), 144.40 (Cq), 155.70 (NH–CϭO), 169.95 ((CϭO)O–
Me), 170.13 ((CϭO)NH), 172.47 (CϭO), 172.93 (CϭO).
HRMS (ESI) calcd for C21H36N3O9S: 506.2094; found:
506.2159 [M ϩ H]ϩ.
2-(Benzylthiomethyl)prop-2-en-1-ol (27)
Prepared according to the general procedure, by reaction of 6
(0.57 mmol, 100 mg) with benzyl mercaptan 17 (0.68 mmol,
80 ␮L), affording 27 (94.5 mg, 86%) as a colorless oil. IR
(neat, cm–1): 756, 907, 1028, 1232, 1453, 1494, 2916, 3347. 1H
NMR (500 MHz, CDCl3) ␦: 3.06 (s, 2H), 3.58 (s, 2H), 4.15 (s,
2H), 4.92 (s, 1H), 5.12 (s, 1H), 7.17–7.27 (m, 5H). 13C NMR
(75.5 MHz, CDCl3) ␦: 34.2 (CH2), 35.4 (CH2), 64.6 (CH2), 113.7
(CH2), 127.1, 128.6, 129.2 (5 CH), 138.1 (Cq), 144.2 (Cq).
HRMS (ESI) calcd for C11H18NOS: 212.1104; found: 211.0785
[M ϩ NH4]ϩ.
N-(tert-Butoxycarbonyl) S-[(2,3,4,6-tetra-O-acetyl-b-D-glucopy-
ranosyl)methyl]allyl glutathione dimethyl ester (32)
Prepared according to the general procedure, by reaction of
the glucose derivative 9 (0.04 mmol, 21.7 mg) with the
glutathione derivative 25 (0.05 mmol, 23.3 mg) in CH3CN,
affording 32 (21.9 mg, 61%) as a colorless oil. [␣]D25 –5.6 (c
0.82, CHCl3). IR (neat, cm–1): 910, 1040, 1167, 1367, 1437,
N-(tert-Butoxycarbonyl) S-(hydroxymethyl)allyl
L-cysteine methyl ester (28)
1
1518, 1660, 1747, 2932, 2953, 3313. H NMR (500 MHz,
Prepared according to the general procedure, by reaction of 6
(0.57 mmol, 100 mg) with the L-cysteine derivative 19 (0.68 mmol,
160.4 mg), affording 28 (90.3 mg, 52%) as a colorless oil.
[␣]D26 ϩ8.5 (c 0.55, CHCl3). IR (neat, cm–1): 913, 1055, 1217, 1367,
1437, 1513, 1698, 2978, 3374. 1H NMR (500 MHz, CDCl3) ␦: 1.42
(s, 9H), 2.00 (s, 2H), 3.20 (s, 2H), 3.73 (s, 3H), 4.11–4.22 (m, 2H),
4.49–4.54 (br s, 1H), 5.01 (s, 1H), 5.16 (s, 1H) 5.26–5.31 (br s, 1H).
13C NMR (75.5 MHz, CDCl3) ␦: 14.3 (CH3), 28.5 (3 CH3),
34.1(CH2), 35.4 (CH2), 52.8 (CH), 64.1 (CH2), 114.2 (CH2), 144.3
(Cq), 171.8 (CO). HRMS (ESI) calcd for C13H27N2O5S: 328.1635;
found: 328.1184 [M ϩ NH4]ϩ.
CDCl3) ␦: 1.43 (s, 9H), 2.00 (s, 3H), 2.03 (s, 3H), 2.05 (s, 3H),
2.10 (s, 3H), 2.31–2.41 (m, 2H), 2.75–2.89 (m, 2H), 3.22
(s, 2H), 3.75 (s, 3H), 3.76 (s, 3H), 4.05 (m, 2H), 4.17–4.19
(m, 1H), 4.21–4.26 (m, 1H), 4.33–4.42 (m, 2H), 4.54–4.63
(m, 2H), 4.98–5.14 (m, 2H), 5.14–5.26 (m, 3H), 5.29–5.36
(m, 1H), 6.72–6.82 (br s, 1H), 7.01–7.08 (br s, 1H). 13C NMR
(75.5 MHz, CDCl3) ␦: 20.8, 20.9, 21.0, 28.5, 29.9, 32.3, 32.8,
34.8, 41.5, 52.5, 52.6, 52.7, 52.9, 62.1, 68.7, 70.2, 71.5, 72.0,
73.0, 100.1, 116.8, 140.3, 169.6, 170.1, 170.5, 170.7, 172.3,
173.0. HRMS (ESI) calcd for C35H57N4O18S: 853.3383;
found: 853.3362 [M ϩ NH4]ϩ.
Published by NRC Research Press

Lachkar et al.
953
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N-(tert-Butoxycarbonyl) S-[(2-O-benzyl-4,6-O-benzylidene-3-
O-(2-naphthylmethyl)-b-D-mannopyranosyl)methyl]allyl
glutathione dimethyl ester (33)
Prepared according to the general procedure, by reaction of
the mannose derivative 12 (0.18 mmol, 120 mg) with the
glutathione derivative 25 (0.24 mmol, 105 mg), affording 33
(113 mg, 63%) as a colorless oil. [␣]D26 –13.4 (c 1.40, CHCl3).
1H NMR (500 MHz, CDCl3) ␦: 1.43 (s, 9H), 1.86–2.00 (br s,
1H), 2.04 (s, 2H), 2.10–2.25 (br s, 1H), 2.28–2.38 (m, 1H),
2.76–2.92 (m, 2H), 3.23 (s, 1H), 3.63–3.68 (m, 1H), 3.72 (s,
6H), 3.88–4.03 (m, 4H), 4.06–4.17 (m, 2H), 4.24 (t, J ϭ
9.6 Hz, 1H), 4.28–4.43 (m, 2H), 4.44–4.65 (m, 3H), 4.76–
4.82 (m, 2H), 4.89–5.00 (m, 1H), 4.83–5.05 (m, 1H), 5.15–
5.21 (m, 2H), 5.27–5.34 (br s, 1H), 5.65 (s, 1H), 6.69–6.81(br
s, 1H), 6.97–7.07 (br s, 1H), 7.21–7.93 (m, 17H). 13C NMR
(75.5 MHz, CDCl3) ␦: 14.4, 28.5, 32.4, 35.0, 41.5, 52.6, 60.6,
67.9, 68.7, 70.5, 72.5, 75.1, 76.0, 78.0, 78.8, 101.7, 116.4,
125.8, 126.0, 126.2, 126.3, 126.5, 127.9, 128.1, 128.3, 128.4,
128.9, 129.1, 133.1, 133.4, 135.9, 137.9, 138.5, 140.6, 170.1,
170.8, 172.3, 173.0.
(2) (a) Crich, D.; Krishnamurthy, V.; Hutton, T. K. J. Am. Chem.
Soc. 2006, 128 (8), 2544. doi:10.1021/ja057521c; (b) Crich, D.;
Krishnamurthy, V.; Brebion, F.; Karatholuvhu, M.; Subrama-
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doi:10.1021/jo8015314; (b) Subramanian, V.; Moumé-
Pymbock, M.; Hu, T.; Crich, D. J. Org. Chem. 2011, 76 (10),
3691. doi:10.1021/jo102411j.
(6) Riague, E. H.; Guillemin, J.-C. Organometallics 2002, 21 (1),
68. doi:10.1021/om010453s.
N-(tert-Butoxycarbonyl) S-[(2-O-benzyl-4,6-O-benzylidene-3-
O-(2-naphthylmethyl)-b-D-mannopyranosyl)methyl]allyl
L-cysteine methyl ester (34)
Prepared according to the general procedure, by reaction of
the mannose derivative 12 (0.18 mmol, 127 mg) with the
L-cysteine derivative 19 (0.23 mmol, 51.3 mg), affording 34
20
(79.6 mg, 57%) as a colorless oil. [␣]D –20.1 (c 0.45,
CHCl3). IR (neat, cm–1): 698, 730, 817, 857, 908, 1049, 1165,
1368, 1453, 1496, 1602, 1709, 2872, 2924. 1H NMR
(500 MHz, CDCl3) ␦: 1.44 (s, 9H), 2.76–2.92 (m, 2H), 3.17 (s,
1H), 3.26–3.37 (m, 1H), 3.60–3.65 (m, 1H), 3.92–3.95 (m,
2H), 4.03–4.12 (m, 1H), 4.18–4.34 (m, 2H), 4.39–4.51 (m,
2H), 4.68–4.84 (q, J ϭ 10.5 Hz, 2H), 4.87 (d, J ϭ 12.3 Hz,
1H), 4.99 (d, J ϭ 12. 3 Hz, 1H), 5.08 (s, 1H), 5.16 (s, 1H), 5.39
(br s, 1H), 5.63 (s, 1H), 7.24–7.81 (m, 17H). 13C NMR
(75.5 MHz, CDCl3) ␦: 28.5, 29.9, 33.2, 35.2, 67.8, 68.8, 70.3,
72.5, 75.0, 75.9, 78.0, 78.8, 101.5, 101.7, 116.2, 125.8, 126.0,
126.2, 126.3, 126.4, 127.8, 128.1, 128.2, 128.4, 128.8, 129.1,
133.1, 133.4, 135.9, 137.8, 138.5, 140.5. HRMS (ESI) calcd
for C43H53N2O10S: 789.3415; found: 789.3381 [M ϩ NH4]ϩ.
(7) Wallace, G. A.; Scott, R. W.; Heathcock, C. H. J. Org. Chem.
2000, 65 (13), 4145. doi:10.1021/jo0002801.
ខ
´
(8) Kałuza, Z.; Kazimierski, A.; Lewandowski, K.; Suwinska, K.;
Szcze˛sna, B.; Chmielewski, M. Tetrahedron 2003, 59 (31),
5893. doi:10.1016/S0040-4020(03)00939-6.
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Biology; Ernst, B., Hart, G. W., Sinaÿ, P., Eds.; Wiley-VCH:
Weinheim, 2000; Vol. 1, p 5.
Monitoring of the reaction of 6 with benzylmercaptan by
1H and 77Se NMR spectroscopy
(10) (a) Garegg, P. J.; Konradsson, P.; Kvarnström, I.; Norberg, T.;
Svensson, S. C. T.; Wigiliu, B. Acta Chem. Scand. A 1985, 39b,
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v79-335; (c) Crich, D.; Dai, Z.; Gastaldi, S. J. Org. Chem. 1999,
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doi:10.1021/ja0111481.
The reaction of 6 (0.23 mmol, 40 mg) with benzyl mercap-
tan (0.27 mmol, 34 mg) in CD3OD (1 mL) was monitored by
1
NMR spectroscopy through an iterative sequence of H spec-
tra (64 scans, 500 MHz, 300 K), 77Se NMR spectra (64 scans,
95 MHz, 300 K), and DEPT 77Se spectra (32 scans, 95 MHz,
300 K). Acquisition parameters for F1: size, 32 768 points;
spectral width, 47 619 Hz).
Acknowledgments
We thank J.-F. Gallard and S. Picard, Institut de Chimie des
Substances Naturelles (ICSN), for help with the recording of
77Se NMR spectra and for the gift of 11, respectively.
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