vessel was charged with 1-chloro-2-methylpropan-2-ol (105.4 g,
0.97 mol) and cooled to Ϫ15 ЊC (ice–salt). An ice-cool solution
of potassium hydroxide (95.2 g, 97 mmol) in water (100 ml) was
added with vigorous stirring whilst the pressure was reduced
to 500 mmHg by a water aspirator controlled by an air bleed.
After 5 hours the vacuum was released and the product dried
over calcium hydride for 15 hours before distilling (using the
same method as above) to yield a colourless liquid (65 g, 90
mmol, 92%). δH: 2.52 (2H, s, CH2), 1.34 (6H, s, (CH3)2). δC: 53.9
(CH2), 53.5 (-C-(CH3)2), 22.1 ((CH3)2).
113.5 ml, 0.275 mol) in hexane was added dropwise to an ice-
cool solution of 16 (47.49 g, 0.229 mol) in THF (200 ml). The
resultant mixture was stirred for 40 minutes before isobutylene
oxide (38.1 g, 0.427 mmol) in THF (50 ml) was added and the
brown solution allowed to warm to room temperature with stir-
ring for 1 hour. The reaction was quenched with ammonium
chloride solution (500 ml) and the aqueous phase was separated
and extracted with diethyl ether (2 × 150 ml). The combined
organic phases were dried over magnesium sulfate, filtered and
the solvent was removed yielding a light brown oil (52.63 g,
0.188 mol, 82.1%). δP: 39.4 (5%), 37.5 (2%), 31.7 (20, 93%).
δH: 7.75 (1H, m, H4), 7.35 (2H, m, H5,6), 7.14 (1H, d, J(H–H)
6.8 Hz, H3), 2.32–2.05 (4H, m, H9,14), 1.45–0.92 (4H, m, H8,13),
1.34 (6H, s, H11,12), 1.27 (6H, s, H16). δC: 150.04 (C2), 130.99
(C4), 130.04 (d, J(P–C) 10 Hz, C5), 126.39 (d, J(P–C) 110 Hz, C1),
125.66 (d, J(P–C) 16.5 Hz, C3), 68.57 (d, J(P–C) 10.7 Hz, C15),
34.55 (C11), 34.50 (d, J(P–C) 22.9 Hz, C14), 33.83 (C10), 30.10 (d,
J(P–C) 19.5 Hz, C16), 28.23 (d, J(P–C) 26.9 Hz, C13), 27.98 (C12),
1-[(Methyl)phenylphosphinoyl]-3-methylbutan-3-ol
(19).
Butyllithium (2 M, 190.07 ml, 0.380 mol) in hexane was added
to an ice-cooled solution of 13 (53.24 g, 0.345 mol) in THF (500
ml) producing an orange solution, which was stirred for 1 hour.
The reaction was cooled to Ϫ78 ЊC (dry ice–acetone) before
isobutylene oxide (24.90 g, 0.340 mol) in THF (50 ml) was
added and the solution allowed to warm to room temperature
with stirring for 15 hours. The reaction was quenched with
aqueous ammonium chloride (500 ml) and the aqueous phase
separated and washed with dichloromethane (2 × 250 ml). The
combined organic phases were dried over magnesium sulfate,
filtered and the solvent was removed yielding a yellow oil (65.93
g, 0.291 mol, 84.5%). δP: 42.9 (17%, disubstituted product), 37.9
(19, 83%). δH: 7.65 (2H, dd, H3,3Ј), 7.42 (3H, m, H2,2Ј ϩ H4),
2.21–1.85 (2H, m, H7), 1.65 (3H, d, J(P–H) 5.74 Hz, H6), 1.75–
1.58 (2H, m, H8), 1.13 (6H, d, H10). δC ϩ DEPT: 134.1 (CR4, d,
J(P–C) 10 Hz, C1), 132.6 (CH, s, C4), 130.9 (CH, d, J(P–C) 10 Hz,
C2,2Ј), 121.9 (CH, d, J(P–C) 10 Hz, C3,3Ј), 69.8 (CR4, d, J(P–C) 5 Hz,
C9), 35.3 (CH2, d, J(P–C) 5 Hz, C8), 26.0 (CH2, d, J(P–C) 70 Hz,
C7), 16.1 (CH3, d, J(P–C) 70 Hz, C6). νmax/cmϪ1: 3350 (br, s, O-H),
3050 (m, Ar-H), 2950 (s, C-H2), 2900 (s, C-H3), 2850 (s, C-H3),
1960, 1900, 1820, 1780 (w, monosubstituted aromatic overtone
24.82 (d, J(P–C) 69.9 Hz, C9), 20.50 (d, J(P–C) 66.2 Hz, C8). νmax
/
cmϪ1: 3350 (br, m, O-H), 3050 (m, Ar-H), 2950 (s, C-H2), 2900
(s, C-H3), 2850 (s, C-H3), 1660 (w, br, H2O bend), 1590 (m, Ar
C᎐C), 1450 (s, CH asym ϩ CH scissor), 1440 (s, Ar-P), 1400
᎐
3
2
(s, CH3 sym), 1370 (s, CO-H), 1360 (s, CO-H), 1250 (s), 1200 (s,
C-OH), 1170 (s, P᎐O), 1150 (s, CH rock), 1070 (m, Ar), 1000
᎐
3
(m, P-Ar), 750 (s, P-C). MS (APCI): m/z 281.2 (Mϩ ϩ H,
100%).
1,1,6,6-Tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]oxide
(18). Polyphosphoric acid was prepared as above by the
addition of phosphorus pentaoxide (1509.43 g, 10.63 mol) to
phosphoric acid (85% wt, 1610.2 ml, 13.96 mol). The crude oil
of the monocyclised alcohol 20 (35.56 g, 0.127 mol) was added
and the mixture heated at 120 ЊC for 15 hours. The reaction was
cooled and poured into ice (1.5 l), then cautiously neutralised
with sodium hydroxide (10 M) before extraction with dichloro-
methane (4 × 250 ml). The combined organic phases were
washed with sodium hydrogen carbonate solution (1 M, 2 × 250
ml) and the solvent was removed yielding a dark brown oil
(17.02 g, 0.064 mol). The brown oil was purified on a silica gel
column eluted with ethyl acetate–methanol 8:1. The first dark
brown fraction contained a mixture of products and was
reserved for further chromatography. Upon removal of solvent,
the second yellow fraction yielded a golden yellow hygroscopic
fibrous powder. The residual yellow fraction, which was
removed with methanol, contained no 18 by 31P NMR spec-
troscopy. After several repeat purifications the total yield of
yellow powder 18 obtained was (23.42 g, 88.58 mol, 48.14%).
δP: 18.5. δH: 7.31 (1H, t, J(H–H) 8.9 Hz, H4), 7.24 (2H, m, H3,3Ј),
2.63–2.45 (2H, m, H7,7Ј), 2.35–2.29 (2H, m, H6,6Ј), 2.17–
1.85 (4H, 2 overlapping multiplets, H6,6Ј ϩ H7,7Ј), 1.45 (6H, s,
C9,9Ј), 1.27 (6H, s, C10,10Ј) (confirmed by 1H COSY NMR).
δC ϩ DEPT: 151.1 (CR4, d, J(P–C) 10 Hz, C2,2Ј), 132.2 (CH, C4),
125.4 (CH, d, J(P–C) 10 Hz, C3,3Ј), 123.5 (CR4, d, J(P–C) 90 Hz, C1),
137.0 (CR4, C8,8Ј), 33.9 (CH2, d, J(P–C) 10 Hz, C7,7Ј), 32.8 (CH3,
d, J(P–C) 10 Hz, C9,9Ј), 31.7 (CH3, C10,10Ј), 22.8 (CH2, d, J(P–C)
60 Hz, C6,6Ј). νmax/cmϪ1: 3350 (br, m, O-H), 3050 (m, Ar-H),
2950 (s, C-H2), 2900 (s, C-H3), 2850 (m, C-H3), 2200 (m), 1700
pattern), 1660 (m, br, H O bend), 1590 (m, Ar C᎐C), 1470 (m,
᎐
2
CH3 asym ϩ CH2 scissor), 1440 (s, Ar-P), 1410 (s, CH3 sym),
1380 (s, CO-H), 1360 (s, CO-H), 1300 (s), 1210 (s, C-OH), 1170
(s, P᎐O), 1150 (s, CH rock), 1070 (w, Ar), 1000 (w, P-Ar), 750
᎐
3
(s, P-C). MS (APCI): m/z 299.2 (100%), 227.1 (Mϩ ϩ H, 50),
209.1 (10).
1,4,4-Trimethyl-1,2,3,4-tetrahydrophosphinoline oxide (16).
Due to the vast excess of reagents required, the reaction was
split into two manageable halves. Polyphosphoric acid was pre-
pared as above using phosphorus pentaoxide (1284 g, 9.04
mol) and phosphoric acid (609.9 ml, 3.65 mol). The crude oil of
19 (33 g, 0.146 mol) was added and the mixture heated at 120 ЊC
for 15 hours, then poured into ice (2 l), allowed to cool and
cautiously neutralised with sodium hydroxide pellets. The
cloudy yellow mixture was extracted with dichloromethane
(4 × 500 ml), the combined organic phases were washed with
sodium hydrogen carbonate solution (1 M, 2 × 750 ml) and the
solvent was removed yielding a brown oil. The total combined
yield for these reactions was (47.79 g, 0.229 mol, 78.8%).
δP: 26.3 (16). δH: 7.75 (1H, dd, J(H–H) 9.9 and 13.2 Hz, H5), 7.35
(2H, m, H3 ϩ H4), 7.24 (1H, t, H6), 2.25 (1H, m, H9), 2.03 (2H,
m, H10), 1.94 (1H, m, H9), 1.65 (3H, d, J(P–C) 12.63 Hz, H8), 1.25
(6H, d, J(P–H) 3.10 Hz, H12 ϩ H13). δC: 149.6 (d, J(P–C) 7 Hz, C2),
130.9 (d, J(P–C) 2.4 Hz, C4), 129.5 (d, J(P–C) 7.2 Hz, C5), 128.7 (d,
J(P–C) 10 Hz, C1), 125.7 (d, J(P–C) 7 Hz, C3), 34.5 (s, C11), 33.9 (s,
C10), 30.0 (d, J(P–C) 7 Hz, C12,13), 22.8 (d, J(P–C) 68 Hz, C9), 16.7
(d, J(P–C) 50 Hz, C8). νmax/cmϪ1: 3300 (br, m, O-H), 3050 (m,
Ar-H), 2950 (s, C-H2), 2900 (s, C-H3), 2850 (m, C-H3), 1640 (w,
(m, br, H O bend), 1580 (s, Ar C᎐C), 1460 (s, CH asym ϩ CH
᎐
2
3
2
scissor), 1440 (s, Ar-P), 1400 (s, CH3 sym), 1260 (s), 1170
(s, P᎐O), 1150 (s, CH rock), 1070 (m, Ar), 1000 (m, P-Ar),
᎐
3
750 (s, P-C). MS (APCI): m/z 263.3 (Mϩ ϩ H, 100%).
The previously attempted synthesis of 18 from the less
reactive alcohol 17 (route 3) following the method described
above, required a reaction time of 5 days and produced a black
oil which contained a mixture of compounds by 31P NMR.
δP (360 MHz): 31.3 (15, s, 10%), 27.0 (16, s, 10%), 24.0 (s, 18%),
22.5 (18, 62%). Any attempts to isolate the desired product
failed.
br, H O bend), 1590 (m, Ar C᎐C), 1480 (s, CH asym ϩ CH
᎐
2
3
2
scissor), 1430 (s, Ar-P), 1400 (s, CH3 sym), 1300 (s), 1170 (s,
P᎐O), 1150 (s, CH rock), 1070 (m, Ar), 1000 (w, P-Ar), 750
᎐
3
(s, P-C). MS (APCI): m/z 417.6 (2Mϩ ϩ H, 100%), 209.3
(Mϩ ϩ H, 15).
1-(3-Hydroxy-3-methylbutyl)-4,4-dimethyl-1,2,3,4-tetra-
hydrophosphinoline oxide (20). Butyllithium solution (2.42 M,
The attempted reduction of this black oil by the previously
reported method,4 also produced a mixture of products by
J. Chem. Soc., Perkin Trans. 1, 2000, 3122–3128
3127