m/z (EI) 266 (Mϩ, 18%), 206 (100), 191 (40), 129 (65) and 69
(60).
3-Phenyl-5,5-diphenylpent-4-enoic acid 31b. A colourless solid
(98%), mp 129–131 ЊC (Found: Mϩ, 328.1463. C23H20O2
requires Mϩ, 328.1463); [α]D20 Ϫ121.8 (c 0.78, CHCl3); νmax/cmϪ1
28.4 [C(CH3)3], 35.2 (CHCH3), 46.5 (CH2NHBoc), 79.0
[C(CH3)3], 127.0 (Arom CH), 127.1 (Arom CH), 127.2 (Arom
CH), 128.1 (Arom CH), 128.4 (Arom CH), 129.7 (Arom CH),
132.5 (CH᎐CPh ), 140.1 (Ph C᎐CH), 142.1 (Arom C), 142.7
᎐
᎐
2
2
(Arom C) and 155.9 (C᎐O); m/z (EI) 337 (Mϩ, 0.3%), 281 (20),
᎐
3054 (CO H), 2987, 1709 (C᎐O) and 1265; δ (400 MHz;
207 (100), 129 (45) and 57 (90).
᎐
2
H
CDCl3) 2.73 (d, 2 H, J 7.2, CH2CO2H), 3.90–3.96 (m, 1 H,
N-(tert-Butoxycarbonyl)-2,4,4-triphenylbut-3-enamine 32b.
CHPh), 6.22 (d, 1 H, J 10.4, CH᎐CPh ), 7.05–7.33 (m, 15 H,
A
colourless solid (61%), mp 118–120 ЊC (Found: Mϩ,
᎐
2
ArH) and 9.0–10.1 (br s, 1 H, CO2H); δC(100 MHz; CDCl3) 41.6
(CHPh), 41.7 (CH2CO2H), 126.6 (Arom CH), 127.2 (Arom
CH), 127.3 (Arom CH), 127.4 (Arom CH), 128.1 (Arom CH),
128.3 (Arom CH), 128.4 (Arom CH), 128.7 (Arom CH), 129.7
399.2198. C27H29NO2 requires Mϩ, 399.2198); [α]D20 Ϫ87.2 (c
0.86, CHCl3); νmax/cmϪ1 3443 (NH), 3054, 2984, 1711 (C᎐O),
᎐
1265 and 1170; δH (400 MHz; CDCl3) 1.39 [s,
9 H,
NHCO2(CH3)3], 3.38–3.48 (m, 2 H, CH2NHBoc), 3.55–3.59 (m,
1 H, CHPh), 4.44 (br s, 1 H, NHBoc), 6.25 (d, 1 H, J 10.3,
(Arom CH), 130.1 (CH᎐CPh ), 139.5 (Ph C᎐CH), 142.0 (Arom
᎐
᎐
2
2
C), 142.7 (Arom C), 143.2 (Arom C) and 177.2 (C᎐O); m/z (EI)
CH᎐CPh ) and 7.12–7.36 (m, 15 H, ArH); δ (100 MHz; CDCl )
᎐
2 C 3
᎐
328 (Mϩ, 7%), 268 (100) and 191 (89).
28.4 [C(CH3)3], 46.0 (CH2NHBoc), 46.3 (CHPh), 79.2
[C(CH3)3], 126.7 (Arom CH), 127.2 (Arom CH), 127.3 (Arom
CH), 127.4 (Arom CH), 127.5 (Arom CH), 128.1 (Arom CH),
128.3 (Arom CH), 128.8 (Arom CH), 129.4 (Arom CH), 129.8
(CH᎐CPh ), 139.8 (Ph C᎐CH), 142.1 (Arom C), 142.1 (Arom
5,5-Diphenyl-3-(2,4,6-trimethylphenyl)pent-4-enoic acid 31c.
A
colourless solid (98%), mp 136–138 ЊC (Found: Mϩ,
370.1932. C26H26O2 requires Mϩ, 370.1932); [α]D20 ϩ160.0 (c 0.90,
CHCl3); νmax/cmϪ1 3058 (CO H), 2921, 1768 (C᎐O) and 1265;
᎐
᎐
᎐
2
2
2
δH (400 MHz; CDCl3) 2.03 (br s, 6 H, 2 × ArCH3), 2.19 (s, 3 H,
ArCH3), 2.59 (dd, 1 H, J 5.1 and 15.0, CHHCO2H), 2.88 (dd, 1
H, J 10.0 and 15.0, CHHCO2H), 4.33–4.39 (m, 1 H, CH-Mes),
6.55 (d, 1 H, J 8.6, CH᎐CPh ), 6.87 (s, 2 H, ArH), 6.91–6.93 (m,
C), 143.6 (Arom C) and 155.8 (C᎐O); m/z (EI) 399 (Mϩ, 10%),
᎐
269 (100) and 191 (62).
N-(tert-Butoxycarbonyl)-2-(2,4,6-trimethylphenyl)but-3-en-
amine 32c. A colourless oil (49%) (Found: Mϩ, 441.2667.
C30H35NO2 requires Mϩ, 441.2667); [α]D20 ϩ155.1 (c 0.25,
᎐
2
2 H, ArH), 7.17–7.24 (m, 8 H, ArH) and 9.0–10.0 (br s, 1 H,
CO2H); δC(100 MHz; CDCl3) 20.6 (ArCH3), 21.2 (2 × ArCH3),
37.3 (CH-Mes), 39.4 (CH2CO2H), 126.9 (Arom CH), 126.9
(Arom CH), 127.1 (Arom CH), 127.9 (Arom CH), 128.1 (Arom
CH), 128.3 (Arom CH), 129.5 (Arom CH), 129.9 (Arom CH),
CHCl3); νmax/cmϪ1 3362 (NH), 2975, 1712 (C᎐O) and 1265;
᎐
δH (400 MHz; CDCl3) 1.46 [s, 9 H, NHCO2C(CH3)3], 2.07 (br s,
6 H, 2 × ArCH3), 2.24 (s, 3 H, ArCH3), 3.25–3.29 (m, 1 H,
CHHNHBoc), 3.48–3.54 (m, 1 H, CHHNHBoc), 4.00–4.06 (m,
1 H, CHMes), 4.55 (br s, 1 H, NHBoc), 6.65 (d, 1 H, J 10.0,
130.4 (CH᎐CPh ), 135.5 (Ph C᎐CH), 136.0 (Arom C), 137.5
᎐
᎐
2
2
(Arom C), 139.7 (Arom C), 141.9 (Arom C), 143.0 (Arom C)
CH᎐CPh ), 6.75 (s, 2 H, ArH), 6.95–6.97 (m, 2 H, ArH) and
᎐
2
and 178.2 (C᎐O); m/z (EI) 370 (Mϩ, 35%), 311 (100), 191 (40)
7.23–7.29 (m, 8 H, ArH); δC(100 MHz; CDCl3) 20.6 (ArCH3),
21.3 (2 × ArCH3), 28.4 [C(CH3)3], 42.1 (CHMes), 43.6
(CH2NHBoc), 79.2 [C(CH3)3], 126.9 (Arom CH), 127.1 (Arom
CH), 128.1 (Arom CH), 128.2 (Arom CH), 129.7 (Arom CH),
129.8 (Arom CH), 129.9 (Arom CH), 129.9 (CH᎐CPh ), 135.6
᎐
and 91 (75).
5,5-Diphenyl-3-(1-naphthyl)pent-4-enoic acid 31d. A colour-
less solid (98%), mp 85–87 ЊC (Found: Mϩ, 378.1619.
C27H22O2 requires Mϩ, 378.1620); [α]D20 ϩ146.8 (c 0.94, CHCl3);
᎐
2
νmax/cmϪ1 3000 (CO H), 2592, 1735 (C᎐O) and 1252; δ (400
(Ph C᎐CH), 135.9 (Arom C), 136.6 (Arom C), 139.8 (Arom C),
᎐
᎐
2
H
2
MHz, CDCl3) 2.79 (dd, 1 H, J 8.7 and 15.1, CHHCO2H), 2.91
(dd, 1 H, J 5.9 and 15.1, CHHCO2H), 4.75–4.81 (m, 1 H, CH-
142.0 (Arom C), 143.7 (Arom C) and 155.9 (C᎐O); m/z (EI) 441
᎐
(Mϩ, 0.2%), 311 (100), 191 (30) and 57 (50).
Naphth), 6.40 (d, 1 H, J 10.1, CH᎐CPh ), 6.98–7.01 (m, 2 H,
N-(tert-Butoxycarbonyl)-2-(1-naphthyl)but-3-enamine 32d. A
colourless oil (52%) (Found: Mϩ, 450.2433. C31H31NO2 requires
Mϩ, 450.2433); [α]D20 ϩ118.2 (c 0.44, CHCl3); νmax/cmϪ1 3446
᎐
2
ArH), 7.18–7.25 (m, 8 H, ArH), 7.37–7.47 (m, 4 H, ArH), 7.63–
7.69 (m, 2 H, ArH), 7.74–7.77 (m, 1 H, ArH) and 9.0–10.0 (br s,
1 H, CO2H); δC(100 MHz; CDCl3) 37.4 (CH-Naphth), 42.4
(CH2CO2H), 123.6 (Arom CH), 124.4 (Arom CH), 125.9
(Arom CH), 126.4 (Arom CH), 127.7 (Arom CH), 127.8 (Arom
CH), 127.9 (Arom CH), 128.5 (Arom CH), 128.6 (Arom CH),
(NH), 3054, 2983, 2932, 1710 (C᎐O) and 1265; δ (250 MHz;
᎐
H
CDCl3) 1.39 [s, 9 H, NHCO2C(CH3)3], 3.43–3.58 (m, 2 H,
CH2NHBoc), 4.47–4.54 (m, 2 H, CHNaphth and NHBoc), 6.45
(d, 1 H, J 10.1, CH᎐CPh ), 7.06–7.23 (m, 2 H, ArH), 7.25–7.30
᎐
2
129.2 (Arom CH), 130.1 (Arom CH), 130.5 (CH᎐CPh ), 131.1
(m, 8 H, ArH), 7.36–7.48 (m, 4 H, ArH) and 7.66–7.85 (m, 3 H,
ArH); δC(62.5 MHz; CDCl3) 28.3 [C(CH3)3], 41.0 (CHNaphth),
46.1 (CH2NHBoc), 79.1 [C(CH3)3], 123.2 (Arom CH), 124.4
(Arom CH), 125.5 (Arom CH), 125.9 (Arom CH), 127.2 (Arom
CH), 127.2 (Arom CH), 127.5 (Arom CH), 128.0 (Arom CH),
᎐
2
(Ph C᎐CH), 134.5 (Arom C), 139.8 (Arom C), 140.2 (Arom C),
᎐
2
142.6 (Arom C), 143.5 (Arom C) and 178.1 (C᎐O); m/z (EI) 378
᎐
(Mϩ, 47%), 319 (92), 241 (75), 191 (70) and 167 (100).
Typical procedure for the modified Curtius reaction
128.2 (Arom CH), 128.7 (Arom CH), 129.5 (CH᎐CPh ), 129.8
᎐
2
A solution of 31b (90 mg, 0.27 mmol), triethylamine (30 mg,
0.30 mmol) and diphenylphosphoryl azide (83 mg, 0.30 mmol)
in tert-butyl alcohol (3 cm3) was refluxed for 16 h, cooled and
then poured into saturated aqueous sodium hydrogen carbon-
ate (10 cm3). The solution was extracted with dichloromethane
(3 × 15 cm3) and the combined extracts were washed with water
(20 cm3) and brine (30 cm3), dried (MgSO4), filtered and evap-
orated to yield a brown oil. Purification of this by ‘flash’ col-
umn chromatography with light petroleum–ether (5:1) gave
compound 32b.
(Arom CH), 134.2 (Ph C᎐CH), 138.2 (Arom C), 138.2 (Arom
᎐
2
C), 139.3 (Arom C), 139.3 (Arom C) and 153.5 (C᎐O); m/z (EI)
᎐
450 (Mϩ, 0.2%), 393 (12), 319 (100) and 241 (40).
Typical procedure for the conversion of the alkenes 32a–d into the
corresponding carboxylic acids 33a–d
To a solution of 32b (50 mg, 0.125 mmol) and sodium meta-
periodate (117 mg, 0.513 mmol) in the solvent system CCl4
(1 cm3), MeCN (1 cm3) and water (1.5 cm3) was added
ruthenium trichloride hydrate (0.57 mg, 0.0027 mmol). The
reaction mixture was stirred at 40 ЊC for 2 h after which it was
diluted with water (10 cm3); the aqueous layer was then separ-
ated and extracted with dichloromethane (3 × 15 cm3). The
combined organic layer and extracts were washed with brine (30
cm3), dried (MgSO4), filtered and evaporated to yield a dark
brown oil. Purification of this by ‘flash’ column chrom-
atography, eluting with light petroleum–ethyl acetate (1:1) gave
compound 33b.
N-(tert-Butoxycarbonyl)-2-methyl-4,4-diphenylbut-3-enamine
32a. A colourless solid (52%), mp 88–90 ЊC (Found: Mϩ,
337.2042. C22H27NO2 requires Mϩ, 337.2042); [α]D20 Ϫ58.3 (c
0.7, CHCl3); νmax/cmϪ1 3359 (NH), 2965, 1712 (C᎐O), 1249 and
᎐
1172; δH (400 MHz; CDCl3) 1.01 (d, 3 H, J 6.6, CH3), 1.41 [s, 9
H, NHCO2C(CH3)3], 2.44–2.49 (m, 1 H, CHCH3), 2.97–3.03
(m, 1 H, CHHNHBoc), 3.03–3.15 (m, 1 H, CHHNHBoc), 4.45
(br s, 1 H, NHBoc), 5.84 (d, 1 H, J 10.2, CH᎐CPh ) and
᎐
2
7.16–7.38 (m, 10 H, ArH); δC(100 MHz; CDCl3) 18.5 (CH3),
3-tert-Butoxycarbonylamino-2-methylpropanoic acid 33a. A
1418
J. Chem. Soc., Perkin Trans. 1, 1997