Synthesis and reactivity of 6H-dibenzo[c,e][1,2]oxaphosphinine 6-sulfide, a novel thiophosphacyclic molecule

Article abstract of DOI:10.3987/COM-10-12124

The new 6H-dibenzo[c,e][1,2]oxaphosphinine 6-sulfide (1) was synthesized and characterized by ¹H-, ¹³C-, ³¹P-NMR, IR spectroscopy as well as X-ray diffraction and HR-MS. The reactivity of (1) was investigated with a series of test reactions, including Michael-type additions and the Atherton-Todd-reaction and finally compared to that of the parent 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

Full text of DOI:10.3987/COM-10-12124

HETEROCYCLES, Vol. 83, No. 4, 2011
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HETEROCYCLES, Vol. 83, No. 4, 2011, pp. 743 - 753. © The Japan Institute of Heterocyclic Chemistry
Received, 16th December, 2010, Accepted, 9th February, 2011, Published online, 18th February, 2011
DOI: 10.3987/COM-10-12124
SYNTHESIS AND REACTIVITY OF
6H-DIBENZO[C,E][1,2]OXAPHOSPHININE 6-SULFIDE, A NOVEL
THIOPHOSPHACYCLIC MOLECULE
Muriel Rakotomalala, Sebastian Wagner, Thomas Zevaco, Michael Ciesielski,
Olaf Walter, and Manfred Döring*
Institute of Catalysis Research and Technology, Karlsruhe Institute of Technology,
Hermann-von-Helmholtz Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
Abstract – The new 6H-dibenzo[c,e][1,2]oxaphosphinine 6-sulfide (1) was
1
13
31
synthesized and characterized by H-, C-, P-NMR, IR spectroscopy as well as
X-ray diffraction and HR-MS. The reactivity of (1) was investigated with a series
of
test
reactions,
including
Michael-type
additions
and
the
Atherton-Todd-reaction and finally compared to that of the parent
9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.
INTRODUCTION
Phosphorus-containing molecules have been the subject of both academic and industrial interest for
several decades.1-3 Many applications for such molecules have been reported in different areas of
chemistry such as coordination chemistry, material science, homogeneous catalysis, development of
biologically active compounds or pesticides.4-9 Recently, there has been a growing interest from the flame
retardant community regarding phosphorus-containing molecules as they are known to impart flame
retardancy to a wide range of polymeric materials.10-12 Although a large number of organophosphorous
compounds have been reported to be flame retardants, the influence of heteroatoms on the phosphorus
environment was scarcely studied. Here, we present the synthesis and reactivity of a new phosphine
sulfide molecule whose applications are not solely restricted to flame retardancy.
RESULTS AND DISCUSSION
To the best of our knowledge, 6H-dibenzo[c,e][1,2]oxaphosphinine 6-sulfide (1) had never been
synthesized prior to our study. Krawiecki and Michalski showed that dialkyl phosphochloridates react

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HETEROCYCLES, Vol. 83, No. 4, 2011
readily with hydrogen sulphide in the presence of tertiary bases to yield tetra-alkyl thiopyrophosphates.13
This method was then successfully used by Zwierzak to obtain a series of cyclic hydrogen
thiophosphites.14 Therefore, our first synthetic approach consisted of reacting DOP-Cl and hydrogen
sulphide gas as a source of sulphur in the presence of triethylamine (Scheme 1). This successfully yielded
the target molecule in quantitative yields. Similar to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-
1
10-oxide (2), the H-NMR spectrum of the obtained crystalline white powder showed a doublet in the
aromatic region (= 8.4 ppm) with a large coupling (1JP-H = 536 Hz) that was associated with a P-H bond
31
(Figure 1). The P-NMR spectrum showed a single peak (= 57.1 ppm) and the major peak in the mass
spectra was at m/z = 232 strongly suggesting that the isolated product was (1). The 1H-NMR spectrum of
(1) revealed well resolved signals which can be attributed via 2-D COSY methods involving both H-H
(gCOSY, gDQFCOSY) and C-H correlations (gHSQC and gHMBC) (Figure 2).
H2O
H2S, Tol., 25 °C
NEt3
O
P
Cl
O
P
O
P
H
DOP-Cl
H
O
S
P2S5, or Lawesson's Reagent
Tol., 55°C
1
2
Scheme 1. Synthesis of 6H-dibenzo[c,e][1,2]oxaphosphinine 6-sulfide (1) from 10-chloro-10H-9-oxa-10-
phosphaphenanthrene (DOP-Cl) and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (2).
Figure 1. 1H NMR spectra of a) 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (2) and b)
6H-dibenzo[c,e][1,2]oxaphosphinine 6-sulfide (1) in CDCl3. Signals * emphasize the doublets
corresponding to the P-H bond.

HETEROCYCLES, Vol. 83, No. 4, 2011
745
Figure 2. H,H-gCOSY of 6H-dibenzo[c,e][1,2]oxaphosphinine 6-sulfide (1) in CDCl3.
Slow diffusion of a concentrated solution of (1) in dry dichloromethane into pentane yielded a single crystal
that indisputably confirmed the isolation of the target molecule (Figure 3). The structure of (1) is similar to
its parent oxide molecule (2), however, (1) has an increased solubility in most organic solvents.15
Figure 3. View of the molecular structure of (1) in the crystal, aromatic H atoms and solvent molecules
were omitted due to reasons of clarity. Selected bond lengths [pm]: (7) S1-P 190.94 (4), O1-P 161.77 (5),
P-H1 138.03 (3).
However, during this synthesis, the use of large amounts of H2S was not desirable, as its toxicity is similar
to that of hydrogen cyanide.16 The two most commonly used sources of sulphur are phosphorus
pentasulfide and Lawesson reagent.3 The use of such thionation agents solved the toxicity issue and also
allowed the use of the commercially available (2) as a starting material rather than DOP-Cl which is highly
air- and moisture-sensitive. Both thionation agents successfully yielded the desired molecule, though the
yields were lower.

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With several practical ways to synthesize molecule (1) in hand, we initiated the comparison of its
reactivity with the parent phosphine oxide molecule (2) whose chemistry mainly involves the reactivity of
the P-H bond. P-H bonds are known to undergo nucleophilic addition onto unsaturated functionalities
such as carbonyl group and acrylates.17 The parent molecule (2) was reported to produce the
hydroquinone derivative in very good yield when heated in presence of benzoquinone.18,19 Hence,
benzoquinone was chosen as -unsaturated carbonyl to assess the reactivity of (1). When a solution of
(1) was heated in the presence of equimolar amounts of benzoquinone, a single product from a Pudovik
reaction could be isolated in a high yield (Figure 4).20
O
OH
Tol, 110°C
O
P
O
P
+
H
S
S
O
HO
3 (74%)
Figure 4. Synthesis of compounds (3) from (1).
Another organophosphorous reaction involving the reactive phosphorous-hydrogen bond in phosphites
and phosphonites is the Atherton-Todd reaction.20-24 The Atherton-Todd reaction, usually involving
dialkyl and diaryl phosphites in the presence of carbon tetrachloride and a base, is known as an effective
way to access functionalised phosphine oxides, in particular phosphoramidates, which are an important
and versatile class of chemicals.
However, this reaction remains relatively unexplored for phosphorous sulfides. In an effort to deepen our
understanding of its reactivity, (1) was reacted with different nucleophiles using the Atherton-Todd
approach as shown in Scheme 2.
CCl4, NEt3
HNuc
O
P
S
O
P
S
O
P
S
Nuc
H
Cl
CHCl3, O °C
4
5; Nuc = C8H9O (71%)
6; Nuc = C8H10N (82%)
7; Nuc = C5H10N (87%)
Scheme 2. Atherton-Todd approach of (1).
With this intention, (1) was dissolved in chloroform and carbon tetrachloride then a solution of
triethylamine and a nucleophile diluted in chloroform was added dropwise. The different nucleophiles
(phenylethylamine, piperidine and 2-phenylethanol) were chosen as models for primary and secondary
amines as well as primary alcohols, respectively. All three desired products were obtained in good yields
with fast reaction times (below 60 minutes). Hence, (1) proved to be a very rewarding reagent for the

HETEROCYCLES, Vol. 83, No. 4, 2011
747
Atherton-Todd reaction. The in situ formation of 10-chloro-9-oxa-10-phospha-phenanthrene 10-sulfide
(4) can be observed using NMR spectroscopy ( (31P, CDCl3) 74.5 ppm) and HR-MS analysis (calculated
for [12C12H8OSPCl]+ 265.9722, found 265.9688). Even though primary alcohols are known to be
problematic substrates for the Atherton-Todd reaction, the formation of compound (5) was observed in
good yields.22 Crystal structures of molecules (5) , (6) and (7) were also obtained and indisputably verify
the desired molecules. Figure 5 presents the crystal structures and selected bond lengths and torsion
angles. The torsion angles are a sign of delocalisation. The P=S bond length in compound (5) was 191.1
pm (6(P=S): 193.6 pm, 7(P=S): 191.9 pm) which coincides with parent structures.25-27 The aliphatic
phosphorus oxygen bond in (5) was 158.5 ppm which fits perfectly with literature.25,28,29 The
phosphorus-nitrogen bonds in molecule (6) (162.0 pm) and (7) (163.7 pm) also correspond to those of
similar structures.28,29 This set of experiments demonstrated that the Atherton-Todd reaction can be
exploited to access different phosphine sulphide molecules.
Figure 5. View of the molecular structure of (5), (6) and (7) in the crystal, H atoms and solvent molecules
omitted due to reasons of clarity. Selected bond lengths [pm] and torsion angles [°]: (5) S1-P 191.15(4),
O2-P 158.57(4), S1-P-O2-C13 37.72; (6) S1-P 193.65(6), N1-P 162.06(4), S1 P-N1-C13 10.07; (7) S1-P
191.96(6), N1-P 163.71(4), S1-P-N1-C13 20.40.

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HETEROCYCLES, Vol. 83, No. 4, 2011
To summarize our findings, we presented the synthesis of the new 6H-dibenzo[c,e][1,2]oxaphosphinine
6-sulfide (1) (DOPS). Compound (1) can be obtained using different thionation agents and undergoes
nucleophilic additions such as the Pudovik reaction as well as the Atherton-Todd reaction. The ease of
synthesis of molecule (1) combined with its broad range of reactivity makes it a promising compound for
a wide spectrum of molecules and applications.
EXPERIMENTAL
General Experimental:
Unless stated otherwise, solvents and chemicals were obtained from commercial sources and used
without further purification. NMR spectra were recorded with a Varian INOVA-400 (400 MHz).
Chemical shifts are reported as δ values relative to the solvent peak. Tetramethylsilane was used as a
standard. All 31P-NMR spectra are measured proton decoupled. All 13C-NMR spectra were measured
1
proton decoupled and phosphorus coupled. H-NMR spectra were measured phosphorus coupled.
Melting points are uncorrected and measured with a Büchi B-545. IR spectra were recorded with a Varian
660-IR (FT-IR). High resolution mass spectrometry (HR-MS) analyses were performed on a MicroMass
GCT (time of flight (TOF); electron ionization (EI), 70 eV). Elemental analysis was performed using a
Vario EL III from Elementar Analysensystem GmbH. Crystal structure analyses were conducted on a
Siemens SMART-1000-CCD with Mo-K (=0.71073, graphite monochromator) at 200 K. A Lorentz
and Polarisation correction was applied. Experimental absorption correction were done with SADABS,
structure solving and refining was done with SHELX 97. XPMA and Mercury 2.2 were used for
visualisation.
Synthesis:
6H-Dibenzo[c,e][1,2]oxaphosphinine 6-sulfide (1): In a flame-dried three-neck round-bottom flask
fitted with a gas inlet, a thermometer and a gas outlet leading to a NaOH aqueous solution, H2S gas was
bubbled through a solution of DOP-Cl (40.0 g, 171 mmol) in dry toluene (120 mL) at room temperature.
The released acid was then trapped with triethylamine (19.0 g, 188 mmol). The suspension was filtered
and concentrated in vacuo to yield a colorless powder (35.2 g, 152 mmol, 89%). mp 88 °C; 31P NMR (101
13
MHz, CDCl3)  57.1 ppm; C NMR (101 MHz, CDCl3) 149.7 (d, J = 11.2 Hz, 1C), 135.7 (d, J = 5.4
Hz, 1C), 134.9 (s, 1C), 131.7 (d, J = 14.0 Hz, 1C), 131.1 (s, 1C), 129.0 (d, J = 14.7 Hz, 1C), 125.6 (d, J =
5.2 Hz, 1C), 125.4 (s, 1C), 124.9 (d, J = 10.4 Hz, 1C), 124.2 (d, J = 9.5 Hz, 1C), 123.6 (d, J = 13.5 Hz,
1C), 120.8 ppm (d, J = 5.9 Hz, 1C); 1H NMR (400 MHz, CDCl3) 8.37 (d, J = 536.8 Hz, 1H), 7.95 (dd, J
= 15.9 Hz, J = 7.6 Hz, 1H), 7.8 (d, J = 8.1 Hz, 1H), 7.83-7.80 (m, 2H), 7.66 (dt, J = 7.7 Hz, J = 1.1 Hz,
1H), 7.50 (dt, J = 7.5 Hz, J = 3.2 Hz, 1H), 7.35 (dt, J = 8.4 Hz, J = 1.1 Hz, 1H), 7.24 (dt, J = 8.0 Hz, J =

HETEROCYCLES, Vol. 83, No. 4, 2011
749
0.8 Hz, 1H), 7.20 ppm (dd, J = 8.1 Hz, J = 0.9 Hz, 1H); IR (KBr) 3061, 2364 (w, P-H), 1578 (m,
P-Caryl), 1194 (vs, P-O), 941 (vs, P=S), 758 (s, C-H bend) cm-1; HR MS (EI) calcd for [C12H9OPS]+
232.0112, found 232.0112. Structural details for 1: Reflections collected / unique /observed (I>2σ): 12328
/ 2584 / 1607 [R(int) = 0.0728]; parameters refined: 141; formula C10H9OPS, MM 208.20 g/mol; T =
200(2) K; monoclinic, P2(1)/c (no. 14, Z = 4); a = 503.9(16) pm; b = 1391.5(5) pm; c = 1503.4(5) pm; α
= 90°; β =94.504°; γ = 90°; V 1051.0(6)*106 pm3; ρ (calc.) = 1.316 g/cm3; Absorption coefficient = 0.417
mm-1; F(000) = 432; Goof (F2) = 1.018; crystal size 0.8 x 0.2 x 0.2 mm3; index ranges -6<=h<=6,
-17<=k<=18, -19<=l<=19; completeness to θ = 28.35: 98.1%; R1 (I>2σ) = 0.0657, wR2 = 0.1536 (all
data), Largest difference peak and hole: 0.555 and -0.524*10-6 e/pm-3.
Alternative experimental procedure for the synthesis of 1:
Using Phosphorus pentasulfide:
DOPO (54 g, 0.25 mol) and dry toluene (150 mL) were fed into a three-neck round-bottom flask
equipped with a mechanical stirrer, a gas inlet and a thermometer. This mixture was heated up to 55 °C
under an Ar atmosphere. P4S10 (13.9 g, 0.03125 mol) was then added and the reaction mixture was stirred
at 55 °C. After 2 h at 55 °C, a second portion (13.9 g) of P4S10 was added and the mixture was stirred at
40 °C over a period of 15 h under an Ar atmosphere. The cloudy solution was decanted up from the
phosphorus sulfides/oxides and was filtered through a thin layer of silica gel. Afterwards the toluene was
removed in vacuo. The resulting oil was dissolved in chloroform (100 mL). A small amount of a
precipitate was removed by filtration. The filtrate was then stirred with an aqueous solution of sodium
hydrogen carbonate (100 mL) for 20 min under argon (the chloroformic phase became milk-like;
evolution of CO2). The cloudy chloroformic phase was collected, dried over sodium sulphate and filtered
over silica gel. The resulting clear solution was concentrated in vacuo to yield an oily product that
gradually solidified (43.5g, 0.18 mol, 70 %). mp 88 °C; 31P NMR (101 MHz, CDCl3)  57.1 ppm.
Using Lawesson reagent:
DOPO (0.32 g, 1.50 mmol), Lawesson reagent (1.22 g, 3.0 mmol) and dry toluene (100 mL) were
charged into a three-neck round-bottom flask equipped with a mechanical stirrer, a gas inlet and a
thermometer. While under Ar atmosphere, this mixture was heated up to 140 °C using an oil bath. After 1
h at 140 °C, the oil bath was removed and the reaction mixture was allowed to cool to room temperature.
Once cooled the solvent was removed in vacuo to yield a brown solid. The impure product was then
redissolved in chloroform and filtered over silica gel. The resulting liquid was then concentrated in vacuo
to yield a pale yellow syrup. The syrup was then recrystallised from acetonitrile to yield a crystalline
white solid (0.118g, 0.51 mmol, 34%). mp 88 °C; 31P NMR (101 MHz, CDCl3)  57.1 ppm.

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HETEROCYCLES, Vol. 83, No. 4, 2011
2-(10-Thioxo-10H-9-oxa-105-phosphaphenanthren-10-yl) benzene-1,4-diol (3): A thoroughly dried
two-neck round-bottom flask fitted with a consender and an Ar gas inlet was charged with DOPS (12.3 g,
53.0 mmol) an dry toluene (20 mL). This solution was heated under positive argon pressure using an oil
bath at 110 °C. While under an Ar atmosphere, benzoquinone (6.30 g, 58.0 mmol) was added in portions
to the stirring solution over a period of 30 min. After 3.5 h under reflux, 1 was fully consumed and the
heat source was removed to allow the reaction mixture to cool down to room temperature. The crude
black reaction mixture was concentrated in vacuo to yield a black solid. The black solid was triturated
with cold dichloromethane and the resulting suspension was filtered to yield a spectroscopically pure
31
13
off-white solid (13.3 g, 39.2 mmol, 74%). mp 127 °C; P NMR(101 MHz, DMSO-d6)  73.6 ppm; C
NMR (101 MHz, DMSO-d6)  152.5 (s, 1C), 150.0 (d, J = 18.2 Hz, 1C), 149.7 (d, J = 9.8 Hz, 1C), 134.0
(d, J = 4.6 Hz, 1C), 132.8 (s, 1C), 131.1 (s, 1C) 130.1 (d, J = 14.2 Hz, 1C), 129.2 (d, J = 106.4 Hz, 1C),
129.2 (d, J = 14.6 Hz, 1C), 126.1 (s, 1C), 125.1 (s, 1C), 124.2 (d, J = 8.8 Hz, 1C), 123.4 (s, 1C), 122.5 (d,
J = 12.4 Hz, 1C), 121.0 (d, J = 5.8 Hz, 1C), 120.4 (d, J = 14.2 Hz, 1C), 118.1 (d, J = 9.2 Hz, 1C), 116.8
1
(d, J = 111.8 Hz, 1C); H NMR (400 MHz, DMSO-d6)  9.53 (s, 1H), 9.21 (s, 1H), 8.11 (d, J = 7.8 Hz,
2H), 7.63 (dt, J = 6.6 Hz, J = 1.3 Hz, 1H), 7.47-7.36 (m, 4H), 7.24 (dt, J = 7.2 Hz, J = 0.8 Hz, 1H), 7.18
(dd, J = 8.1 Hz, J = 0.6 Hz, 1H), 6.85 (dd, J = 8.7 Hz, J = 2.8 Hz, 1H), 6.58 ppm (t, J = 5.6 Hz, 1H);
IR (KBr) 3267 (br, -OH), 3190, 1591 (s, P-Caryl), 1580, 1471, 1221 (vs, P-O), 1182 (vs, P-O), 901 (vs,
P=S), 752 cm-1; HRMS (EI) calcd for [12C18H13PO3S]+ 340.0326, found 340.0323; Anal. Calcd for
C18H13PO3S: C, 63.52; H, 3.85. Found: C, 63.22; H, 4.15.
The experimental data for compound 7 is given as a typical representative of an Atherton-Todd reaction
involving DOPS (1) as a substrate.
1-(10-Thioxo-10H-9-oxa-105-phosphaphenanthren-10-yl)piperidine (7): A flame dried three neck
flask with a condenser, thermometer and an addition funnel was charged with 1 (3.80 g, 16.4 mmol),
carbon tetrachloride (2.77 g, 18.0 mmol) and 20 mL of dry chloroform. The reaction mixture was cooled
with an ice bath to 5 °C. The addition funnel was charged with triethylamine (1.80 g, 18.0 mmol) and
piperidine (1.39 g, 16.4 mmol) dissolved in 20 mL of dry chloroform. The triethylamine mixture was
added dropwise under vigorous stirring. The reaction temperature was not allowed to exceed 10 °C. After
1 h the addition was completed and NMR analysis indicated the complete conversion of the starting
material. The reaction mixture was washed three times with 50 mL water to remove the triethylamine
hydrochloride. The organic phase was isolated, dried over MgSO4 and the solvent was removed in vacuo.
The spectroscopically pure product was obtained as a brown solid (4.51 g, 14.3 mmol, 87%) mp
72-74 °C; 31P NMR (101 MHz, CDCl3)  72.3 ppm; 13C NMR (101 MHz, CDCl3)  149.2 (s, 1C), 136.0

HETEROCYCLES, Vol. 83, No. 4, 2011
751
(s, 1C), 132.1 (s, 1C), 130.2 (s, 1C), 129.1 (d, J = 11.0 Hz, 1C), 128.6 (d, J = 14.7 Hz, 1C), 128.2 (d, J =
137.0 Hz, 1C), 124.9 (s, 1C), 124.2 (s, 1C), 123.7 (d, J = 10.7 Hz, 1C), 122.5 (d, J = 11.8 Hz, 1C), 120.6
(d, J = 5.7 Hz, 1C), 46.0 (2C), 26.2 (s, 1C), 26.1 (s, 1C), 24.5 ppm (s, 1C); 1H NMR (400 MHz, CDCl3) 
7.92–7.87 (m, 2H,), 7.77 (ddd, J = 15.1 Hz, J = 7.6 Hz, J = 1.2 Hz, 1H), 7.60 (tt, J = 7.5 Hz, J = 1.3 Hz,
1H), 7.46 (ddt, J = 7.5 Hz, J = 3.1 Hz, J = 0.9 Hz, 1H), 7.35 (tt, J = 7.6 Hz, J = 1.2 Hz, 1H), 7.26–7.18 (m,
2H), 3.34–3.28 (m, 4H, N-CH2), 1.63–1.60 (m, 2H, CH2), 1.54–1.49 ppm (m, 4H, CH2); IR (KBr) ν 3052,
2955, 2934, 2918, 2848, 1604 (w, P-Caryl), 1580, 1474, 1443, 1425, 1206 (vs, P-O), 1164, 1113, 1059 (vs,
P-N), 962 (vs, P=S), 783, 746, 725 cm-1; HRMS (EI) calcd for [12C17H18NPOS]+ 315.0847, found
315.0852. Anal. Calcd for C17H18NPOS. ¼ H2O: C, 63.83; H, 5.83; N, 4.38. Found: C, 64.03; H, 5.67; N,
3.96; Structural details for 7: Reflections collected / unique /observed (I>2σ): 19987 / 3768 / 2523 [R(int)
= 0.0891]; parameters refined: 192; formula C17H18NOPS, MM 315.35 g/mol; T = 200(2) K; monoclinic,
P2(1)/c (no. 14, Z = 4); a = 1124.0(5) pm; b = 1302.0(6) pm; c = 1174.8(5) pm; α = 90°; β =116.068(5)°;
γ = 90°; V 1544.3(11)*106 pm3; ρ (calc.) = 1.356 g/cm3; Absorption coefficient = 0.311 mm-1; F(000) =
664; Goof (F2) = 1.109; crystal size 0.4 x 0.4 x 0.06 mm3; index ranges -14<=h<=14, -17<=k<=17,
-15<=l<=15; completeness to θ = 28.44: 92.8%; R1 (I>2σ) = 0.1135, wR2 = 0.2931 (all data), Largest
difference peak and hole: 1.561 and -0.506*10-6 e/pm-3.
10-Phenethyloxy-9-oxa-10-phosphaphenanthrene 10-sulfide (5). The product was isolated as a white
solid (4.31 g, 12.2 mmol, 75%). mp 102-104 °C;31P NMR (101 MHz, CDCl3)  76.9 ppm; 13C NMR (101
MHz, CDCl3)  149.7 (d, J = 11.3 Hz, 1C), 136.7 (s, 1C), 134.4 (d, J = 4.9 Hz, 1C), 133.1 (s, 1C), 130.6
(J = 14.7 Hz, 1C), 130.2 (s, 1C), 128.6 (s, 2C), 128.4 (s, 2C), 128.0 (s, 1C), 126.8 (d, J = 145.7 Hz, 1C),
126.4 (s, 1C), 125.1 (s, 1C), 124.6 (s, 1C), 123.6 (d, J = 10.6 Hz, 1C), 122.6 (d, J = 12,2 Hz, 1C), 119.9 (d,
1
J = 5.8 Hz, 1C), 66.9 (d, J = 6.7 Hz, 1C, CH2), 36.3 ppm (d, J = 6.2 Hz, 1C, CH2); H NMR (400 MHz,
CDCl3) 7.91 (dd, J = 16.9 Hz, J = 7.6 Hz, 1H), 7.78–7.74 (m, 2H), 7.54 (dt, J = 7.5 Hz, J = 1.2 Hz, 1H),
7.35 (dt, J = 7.5 Hz, J = 3.7 Hz, 1H), 7.25-721 (m, 1H), 7.13 (t, J = 7.8 Hz, 1H), 7.08-702 (m, 4H),
6.88-6.86 (m, 2H) 4.24–4.18 (m, 2H, CH2), 2.77-2.66 ppm (m, 2H, CH2); IR (KBr) ν 3062, 3023, 2977,
2947, 2889, 1606 (w, P-Caryl), 1580, 1559, 1496, 1474, 1447, 1429, 1194 (vs, P-O), 1115 (vs, P-O), 1045,
902 (vs, P=S), 754, 733, 716, 696 cm-1; HRMS (EI) calcd for [12C20H15PO2S]+ 352.0687, found 352.0721.
Elemental analysis for C, H, N, was not within limits indicating the thermal instability of 5. Structural
details for 5: Reflections collected / unique /observed (I>2σ): 21958 / 4083 / 3336 [R(int) = 0.0343];
parameters refined: 220; formula C20H17O2PS , MM per molecule 352.37 g/mol; T = 200(2) K;
monoclinic, P2 (1)/n (No. 14, Z = 4); a = 969.9(3) pm; b = 1349.1(4) pm; c = 1307.3(4) pm; α = 90 °; β =
100.997(4)°; γ = 90°; V = 1679.3(8)*106 pm3; ρ (calc.) = 1.394 g/cm3; Absorption coefficient = 0.297

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HETEROCYCLES, Vol. 83, No. 4, 2011
mm-1; F(000) = 736; Goof (F2) = 1.037; crystal size = 1.8 x 0.6 x 0.4 mm3; index ranges -12<h<12,
-17<k<17, -17<l<17; completeness to θ = 28.28: 94.1%; R1 (I>2σ) = 0.0468, wR2 = 0.1099 (all data),
Largest difference peak and hole: 0.379 and -0.263*10-6 e/pm-3.
Phenethyl-(10-thioxo-10H-9-oxa-105-phosphaphenanthren-10-yl)amine (6). The product was
31
isolated as a white solid (5.76g, 16.4 mmol, 82%). mp 106-109 °C; P NMR (101 MHz, CDCl3)  69.3
ppm; 13C NMR (101 MHz, CDCl3)  137.2 (s, 1C), 133.7 (d, J = 6.6 Hz, 1C), 131.5 (s, 1C), 129.4 (s, 1C),
128.6 (d, J = 11.6 Hz, 1C), 127.8 (s, 2C), 127.6 (s, 1C), 127.5 (s, 1C), 126.5 (d, J = 133 Hz, 1C), 125.6 (s,
1C), 124.0 (s, 1C), 123.5 (s, 1C), 122.7 (d, J = 10.6 Hz, 1C), 121.6 (d, J = 12.1 Hz, 1C), 119.8 (d, J = 5.9
1
Hz, 1C), 42.5 (s, 1C), 36.8 ppm (d, J = 5.3 Hz, 1C); H NMR (400 MHz, CDCl3) 7.83 (d, J = 8.1 Hz,
1H), 7.82 (d, J = 6.5 Hz, 1H), 7.73 (dd, J = 14.9, J = 7.1 Hz, 1H), 7.55 (dt, J = 8.5 Hz, J = 1.3 Hz, 1H),
7.38 (dt, J = 7.5 Hz, J = 3.3 Hz, 1H), 7.31 (dt, J = 8.2 Hz, J = 1.1 Hz, 1H), 7.20-7.11 (m, 6H), 7.00 (dd, J
= 8.0 Hz, J = 0.9 Hz, 2H), 3.30 (q, J = 6.7 Hz, 1H), 3.19-3.09 (m, 2H), 2.74-2.62 ppm (m, 2H); IR (KBr)
3301 (br, -NH), 3062, 3028, 2932, 1582 (m, P-Caryl), 1477, 1211 (vs, P-O), 1092 (vs, P-N), 745 cm-1;
HRMS (EI) calcd for [12C20H18NPOS]+ 351.0847, found 351.0891. Anal. Calcd for C20H18NPOS. ½ H2O:
C, 66.65; H, 5.31; N, 3.89. Found: C, 66.98; H, 5.35; N, 3.64. Structural details for 6: Reflections
collected / unique / observed (I>2σ): 42678 / 4249 / 2789 [R(int) = 0.0711]; parameters refined: 224;
formula C20H18NOPS, MM 351.35 g/mol; T = 200(2) K; orthorhombic, Pbca (no. 61, Z = 8); a = 729.4(3)
pm; b = 1989.0(8) pm; c = 2369.8(9) pm; α = 90°; β =90°; γ = 90°; V 3438(2)*106 pm3; ρ (calc.) = 1.358
g/cm3; Absorption coefficient = 0.287 mm-1; F(000) = 1472; Goof (F2) = 1.059; crystal size 0.4 x 0.4 x
0.2 mm3; index ranges -9<=h<=9, -26<=k<=25, -31<=l<=31; completeness to θ = 28.32: 88.1%; R1
(I>2σ) = 0.0937, wR2 = 0.1453 (all data), Largest difference peak and hole: 0.551 and -0.325*10-6 e/pm-3.
X Ray structure:
The crystal structures of molecule 1, 5, 6 and 7 were deposited at the Cambridge Crystallographic Data
Centre and the corresponding data can be found at the deposition numbers: CCDC 802202 – 802205.
ACKNOWLEDGEMENTS
The authors would like to thank Mr. Zwick for measuring the HR-MS, Ms Schmelcher and Ms Kölmel
for elemental analysis and Mrs. Lenzner for carrying out the differential scanning calorimetry
experiments.
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