1
monitored by H and 31P NMR spectroscopy. Phosphaalkene 1
Ar 2- and 3-H
7.26–7.28 (m, 3 H, Bi–Ar 4-H
H, Ph o-H
); 13C NMR (C6D6) δ 20.85 (Mes p-C
JPC = 17 Hz, Mes o-CH3), 46.04 (d, JPC = 13 Hz, P–C
54.82 (OCH3), 114.18 (Ar m-C), 126.76 (Ph p-C), 127.38 (d,
), 128.27–128.29 (Bi–Ar 2/3-C),
), 128.68 (Ph m-C), 129.50 (d, JPC
),
), 130.43 (d, JPC = 9.2 Hz, Ph
), 135.64 (d, JPC = 3.5 Hz, Ar i-C), 137.12 (d, JPC = 3.5 Hz,
PCHPh–CvC), 138.55 (d, JPC = 12 Hz, PCHPh–CvC), 139.50
(Mes p-C), 140.89 (d, JPC = 11 Hz, Ph i-C), 144.10 (d, JPC = 10
Hz, P–CHvC ), 159.59
̲
̲
),
was completely consumed after 20 h, 4 days, or 6 days of
heating with 4-trifluoromethyl-1-ethynylbenzene, phenylacety-
lene, or 4-ethynylanisole, respectively. Upon completion of the
reaction, the solvent and excess alkyne were removed under
vacuum. The crude products were sticky yellow solids. Prepara-
tive thin-layer chromatography was performed to purify the
crude products (silica gel, 1 : 1 CH2Cl2–hexanes) yielding 1,2-
dihydrophosphinine 4a–c (23–33% isolated yields) as bright
green waxy solids. Compounds 4a–c oxidized slowly in air and
upon adsorption to silica, and thus, it was difficult to obtain
samples of high purity (>95%). The products were stored under
nitrogen to prevent further oxidation.
̲
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̲
JPC = 23 Hz, Mes i-C
128.50–128.54 (Bi–Ar 1/4-C
̲
̲
̲
= 18 Hz, P–C
130.15 (d, JPC = 4.7 Hz, Mes m-C
o-C
HvCAr), 129.81 (d, JPC = 3.5 Hz, Ar o-C
̲
̲
̲
̲
̲
̲
Ar), 145.69 (d, JPC = 15 Hz, Mes o-C
4a: green waxy solid; UV-VIS (THF): λmax = 344 nm, λem
=
(Ar p-C); 31P NMR (C6D6) δ −27.3; High-Resolution EI-MS for
C31H29PO m/z calcd 448.1956, found 448.1966.
449, 476 nm; 1H NMR (C6D6) δ 1.93 (s, 3 H, Mes p-CH3
(s, 6 H, Mes o-CH3), 5.53 (br s, 1 H, P–CH
17 Hz, 1 H, P–CHvCAr), 6.58 (br s, 2 H, Mes–H
(m, 3 H, Bi–Ar 2/3/4-H), 6.95–6.97 (m, 1 H, Ph p-H
(m, 3 H, Ph m-H/Bi–Ar 1-H), 7.11–7.12 (m, 2 H, Ar o-H
7.33–7.35 (m, 4 H, Ph o-H/Ar m-H
); 13C NMR (C6D6) δ 20.85
(Mes p-CH3), 24.14 (d, JPC = 16 Hz, Mes o-CH3), 45.90 (d, JPC
= 12 Hz, P–CHPh), 125.07 (q, JFC = 270 Hz, CF3), 125.61 (q,
JFC = 4.0 Hz, Ar m-C), 126.63 (d, JPC = 21 Hz, Mes i-C),
126.91 (Bi-Ar 3-C), 126.96 (d, JPC = 2.9 Hz, Ph p-C
), 128.133
(Bi-Ar 4-C), 128.53 (Bi-Ar 2-C), 128.65 (d, JPC = 5.7 Hz, Bi-Ar
1-C), 128.79 (Ph m-C), 128.89 (d, JPC = 2.9 Hz, Ar o-C), 129.30
(q, JFC = 18 Hz, Ar p-C), 130.21 (d, JPC = 3.9 Hz, Mes m-C),
130.40 (d, JPC = 8.6 Hz, Ph o-C), 132.78 (d, JPC = 19 Hz,
P–CHvCAr), 136.20 (d, JPC = 2.9 Hz, PCH–CvCAr), 138.33
(d, JPC = 13 Hz, PCHPh–CvC), 139.90 (Mes p-C), 140.42 (d,
JPC = 12 Hz, Ph i-C), 142.90 (d, JPC = 12 Hz, P–CHvCAr),
); 31P NMR
̲
), 2.47
̲
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̲
Oxidation of 1,2-dihydrophosphinine 4a–c with sulfur
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Sulfur powder (25 mg, 0.75 mmol) was added to a solution of
4a–c34 (0.3 mmol)35 in dichloromethane (3 mL) at room temp-
erature. The reaction mixture was allowed to stir overnight. The
excess sulfur powder was removed by filtration and the product
mixture was purified by preparative thin-layer chromatography
(silica gel, 9 : 1 hexanes–acetone). 1,2-Dihydrophosphinine
sulfides 6a–c were obtained as white solids (20–23% isolated
yields). Compounds 6a–c were contaminated with a small
amount of the corresponding phosphinine oxides. Colourless
crystals were grown by the slow diffusion of hexanes into an
ether–benzene solution of 6a–c and the molecular structures
were determined by X-ray crystallography.
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145.66 (d, JPC = 15 Hz, Mes o-C
), 146.65 (Ar i-C
̲
6a: colourless solid; IR cm−1 701 (m), 739 (s, PvS), 824 (w),
1018 (w), 1067 (m), 1128 (m), 1168 (m), 1265 (m), 1323 (s),
1407 (w), 1451 (w), 1605 (w), 2850 (w), 2919 (w), 3052 (w);
(C6D6) δ −26.0; 19F NMR (C6D6) δ −62.1; High-Resolution
EI-MS for C31H26PF3 m/z calcd 486.1724, found 486.1716.
4b: green waxy solid; UV-VIS (THF): λmax = 336 nm, λem
=
1H NMR (C6D6) δ 1.79 (s, 3 H, Mes p-CH3
̲
), 2.64 (br s, 6 H,
3), 5.17 (d, JPH = 14 Hz, 1 H, P–CHPh), 6.03 (d, JPH
= 15 Hz, 1 H, P–CHvCAr), 6.43 (d, JPH = 3.6 Hz, 2 H, Mes–
), 6.63–6.69 (m, 3 H, Bi–Ar 2/3/4-H), 6.74–6.75 (m, 1 H, Bi–
Ar 1-H), 7.07–7.10 (m, 3 H, Ar o-H/Ph p-H), 7.22 (t, J = 7.5
Hz, 2 H, Ph m-H), 7.29–7.31 (m, 2 H, Ar m-H), 7.56 (d, J = 7.8
Hz, 2 H, Ph o-H H3), 24.73
); 13C NMR (C6D6) δ 20.54 (Mes p-C
(Mes o-CH3), 50.10 (d, JPC = 47 Hz, P–CHPh), 124.75 (q, JFC
270 Hz, CF3), 125.54 (d, JPC = 73 Hz, P–CHvCAr), 125.86 (q,
JFC = 3.5 Hz, Ar m-C), 127.62 (d, JPC = 3.5 Hz, Ph p-C),
128.133 (Ph m-C), 128.233 (Bi–Ar 3-C
), 128.52 (d, JPC = 3.3 Hz,
Bi–Ar 4-C ), 128.84 (Ar o-
), 128.633 (d, JPC = 90 Hz,36 Mes i-C
), 129.72 (Bi–Ar 2-C), 130.44 (d, JPC = 4.7 Hz, Ph o-C),
130.75 (q, JFC = 32 Hz, Ar p-C), 130.87 (d, JPC = 8.1 Hz, Bi–Ar
1-C), 131.49 (d, JPC = 12 Hz, Mes m-C), 133.97 (d, JPC = 4.7
Hz, Ph i-C), 134.46 (d, JPC = 14 Hz, PCHPh–CvC), 136.03 (d,
JPC = 5.7 Hz, PCHPh–CvC), 140.09 (d, JPC = 2.4 Hz, Mes p-
), 140.63 (d, JPC = 9.2 Hz, Mes o-C), 143.28 (d, JPC = 15 Hz,
Ar i-C), 147.04 (P-CHvC
Ar); 31P NMR (C6D6) δ 30.0; 19F
449, 478 nm; 1H NMR (C6D6) δ 1.92 (s, 3 H, Mes p-CH3
(s, 6 H, Mes o-CH3), 5.56 (br s, 1 H, P–CH
19 Hz, 1 H, P–CHvCAr), 6.57 (br s, 2 H, Mes–H
(m, 2 H, Bi-Ar 2/4-H), 6.95 (t, J = 7.5 Hz, 1 H, Ph p-H
7.02–7.05 (m, 3 H, Ph m-H/Bi–Ar 1-H), 7.10–7.13 (m, 1 H, Ar
p-H), 7.15–7.18 (m, 3 H, Bi–Ar 3-H/Ar m-H), 7.32–7.34 (m, 2
H, Ar m-H), 7.36 (d, J = 8.4 Hz, 2 H, Ph o-H
); 13C NMR
(C6D6) δ 20.86 (Mes p-CH3), 24.16 (d, JPC = 17 Hz, Mes o-
H3), 45.99 (d, JPC = 11 Hz, P–CHPh), 126.77 (Ph p-C), 126.80
(Bi–Ar 4 or 2-C), 127.18 (d, JPC = 22 Hz, Mes i-C), 127.43 (Ar
p-C), 128.30, 128.50, 128.53, 128.66, 128.68, 128.70 (Ph m-C
Bi–Ar 1 and 3-C/Bi–Ar 2 or 4-C/Ar o- and m-C), 130.13 (d, JPC
= 3.5 Hz, Mes m-C), 130.42 (d, JPC = 8.0 Hz, Ph o-C), 130.69
(d, JPC = 18 Hz, P–CHvCAr), 136.89 (d, JPC = 3.5 Hz,
PCHPh–CvC), 138.38 (d, JPC = 13 Hz, PCHPh–CvC), 139.56
(Mes p-C), 140.82 (d, JPC = 11 Hz, Ph i-C), 143.32 (d, JPC = 2.3
Hz, Ar i-C), 144.43 (d, JPC = 10 Hz, P–CHvCAr), 145.68 (d,
JPC = 16 Hz, Mes o-C
); 31P NMR (C6D6) δ −27.0; High-Resol-
̲
), 2.48
=
Mes o-CH
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H
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=
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C
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C
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C
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ution EI-MS for C30H27P m/z calcd 418.1850, found 418.1844.
4c: green waxy solid; UV-VIS (THF): λmax = 344 nm, λem
NMR (C6D6) δ −62.4; High-Resolution EI-MS for C31H26F3PS
m/z calcd 518.1445, found 518.1435.
=
467 nm; 1H NMR (C6D6) δ 1.93 (s, 3 H, Mes p-CH3
̲
), 2.52 (s, 6
), 5.58 (br s, 1 H, P–CHPh),
vCAr), 6.58 (br s, 2 H, Mes–
), 6.89–7.00 (m, 3 H, Ph p-H/Bi–
6b: colourless solid; IR cm−1 685 (m), 698 (s, PvS), 735
(m), 780 (m), 850 (w), 1031 (w), 1076 (w), 1266 (w), 1444 (m),
1494 (m), 1556 (w), 1603 (m), 2922 (w), 3028 (w), 3058 (w);
H, Mes o-CH
6.53 (d, JPH = 18 Hz, 1 H, P–CH
), 6.78–6.80 (m, 2 H, Ar m-H
̲
3), 3.33 (s, 3 H, OCH3
̲
̲
̲
H
̲
̲
̲
1H NMR (C6D6) δ 1.78 (s, 3 H, Mes p-CH3
̲
), 2.69 (br s, 6 H,
This journal is © The Royal Society of Chemistry 2012
Dalton Trans., 2012, 41, 3294–3301 | 3299