Organo phosphorus-selenium heterocycles derived from haloalkanols and alkenes

Article abstract of DOI:10.1055/s-0032-1317310

Treating Woollins reagent with an equimolar amount of sodium 2-bromoalkanolates (which were prepared in situ from the reaction of bromoalkanol and NaH) in THF gave five- or six-membered PSeOC(n=2 or 3) phosphorus-selenium heterocycles 3 and 4 in good yields. Woollins reagent reacting with one equivalent of conjugated 1,3-dienes led to the formation of different end products: with 1,4-diphenylbuta-1,3-diene giving a five-membered 2,3,5-triphenyl-4-styryl-1,2,5-selenadiphospholane 2,5-diselenide; however, with 2,3-dibenzyl-1,3-butadiene affording 4,5-dibenzyl-2-phenyl-3,6-dihydro-2H-1,2- selenaphosphinine 2-selenide as a major isolable product. Refluxing Woollins reagent with one equivalent of unconjugated 2,5-dimethyl-1,5-hexyldiene in toluene produced P-Se heterocyclic compound 3-methyl-3-(3-methylbut-3-en-1-yl)- 2,5-diphenyl-1,2,5-selenadiphospholane 2,5-diselenide with the same five-membered C(Se)SeP(Se) motif as 2,3,5-triphenyl-4-styryl-1,2,5- selenadiphospholane 2,5-diselenide. Furthermore, heating a toluene solution of Woollins reagent with an equimolar amount of N-allylaniline gave rise of a five-membered CP(Se)Se heterocycle 5-methyl-2,3-diphenyl-1,3,2- selenazaphospholidine 2-selenide; carrying out a reaction of cinnamonitrile with an equivalent of Woollins reagent under identical conditions did not give any air-stable product, however, 3-phenylprop-2-eneselenoamide was isolated in 95% yield after treatment with water. Three demonstrative X-ray structures are reported.

Full text of DOI:10.1055/s-0032-1317310

LETTER
▌2453
letter
Organo Phosphorus–Selenium Heterocycles Derived from Haloalkanols and
Alkenes
Reactions of Woollins’ Reagent
Guoxiong Hua, Amy L. Fuller, Alexandra M. Z. Slawin, J. Derek Woollins*
EastChem School of Chemistry, University of St Andrews, Fife, KY16 9ST, UK
Fax +44(1334)463384; E-mail: jdw3@st-and.ac.uk
Received: 23.07.2012; Accepted after revision: 27.08.2012
2,4-Bis(phenyl)-1,3-diselenadiphosphetane-2,4-diselenide
Abstract: Treating Woollins’ reagent with an equimolar amount of
[PhP(Se)(μ-Se)]2, known as Woollins’ reagent (WR), is
sodium 2-bromoalkanolates (which were prepared in situ from the
reaction of bromoalkanol and NaH) in THF gave five- or six-mem-
bered PSeOCn (n = 2 or 3) phosphorus–selenium heterocycles 3 and
an efficient selenating reagent in synthetic chemistry.5
WR has been widely utilized as a selenation reagent for
4 in good yields. Woollins’ reagent reacting with one equivalent of the synthesis of a wide range of selenium-containing and
conjugated 1,3-dienes led to the formation of different end prod-
nonselenium-containing compounds as well as for the
ucts: with 1,4-diphenylbuta-1,3-diene giving a five-membered
synthesis of a variety of phosphorus–selenium hetero-
2,3,5-triphenyl-4-styryl-1,2,5-selenadiphospholane 2,5-diselenide;
cycles.6–15 In continuation of our studies investigating the
however, with 2,3-dibenzyl-1,3-butadiene affording 4,5-dibenzyl-
reactivity of WR towards different organic substrates as
2-phenyl-3,6-dihydro-2H-1,2-selenaphosphinine 2-selenide as a
precursors or building blocks, herein, we report the syn-
thesis and characterization of six small phosphorus–
selenium heterocycles and one selenium-containing het-
eroatom compound from the reaction of WR with alkenes
or haloalkanols and three representative X-ray structures.
major isolable product. Refluxing Woollins’ reagent with one
equivalent of unconjugated 2,5-dimethyl-1,5-hexyldiene in toluene
produced P–Se heterocyclic compound 3-methyl-3-(3-methylbut-3-
en-1-yl)-2,5-diphenyl-1,2,5-selenadiphospholane
2,5-diselenide
with the same five-membered C2P(Se)SeP(Se) motif as 2,3,5-tri-
phenyl-4-styryl-1,2,5-selenadiphospholane 2,5-diselenide. Further-
more, heating a toluene solution of Woollins’ reagent with an
Heating 1-bromoethanol or 1-bromopropanol with an
equimolar amount of N-allylaniline gave rise of a five-membered equimolar amount of NaH in THF at 70 °C for two hours,
C2NP(Se)Se heterocycle 5-methyl-2,3-diphenyl-1,3,2-selenaza-
phospholidine 2-selenide; carrying out a reaction of cinnamonitrile
with an equivalent of Woollins’ reagent under identical conditions
five- or six-membered phosphorus–selenium heterocycles
did not give any air-stable product, however, 3-phenylprop-2-ene-
selenoamide was isolated in 95% yield after treatment with water.
followed by treating with a half-molar amount of WR at
room temperature for 24 hours gave the corresponding
3 and 4 in 91% and 86% yields, respectively (Scheme 1).
Apparently, WR reacts with sodium 2-bromoalkanolates
first producing the intermediates 1 and 2 as salts, followed
by intramolecular cyclization to give the final products 3
and 4. However, when bromoalkanols with long alkene
chains (n ≥ 4) were used, the reactions were too complex
to isolate any pure product.
Three demonstrative X-ray structures are reported.
Key words: Woollins’ reagent, phosphorus–selenium hetero-
cycles, alkenes, haloalkanols, selenoamide
Selenium-containing heterocyclic compounds have been
attracting considerable attention due in part to their inter-
esting reactivities and potential pharmaceutical proper-
ties,1,2 applications as new materials3 as well as reagents
and catalysts.4 However, the synthesis of selenium-
containing organic heterocycles is not always easy be-
cause of the inconvenience of typical selenium reagents
such as H2Se, NaHSe, TMS2Se, potassium selenocyanate,
and tetraethylammonium tetraselenotungstate [Et4N]2WSe4,
each exhibiting its own problems including toxicity,
solubility, difficulty in handling, and poor reactivity.
Compounds 3 and 4 are air- and moisture-stable for sev-
eral months without any decomposition and soluble in
normal organic solvents. Compounds 3 and 4 were fully
characterized by multinuclear NMR and IR spectroscopy
and accurate mass measurement. Both compounds
showed the anticipated molecular ion peaks [M + H]+ and
were confirmed by satisfactory accurate mass measure-
ments. 31P NMR spectra of 3 and 4 showed sharp singlets
at δ = 88.4 and 68.4 ppm, respectively, flanked by two
pairs of selenium satellites with 31P–77Se coupling con-
stants of 390/381 Hz and 852/832 Hz, indicating the pres-
Se
Se
Ph
Ph
Se
Se
SeNa
Br(CH2)nONa
THF, r.t., 24 h
Se
O
Se
Ph
intra-cyclization
P
P
P
(CH2)nBr
P
(CH2)n
O
Se Ph
1 n = 2
2 n = 3
3 n = 2
4 n = 3
WR
Scheme 1 Synthesis of phosphorus–selenium heterocycles 3 and 4
SYNLETT 2012, 23, 2453–2458
Advanced online publication: 28.09.2012
0
9
3
6
-
5
2
1
4
1
4
3
7
-
2
0
9
6
DOI: 10.1055/s-0032-1317310; Art ID: ST-2012-B0618-L
© Georg Thieme Verlag Stuttgart · New York

2454
G. Hua et al.
LETTER
ence of both P–Se single bond and P=Se double bonds in another equivalent of WR under identical conditions lead-
these heterocyclic compounds. This was further supported ing to recovery of the starting materials.
by the 77Se NMR spectra which showed two doublets at δ
= 342.5/370.4 ppm and –0.4/–40.5 ppm with matching
Se
Ph
31P–77Se coupling constants.
Se
Ph
Se
Se
Se P
P
P
Ph
Se
P
Refluxing a toluene solution of 1,4-diphenylbuta-1,3-di-
ene with an equimolar amount of WR led to the new five-
membered 2,3,5-triphenyl-4-styryl-1,2,5-selenadiphos-
pholane 2,5-diselenide (5) with one C=C double bond un-
reacted in 36.2% yield via the cleavage of the four-
membered [P(Se)(μ-Se)]2 ring as shown in Scheme 2.
Carrying on the reaction of WR with two or more equiv-
alents of 1,4-diphenylbuta-1,3-diene under identical con-
ditions furnished the same product with a slight
improvement of yield. Prolonged reactions had no impact
on the yield. Furthermore, to investigate the reactivity of
the remaining C=C double bond in compound 5 towards
WR, the reaction of compound 5 with one equivalent of
WR was performed in refluxing toluene. As expected, no
new products were isolated with recovery of the starting
materials, compounds 5 and WR. The result suggests that
the steric hindrance effectively shields the further reaction
of WR with the remaining pendant C=C double bond.
toluene,
reflux, 24 h
Se Ph
7
WR
Scheme 4 Synthesis of heterocycle 7 from the selenation of 2,5-di-
methyl-1,5-hexyldiene
Compounds 5–7 were spectrally characterized by multi-
nuclear NMR and IR spectroscopy and accurate mass
measurement. All new compounds showed the anticipated
molecular ion peaks [M + H]+ and were confirmed by sat-
isfactory accurate mass measurements. The phosphorus
atoms in compounds 5–7 are potentially stereogenic cen-
ters. In fact, two stereoisomers were observed by multinu-
clear NMR in compounds 5 and 7. 31P NMR spectra of 5–
7 showed sharp singlets in the range of δ = 43.0–61.8
ppm, flanked by two pairs of selenium satellites with 31P–
77Se coupling constants in the ranges of 333–416 Hz and
756–803 Hz, indicating the presence of both P–Se single
bond and P=Se double bond in these heterocyclic com-
pounds. This was further supported by the 77Se NMR
spectra which showed one set of triplets at δ = 364.1 and
469.1 ppm for 5 and 7, respectively, and two doublets in
the range of δ = –179.0 to –103.1 ppm with matching 31P–
77Se coupling constants, and displayed two pairs of dou-
blets at δ = 286.5 and –133.6 ppm with matching 31P–77Se
coupling constants in compound 6. The IR spectra of com-
pound 6 showed a strong bond at 2009 cm–1, indicating the
presence of an unconjugated C=C double bond supporting
the formation of the six-membered heterocycle.
The X-ray crystal structure of 5 is shown in Figure 1.16
The newly formed ring is nonplanar, and there is a trans
arrangement of two phenyl groups being inclined each
other by 16.6° and a trans arrangement of two exo-seleni-
um atoms bonded to the phosphorus atoms. The P···P
cross-ring distance (3.27 Å) is approximately midway be-
tween the P–P single bond (2.20 Å) and van der Waals’
separation (3.80 Å). The distances of P=Se double bonds
[2.0914(16) and 2.0944(17) Å] and P–Se single bonds
[2.273(2) and 2.2768(15) Å] are similar to P=Se and P–Se
bond lengths previously observed in other related com-
pounds containing the P(Se)(μ-Se) unit.17–19
Ph
Ph
Se Se
P
Se
P
H
Ph
Se
Se
Ph
Se
Ph
P
P
+
toluene, reflux, 24 h
Se Ph
H
Ph
H
Ph
H
WR
5
Scheme 2 Synthesis of heterocycle 5 from the selenation of 1,4-di-
phenylbuta-1,3-diene
Surprisingly, WR reacting with an equimolar amount of
2,3-dibenzyl-1,3-butadiene in refluxing toluene led to 4,5-
dibenzyl-2-phenyl-3,6-dihydro-2H-1,2-selenaphosphinine
2-selenide (6) in 45.6% yield as a unique product rather
than a five-membered ring as compound 5 (Scheme 3).
Once again, we carried on the reaction of the product 6
with one more equivalent of WR under identical condi-
tions, but no new product was identified.
Ph
Se
Ph
Se
Se
Ph
H
Ph
H
P
P
Se
+
toluene,
reflux, 24 h
P
Se
Ph
Ph
Se Ph
6
WR
Scheme 3 Synthesis of heterocycle 6 from the selenation of 2,3-di-
We tested other organic substrates with C=C double
bonds in reactions with WR. Surprisingly, five-mem-
bered heterocycle 8 was obtained in 72% yield when
N-allylaniline reacted with an equivalent of WR in reflux-
ing toluene solution (Scheme 5). Compound 8 represents
a symmetric cleavage product of WR rather than the ex-
pected five-membered ring diphosphorus species. A two-
step reaction mechanism can be proposed for the forma-
tion of 8. The first step is that N-allylaniline reacts with
the true reactive species PhPSe2 (I) from WR at elevated
temperature leading to the intermediate II. Then, an intra-
benzyl-1,3-butadiene
The above results prompted us to investigate related reac-
tions. Unconjugated 2,5-dimethyl-1,5-hexyldiene reacted
with an equimolar amount of WR in refluxing toluene re-
sulting in a unique P–Se heterocyclic compound 7 with a
five-membered C2P(Se)SeP(Se) motif in 46.1% isolated
yield after workup (Scheme 4). Once more, the remaining
unconjugated C=C double bond in the heterocycle 7 re-
mained unreacted. The product was further treated with
Synlett 2012, 23, 2453–2458
© Georg Thieme Verlag Stuttgart · New York

LETTER
Reactions of Woollins’ Reagent
2455
with water, selenoamide 11 was isolated in 95% yield
(Scheme 6). We propose that the heterocyclic compound
10 was readily formed via a [2+2] cycloaddition of
PhPSe2 from WR with the triple bond C≡N of cinnamo-
nitrile (due to the double bond C=C being less reactive
than the triple bond C≡N towards WR). However, the in-
termediate 10 is not isolable and easily decomposed to
selenoamide 11 after hydrolysis. This might be following
a similar mechanism that was suggested in the previous
report of the preparation of primary arylselenoamides.19
The proposed structures of 8 and 11 are based on their
spectral analyses and accurate mass measurement. Both
compounds 8 and 11 showed the anticipated molecular
ion peaks [M + H]+, and their formulae were confirmed by
satisfactory accurate mass measurements. For 8, two ste-
reoisomers were found in ca. 2:1 intensity ratio in multi-
NMR spectra. The 31P NMR spectrum of 8 comprises
sharp singlets at δ = 60.8/59.8 ppm, the singlet in each
case being flanked by two pairs of selenium satellites with
31P–77Se coupling constants of δ = 379/379 Hz and
806/806 Hz, indicating both P–Se single-bond and P=Se
double-bond characters. This was further confirmed by
the 77Se NMR exhibiting double doublets at δ =
482.8/465.9 ppm with matching 31P–77Se coupling con-
stants. For 11, the IR spectra showed a strong band at 1630 cm–1
from the C=C double bond, and intense bands at 746 cm–1
and medium bands at 372 cm–1 are characteristic of the
C=Se group.21 77Se NMR spectrum displayed a singlet
signal at δ = 592.3 ppm which is typical of seleno-
amides.20,22
Figure 1 X-ray crystal structure of 5 (hydrogen atoms omitted for
clarity). Selected bond lengths (Å) and angles (°, esds in parentheses):
Se(1)–P(1) 2.0914(16), Se(2)–P(2) 2.0944(17), Se(3)–P(1) 2.273(2),
Se(3)–P(2) 2.2768(15), P(1)–C(1) 1.872(5), P(1)–C(17) 1.810(6),
P(2)–C(23) 1.801(7), P(2)–C(2) 1.846(6), C(1)–C(2) 1.517(9); P(1)–
Se(2)–P(2) 91.75(6), Se(1)–P(1)–Se(3) 112.55(8), Se(1)–P(1)–C(1)
116.26(19), Se(1)–P(1)–C(17) 114.23(18), Se(3)–P(1)–C(1)
101.6(2), Se(3)–P(1)–C(17) 106.9(2), C(1)–P(1)–C(17) 104.1(2),
Se(2)–P(2)–Se(3) 116.68(7), Se(2)–P(2)–C(2) 114.1(2), Se(2)–P(2)–
C(23) 114.69(19), Se(3)–P(2)–C(2) 98.19(17), Se(3)–P(2)–C(23)
105.66(19), C(2)–P(2)–C(23) 105.7(2), P(1)–C(1)–C(2) 111.1(4).
Ph
H
Se
N
P
Se
P
Se
Ph
Se
Se
Ph
Se
P
N
+
toluene,
reflux, 7 h
Compounds 8 and 11 were crystallized by slow diffusion
of hexane into dichloromethane solutions to give trans-
parent, colorless cubic crystals.23 Compound 8 crystalliz-
es in the triclinic space group P-1 with two
crystallographically independent molecules in the asym-
metric unit (Figure 2) and confirms the presence of the
five-membered heterocyclic ring. Compound 8 adopts an
envelope conformation with the Se(1)–P(2) 2.2263(19)
[2.2263(19)] Å and Se(2)–P(2) 2.0855(17) [2.0915(17)]
Å distances being typical of P–Se single [2.2–2.3 A˚Å]
and P=Se double bonds [2.08–2.12 Å].24,25 The P–N bond
length {P(2)–N(3) 1.693(5) [1.693(6)] Å} is appropriate
for a P–N single bond. The geometry around P(2) [Se(1)–
P(2)–Se(2) 114.42(9) [113.99(6)]° is a distorted tetrahe-
dron due to the steric hindrance of the phenyl groups. One
WR
Se
Se
Ph
cyclization
Ph
P
Se
P
I
SeH
N
II
Scheme 5 Synthesis of heterocycle 8 from the selenation of N-allyl-
aniline
molecular [2+2] addition resulting in the ring closure of
intermediate II gives five-membered heterocycle 8.
Treating cinnamonitrile with an equivalent of WR in re-
fluxing toluene did not lead to any stable isolable product.
However, when the resulting reaction mixture was treated
N
Se
Ph
C
P
N
Se
P
Se
Se
Ph
Se
P
Se
WR
Ph
Se
Ph
9
P
toluene, reflux, 6 h
Se
Se
Ph
H2O
C
P
Se
N
NH2
11
10
Scheme 6 Synthesis of selenoamide 11 from the selenation of cinnamonitrile
© Georg Thieme Verlag Stuttgart · New York
Synlett 2012, 23, 2453–2458

2456
G. Hua et al.
LETTER
of two phenyl rings is co-planar with the newly formed
five-membered ring with two phenyl rings oriented cis to
one another being inclined by 83.2° [76.8°] to each other.
Figure 3 X-ray crystal structure of 11. Selected bond lengths (Å) and
angles (°, esds in parentheses): Se(1)–C(1) 1.861(7), N(1)–C(1)
1.337(10), C(1)–C(2) 1.440(12), C(2)–C(3) 1.339(11), C(3)–C(4)
1.446(11); Se(1)–C(1)–N(1) 119.1(6), Se(1)–C(1)–C(2) 123.3(5),
N(1)–C(1)–C(2) 117.6(7), C(1)–C(2)–C(3) 122.4(7), C(2)–C(3)–
C(4) 128.0(7).
Figure 2 X-ray crystal structure of 8 (hydrogen atoms omitted for
clarity). There are two independent molecules in the asymmetric unit.
Selected bond lengths (Å) and angles (°, esds in parentheses; dimen-
sions for second independent molecule in square parentheses): Se(1)–
P(2) 2.2263(19) [2.2263(19)], Se(2)–P(2) 2.0855(17) [2.0915(17)],
Se(1)–C(5) 1.983(8) [1.983(8)], P(2)–N(3) 1.693(5) [1.693(6)], P(2)–
C(7) 1.797(5) [1.792(6)], N(3)–C(13) 1.424(9) [1.410(8)], N(3)–
C(4), 1.472(8) [1.472(8)], C(4)–C(5) 1.462(11) [1.462(11)]; P(2)–
Se(1)–C(5) 88.5(2) [88.0(2)], Se(1)–P(2)–Se(2) 114.42(9)
[113.99(6)], Se(1)–P(2)–C(7) 106.1(2) [108.6(2)], Se(2)–P(2)–C(7)
111.96(19) [111.8(2)], Se(1)–P(2)–N(3) 96.5(2) [96.75(16)], Se(2)–
P(2)–N(3) 120.06(18) [118.8(2)], N(3)–P(2)–C(7) 106.0(2)
[105.6(2)], P(2)–N(3)–C(4) 117.9(5) [117.3(4)], N(3)–C(4)–C(5)
114.5(5) [115.3(7)], Se(1)–C(5)–C(4) 106.7(5) [107.2(5)].
butadiene producing a monophosphorus species hetero-
cyle with a C(4)P(Se)Se motif. Treating Woollins’ re-
agent with N-allylaniline under identical conditions
resulted in a new five-membered C(2)NP(Se)Se hetero-
cycle. Reaction of cinnamonitrile with an equivalent of
Woollins’ reagent under identical conditions did not give
any isolable product apart from selenoamide, which was
isolated in 95% yield after treatment with water. The
structures of all new compounds have been elucidated by
using 1H, 13C, 31P, and 77Se NMR spectroscopy and accu-
rate mass measurement in conjunction with single-crystal
X-ray crystallography of three structures.
Compound 11 crystallizes in the monoclinic space group
P21/c (Figure 3) and indicates the presence of a seleno-
amide. The C=Se double-bond length [1.861(7) Å] is mar-
ginally longer that in arylselenoamides [1.820(4)–
1.848(2)]20,26,27 due to the selenocarbonyl group being sta-
Unless otherwise stated, all reactions were carried out under an
oxygen-free nitrogen atmosphere using predried solvents and stan-
bilized by conjugation with the free electron pairs at the dard Schlenk techniques, subsequent chromatographic and workup
procedures were performed in air. 1H (270 MHz), 13C (67.9 MHz),
nitrogen and the conjugated C=C double bond. A similar
31P-{1H} (109 MHz), and 77Se-{1H} (51.4 MHz referenced to exter-
C=Se double-bond distance [1.837(4) Å] was found in
nal Me2Se) NMR spectra were recorded at 25 °C (unless stated oth-
N,N-diethyl-2-methyl-3,3-diphenylprop-2-eneselenoamide.28
erwise) on a JEOL GSX 270. IR spectra were recorded as KBr
pellets in the range of 4000–250 cm–1 on a Perkin-Elmer 2000 FTIR/
Raman spectrometer. Mass spectrometry was performed by the EP-
SRC National Mass Spectrometry Service Centre, Swansea and the
University of St Andrews Mass Spectrometry Service. X-ray crystal
data for 5 were collected using Rigaku SCX Mini Mercury CCD
system and for 8 and 11 using the Rigaku STANDARD system.29
Intensity data were collected using ω steps accumulating area detec-
tor images spanning at least a hemisphere of reciprocal space. All
data were corrected for Lorentz polarization effects. Absorption ef-
fects were corrected on the basis of multiple equivalent reflections
or by semi-empirical methods. Structures were solved by direct
methods and refined by full-matrix least-squares against F2 by using
the program SHELXTL.30 Hydrogen atoms were assigned riding
isotropic displacement parameters and constrained to idealized geo-
metries. These data can be obtained free of charge via
www.ccdc.cam.ac.uk/conts/retrieving.html or from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge CB2
1EZ, UK; fax +44(1223)336033; e-mail: deposit@ccdc.cam.ac.uk.
CCDC Nos 5 893079; 8 893078; 11 893077.
The shortness of the C–N bond length in which the C–N
bonds are adjacent to the C=Se double bond [1.337(10)
Å], compared to the normal C–N bond distances [1.45–
1.48 Å],20 suggests some multiple-bonding character. It
should be noted that N(1)–C(1)–C(2)–C(3) is approxi-
mately co-planar with the phenyl ring, while Se(1) lies
0.182 Å out of this plane.
Molecules of 11 pack into a herringbone arrangement
with intermolecular N–H·Se hydrogen bonds [H·Se
2.571(5), N···Se 3.44(2) Å, N–H·Se 172.2(6)°].
In conclusion, Woollins’ reagent reacting with an equimo-
lar amount of sodium 2-bromoalkanolates gave the corre-
sponding five- or six-membered phosphorus–selenium
heterocycles in good yields. Woollins’ reagent reacting
with dienes resulted in the formation of different end
products: with conjugated 1,4-diphenylbuta-1,3-diene
and unconjugated 2,5-dimethyl-1,5-hexyldiene affording
General Procedure for the Synthesis of Heterocyles 3 and 4
A white suspension of 2-bromoalkanol (2.0 mmol) and NaH (0.16
g, 4.0 mmol) in THF (50 mL) was heated at 70 °C for 2 h. Upon
diphosphorus
species
heterocyles
with
a
C(2)P(Se)SeP(Se) motif; however, with 2,3-dibenzyl-1,3-
Synlett 2012, 23, 2453–2458
© Georg Thieme Verlag Stuttgart · New York

LETTER
Reactions of Woollins’ Reagent
2457
cooling to r.t. and removing unreacted solid, the filtrate was added
to WR (0.54 g, 1.0 mmol), and the mixture was stirred at r.t. for 24
h. After removing unreacted solid by filtration and evaporating the
solvent in vacuo, the residue was purified by column chromatogra-
phy on silica gel (EtOAc–CH2Cl2 = 1:9) to give the compounds 3
and 4.
1090 (s), 1027 (m), 996 (m), 730 (s), 726 (m), 695 (s), 537 (m), 514
(m) cm–1. 1H NMR (CD2Cl2): δ = 7.99–7.92 (m, 2 H, ArH), 7.49–
7.46 (m, 3 H, ArH), 7.36–7.03 (m, 10 H, ArH), 3.83 (s, 2 H, CH2),
3.67–3.53 (m, 2 H, CH2), 3.28–3.01 (m, 4 H, CH2) ppm. 13C NMR
(CD2Cl2): δ = 138.9, 138.3, 138.2, 136.2, 136.0, 134.2, 133.4, 132.6
[d, J(P,C) = 12.5 Hz], 132.2, 132.1, 131.8 [d, J(P,C) = 3.1 Hz],
129.1, 129.0, 128.7, 128.4 [d, J(P,C) = 12.5 Hz], 126.6 [d,
J(P,C) = 12.5 Hz], 105.5, 45.2 [d, J(P,C) = 29.1 Hz], 39.4 [d,
J(P,C) = 81 Hz], 39.3 [d, J(P,C) = 83 Hz], 28.3 [d, J(P,C) = 7.3 Hz]
ppm. 31P NMR (CD2Cl2): δ = 48.1 [s, J(P–Se) = 416 Hz,
J(P=Se) = 756 Hz], 48.0 [s, J(P–Se) = 416 Hz, J(P=Se) = 756 Hz]
ppm. 77Se NMR (CD2Cl2): δ = 286.5 [d, J(P–Se) = 415 Hz], –133.6
[d, J(P=Se) = 756 Hz] ppm. MS (CI+): m/z = 503 [M + H]+. HRMS
(CI+) m/z calcd for C24H23PSe2H: 502.9946; found: 502.9941 [M +
H]+.
2-Phenyl-1,3,2-oxaselenaphospholane 2-Selenide (3)
Yellow oil (0.275 g, 91% yield). Selected IR (KBr): 1435 (m), 1259
(m), 1185 (w), 1100 (s), 1016 (s), 983 (s), 925 (m), 745 (s), 688 (m),
547 (s), 549 (s), 520 (m) cm–1. 1H NMR (CD2Cl2): δ = 8.00–7.87 (m,
2 H, ArH), 7.52–7.49 (m, 3 H, ArH), 4.82–4.64 (m, 2 H, OCH2),
3.78–3.60 (m, 2 H, SeCH2) ppm. 13C NMR (CD2Cl2): δ = 136.9 [d,
J(P,C) = 93.0 Hz], 133.2 [d, J(P,C) = 3.1 Hz], 131.0 [d,
J(P,C) = 12.5 Hz], 128.6 [d, J(P,C) = 14.5 Hz], 72.7, 34.8 ppm. 31
P
NMR (CD2Cl2): δ = 88.4 [s, J(P,Se) = 390 Hz, J(P,Se) = 852 Hz]
ppm. 77Se NMR (CD2Cl2): δ = 342.5 [d, J(P,Se) = 390 Hz], –0.4 [d,
J(P,Se) = 852 Hz] ppm. HRMS (EI+): m/z calcd for C8H9OP76Se2:
303.8770; found: 303.8773 [M]+.
Synthesis of 3-Methyl-3-(3-methylbut-3-en-1-yl)-2,5-diphenyl-
1,2,5-selenadiphospholane 2,5-Diselenide (7)
A suspension of 2,5-dimethyl-1,5-hexyldiene (0.11 g, 1.0 mmol)
and WR (0.54 g, 1.0 mmol) in toluene (20 mL) was refluxed for 24
h. The red suspension disappeared, and a yellow solution with some
black solid formed. The solvent was removed in vacuo, and the or-
ganic residue was purified by column chromatography on silica gel
(eluent hexane–CH2Cl2 =1:1) to give a reddish yellow oil in 46.1%
yield (0.260 g). Two stereoisomers were found in ca. 2:3 intensity
ratio. Selected IR (KBr): 1660 (m, C=C), 1658 (m, C=C), 1435 (s),
1378 (m), 1308 (m), 1091 (s), 1021 (m), 844 (m), 817 (m), 741 (s),
688 (s), 563 (s), 522 (s) cm-1. 1H NMR (CD2Cl2): δ = 8.14–8.08 (m,
2 × 4 H, ArH), 7.52–7.48 (m, 2 × 6 H, ArH), 5.40 [d, J(P,H) = 10.2
Hz, 2 × 2 H, CH2], 4.81–4.73 (m, 2 × 2 H, CH2), 4.09 (s, 1 H, CH2),
4.07 (s, 1 H, CH2), 4.05 (s, 1 H, CH2), 4.03 (s, 1 H, CH2), 1.99 (s, 3
H, CH3), 1.95 (s, 3 H, CH3), 1.75–1.70 (m, 2 × 2 H, CH2), 1.56 (s, 3
H, CH3), 1.54 (s, 3 H, CH3), ppm. 13C NMR (CD2Cl2): δ = 138.7,
138.5, 132.6, 131.9, 131.6, 131.5, 128.5, 128.3, 123.4, 122.7, 58.4,
57.3, 55.0, 54.7, 46.5, 44.4, 33.4, 33.1, 25.7, 25.5, 18.9, 18.1 ppm.
31P NMR (CD2Cl2): δ = 43.8 [s, J(P–Se) = 366 Hz, J(P=Se) = 760
Hz], 43.0 [s, J(P–Se) = 380 Hz, J(P=Se) = 760 Hz] ppm. 77Se NMR
2-Phenyl-1,3,2-oxaselenaphosphinane 2-Selenide (4)
Yellow oil (0.280 g, 86% yield). Selected IR (KBr): 1434 (m), 1258
(m), 1183 (m), 1104 (s), 979 (vs), 895 (m), 864 (m), 742 (s), 688
(m), 583 (s), 547 (vs), 524 (s) cm–1. 1H NMR (CD2Cl2): δ = 8.08–
8.00 (m, 2 H, ArH), 7.55–7.50 (m, 3 H, ArH), 4.90–4.76 (m, 2 H,
OCH2), 4.29–4.14 (m, 2 H, SeCH2), 3.08–3.02 (m, 2 H, CH2) ppm.
13C NMR (CD2Cl2): δ = 135.0 [d, J(P,C) = 93.4 Hz], 133.2 [d,
J(P,C) = 3.1 Hz], 131.0 [d, J(P,C) = 12.5 Hz], 128.7 [d,
J(P,C) = 14.5 Hz], 68.2, 27.1, 23.7 ppm. 31P NMR (CD2Cl2): δ =
68.4 [s, J(P,Se) = 381 Hz, J(P,Se) = 832 Hz] ppm. 77Se NMR
(CD2Cl2): δ = 370.4 [d, J(P,Se) = 381 Hz], –40.5 [d, J(P,Se) = 832
Hz] ppm. HRMS (EI+): m/z calcd for C9H11OP76Se2: 317.8926;
found: 317.8924 [M]+.
Synthesis of 2,3,5-Triphenyl-4-styryl-1,2,5-selenadiphos-
pholane 2,5-Diselenide (5)
A solution of 1,4-diphenyl-1,3-butadiene (0.21 g, 1.0 mmol) and
WR (0.54 g, 1.0 mmol) in toluene (20 mL) was refluxed for 24 h.
Upon cooling to r.t., the resulting red suspension was evaporated
under reduced pressure, and the residue was extracted with CH2Cl2
(2 mL) and purified by column chromatography on silica gel (eluent
CH2Cl2–hexane = 1:1) to give a dark yellow solid in 36.2% yield
(0.235 g). Two stereoisomers were found in ca. 1:1 intensity ratio.
Selected IR (KBr): 1657 (m, C=C), 1636 (m, C=C), 1577 (m, C=C),
1493 (w), 1434 (m), 1089 (s), 956 (m), 746 (m), 726 (m), 689 (s),
544 (vs), 515 (m), 478 (m), 417 (m), 372 (m) cm–1. 1H NMR
(CD2Cl2): δ = 8.40–8.33 (m, 2 × 4 H, ArH), 7.61 (d, 2 × 2 H, ArH),
7.35–6.88 (m, 2 × 14 H, ArH), 5.98 (d, 2 × 1 H, CH), 5.12 (m, 2 ×
1 H, CH), 4.57 (m, 2 × 2 H, CH) ppm. 13C NMR (CD2Cl2): δ =
136.6, 136.4, 133.6, 133.5, 130.0, 130.9, 130.5, 130.1, 129.0, 128.8,
128.5, 128.4, 127.9, 127.6, 126.8, 126.4, 121.4, 121.1, 121.0, 120.9,
56.5, 56.9, 30.1, 29.9, 29.8, 29.6 ppm. 31P NMR (CD2Cl2): δ = two
phosphorus species were observed: 61.8 [s, J(P–Se) = 333 Hz,
J(P=Se) = 803 Hz], 56.8 [s, J(P–Se) = 338 Hz, J(P=Se) = 792 Hz]
ppm. 77Se NMR (CD2Cl2): δ = one endo-Se atom and two exo-Se
atoms were observed: 469.1 [t, J(P–Se) = 333 Hz], –160.7 [d,
J(P=Se) = 803 Hz], –179.0 [d, J(P=Se) = 792 Hz] ppm. MS (CI+):
m/z = 661 [M + H]+. HRMS (CI+): m/z calcd for C28H25P276Se3:
650.9002; found: 650.9014 [M + H]+.
(CD2Cl2):
δ = 364.1 [t, J(P–Se) = 367 Hz], –103.1 [d,
J(P=Se) = 760 Hz], –110.5 [d, J(P=Se) = 760 Hz] ppm. MS (CI+):
m/z = 565 [M + H]+. HRMS (CI+) m/z calcd for C20H25P2Se3:
565.9013; found: 565.9007 [M + H]+.
Synthesis of 5-Methyl-2,3-diphenyl-1,3,2-selenazaphos-
pholidine 2-Selenide (8)
A mixture of N-allylaniline (0.135 g, 1.0 mmol) and WR (0.54 g,
1.0 mmol) in anhydrous toluene (10 mL) was refluxed for 7 h. The
red suspension disappeared, and a brown solution was formed. Af-
ter removing the solvent in vacuo the residue was purified by silica
gel column (toluene as eluent) to give a pale yellow solid in 89.7%
yield (0.288 g). Selected IR (KBr): 1595(s, C=C), 1490 (s), 1435
(s), 1267 (s), 1248 (s), 1091 (s), 880 (s), 757 (s), 688 (vs), 608 (s),
526 (s), 491 (s) cm–1. Two stereoisomers were found in ca. 2:1 in-
tensity ratio. 1H NMR (CD2Cl2): δ = 8.14–8.05 (m, 2 × 2 H, ArH),
7.52–7.48 (m, 2 × 3 H, ArH), 7.22–6.61 (m, 2 × 5 H, ArH), 5.37–
5.17 (m, 2 × 1 H, CH), 4.42–3.75 (m, 2 × 2 H, CH2), 1.90–1.67 (m,
2 × 3 H, CH3) ppm. 13C NMR (CD2Cl2): δ = 142.1, 142.0, 135.7,
132.7, 132.5, 132.1, 131.6, 131.5, 131.4, 131.3, 128.9, 128.8, 128.5,
128.4, 128.3, 124.3, 124.2, 123.1, 122.7, 63.2, 63.1, 41.3, 41.2,
21.0, 18.3 ppm. 31P NMR (CD2Cl2): δ = 60.8 [s, J(P–Se) = 379 Hz,
J(P=Se) = 806 Hz], 59.8 [s, J(P–Se) = 379 Hz, J(P=Se) = 806 Hz]
ppm. 77Se NMR (CD2Cl2): δ = 482.8 [d, J(P–Se) = 379 Hz], 465.9
[d, J(P–Se) = 379 Hz], –20.7 [d, J(P=Se) = 806 Hz], –83.6 [d,
J(P=Se) = 806 Hz] ppm. MS (CI+): m/z = 322 [M + H]+. HRMS
(CI+): m/z calcd for C15H17NPSe2: 322.0264; 322.0260 [M + H]+.
Synthesis of 3-Benzyl-2,5-diphenyl-3-(3-phenylprop-1-en-2-yl)-
1,2,5-selenadiphospholane 2,5-Diselenide (6)
A mixture of 2,3-dibenzyl-1,3-butadiene (0.24 g, 1.0 mmol) and
WR (0.54 g, 1.0 mmol) in toluene (150 mL) was refluxed for 24 h.
The red suspension disappeared, and a yellow solution with some
black solid formed. Upon cooling to r.t., the solvent was removed
under reduced pressure, and the organic residue was extracted with
CH2Cl2 (2 mL) and purified by column chromatography on silica
gel (eluent CH2Cl2) to give a pale yellow paste in 62.8% yield
(0.315 g). Selected IR (KBr): 2009 (vs, C=C), 1492 (m), 1433 (m),
Synthesis of 3-Phenylprop-2-eneselenoamide (11)
A mixture of trans-cinnamonitrile (0.13 g, 1.0 mmol) and WR (0.54
g, 1.0 mmol) in toluene (20 mL) was refluxed for 6 h. The red sus-
pension disappeared, and a red solution was formed. Upon cooling
to 90 °C, H2O (1.0 mL) was added, and the mixture was refluxed for
© Georg Thieme Verlag Stuttgart · New York
Synlett 2012, 23, 2453–2458

2458
G. Hua et al.
LETTER
(12) Hua, G.; Fuller, A. L.; Slawin, A. M. Z.; Woollins, J. D.
another 1 hour. After cooling to r.t. the solvent was removed in vac-
uo, and the organic residue was extracted with CH2Cl2 and purified
by column chromatography on silica gel (eluent EtOAc–CH2Cl2 =
1:5) to afford a red solid in 95.2% yield (0.200 g). Selected IR
(KBr): 1664 (m, C=C), 1630 (vs, C=C), 1426 (vs), 1292 (m), 1250
Eur. J. Org. Chem. 2011, 3067.
(13) Hua, G.; Griffin, J. M.; Ashbrook, S. E.; Slawin, A. M. Z.;
Woollins, J. D. Angew. Chem. Int. Ed. 2011, 50, 4123.
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Woollins, J. D. Tetrahedron Lett. 2011, 52, 3311. (b) Hua,
G.; Slawin, A. M. Z.; Woollins, J. D. Synlett 2012, 23, 1170.
(15) Pilkington, M. J.; Slawin, A. M. Z.; Williams, D. J.; Wood,
P. T.; Woollins, J. D. Heteroat. Chem. 1990, 1, 351.
(16) Crystallographic Data for Compound 5
C28H24P2Se3, M = 659.33, monoclinic, space group P21/c,
a = 13.065(3), b = 19.737(3), c = 11.192(2) Å,
β = 112.23(4), U = 2671.4(9) Å3, Z = 4, μ = 1.639 mm–1,
16123 reflections, 4685 unique (Rint = 0.061); R1 = 0.0659,
wR2 = 0.1073.
(m), 1019 (m), 968 (s), 746 (vs), 688 (s), 372 (m) cm–1. H NMR
1
(CD2Cl2): δ = 8.35 (s, 2 H, NH), 7.84–7.38 (m, 5 H, ArH), 6.88 [d,
J(H,H) = 7.0 Hz, 1 H, CH], 5.90 [d, J(H,H) = 7.0 Hz, 1 H, CH]
ppm. 13C NMR (CD2Cl2): δ = 202.4, 144.9, 130.5, 129.3, 129.2,
128.4, 128.0 ppm. 77Se NMR (CD2Cl2): δ = 592.3 ppm. MS (ES+):
m/z = 233 [M + Na]+. HRMS (ES+): m/z calcd for C9H9NSeNa:
233.9798; 233.9795 [M + Na]+.
Acknowledgment
(17) Bhattacharyya, P.; Slawin, A. M. Z.; Woollins, J. D.
J. Organomet. Chem. 2001, 623, 116.
The authors are thankful to the University of St Andrews for finan-
cial support and the EPSRC National Mass Spectrometry Service
Centre (Swansea) for mass spectral measurements.
(18) (a) Bhattacharyya, P.; Slawin, A. M. Z.; Woollins, J. D.
Chem. Eur. J. 2002, 8, 2705. (b) Bhattacharyya, P.; Slawin,
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Phosporus Sulfur Relat. Elem. 1988, 39, 153.
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2006, 8, 5251.
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(23) Crystallographic Data for Compound 8
C15H16NPSe2, M = 399.19, triclinic, space group P-1,
a = 8.785(4), b = 9.7406(19), c = 19.590(11) Å,
α = 76.22(4), β = 87.46(5), γ = 69.26(4), U = 1521.2(11) Å3,
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Crystallographic Data for Compound 11
C9H9NSe, M = 210.14, monoclinic, space group P21/c,
a = 20.158(10), b = 5.509(3), c = 7.846(4) Å,
β = 98.756(12), U = 861.1(8) Å3, Z = 4, μ = 1.621 mm–1,
4686 reflections, 1509 unique (Rint = 0.055); R1 = 0.0628,
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Synlett 2012, 23, 2453–2458
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