Table 5 NMR spectroscopic data for the spiro-β-lactones
Spiro-β-lactone
δH
δC
3a
8.02–7.27 (5H, m, ArH), 3.82 (2H, s, CH2COO), 3.14 (1H, Not determined
dd, J 7.0 and 8.1, CHCH2), 2.44 (1H, t, J 7.0, CHCH(H)),
1.52 (1H, dd, J 7.0 and 8.1, CHCH(H))
4a
3b
8.04–7.51 (5H, m, ArH), 3.82 and 3.61 (2H, 2d, J 15.9,
CH2COO), 3.45 (1H, dd, J 7.0 and 8.4, CHCH2), 1.92 (2H,
m, CHCH2)
Not determined
4.21 (2H, q, J 7.1, CH2CH3), 3.72 (2H, s, CH2CO2), 2.11
168.5 (C᎐O), 165.7 (C᎐O), 64.4 (s), 61.1, 43.3 (t), 22.1 (d), 14.8
᎐ ᎐
(1H, dd, J 10.4 and 7.0, CHCH2), 2.05 (1H, t, J 7.0 (t), 14.0 (q)
CH(H)CH), 1.43 (1H, dd, J 10.4 and 7.0, CH(H)H), 1.29
(3H, t, J 7.1 CH2CH3)
4b
4.15 (2H, q, J 7.2, CH2CH3), 3.74 and 3.65 (2H, 2d, J 17.0,
170.4 (C᎐O), 165.8 (C᎐O), 64.5 (s), 61.1, 41.8 (t), 21.2 (d), 14.8
᎐ ᎐
CH2CO2), 2.32 (1H, dd, J 10.5 and 6.9, CH(H)CH), 1.72 (t), 14.0 (q)
(1H, dd, J 10.5 and 6.9, CH(H)CH), 1.52 (1H, t, J 6.9,
CH(H)CH), 1.25 (3H, t, J 7.2, CH2CH3)
4c
3d
4.17 (2H, q, J 7.1, CH2CH3), 3.74 and 3.63 (2H, 2d, J 17.2,
CH2CO2), 1.72 and 1.38 (2H, 2d, J 17.2, cyclopropyl CH2),
1.44 (3H, s, CH3), 1.27 (3H, t, J 7.1, CH2CH3)
171.7 (C᎐O), 166.3 (C᎐O), 67.9 (s), 61.1, 42.2 (t), 25.3 (s), 21.4
(t), 14.0 and 13.6 (q)
᎐
᎐
4.02 (2H, m, CO2CH2CH3), 3.55 and 3.45 (2H, 2d, J 17.2,
171.1 (C᎐O), 166.3 (C᎐O), 68.2 (s), 61.0, 42.5 (t), 31.1 (s), 21.5
᎐ ᎐
CH2CO2), 1.76 (1H, m, CH(H)CCO2), 1.50 and 1.19 (2H, (t), 20.0 (t), 14.0 and 11.5 (q)
2d, J 7.3 cyclopropyl H), 1.48 (1H, m, CH(H)CCO2),
1.12 (3H, t, J 7.3, CO2CH2CH3), 0.90 (3H, t, J 7.3,
CH3CH(H)CCO2)
4d
4.21 (2H, m, CO2CH2CH3), 3.64 and 3.54 (2H, 2d, J 17.1,
CH2CO2), 2.30 (1H, m, CH3CH(H)CCO2), 2.19 and 1.05
169.1 (C᎐O), 165.8 (C᎐O), 67.1 (s), 61.2, 40.8 (t), 31.6 (s), 24.2,
17.9 (t), 14.0 and 10.5 (q)
᎐ ᎐
(2H, 2d,
J 7.0 cyclopropyl H), 1.26 (3H, t, J 7.3,
CO2CH2CH3), 0.99 (3H, t, J 7.3, CH3CH(H)CCO2), 0.85
(1H, m, CH3CH(H)CCO2)
4.11 (2H, m, CH2CH3), 3.64 (2H, s, CH2CO2), 1.65–1.58
(2H, overlapping signals, iPr H and cyclopropyl H), 1.30
(1H, d, J 6.7, cyclopropyl H), 1.29–1.09 (9H, overlapping
signals, CH3)
3e
4e
168.6 (C᎐O), 165.9 (C᎐O), 67.1 (s), 61.0, 40.9 (t), 35.0 (s), 31.9
᎐ ᎐
(d), 19.5 and 18.9 (q), 18.3 (t) and 14.0 (q)
4.14 (2H, m, CH2CH3), 3.74 and 3.75 (2H, 2d, J 16.8, 170.4 (C᎐O), 166.4 (C᎐O), 68.4 (s), 60.7, 42.9 (t), 34.4 (s), 30.2
᎐
᎐
CH2CO2), 2.07 (1H, d, J 7.4, cyclopropyl H), 1.36 (1H, m, (d), 20.9 (t), 19.6, 19.0 and 14.0 (q)
iPr H), 1.31–1.16 (7H, overlapping signals, iPr H and cyclo-
propyl H), 0.99 (3H, t, J 7.4, CH2CH3)
12a
12b
7.88–6.80 (8H, m, Ar H), 3.92 and 3.64 (2H, 2d, J 16.4,
CH2CO2), 2.46 and 2.12 (2H, 2d, J 7.8, cyclopropyl H)
8.48–6.71 (8H, m, Ar H), 3.82 and 3.33 (2H, 2d, J 16.7,
CH2CO2), 2.75 and 2.45 (2H, 2d, J 9.0, cyclopropyl H)
165.8 (C᎐O), 143.5, 142.2, 140.8, 139.5 (s), 126.7, 126.4, 121.9,
121.6, 120.1, 119.8 (d), 69.2 (s), 41.0 (t), 34.9 (s), 21.2 (t)
᎐
183.3 (C᎐O), 165.7 (C᎐O), 140.3, 138.2 (s), 133.7, 133.3, 133.0
᎐
᎐
(d), 132.6, 132.4 (s), 128.5, 128.0, 127.3, 125.2, 122.7 (d), 71.5
(s), 42.6 (t), 28.6 (s), 24.8 (t)
12c
12e
᎐
16.1, CH2CO2), 2.29 and 2.09 (2H, 2d, J 16.1, cyclopropyl
CH2)
12f
7.39–7.12 (10H, m, Ar H), 3.60 and 3.49 (2H, 2d, J 16.6, 166.5 (C᎐O), 140.6, 139.4 (s), 129.1, 128.8, 128.5, 127.7, 127.2,
CH2CO2), 2.02 and 1.93 (2H, 2d, J 7.7, cyclopropyl H)
᎐
127.0 (d), 68.0 (s), 42.2 (t), 35.8 (s), 21.7 (t)
Ethyl trans-1-methyl-5-oxo-4-oxaspiro[2.3]hexane-1-carboxyl-
ate 4c
graphy of this oil (ether–petroleum ether, 3:7) gave in order of
elution, 4d (0.27 g, 13%) and 3d (0.36 g, 17%). Physical and
spectroscopic data for the title compounds are given in Tables 4
and 5.
Ethyl 2-diazopropionate7 2c (2.0 g, 15.6 mmol) in benzene was
added dropwise to a stirred mixture of Rh2(OAc)4 (6 mg, 0.14
mmol) and diketene (15.0 g, 0.178 mol) over 2 h at 70 ЊC. The
mixture was stirred for a further hour and then allowed to cool.
After filtering through a short column of silica gel the excess
diketene was removed (25 ЊC, 0.1 mmHg) to give a red oil. The
title compound was obtained as a colourless oil after chromato-
graphy (0.32 g, 32%). Physical and spectroscopic data for 4c are
given in Tables 4 and 5.
Ethyl cis-1-(methylethyl)-5-oxo-4-oxaspiro[2.3]hexanecarboxyl-
ate 3e and ethyl trans-1-(methylethyl)-5-oxo-4-oxaspiro[2.3]-
hexanecarboxylate 4e
A solution of ethyl 2-diazoisovalerate8 (2e, 1.6 g, 0.1 mol),
diketene (10.0 g, 0.12 mol) and benzophenone (1.8 g, 0.1 mol)
in acetonitrile (50 cm3) was placed in a Rayonet reactor and was
irradiated for 18 h. The acetonitrile and excess diketene was
removed by distillation at room temperature under water and
oil pump vacuum, respectively, to give a yellow oil. Chromato-
graphy of this oil (ether–petroleum ether, 3:7) gave in order of
elution, 4e (0.50 g, 26%) and 3e (0.36 g, 18%). Physical and
spectroscopic data for the title compounds are given in Tables 4
and 5.
Ethyl cis-1-ethyl-5-oxo-4-oxaspiro[2.3]hexanecarboxylate 3d
and ethyl trans-1-ethyl-5-oxo-4-oxaspiro[2.3]hexanecarboxylate
4d
A solution of ethyl 2-diazobutyrate8 (2d, 1.4 g, 0.1 mol),
diketene (10.0 g, 0.12 mol) and benzophenone (1.8 g, 0.1 mol)
in acetonitrile (50 cm3) was placed in a Rayonet reactor and was
irradiated for 18 h. The acetonitrile and excess diketene was
removed by distillation at room temperature under water and
oil pump vacuum, respectively, to give a yellow oil. Chromato-
trans-1-Heptanoyl-5-oxo-4-oxaspiro[2.3]hexane 4f17
A solution of 1-diazooctan-2-one9 2f (2.3 g, 0.015 mol) in
2116
J. Chem. Soc., Perkin Trans. 1, 2000, 2109–2119