Synthesis and electrophilic cyclization reactions of diphenyl 3-methylhexa- 1,3,4-trien-3-yl phosphine oxide

Article abstract of DOI:10.1002/hc.21023

Diphenyl 3-methylhexa-1,3,4-trien-3-yl phosphine oxide can be readily prepared via an atom-economical 2,3-sigmatropic rearrangement of the mediated alkenynyl phosphinite formed in situ by a reaction of 2-methylhex-5-en-3-yn-2-ol with diphenylchlorophosphine. Electrophilic cyclization reactions of prepared 1-vinylallenyl phosphine oxide were investigated as it was established that the reactions proceeded with formation of heterocyclic compounds with participation of the allenic and/or 1,3-dienic part of the vinylallenic system with neighboring group participation of the phosphoryl and/or vinylic group.

Full text of DOI:10.1002/hc.21023

Heteroatom Chemistry
Volume 00, Number 0, 2012
Synthesis and Electrophilic Cyclization
Reactions of Diphenyl 3-Methylhexa-
1,3,4-trien-3-yl Phosphine Oxide
Ivaylo K. Ivanov and Valerij Ch. Christov
Department of Organic Chemistry & Technology, Faculty of Natural Sciences, Konstantin
Preslavsky University of Shumen, BG-9700 Shumen, Bulgaria
Received 1 November 2011; revised 28 January 2012
extensively in recent years, and this has led to the de-
ABSTRACT: Diphenyl 3-methylhexa-1,3,4-trien-3-yl
velopment of novel methods for the construction of
phosphine oxide can be readily prepared via an
a variety of functionalized heterocyclic and carbo-
atom-economical 2,3-sigmatropic rearrangement of
cyclic systems [2].
the mediated alkenynyl phosphinite formed in situ
One of the characteristic reactions of the allenes
by a reaction of 2-methylhex-5-en-3-yn-2-ol with
is the electrophilic addition reactions in which the
diphenylchlorophosphine. Electrophilic cyclization re-
addition products of the reagent to the one and/or
actions of prepared 1-vinylallenyl phosphine oxide
other double bond of the allenic system are usually
were investigated as it was established that the reac-
obtained [3]. Functionalized allenes are very inter-
tions proceeded with formation of heterocyclic com-
esting substrates as a material of choice to study
pounds with participation of the allenic and/or 1,3-
the electrophilic addition reactions on the carbon–
dienic part of the vinylallenic system with neighboring
carbon double bonds [4–6]. Unlike the allenic hydro-
group participation of the phosphoryl and/or vinylic
carbons, the presence of a functional group linked to
ꢀ
C
group. 2012 Wiley Periodicals, Inc. Heteroatom Chem
the allenic system considerably changes the course
of the reactions with electrophilic reagents. It has
been shown [4–6] that the reactions proceeded with
00:1–7, 2012; View this article online at wileyonlineli-
brary.com. DOI 10.1002/hc.21023
cyclization of the allenic system bearing a functional
group give heterocyclic compounds in most cases. It
makes the investigations on the functionalized al-
lenes, more specifically in studying their reactions
with electrophilic reagents, quite an interesting and
topical task.
Recently, we have developed the electrophilic cy-
clization reactions of 1- and 3-vinylallenyl sulfox-
ides [7] and sulfones [8]. In all the cases, the elec-
trophilic atom has been introduced to the central
carbon atom of the allene moiety and the reactions
proceeded with participation of the allenic and/or
1,3-dienic part of the vinylallenic system with neigh-
boring group participation of the sulfinyl (sulfonyl)
and/or vinylic group [7,8].
INTRODUCTION
The presence of two π electron clouds separated by
a single sp-hybridized carbon atom is the identify-
ing structural characteristic of allenes, and it is this
unique structural and electronic arrangement that
is responsible for the extraordinary reactivity profile
displayed by allenic compounds [1]. The synthetic
potential of functionalized allenes has been explored
Correspondence to: Valerij Ch. Christov; e-mail: vchristo@shu-
bg.net.
Contract grant sponsor: Research Fund of the Konstantin
Preslavsky University of Shumen.
The literature data on the electrophilic addition
reactions to phosphorylated allenes (phosphonates,
Contract grant numbers: RD-05-367/2010 and RD-05-137/2011.
2012 Wiley Periodicals, Inc.
c
ꢀ
1

2
Ivanov and Christov
Me
Me
Me
Me
OH
Me
Me
[2,3]-
Et3N
•
+ Ph2PCl
O
Ph2P
CH2Cl2
O
PPh2
1
2, 65%
A
SCHEME 1
phosphinates, and phosphine oxides) show that
various five-membered heterocyclizations proceed
in most cases [4,6,9–12]. On the other hand, the
reactions of 1,2,4- and 1,3,4-alkatrienephosphonates
with electrophiles lead to the synthesis of various
heterocyclic compounds. For example, the halogena-
tion reactions afford 3- or 5-vinyl-substituted 2,5-
dihydro-1,2-oxaphospholes [13,16], whereas the in-
teraction with sulfenyl [14,16] and selenenyl [15,16]
chlorides gives thiophene- or selenophene-2- or
cleotides containing a purine or pyrimidine moiety
and an allenic skeleton [22e,22f].
Our strategy for the synthesis of diphenyl 3-
methylhexa-1,3,4-trien-3-yl phosphine oxide 2, us-
ing our experience on the preparation of the vinyl-
allenyl sulfoxides [7] and sulfones [8] relies on the
well-precedented 2,3-sigmatropic shift of propar-
gylic phosphinites to allenyl phosphine oxides [21].
Diphenyl 3-methylhexa-1,3,4-trien-3-yl phos-
phine oxide 2 can be readily prepared via an atom-
economical 2,3-sigmatropic rearrangement of the
mediated alkenynyl phosphinite A formed in situ
by a reaction of 2-methylhex-5-en-3-yn-2-ol 1 with
diphenylchlorophosphine in the presence of triethyl-
amine according to Scheme 1.
1-Vinylallenyl phosphine oxide 2 isolated in
preparative amounts allowed us to study its chemical
behavior in the reactions with electrophilic reagents.
From general considerations as well as from the
literature data on the electrophilic addition reac-
tions [23] to phosphorylated allenes [4], 1,2,4- and
1,3,4-alkatrienephosphonates [13–16], 3-vinylallenyl
phosphine oxide [17], vinylallenyl sulfoxides [7], and
sulfones [8], the following pathways of the reactions
could be assumed:
3-phosphonates.
Reactions
of
diphenyl
3-methylpent-1,2,4-trienyl phosphine oxide with
electrophiles proceeded with formation of various
heterocyclic or highly unsaturated compounds [17].
There are methods [18] for the synthesis of
phosphorus-containing allenes (phosphonates [19],
phosphinates [20], and phosphine oxides [21]),
including reactions of α-alkynols with chloride-
containing derivatives of phosphorus acids followed
by a [2,3]-sigmatropic rearrangement.
As a part of our long-standing program on the
synthesis and cyclization reactions of sulfur- and
phosphorus-functionalized vinylallenes, we now re-
port the results on the synthesis of diphenyl 3-
methylhexa-1,3,4-trien-3-yl phosphine oxide and the
reactions with some electrophilic reagents for the
study of the electrophilic cyclization reactions.
I. attack of the reagent on the C4–C5 double bond
with formation of 4,5-adduct;
II. attack of the reagent on the C3–C4 double bond
RESULTS AND DISCUSSION
Since its discovery five decades ago [19a,20a,20b],
the reversible interconversion of propargylic P(III)
esters (phosphites, phosphonites, and phosphinites)
to allenyl phosphonates, phosphinates, and phos-
phine oxides has become one of the most studied and
synthetically useful 2,3-sigmatropic rearrangement.
Numerous synthetic applications of the rearrange-
ment have been reported, including its use in the
synthesis of allenic steroids as substrate-induced in-
activation of aromatase [22a], in the efficient synthe-
sis of (2R)-2-amino-5-phosphonopentanoic acid as a
powerful and selective N-methyl-d-aspartate antag-
onist [22b], in the preparation of the phosphonate
analogues of phosphatidyl derivatives [22c,22d],
and, in the synthesis of new acyclic analogues of nu-
with formation of 4,3- and/or 4,1-adduct;
III. attack of the reagent on the C4–C5 double bond
of the trienic system and following neighboring
group participation of the internal nucleophile
(phosphoryl group) and ring closure to a five-
membered cyclic compound;
IV. attack of the reagent on the C3–C4 double bond
of the trienic system and following neighboring
group participation of the C1–C2 double bond
and ring closure to the cyclic compound;
V. attack of the reagent on the C1–C2 double bond
with formation of 1,2- and/or 1,4-adduct; and
VI. elimination reactions after realization of some
of the above-mentioned pathways (I–V).
Heteroatom Chemistry DOI 10.1002/hc

Synthesis and Electrophilic Cyclization Reactions of Diphenyl 3-Methylhexa-1,3,4-trien-3-yl Phosphine Oxide
3
X
Me
Me
X2
Me
Me
•
Ph2P
X
CH2Cl2
O
Ph2P
O
2
3
X = Cl, 3a, 76%
X = Br, 3b, 78%
Y
X
Yield (%)
Ratio
SCHEME 2
4
55
52
–
5
6
7
S
S
Cl
Br
Cl
Br
5a, 14
–
–
3.93 : 1
4.0 : 1
5b, 13
–
–
Se
Se
–
–
53
50
7a, 14
7b, 13
3.79 : 1
3.85 : 1
We initially examined the halogenation reac-
tion of diphenyl 3-methylhexa-1,3,4-trien-3-yl phos-
phine oxide 2. According to our previous ex-
perimental results on the electrophilic cyclization
reactions of functionalized vinylallenes [7,8,17],
dichloromethane was a good solvent for electrophilic
addition reactions to allenes. When CH2Cl2 was used
as the solvent, diphenyl 3-methylhexa-1,3,4-trien-3-
yl phosphine oxide 2 reacted with sulfuryl chloride
or bromine at −20◦ C to give 4-halo-2,2-diphenyl-
3-vinyl-2,5-dihydro-1,2-oxaphosphol-2-ium chloride
3a or bromide 3b in 76% and 78% yield, according
to the reaction sequence outlined in Scheme 2.
Obviously, the electrophilic halocyclization re-
action occurs by neighboring group participation of
the phosphine oxide group with formation of the
five-membered cyclic products 3.
Surprisingly, the reaction of 1,3,4-trienyl
phosphine oxide 2 with benzenesulfanyl chlo-
ride or bromide proceeds with two types of
electrophilic cyclization by neighboring group
participation of both the vinylic double bond and
the phosphine oxide group to give mixtures of 3-
(diphenylphosphinoyl)-2-isopropyl-thiophene 4 and
2,2-diphenyl-4-phenylsulfanyl-3-vinyl-2,5-dihydro-1,
2-oxaphosphol-2-ium chloride 5a or bromide 5b
in 65% and 69% overall yields according to the
sequence outlined in Scheme 3.
–
SCHEME 3
nals of the main signal in the 1H and 13C NMR spectra
[24].
Our results on the electrophilic halo-, sulfano-,
and selano-cyclization reactions of 1-vinylallenyl
phosphine oxide 2 are in contrast to Ma and
coworkers’ studies on the electrophilic iodohydrox-
ylation [9], fluorohydroxylation [10], and selenohy-
droxylation [11] reactions of allenyl phosphine ox-
ides with iodine, Selectfluor, and benzeneselanyl
chloride affording 2-iodo(respectively, 2-fluoro, or
2-phenylselanyl)-3-hydroxy-1(E)-alkenyl phosphine
oxides with high regio- and stereoselectivities, which
the authors [9–11] believed to be determined by
the neighboring group participation effect of the
diphenyl phosphine oxide functionality.
On the basis of previous results [7,8,17], a plau-
sible mechanism is proposed (Scheme 4). The initial
act is the attack of the electrophile (X+, S+, or Se+) on
the most nucleophilic atom of the trienic system of
π-bonds (C4) with the formation of two cyclic onium
(halogenonium, thiiranium, or seleniranium) ions A
and B after attacks on the relatively electron-rich
C4–C5 (in all cases) and C3–C4 (in the case of sulfanyl
and selanyl electrophiles only) double bonds, respec-
tively. The ions A are in the plane of the π-bond of
the vinyl group (s-cis conformation), and for this
reason A are easily transformed into the more sta-
ble five-membered cyclic ions C. Furthermore, the
ions C undergo elimination of phenyl halide, 1,5-
prototropic shift, and aromatization to give thio-
phene 4 or selenophene 6. The five-membered cyclic
phosphonium chlorides and bromides 3, 5, and 7
are formed via neighboring group participation of
the oxygen atom of the diphenyl phosphine oxide
functionality in the stage of ion B formation.
In a similar way, ca. 3.8:1 mixture of 3-
(diphenylphosphinoyl)-2-isopropyl-selenophene
and 2,2-diphenyl-4-phenylselanyl-3-vinyl-2,5-
6
dihydro-1,2-oxaphosphol-2-ium chloride 7a or
bromide 7b was obtained with 67% and 63% overall
yield from the reaction of 1-vinylallenyl phosphine
oxide 2 with benzeneselanyl chloride or bromide
in dry dichloromethane at −20◦ C as outlined in
Scheme 3.
The obtained compounds 6 and 7a, b contain
the isotope 77Se, which is magnetically active and in-
teracts with other nuclei. This interaction becomes
evident with the protons and carbons of the neigh-
boring groups, which exhibit symmetric satellite sig-
Heteroatom Chemistry DOI 10.1002/hc

4
Ivanov and Christov
Ph
Y
Ph
Y
Me
H
H
PhYX
[1,5- ]
-PhX
4, 6
Me
PPh2
Y=S, Se
X=Cl, Br
Ph2P
X
Me
Me
O
X
Me
Me
Me
O
•
A
C
Ph2P
O
E
2
E-Nu
3, 5, 7
Ph2P
Nu
E=Cl, Br, SPh, SePh
Nu=Cl, Br
O
Me
B
SCHEME 4
The simultaneous realization of the both hetero-
cyclization processes is connected with introduction
of the allenic and 1,3-dienic parts of the trienic
system into the reaction course. This fact is obvi-
ously due to the ability of the halogens, sulfur, and
selenium to form cyclic ions [25], which are fur-
ther transformed into five-membered heterocyclic
compounds.
of selected heterocyclic products are now under
investigation in our laboratory.
Furthermore, a continuation of these studies to-
ward the synthesis and electrophilic cyclization reac-
tions of other functionalized vinylallenes is currently
in progress in our laboratory.
EXPERIMENTAL
General
CONCLUSIONS
All new synthesized compounds were purified by
column chromatography and characterized on the
basis of NMR, IR, and microanalytical data. NMR
spectra were recorded on a DRX Bruker Avance-250
(Bruker BioSpin GmbH, Karlsruhe, Germany) (1H
at 250.1 MHz, 13C at 62.9 MHz, 31P at 101.2 MHz)
and Bruker Avance II+600 (1H at 600.1 MHz, 13C
at 150.9 MHz, 31P at 242.9 MHz) spectrometers for
solutions in CDCl3. Chemical shifts are in parts per
million downfield from internal TMS. J values are
given in hertz. IR spectra were recorded with an
FT-IRAffinity-1 Shimadzu spectrophotometer (Shi-
madzu Corp., Japan). Elemental analyses were car-
ried out by the Microanalytical Service Laboratory
of Faculty of Chemistry, University of Sofia using
Vario EL3 CHNS(O) (Elementar Analysensysteme
GmbH, Hanau, Germany). Column chromatography
was performed on Kieselgel F25460 (70–230 mesh
ASTM, 0.063–0.200 nm, Merck). The melting points
were measured in open capillary tubes and are un-
corrected. The solvents were purified by standard
methods. Reactions were carried out in oven-dried
glassware under an argon atmosphere and exclusion
of moisture. All compounds were checked for purity
on TLC plates Kieselgel F25460, Merck.
We note the following points from this investigation:
1. Diphenyl 3-methylhexa-1,3,4-trien-3-yl phos-
phine oxide 2 can be readily prepared via an
atom-economical 2,3-sigmatropic rearrangement
of the mediated alkenynyl phosphinite formed in
situ by a reaction of 2-methylhex-5-en-3-yn-2-ol
with diphenylchlorophosphine.
2. Electrophilic cyclization reactions of 1-
vinylallenyl phosphine oxide 2 were investigated
as it was established that the reactions pro-
ceeded with formation of various heterocyclic
compounds with participation of the allenic
and/or 1,3-dienic part of the vinylallenic system
with neighboring participation of the phosphoryl
and/or vinylic group;
3. Diphenyl 3-methylhexa-1,3,4-trien-3-yl phos-
phine oxide 2 is a versatile synthone for hetero-
cyclic compounds in organic synthesis. Owing
to the importance of phosphine-containing
compounds, both as reagents and ligands, as well
as due to the presence of carbon–carbon double
bonds, carbon–heteroatom (halogen, sulfur,
selenium) bond, and five-membered heterocyclic
moiety, this reaction shows its potential and
will be useful in organic synthesis. Further
studies on the score, the synthetic applications
of this reaction, and the physiological activity
Starting Materials
Benzenesulfanyl chloride was prepared from
diphenyl disulfide and sulfuryl chloride in
Heteroatom Chemistry DOI 10.1002/hc

Synthesis and Electrophilic Cyclization Reactions of Diphenyl 3-Methylhexa-1,3,4-trien-3-yl Phosphine Oxide
5
dichloromethane and distilled in vacuo (bp 80–
81◦ C/20 mmHg) before use [26]. Benzenesulfanyl
bromide was freshly prepared from diphenyl
disulfide and bromine in dichloromethane and
used without purification. Benzeneselanyl bromide
was freshly prepared from diphenyl diselenide and
bromine in dichloromethane and used without
purification. 2-Methylhex-5-en-3-yn-2-ol, benzene-
selanyl chloride, diphenyl disulfide, and diphenyl
diselenide were commercially available and were
purified by usual methods.
temperature and for 4 h at rt. The solvent was re-
moved using a rotatory evaporator, and the residue
was purified by column chromatography on silica gel
(Kieselgel Merck 60 F254) with ethyl acetate/hexane.
4-Chloro-5,5-dimethyl-2,2-diphenyl-3-vinyl-2,5-
dihydro-1,2-oxaphosphol-2-ium Chloride (3a). Pale
yellow oil, yield: 76%. Eluent for TLC: ethyl acetate
: hexane = 4:1, R 0.83; IR (neat, cm−1): 1445,
f
1476 (Ph), 1577, 1616 (C C). 1H NMR (CDCl3,
δ): 1.77 (s, 6H, 2Me), 5.33 (dd, Jtrans = 14.8 Hz,
JHP = 5.8 Hz, 1H, CHa CHaHb), 6.07 (dd, Jcis
=
8.9 Hz, JHP = 5.5 Hz, 1H, CHa CHaHb), 7.32 (m, 1H,
CHa CHaHb), 7.62–8.25 (m, 10H, 2Ph). 13C NMR
(CDCl3, δ): 28.9, 97.8 (J = 12.8 Hz), 125.3 (J =
7.0 Hz), 129.4 (J = 7.2 Hz), 140.5 (J = 50.8 Hz),
164.3 (J = 33.2 Hz), 111.9–137.4 (2Ph). 31P NMR
(CDCl3, δ): 77.2. C19H19OPCl2 (365.25). Calcd.: C
62.48, H 5.24; found: C 62.40, H 5.27.
Synthesis of Diphenyl 3-Methylhexa-1,3,
4-trien-3-yl Phosphine Oxide (2)
To a solution of 2-methylhex-5-en-3-yn-2-ol 1 (3.30 g,
30 mmol) and triethylamine (3.34 g, 33 mmol) in dry
dichloromethane (50 mL) at −70◦ C, a solution of
freshly diphenylchlorophosphine (6.62 g, 30 mmol)
in the same solvent (20 mL) was added dropwise
with stirring. The reaction mixture was stirred for
2 h at the same temperature and for 3 h at rt and then
washed with water (50 mL), 2 N HCl, extracted with
dichloromethane, and the extract was washed with
saturated NaCl, and dried over anhydrous sodium
sulfate. Evaporation yielded the crude product 2,
which was purified by column chromatography on
silica gel. The pure product had the following prop-
erties:
4-Bromo-5,5-dimethyl-2,2-diphenyl-3-vinyl-2,5-
dihydro-1,2-oxaphosphol-2-ium Bromide (3b). Pale
orange crystals, yield: 78%. Eluent for TLC: ethyl
acetate : hexane = 4:1, R 0.81; mp 133–134◦C; IR
f
(Nujol, cm−1): 1440, 1479 (Ph), 1580, 1615 (C C).
1H NMR (CDCl3, δ): 1.86 (s, 6H, 2Me), 5.45 (dd, Jtrans
= 15.3 Hz, JHP = 6.0 Hz, 1H, CHa CHaHb), 5.79 (dd,
Jcis = 9.4 Hz, JHP = 5.8 Hz, 1H, CHa CHaHb), 6.76
(m, 1H, CHa CHaHb), 7.68–8.32 (m, 10H, 2Ph). 13C
NMR (CDCl3, δ): 27.9, 100.7 (J = 13.2 Hz), 129.4 (J
= 6.7 Hz), 132.0 (J = 7.3 Hz), 135.1 (J = 51.3 Hz),
151.3 (J = 32.0 Hz), 113.4–130.4 (2Ph). 31P NMR
(CDCl3, δ): 80.7. C19H19OPBr2 (454.18). Calcd.: C
50.25, H 4.22; found: C 50.32, H 4.17.
Pale yellow crystals, yield: 65%. Eluent for TLC:
ethyl acetate : hexane = 4:1, R 0.43; mp 95–96◦C;
f
IR (Nujol), cm−1: 1189 (P O), 1440, 1461 (Ph), 1612
(C C), 1944 (C C C).
1H NMR (CDCl3, δ): 1.43 (d, JHP 6.2 Hz, 6H,
2Me), 5.24 (dd, Jtrans = 15.7 Hz,JHP = 5.7 Hz,
1H, P CHa CHaHb), 5.61 (dd, Jcis = 10.2 Hz,
JHP = 5.9 Hz, 1H, P CHa CHaHb), 6.25 (m, 1H,
P CHa CHaHb), 7.42–7.78 (m, 10H, 2Ph). 13C NMR
(CDCl3, δ): 19.0 (J = 5.6 Hz), 97.6 (J = 182.0 Hz),
99.2 (J = 7.8 Hz), 118.8 (J = 7.6 Hz), 129.4 (J =
7.3 Hz), 209.8, 127.2–131.8 (2Ph). 31P NMR (CDCl3,
δ): 31.5. C19H19OP (280.32). Calcd.: C 77.52, H 6.51;
found: C 77.47, H 6.55.
3-(Diphenylphosphinoyl)-2-isopropyl-thiophene
(4). Yellow oil: 55% (when PhSCl is the reagent),
52% (when PhSBr is the reagent). Eluent for TLC:
ethyl acetate : hexane = 4:1, R 0.60. IR (neat,
f
cm−1): 1160 (P O), 1439, 1486 (Ph), 1464, 1551
(thiophene). 1H NMR (CDCl3, δ): 1.38 (d, JHP
=
6.4 Hz, 6H, 2Me), 2.82 (m, 1H, CHMe2), 6.85 (dd,
JHH = 5.1 Hz, JHP = 4.1 Hz, 1H, SCH CH), 7.09 (dd,
JHH = 5.3 Hz, JHP = 5.3 Hz, 1H, SCH CH), 7.1–7.73
(m, 10H, 2Ph). 13C NMR (CDCl3, δ): 20.4, 36.2 (J =
7.8 Hz), 130.4 (J = 8.3 Hz), 133.8 (J = 8.0 Hz), 134.9
(J = 122.8 Hz), 161.8 (J = 15.5 Hz), 129.1–136.8
(2Ph). 31P NMR (CDCl3, δ): 29.3. C19H19OPS (326.41).
Calcd.: C 69.91, H 5.87; found: C 70.02, H 5.79.
General Procedure for the Electrophilic
Cyclization Reactions of Diphenyl
3-Methylhexa-1,3,4-trien-3-yl Phosphine Oxide 2
To a solution of triene 2 (2.80 g, 10 mmol) in
dry dichloromethane (20 mL) at −20◦ C, a solution
of electrophilic reagent (sulfuryl chloride, bromine,
benzenesulfanyl chloride, or bromide, benzenese-
lanyl chloride or bromide) (10 mmol) in the same
solvent (10 mL) was added dropwise with stirring.
The reaction mixture was stirred for 2 h at the same
5,5-Dimethyl-2,2-diphenyl-4-phenylsulfanyl-3-
vinyl-2,5-dihydro-1,2-oxaphosphol-2-ium
Chloride
(5a). Pale orange oil, yield: 14%. Eluent for TLC:
ethyl acetate : hexane = 4:1, R 0.79; IR (neat,
f
cm−1): 1436, 1473 (Ph), 1579, 1620 (C C). H NMR
1
Heteroatom Chemistry DOI 10.1002/hc

6
Ivanov and Christov
(CDCl3, δ): 1.80 (s, 6H, 2Me), 5.47 (dd, Jtrans
=
5,5-Dimethyl-2,2-diphenyl-4-phenylselanyl-3-vinyl-
2,5-dihydro-1,2-oxaphosphol-2-ium Bromide (7b).
Orange oil: 13%. Eluent for TLC: ethyl acetate :
15.1 Hz, JHP = 5.4 Hz, 1H, CHa CHaHb), 6.21 (d,
Jcis = 9.0 Hz, JHP = 5.7 Hz, 1H, CHa CHaHb), 7.42
(m, 1H, CHa CHaHb), 7.04–8.10 (m, 15H, 3Ph).
13C NMR (CDCl3, δ): 31.2 (J = 8.2 Hz), 33.0 (J =
8.2 Hz), 87.1 (J = 13.1 Hz), 118.9 (J = 7.0 Hz),
123.2 (J = 7.7 Hz), 144.7 (J = 50.2 Hz), 166.2
(J = 32.7 Hz), 111.5–138.9 (3Ph). 31P NMR (CDCl3,
δ): 79.4. C25H24OPSCl (438.97). Calcd.: C 68.40, H
5.51; found: C 68.33, H 5.59.
hexane = 4:1, R 0.69; IR (neat, cm−1): 1452, 1479
f
(Ph), 1584, 1620 (C C). 1H NMR (CDCl3, δ): 1.65 (s,
6H, 2Me), 5.14 (dd, Jtrans = 14.5 Hz, JHP = 4.7 Hz, 1H,
CHa CHaHb), 5.86 (dd, Jcis = 8.9 Hz, JHP = 5.7 Hz,
1H, CHa C HaHb), 7.09 (m, 1H, CHa CHaHb),
7.02–8.72 (m, 15H, 3Ph). 13C NMR (CDCl3, δ): 27.0
(J = 7.6 Hz), 28.8 (J = 7.6 Hz), 95.6 (J = 15.9 Hz),
126.6 (J = 6.9 Hz), 136.7 (J = 7.5 Hz), 152.1 (J =
50.1 Hz), 171.2 (J = 16.6 Hz), 109.7–137.5 (3Ph).
31P NMR (CDCl3, δ): 87.0. C25H24OPSeBr (530.27).
Calcd.: C 56.62, H 4.56; found: C 56.56, H 4.57.
5,5-Dimethyl-2,2-diphenyl-4-phenylsulfanyl-3-vinyl-
2,5-dihydro-1,2-oxaphosphol-2-ium Bromide (5b).
Orange oil, yield: 13%. Eluent for TLC: ethyl acetate
: hexane = 4:1, R 0.66; IR (neat, cm−1): 1441, 1476
f
(Ph), 1587, 1618 (C C). 1H NMR (CDCl3, δ): 1.80 (s,
6H, 2Me), 5.44 (dd, Jtrans = 14.6 Hz, JHP = 5.3 Hz, 1H,
CHa CHaHb), 6.17 (d, Jcis = 9.2 Hz, JHP = 5.5 Hz, 1H,
CHa CHaHb), 7.34 (m, 1H, CHa CHaHb), 7.07–8.07
(m, 15H, 3Ph). 13C NMR (CDCl3, δ): 31.0 (J =
8.0 Hz), 32.9 (J = 8.0 Hz), 89.3 (J = 13.3 Hz),
124.0 (J = 6.8 Hz), 127.4 (J = 7.7 Hz), 149.6 (J =
51.1 Hz), 171.5 (J = 32.4 Hz), 114.4–139.4 (3Ph).
31P NMR (CDCl3, δ): 83.2. C25H24OPSBr (483.38).
Calcd.: C 62.11, H 5.00; found: C 62.23, H 5.09.
ACKNOWLEDGMENTS
We specially thank to Mr. Hasan Hasanov and Ms.
Nelly P. Atanasova for their technical help during the
chromatographic separation of compounds.
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