PAPER
2,6-Di-tert-butylphenyl Derivatives
2127
13C NMR (100.6 MHz, CDCl3): d = 32.80 [qm, 1J = 125.9 Hz,
The elution rate had to be decreased very much on increasing the
Et2O concentration, so as to avoid heating and breaking of the silica
gel column. The almost pure product 10a (14.90 g, 84%) was eluted
with the next 100-mL portions of PE–Et2O (4:1, then 2:1) and Et2O,
followed by other byproducts with additional Et2O. The analytically
pure sample was obtained as a colorless oil through rechromatogra-
phy.
2
3J = 4.9 Hz, 2 × C(CH3)3], 36.98 [m, J = 3.7 Hz, 2 × C(CH3)3],
38.23 (sharp q, 1J = 127.3 Hz, CH3-a), 125.66 (ddd, 1J = 157.3 Hz,
3J = 7.5 Hz, 2J = +1.5 Hz, C-3/-5), 127.64 [app. dd, 1J = 159.43 Hz,
3
4
2J = –0.01 ( 0.03) Hz, C-4], 140.26 (tdq, J = 6.78 Hz, J =
3
3
–1.65 Hz, J = +0.89 Hz, C-1), 145.17 [dm, J = 7.40 Hz to 4-H,
2J = +1.13 Hz to 3-H or 5-H, 4J = –1.20 Hz to 5-H or 3-H,
3J = 3.68 Hz to 2-C(CH3)3 or 6-C(CH3)3, C-2/-6], 210.89 (qtd,
2J = –5.57 Hz, 4J = 1.13 Hz, 5J = –0.01 Hz, C=O); assigned
through the following selective {1H} decoupling experiments: {3-/
4-/5-H} → C=O as a sharp quartet with 2J = 5.6 Hz, C-1 as a br sin-
glet (3J q unresolved), C-2/-6 as a sharp decet; {CH3-a} → C=O as
IR (film): 2967, 2912, 1647, 1364, 1274, 1256, 1056, 1033, 993
(vs), 807 cm–1.
3
1H NMR (400 MHz, CDCl3): d = 1.35 [td, JHH = 7.0 Hz,
4JPH = 1.1 Hz, 6 H, 2 × POC(CH3)], 1.49 (s, 18 H), ~4.19 and ~4.23
(2 × m, 4 H, diastereotopic H of 2 × POCH2 groups, including 3JPH),
4.80 (dd, 2JHH = 2.8 Hz, 4JPH = 1.7 Hz, 1 H, 1 b-H syn to aryl), 5.42
(dd, 2JHH = 2.8 Hz, 4JPH = 0.5 Hz, 1 H, 1 b-H anti to aryl), 7.23 and
7.42 (arom. AB2 system, 3J = 8.0 Hz, 3 H).
4
3
a triplet with J = 1.1 Hz, C-1 as a triple-doublet with J = 6.7 Hz
and 4J = 1.5 Hz; signs and values of the long-range couplings were
determined through computer simulation.
Anal. Calcd for C16H24O: C, 82.70; H, 10.41. Found: C, 82.77; H,
10.32.
1
13C NMR (100.6 MHz, CDCl3): d = 16.08 (qtd, JCH = 127.5 Hz,
3
2JCH = 2.7 Hz, JCP = 7.2 Hz,
2
×
POCCH3), 33.0 [qsept,
1JCH = 126 Hz, JCH = 4.8 Hz,
2
×
C(CH3)3], 37.51 [m,
3
2,6-Di-tert-butylpropiophenone (8b)
2JCH = 3.8 Hz,
2
×
C(CH3)3], 64.26 (tqd, JCH = 148.5 Hz,
1
Purified acid chloride 7 (1.43 g, 5.66 mmol) in anhydrous THF (24
mL) was stirred magnetically under argon gas in a dried Schlenk
flask (100 mL) during the dropwise addition of a THF solution of
EtMgBr (11.3 mmol, 11.3 mL) within 15 min. The darkening mix-
ture became hot and was stirred for 2 h at r.t., then poured into iced
aq NH4Cl (50 mL) and shaken with Et2O (3 × 25 mL). The com-
bined organic extracts were washed with distilled H2O (2 × 40 mL),
dried over Na2SO4, and evaporated to dryness, affording the uncon-
taminated ketone 8b.
2
2JCH = 4.5 Hz, JCP = 6.2 Hz,
2
×
POCH2), 104.04 (td,
1JCH = 161.5 Hz, 3JCP = 2.2 Hz, olefinic CH2-b), 125.34 (dm, 1JCH
=
1
~158 Hz, C-3/-5), 128.46 (dm, JCH = ~159 Hz, C-4), 133.62 (m
3
3
from JCP = 10.6 Hz and several differing JCH, C-1), 150.36 (app.
octet, 3JCH = 3.6 Hz, C-2/-6), 151.94 (td, 2JCH = 6.0 Hz,
2JCP = 8.9 Hz, C-a).
Anal. Calcd for C20H33PO4: C, 65.20; H, 9.03. Found: C, 65.00; H,
8.87.
Yield: 1.36 g (97%); yellow, very viscous liquid (later a waxy solid,
mp 46–48 °C); bp 85–90 °C (bath temp)/0.1 mbar.
IR (film): 2970, 1708 (s), 1474, 1457, 1364, 1203, 945, 741 cm–1.
Diethyl 1-(2,6-Di-tert-butylphenyl)-1-propenyl Phosphate (10b)
In a procedure similar to that used for 10a, 2,6-di-tert-butylpro-
piophenone (8b) was treated with n-BuLi (1.9 equiv) and Cl-
PO(OEt)2 (2 equiv) to give the enol phosphate 10b (63–70% after
chromatography as above).
1H NMR (400 MHz, CDCl3): d = 1.16 (t, 3J = 7.0 Hz, 3 H, CH3-b),
3
1.33 (s, 18 H), 2.85 (q, J = 7.0 Hz, 2 H, CH2-a), 7.22 and 7.35
(arom. AB2 system, 3J = 8.0 Hz, 3 H).
1H NMR (400 MHz, CDCl3): d = 1.33 (d, 3JHH = 7.1 Hz, 3 H, CH3-
g), 1.34 [td, 3JHH = 7.1 Hz, 4JPH = 1.1 Hz, 6 H, 2 × POC(CH3)], 1.45
(s, 18 H), ~4.18 and ~4.21 (2 m, 4 H, diastereotopic H of 2 × POCH2
13C NMR (100.6 MHz, CDCl3): d = 7.16 (qt, 1J = 127.4 Hz,
1
3
2J = 3.7 Hz, CH3-b), 32.74 [qsept, J = 126.1 Hz, J = 4.9 Hz, 2 ×
C(CH3)3], 37.11 [m, 2J = 3.7 Hz, 2 × C(CH3)3], 42.73 (tq,
1J = 124.1 Hz, 2J = 4.4 Hz, CH2-a), 125.73 (dd, 1J = 158.0 Hz,
3
3
4
groups, including JPH), 5.60 (qd, JHH = 7.1 Hz, JPH = 0.7 Hz,25
1 H, 1 b-H anti to aryl), 7.24 and 7.43 (arom. AB2 system,
3J = 8.0 Hz, 3 H).
1
3J = 7.4 Hz, C-3/-5), 127.56 (dm, J = 160.6 Hz, C-4), 139.76 (td,
3J = 6.6 Hz, 4J = 1.5 Hz, C-1), 145.40 (m, 3J = 3.7 Hz, C-2/-6),
212.31 (m, 3J = ~ 2J = 4.9 Hz, C=O); assigned through the follow-
ing selective {1H} decoupling experiments: {3-/4-/5-H} → C=O as
1
13C NMR (100.6 MHz, CDCl3): d = 15.39 (qd, JCH = 127.3 Hz,
1
2
2JCH = 1.4 Hz, CH3-g), 16.11 (qtd, JCH = 127.3 Hz, JCH = 2.6 Hz,
1
3JCP = 7.2 Hz,
2
×
POCCH3), 33.00 [qsept, JCH = 126 Hz,
3
2
a sextet with J = ~ J = 4.8 Hz, C-1 as a singlet with linewidth =
1.2 Hz (⏐3J⏐ < 0.3 Hz unresolved); {CH2-a} → CH3-b as a sharp
quartet with 1J = 127 Hz; {CH3-b} → CH2-a as a sharp triplet with
3JCH = 4.9 Hz, 2 × C(CH3)3], 37.70 [m, JCH = ~3.7 Hz, 2 ×
2
C(CH3)3]), 64.07 (tqd, 1JCH = 148 Hz, 2JCH = 4.5 Hz, 2JCP = 6.2 Hz,
1
2
2
× POCH2), 111.32 (dqd, JCH = 154.1 Hz, JCH = 7.1 Hz,
2
4
1J = 124.1 Hz, C=O as a triple-triplet with J = 4.8 Hz and J =
3JCP = 2.2 Hz, olefinic CH-b), 125.81 (dm, 1JCH = ~157 Hz, C-3/-5),
~1.1 Hz.
128.34 (dm, 1JCH = ~158 Hz, C-4), 130.80 (m from 3JCP = 10.6 Hz
3
Anal. Calcd for C17H26O: C, 82.87; H, 10.64. Found: C, 82.98; H,
10.84.
and several differing JCH, C-1), 146.39 (unresolved, includes d,
2JCH = 6.0 Hz and d, JCP = 9.4 Hz, C-a), 150.73 (unresolved, in-
2
cludes d, 3JCH = 7.0 Hz to 4-H, C-2/-6); assigned through selective
{1H} decoupling experiments as follows: {3-/4-/5-H} → C-1 as a
Diethyl a-(2,6-Di-tert-butylphenyl)vinyl Phosphate (10a)
3
3
2,6-Di-tert-butyl acetophenone (8a; 11.24 g, 48.37 mmol) in anhy-
drous THF (225 mL) was stirred magnetically in a dry Schlenk flask
(500 mL) under argon gas and cooled to –60 °C. The yellow solu-
tion turned red and the internal temperature rose to –30 °C on addi-
tion of n-BuLi (2.4 M in hexane, 30.25 mL, 72.6 mmol) within 5
min. After further stirring for 5 min, ClPO(OEt)2 (13.94 mL, 96.68
mmol) was added at –30 °C. The mixture was warmed to r.t. and
poured into aq NaOH (1 M, 200 mL). The aqueous layer was shaken
with Et2O (2 × 100 mL) and the combined three organic layers were
washed with distilled H2O (3 × 50 mL), dried over MgSO4, and
concentrated to give a yellow liquid containing 10a and residual Cl-
PO(OEt)2. Chromatography in a column (diameter 35 mm) of silica
gel (63–200 mesh; 60 Å; 200 g) with low-boiling PE (500 mL) and
then PE–Et2O (4:1, 300 mL) removed part of the contamination.
dd of JCP and JCH = 6.2 Hz;25 {all CH3} → CH-b as a dd (1JCH
,
d
3JCP), C-a as
a
dd (2JCH = 6.0 Hz, JCP), C-2/-6 as
a
2
(3JCH = 7.0 Hz), and POCH2 as a td (1JCH, 2JCP).
Anal. Calcd for C21H35PO4: C, 65.95; H, 9.22. Found: C, 66.21; H,
9.23.
2,6-Di-tert-butylphenylacetylene (11a)
Anhydrous t-BuOMe (50 mL) in a dried Schlenk flask (500 mL) un-
der argon gas was stirred magnetically during the addition of the
sticky oil 10a (14.49 g, 39.32 mmol) together with further t-BuOMe
(150 mL). After complete dissolution and subsequent cooling to
–70 °C, t-BuLi (1.7 M in hexane, 62.5 mL, 106.2 mmol) was added
dropwise with stirring. The resulting red solution was stirred for 10
min at –70 °C and for 15 min at r.t., then poured onto iced H2O (500
Synthesis 2010, No. 13, 2124–2128 © Thieme Stuttgart · New York