Vinylcyclopropylacyl and polyeneacyl radicals. Intramolecular ketene alkyl radical additions in ring synthesis

Article abstract of DOI:10.1039/b413816n

Treatment of a variety of substituted vinylcyclopropyl selenyl esters, e.g. 11, with Bu₃SnH-AIBN in refluxing benzene leads to the corresponding acyl radical intermediates, which undergo rearrangement and intramolecular cyclisations via their ketene alkyl radical equivalents producing cyclohexenones in 50-60% yield. By contrast, treatment of conjugated triene selenyl esters, e.g. 32, with Bu₃SnH-AIBN produces substituted 2-cyclopentenones via intramolecular cyclisations of their ketene alkyl radical intermediates. Under the same radical-initiating conditions the selenyl esters derived from o-vinylbenzoic acid and o-vinylcinnamic acid undergo intramolecular cyclisations producing 1-indanone and 5,6-dihydrobenzocyclohepten-7-one respectively in 60-70% yields. A tandem radical cyclisation from the α,β,γ, δ-diene selenyl ester 31 provides an expeditious synthesis of the diquinane 35 in 69% yield.

Full text of DOI:10.1039/b413816n

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A R T I C L E
Vinylcyclopropylacyl and polyeneacyl radicals. Intramolecular
ketene alkyl radical additions in ring synthesis
Benoˆıt De Boeck, Nicola M. A. Herbert, Nicole M. Harrington-Frost and Gerald Pattenden*
School of Chemistry, The University of Nottingham, Nottingham, NG7 2RD, UK
Received 7th September 2004, Accepted 27th October 2004
First published as an Advance Article on the web 16th December 2004
Treatment of a variety of substituted vinylcyclopropyl selenyl esters, e.g. 11, with Bu3SnH–AIBN in refluxing benzene
leads to the corresponding acyl radical intermediates, which undergo rearrangement and intramolecular cyclisations
via their ketene alkyl radical equivalents producing cyclohexenones in 50–60% yield. By contrast, treatment of
conjugated triene selenyl esters, e.g. 32, with Bu3SnH–AIBN produces substituted 2-cyclopentenones via
intramolecular cyclisations of their ketene alkyl radical intermediates. Under the same radical-initiating conditions
the selenyl esters derived from o-vinylbenzoic acid and o-vinylcinnamic acid undergo intramolecular cyclisations
producing 1-indanone and 5,6-dihydrobenzocyclohepten-7-one respectively in 60–70% yields. A tandem radical
cyclisation from the a,b,c,d-diene selenyl ester 31 provides an expeditious synthesis of the diquinane 35 in 69% yield.
Introduction
In the immediately preceding paper we demonstrated how a,b-
unsaturated acyl radical intermediates 1 are able to react via their
a-ketenyl alkyl radical equivalents, viz. 2, in tandem cyclisation
reactions involving proximate alkene bonds leading to a concise
synthesis of diquinanes 3.1 We also demonstrated some scope for
the corresponding cyclopropylacyl radicals 4 and their b-ketenyl
alkyl radical counterparts 5 in ring synthesis. In this paper we
describe our further studies of the scope for ketene alkyl radicals
in synthesis by examining the chemistry of a,b-unsaturated
acyl radicals containing additional cyclopropane and alkene
unsaturation at their b-centres, i.e. vinylcyclopropylacyl 6, 7 and
polyeneacyl 8 radicals, respectively.2
Scheme 1 Reagents: i, EtO2CCH2PO(OEt)2, NaH, THF, 80–90%;
ii, LiOH, THF–H2O, 90–99%; iii, NPSP, Bu3P, CH2Cl2, 70–90%
tributylphosphine. When solutions of the 3-methyl-substituted
vinylcyclopropyl selenyl esters 11a and 11b in benzene under
reflux were treated separately with Bu3SnH (dropwise over 2 h)
in the presence of AIBN, work up and chromatography gave the
2-cyclohexenones 14a and 14b, respectively, in 50–60% yield.
The cyclohexenones 14 are produced from the selenyl esters 11
as a result of intramolecular 6-exo/endo-dig cyclisations of the
ketene radical intermediates 13 produced from delocalisation
of the acyl radical precursors 12 through their conjugated
vinylcyclopropane systems, i.e. 11→12→13→14 (Scheme 2).
In a similar manner, the phenyl-substituted analogue 11c led
to the corresponding 6-phenyl-substituted cyclohexenone on
treatment with Bu3SnH–AIBN, but both the D2 and D3 isomers,
i.e. 15, 16, were isolated. Interestingly, no cyclohexenone was
produced when the vinylcyclopropane 17 lacking 3-methyl sub-
stitution was treated with Bu3Sn–AIBN but the corresponding
Results and discussion
Acyl radical intermediates can be derived from a range of
carboxylic acid derivatives.3 We have found that treatment of
phenyl selenyl esters with Bu3SnH–AIBN in benzene under
reflux is one of the most reliable and practical procedures.4 Thus,
we first synthesised a range of substituted vinylcyclopropane
carboxylic acid esters 10 from the corresponding cyclopropyl
methyl ketones (and aldehydes) using routine Wittig reactions
as the key step, as shown in Scheme 1. Saponification of
the esters 10 next led to the corresponding carboxylic acids,
which were then converted into their phenyl selenyl esters, e.g.
11, by reaction with N-(phenylseleno)phthalimide (NPSP) and
3 2 8
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 3 2 8 – 3 3 9
T h i s j o u r n a l i s
T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 5
©

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diester 29 in 63% yield. This outcome clearly established the
intermediacy of the delocalised ketene alkyl radical species 30,
analogous to 20, and the counterpart of the acyl radical 28,
which in this reaction undergoes dimerisation and addition of
methanol to the ketene unit, leading to the novel dimer 29.
We next synthesised the conjugated diene and triene phenyl
selenyl esters 31 and 32, respectively, and examined their
preferred modes of cyclisation under radical conditions. The
selenyl esters were synthesised in the usual manner from
the corresponding known carboxylic acids by treatment with
N-(phenylseleno)phthalimide and tributylphosphine.4 When a
solution of the selenyl ester 31 in benzene was heated under
reflux over 4.5 h in the presence of Bu3SnH and AIBN,
it underwent tandem radical cyclisation to produce a 1 : 1
mixture of diastereoisomers of the bicyclo[3.3.0]octenone 35
in 69% yield. The structures of the diastereoisomeric bicy-
clooctenones, which could be separated by chromatography,
followed from examination of their NMR data and comparison
with corresponding data for similar angular methyl-substituted
bicyclo[3.3.0]octenones in the literature.5,6 The bicyclooctenone
35 is produced from the selenyl ester 31 by way of: (i) 5-
exo-dig cyclisation of the delocalised ketenyl alkyl radical
equivalent, i.e. 33, of the corresponding a,b,c,d-unsaturated acyl
radical, leading to the dienolate radical 34, followed by (ii) an
intramolecular 5-exo-trig cyclisation of this delocalised radical
into the non-conjugated alkene bond (Scheme 5).
Scheme 2
phenylcyclopropane 18 gave the cyclohexenone 19 in 40%
yield. These features clearly demonstrate the importance of
substitution on the alkene and cyclopropane ring in determining
the efficiency of the aforementioned vinylcyclopropane acyl
radical-cyclohexenone interconversions.
By contrast, and to our surprise, when the related a,b,c,d-
unsaturated selenyl ester 38 prepared from E-8-methylnona-2,7-
dien-4-one 36, as shown in Scheme 6, was treated with Bu3SnH–
AIBN under similar conditions, the only product isolated was
the substituted cyclopentenone 40 resulting from cyclisation
of the ketene alkyl radical 39. Neither of the anticipated
bicyclooctenones 41 and 42, resulting from further cyclisation
of the intermediate, was isolated or detected in the crude
product mixture. Also surprising was the finding that when
the conjugated triene phenyl selenyl ester 32 was treated with
Bu3SnH–AIBN, the only product isolated was a mixture of E-
and Z-isomers of the 3-methyl-5-substituted cyclopent-2-enone
47 in 76% yield. We believe that the acyl radical 43 produced from
the selenyl ester 32 is fully delocalised through its triene system,
but similar to the polyene systems already described, cyclisation
at the d-position into the extended ketene 44 is favoured over
competing cyclisations leading to a 7-membered-ring system,
i.e. 45 via 46.
Finally, we also examined the propensity for acyl radicals
associated with aromatic rings to undergo intramolecular cy-
clisation. Thus, when a solution of the phenyl selenyl ester 48
derived from 2-vinylbenzoic acid in benzene was treated with
Bu3SnH–AIBN under reflux, it underwent facile cyclisation
producing indanone 51 in 56% yield. In a similar manner, under
the same conditions, the corresponding cinnamyl selenyl ester
52 was converted into the benzene ring fused cycloheptenone
54 in 70% yield. Indanone has been produced previously
by flash vacuum pyrolysis of o-vinylbenzaldehyde, where the
mechanism was thought to involve a 5-endo-trig cyclisation from
the intermediate acyl radical species 49.7 In keeping with our
contemporaneous studies with acyclic conjugated polyene and
cyclopropane acyl radical species, we favour mechanisms for the
conversions 48→51 and 52→54 which involve the delocalised
ketene alkyl radical species 50 and 53 respectively. It is a
debatable point however, since although there is clear chemical
and theoretical evidence which shows that a,b-unsaturated acyl
radicals exist as a-ketene alkyl radical species, they do not all
necessarily undergo cyclisations with proximate alkene bonds
via an exo-dig pathway to the exclusion of the alternative
endo-trig process. Nevertheless, whatever the precise reaction
pathway, a,b-unsaturated acyl radicals and their a-ketene alkyl
equivalents are clearly valuable and versatile intermediates in
organic synthesis, as evidenced in this study and previous work.
To reinforce this statement, in the following paper we describe
We anticipated that including additional alkene unsaturation
on the cyclopropane ring in the vinylcyclopropane selenyl esters
11 would provide us with an opportunity to examine the
scope for extended ketene alkyl radicals, viz. 20, in elaborating
cyclooctadienones, i.e. 21, as illustrated in Scheme 3. We
therefore synthesised the 1,2-divinylcyclopropyl selenoesters 24a
and 24b from the corresponding vinylcyclopropyl carbonyl
precursors, i.e. 22, using an identical sequence to that used
to prepare 11 from 9, as shown in Scheme 4. To our disap-
pointment however, neither of the selenyl esters 24 led to a
corresponding cyclooctenone product of type 21 on treatment
with Bu3SnH–AIBN. Instead, they produced the corresponding
cyclohexenones 25 and 26, respectively, by way of a sequence
analogous to that shown in Scheme 2.
Scheme 3
Interestingly, however, when the substituted 1,2-divinyl-
cyclopropane selenyl ester 27 lacking methyl group substitution
at C-3, was treated with Bu3SnH–AIBN in hot benzene in the
presence of methanol, it gave the symmetrical dimeric tetraene
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 3 2 8 – 3 3 9
3 2 9

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Scheme 4
Scheme 5
Scheme 6 Reagents: i, Me3SiCH2CO2Me, LDA, THF–H2O, 94%; iii, NPSP, Bu3P, CH3Cl2, 56%.
3 3 0
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 3 2 8 – 3 3 9

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how we have applied a,b-unsaturated acyl radical species in
the synthesis of the triquinane sesquiterpenes pentalenene and
modhephene.
diluted with water and washed with diethyl ether. The separated
aqueous layer was acidified with HCl (2 mol dm−3) and extracted
with diethyl ether. The combined organic extracts were dried
(MgSO4) and concentrated under reduced pressure to leave the
crude a,b-unsaturated acid as a viscous oil.
(iii) a,b-Unsaturated selenyl esters. Using a modification
of the literature procedure,4 tributylphosphine (1.5 eq.) was
added dropwise to a stirred solution of the a,b-unsaturated
acid (1 eq.) in dichloromethane (0.8 mol dm−3) at −30 ◦C. The
mixture was stirred at −30 ◦C for 5 min and then solid N-
phenylselenophthalimide (1.5 eq.) was added in one portion. The
mixture was stirred and allowed to warm to room temperature
over 10 min. The mixture was diluted with dichloromethane
and washed with saturated NaHCO3 solution and brine, dried
(MgSO4) and concentrated under reduced pressure to leave the
crude selenyl ester as a yellow oil.
Phenyl 3-cyclopropylbut-2-enyl selenoate 11a
Following the general procedure, a solution of a 1 : 4 mixture
of Z- and E-isomers of ethyl 3-cyclopropylbut-2-enoate9 (1.5 g,
9.7 mmol) in ethanol (23 ml) and water (1.8 ml) was treated with
sodium hydroxide (1.5 g) to give the corresponding acid (1.0 g,
94%), as a colourless solid. Recrystallisation from petrol–diethyl
ether gave E-3-cyclopropylbut-2-enoic acid as needles, m.p. 59–
63 ◦C; (found: C, 66.7; H, 8.1; C7H10O2 requires C, 66.6; H,
8.0%); mmax(soln. CHCl3)/cm−1 3169 (br), 2925 (br), 1682, 1622;
1
major (E) isomer: H NMR (250 MHz, CDCl3) d 5.73 (1H,
=
br. s, CH C), 1.99 (3H, s, CH3), 1.56 (1H, m, cyclopropyl CH),
0.93–0.67 (4H, m, 2 × cyclopropyl CH2); 13C NMR (67.8 MHz,
CDCl3) d 172.4 (s), 164.9 (s), 112.8 (d), 20.4 (d), 15.2 (q), 7.2
(2 × t); minor (Z) isomer: 1H NMR (250 MHz, CDCl3) d 5.76
Experimental
For general experimental details see the preceding paper.1
(1H, br. s, CH C); 13C NMR (67.8 MHz, CDCl3) d 172.8 (s),
=
164.2 (s), 115.7 (d), 18.6 (d), 14.2 (q), 5.9 (2 × t); m/z (EI) found
126.0684 (M+), C7H10O2 requires 126.0681.
General procedures
Following the general procedure, a solution of 3-cyclo-
propylbut-2-enoic acid (100 mg, 0.8 mmol) in dichloromethane
was treated with tributylphosphine (220 ll, 0.9 mmol) and N-
phenylselenophthalimide (480 mg, 1.6 mmol). Chromatography
on silica using petroleum ether–diethyl ether (10 : 1) as eluent
gave a 1 : 4 mixture of Z- and E-siomers of the selenyl ester
(140 mg, 67%) as a colourless oil; kmax(EtOH)/nm 225 (10 610),
257 (14 440), 301 (6420); mmax(film)/cm−1 1693, 1592, 1476; major
(i) Wadsworth–Emmons olefination reactions. Using
a
modification of the procedure described by Petter and co-
workers,8 a solution of triethyl phosphonoacetate (2.5 eq.) in
THF (2.5 mol dm−3) was added dropwise over 30 min to a stirred
suspension of sodium hydride (2.4 eq.) in THF (5 mol dm−3) at
room temperature. The mixture was stirred at room temperature
for 1 h and then a solution of the ketone/aldehyde (1 eq.) in
THF (2.5 mol dm−3) was added in one portion. The mixture was
heated under reflux for 30 min, then stirred at room temperature
overnight before saturated aqueous NH4Cl solution was added.
The mixture was evaporated in vacuo and the residue was then
partitioned between water and diethyl ether. The separated
aqueous layer was extracted with diethyl ether and the combined
organic extracts were then washed with brine, dried (MgSO4)
and concentrated under reduced pressure.
1
(E) isomer: H NMR (400 MHz, CDCl3) d 7.56–7.37 (5H, m,
=
ArH), 6.17 (1H, br. s, CH C), 1.89 (3H, s, CH3), 1.55 (1H, m,
cyclopropyl CH), 0.95–0.76 (4H, m, 2 × cyclopropyl CH2); 13
C
NMR (67.8 MHz, CDCl3) d 188.5 (s), 160.2 (s), 135.8 (2 × d),
129.2 (2 × d), 128.2 (d), 127.4 (s), 122.3 (d), 20.3 (d), 16.0 (q),
1
7.6 (2 × t); minor (Z) isomer: H NMR (400 MHz, CDCl3) d
6.20 (1H, br. s, CH C); 13C NMR (67.8 MHz, CDCl3) d 189.2
=
(s), 159.7 (s), 135.8 (2 × d), 129.2 (2 × d), 128.2 (d), 127.4 (s),
125.1 (d), 18.3 (q), 15.7 (d), 7.8 (2 × t).
(ii) Saponifications of esters. (a) Lithium hydroxide (3 eq.)
was added in one portion to a stirred solution of the saturated
ester (1 eq.) in THF and water (1 : 1, 0.1 mol dm−3) at
room temperature and the mixture was then stirred at room
temperature for 24 h. The mixture was evaporated in vacuo
and the residue was then partitioned between water and diethyl
ether. The separated aqueous layer was washed with diethyl
ether, then acidified with HCl (2 mol dm−3) and extracted
with diethyl ether. The combined organic extracts were dried
(MgSO4) and concentrated under reduced pressure to leave the
crude carboxylic acid as a viscous oil.
(b) Sodium hydroxide was added in one portion to a stirred
solution of the a,b-unsaturated ethyl ester (1 : 1 w/w) in ethanol
and water (12 : 1, 0.4 mol dm−3), and the mixture was heated
under reflux for 1 h and then cooled to room temperature.
The mixture was evaporated in vacuo and the residue was then
Phenyl 3-(2,2-dimethylcyclopropyl)but-2E-enyl selenoate 11b
Following the general procedure, 2-(2,2-dimethylcyclopropyl)-
ethan-2-one10 (560 mg, 5.0 mmol) was treated with sodium
hydride (60% dispersion in oil, 360 mg, 15 mmol) and triethyl
phosphonoacetate (3.4 g, 15 mmol) in THF (7 ml). The
crude product was purified by chromatography on silica using
petroleum ether–diethyl ether (9 : 1) as eluent to give ethyl 3-
(2,2-dimethylcyclopropyl)but-2(E)-enoate (770 mg, 84%) as a
1
colourless liquid; mmax(film)/cm−1 1716, 1645, 1448; H NMR
=
(250 MHz CDCl3) d 5.50 (1H, br. s, CH C(CH3)), 4.15 (2H, q,
J 7.1 Hz, OCH2CH3), 2.23 (3H, br. s, CH C(CH3)), 1.34–1.22
=
(4H, m, OCH2CH3 + cyclopropyl CH), 1.19 (3H, s, CH3), 0.94
(3H, s, CH3), 0.69–0.6 (2H, m, cyclopropyl CH2); 13C NMR
(67.8 MHz, CDCl3) d 166.9 (s), 159.0 (s), 114.9 (d), 59.4 (t), 34.8
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 3 2 8 – 3 3 9
3 3 1

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(q), 21.0 (q), 20.2 (s), 19.1 (q), 18.5 (t), 14.4 (q); m/z (EI) found
136.0892 (M+ − HOEt), C9H12O requires 136.0888.
(67.8 MHz, CDCl3) d 172.0 (s), 162.7 (s), 141.2 (s), 128.5 (2 ×
d), 126.2 (d), 126.0 (2 × d), 113.3 (d), 32.7 (d), 25.8 (d), 16.3
(q), 16.1 (t); m/z (EI) found 202.0999 (M+), C13H14O2 requires
202.0994.
Following the general procedure, a solution of ethyl 3-
(2,2-dimethylcyclopropyl)but-2(E)-enoate (0.7 g, 3.8 mmol) in
ethanol (9.2 ml) and water (0.7 ml) was treated with sodium
hydroxide (0.7 g) to give the crude acid as a solid. Recrystalli-
sation from petroleum ether–diethyl ether gave the E-carboxylic
acid (320 mg, 53%) as colourless crystals, m.p. 97–103 ◦C;
(found: C, 70.4; H, 9.4; C9H14O2 requires C, 70.1; H, 9.2%);
kmax(EtOH)/nm 234 (9260); mmax(film)/cm−1 3524 (br), 2991 (br),
Following the general procedure, a solution of trans-3-(2-
phenylcyclopropyl)-but-2-enoic acid (100 mg, 0.5 mmol) in
dichloromethane (11 ml) was treated with N-phenylseleno-
phthalimide (300 mg, 1.0 mmol) and tributylphosphine (250 ll,
1.0 mmol). The crude product was purified by chromatography
on silica using petroleum ether–diethyl ether (10 : 1) as eluent
to give a 1 : 4 mixture of Z- and E-isomers of the selenyl ester
(160 mg, 94%), as a pale yellow oil; kmax(EtOH)/nm 222 (13 580),
267 (11 060); mmax(film)/cm−1 1693, 1682, 1592; major (E) isomer:
1H NMR (400 MHz, CDCl3) d 7.61–7.10 (10H, m, ArH), 6.17
1
1693, 1650; H NMR (270 MHz, CDCl3) d 5.17 (1H, br. s,
=
=
CH C(CH3)), 1.89 (3H, s, CH C(CH3)), 1.02, (1H, t, J 7.3 Hz,
cyclopropyl CH), 0.85 (3H, s, CH3), 0.59 (3H, s, CH3), 0.40–
0.27 (2H, m, cyclopropyl CH2); 13C NMR (67.8 MHz, CDCl3) d
172.7 (s), 162.4 (s), 114.3 (d), 35.2 (d), 27.5 (q), 21.4 (q), 20.8 (s),
19.1 (q), 18.8 (t); m/z found 154.0095 (M+), C9H14O2 requires
154.0094.
=
(1H, br. s, CH C), 2.25 (1H, m, cyclopropyl CH), 2.02 (3H, s,
CH3), 1.77 (1H, m, cyclopropyl CH), 1.34 (2H, m, cyclopropyl
CH2); 13C NMR (67.8 MHz, CDCl3) d 189.1 (s), 158.2 (s), 141.3
(s), 136.2 (d), 129.6 (2 × d), 129.0 (d), 128.9 (2 × d), 127.6
(s), 126.7 (d), 126.5 (d), 126.3 (d), 123.2 (d), 33.0 (d), 26.4 (d),
19.5 (q), 16.7 (t); minor (Z) isomer (where observed): 1H NMR
Following the general procedure, a solution of the E-
carboxylic acid (100 mg, 0.7 mmol) in dichloromethane
(6 ml) was treated with N-phenylselenophthalimide (390 mg,
1.3 mmol) and tributylphosphine (160 ll, 1.3 mmol). The
crude product was purified by chromatography on silica using
petroleum ether–diethyl ether (10 : 1) as eluent to give the selenyl
ester (150 mg, 79%) as a pale yellow oil; (found: C, 61.5; H, 6.4;
C15H18OSe requires C, 61.4; 6.2%); kmax(EtOH)/nm 224 (9350),
=
(400 MHz, CDCl3) d 6.20 (1H, br. s CH C), 2.30 (1H, m,
cyclopropyl CH); 13C NMR (67.8 MHz, CDCl3) d 27.7 (d),
26.0 (d), 17.6 (t), 17.3 (q); m/z (FAB) found 343.0633 (M+
+
H), C19H19O80Se requires 343.0601; found 341.0625, C19H19O78Se
requires 341.0609.
1
259 (12600), 302 (6200); mmax(film)/cm−1 1776, 1694, 1607; H
NMR (250 MHz, CDCl3) d 7.56–7.38 (5H, m, ArH), 5.92 (1H,
3-Methylcyclohex-2-en-1-one 14a
=
=
br. s, CH C(CH3)), 2.15 (3H, s, CH C(CH3)), 1.33 (1H, t, J
7.0 Hz, cyclopropyl CH), 1.21 (3H, s, CH3), 0.97 (3H, s, CH3),
0.71 (2H, m, cyclopropyl CH2); 13C NMR (67.8 MHz, CDCl3) d
189.2 (s), 157.6 (s), 135.8 (2 × d), 129.2 (d), 128.6 (2 × d), 127.3
(s), 123.4 (d), 34.8 (d), 27.5 (q), 22.5 (q), 21.6 (s), 19.3 (q), 19.2
(t); m/z (FAB) found 295.0590 (M+ + H), C15H19O80Se requires
295.0601.
A solution of tributyltin hydride (140 ll, 0.38 mmol) and
catalytic AIBN (3 mg) in dry degassed benzene (2.0 ml) was
added dropwise over 2 h, via syringe pump, to a solution of the
selenyl ester 11a (50 mg, 0.19 mmol) and AIBN (2 mg) in benzene
(63 ml) under reflux in an atmosphere of argon. The mixture
was stirred under reflux for a further 2 h, then cooled to room
temperature and the solvent was evaporated in vacuo to leave
a yellow oil. The oil was purified by chromatography on silica
using petroleum ether–diethyl ether (9 : 1) as eluent to give the
cyclohex-2-enone11 (10 mg, 48%) as an oil; mmax(film)/cm−1 2928,
Phenyl trans-3-(2-phenylcyclopropyl)but-2-enyl selenoate 11c
Following the general procedure, a solution of trans-1-(2-
phenylcyclopropyl)ethan-1-one in THF (1.5 ml) was treated with
sodium hydride (60% dispersion in oil, 520 mg, 13 mmol) and
triethyl phosphonoacetate (2.2 ml, 11 mmol) in THF (4.5 ml).
The crude product was purified by chromatography on silica
using petroleum ether–diethyl ether (5 : 1) as eluent to give a
1 : 9 mixture of Z- and E-isomers of the corresponding a,b-
unsaturated ester (770 mg, 77%), as a colourless oil; (found: C,
78.2; H, 8.1; C15H18O2 requires C, 78.2; H, 7.9%); mmax(film)/cm−1
1
2854, 1659, 1456; H NMR (400 MHz, CDCl3) d 5.85 (1H, s,
=
CH ), 2.32 (2H, t, J 6.4 Hz, CH2C(O)), 2.26 (2H, t, J 6.4 Hz,
CH2CH2C ), 1.97 (2H, app. qn, J 6.4 Hz, CH2CH2CH2); 13C
=
NMR (67.8 MHz, CDCl3) d 218.1 (s), 162.3 (s), 126.7 (d), 37.0
(t), 30.9 (t), 24.5 (q), 22.5 (t); m/z (EI) found 110.0732 (M+),
C7H10O requires 110.0732.
3,6,6-Trimethylcyclohex-2-enone 14b
1
1710, 1604; major (E) isomer: H NMR (270 MHz, CDCl3)
=
d 7.43–7.20 (5H, m, ArH), 5.83 (1H, br. s, CH C), 4.26
A solution of tributyltin hydride (120 ll, 0.34 mmol) and AIBN
(3 mg) in dry degassed benzene (1 ml) was added dropwise over
1 h, via syringe pump, to a solution of the selenyl ester 11b (50 mg,
0.17 mmol) and AIBN (2 mg) in dry degassed benzene (57 ml)
under reflux in an atmosphere of argon. The mixture was stirred
under reflux overnight, then cooled to room temperature and
the solvent was evaporated in vacuo. The residue was purified by
chromatography on silica using petroleum ether–diethyl ether
(9 : 1) as eluent to give the cyclohexenone12 (14 mg, 60%), as a
colourless oil; mmax(film)/cm−1 1714, 1657; 1H NMR (250 MHz,
(2H, q, J 6.9 Hz, OCH2CH3), 2.29 (1H, m, cyclopropyl CH),
2.20 (3H, s, CH3), 1.85 (1H, m, cyclopropyl CH), 1.50 (1H,
m, cyclopropyl CHH), 1.41 (1H, m, cyclopropyl CHH), 1.40
(3H, t, J 6.9 Hz, OCH2CH3); 13C NMR (67.8 MHz, CDCl3)
d 166.7 (s), 159.3 (s), 141.5 (s), 128.4 (2 × d), 126.0 (d),
125.9 (2 × d), 113.8 (d), 59.4 (t), 32.4 (d), 25.5 (d), 16.1 (q),
15.8 (t), 14.3 (q); minor (Z) isomer: dH (270 MHz, CDCl3)
5.89 (1H, br. s, CH C); 13C NMR (67.8 MHz, CDCl3) d
=
116.7 (d); m/z (EI) found 230.1324 (M+), C15H18O2 requires
230.1307.
=
CDCl3) d 5.78 (1H, br. s, CH C(CH3)), 2.30 (2H, br. t, J 6.1 Hz,
=
Following the general procedure, a solution of ethyl trans-3-
(2-phenylcyclopropyl)but-2 enoate (700 mg, 3 mmol) in ethanol
(7.4 ml) and water (0.5 ml) was treated with sodium hydroxide
(700 mg) to give the crude carboxylic acid as a viscous yellow oil
which solidified on standing. Recrystallisation from petroleum
ether–diethyl ether gave the E-carboxylic acid (620 mg, ∼100%)
as colourless plates, m.p. 89–91 ◦C; (found: C, 77.3; H, 7.1;
C13H14O2 requires C, 77.2; H, 7.0%); kmax(EtOH)/nm 245
(11 970); mmax(film)/cm−1 3204, 1692, 1629; 1H NMR (400 MHz,
CH2CH2C(CH3) ), 1.93 (3H, s, CH3), 1.81 (2H, t, J 6.1 Hz,
13
=
CH2CH2C(CH3) ), 1.10 (6H, s, 2 × CH3); C NMR (67.8 MHz,
CDCl3) d 203.8 (s), 160.2 (s), 125.1 (d), 40.1 (s), 36.3 (t), 29.7 (t),
24.2 (2 × q), 24.0 (q); m/z (EI) found 138.1036 (M+), C9H14O
requires 138.1045.
6-Phenyl-3-methylcyclohex-2-en-1-one 15 and 6-phenyl-3-
methylcyclohex-3-en-1-one 16
=
CDCl3) d 7.32–7.10 (5H, m, ArH), 5.75 (1H, br. s, CH C),
2.22 (1H, m, cyclopropyl CH), 2.14 (3H, s, CH3), 1.44 (1H,
A solution of tributyltin hydride (110 ll, 0.3 mmol) and AIBN
(2 mg) in dry degassed benzene (1 ml) was added over 2 h via
syringe pump to a stirred solution of the selenyl ester 11c (50 mg,
m, cyclopropyl CH), 1.34 (1H, m, cyclopropyl CH); 13C NMR
3 3 2
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 3 2 8 – 3 3 9

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0.15 mmol) and AIBN (2 mg) under reflux in an atmosphere of
argon. The mixture was allowed to stir at reflux for 4 h then
cooled to room temperature and the solvent was evaporated in
vacuo. The residue was purified by chromatography on silica
using petroleum ether–diethyl ether (10 : 1 then 5 : 1) as eluent
to give: (i), 6-phenyl-3-methylcyclohex-3-en-1-one (4 mg, 15%)
(eluted first) as a pale yellow oil; mmax(film)/cm−1 1716, 1674;
1H NMR (250 MHz, CDCl3) d 7.39–7.16 (5H, m, ArH), 5.69
NMR (67.8 MHz, CDCl3) d 166.9 (s), 151.9 (d), 141.1 (s), 128.8
(2 × d), 126.5 (d), 126.2 (2 × d), 119.2 (d), 60.4 (t), 27.17 (2 ×
d), 18.1 (t), 14.6 (q); m/z (EI) found 216.1153 (M+), C14H16O2
requires 216.1150.
Following the general procedure,
a solution of the
(phenylcyclopropyl)prop-2(E)-enoate (500 mg, 2.3 mmol) in
ethanol (5 ml) and water (0.5 ml), was treated with sodium
hydroxide (500 mg) to give the corresponding carboxylic acid
(410 mg, 95%) as a viscous oil; (found: C, 76.7; H, 6.4; C12H12O2
requires C, 76.6; H, 6.4%); kmax(EtOH)/nm 244 (7150); mmax(soln.
=
(1H, br. s, CH C), 3.78 (1H, t, J 8.3 Hz, PhCHC(O)), 2.91
(2H, app. d, J 8.3 Hz, CH2CHPh), 2.76 (2H, m, CH2C(O)),
1.79 (3H, s, CH3); 13C NMR (67.8 MHz, CDCl3) d 209.3 (s),
138.7 (s), 128.5 (d), 128.3 (2 × d), 127.1 (2 × d), 120.6 (d), 53.9
(d), 44.5 (t), 32.8 (t), 22.6 (q); (ii), a 1 : 4 mixture of the Z-
and E-isomers of 6-phenyl-3-methylhex-3-en-1-al (3 mg, 11%),
(eluted second) as a viscous yellow oil; mmax(film)/cm−1 1722,
1673, 1602; major isomer: 1H NMR (250 MHz, CDCl3) d 9.60
(1H, t, J 2.5 Hz, CHO), 7.35–7.16 (5H, m, ArH), 5.38 (1H,
1
CHCl3)/cm−1 3178 (br), 2826 (br), 2677 (br), 1694, 1644; H
NMR (400 MHz, CDCl3) d 7.32–7.09 (5H, m, ArH), 6.72 (1H,
=
dd, J 15.0 and 9.0 Hz, CH CHCO2H), 5.81 (1H, d, J 15 Hz,
CH CHCO2H), 2.24 (1H, m, cyclopropyl CH), 1.85 (1H, m,
=
cyclopropyl CH), 1.51 (1H, m, cyclopropyl CHH), 1.32 (1H, m,
cyclopropyl CHH); 13C NMR (67.8 MHz, CDCl3) d 172.0 (s),
154.7 (d), 140.4 (s), 128.5 (2 × d), 126.3 (d), 125.8 (2 × d), 118.0
(d), 27.2 (d), 26.9 (d), 18.0 (t); m/z (EI) found 188.0838 (M+),
C12H12O2 requires 188.0837.
=
br. t, J 5.0 Hz, CH2CH C), 3.06 (2H, br. s, CH2CHO), 2.57
(2H, m, CH2CH C), 2.41 (2H, m, CH2Ph), 1.58 (3H, s, CH3);
=
13C NMR (67.8 MHz, CDCl3) d 201.8 (s), 130.8 (s), 130.3 (d),
129.7 (s), 128.9 (2 × d), 128.8 (d), 126.4 (2 × d), 54.7 (t), 36.1
(2 × t), 30.5 (q); minor isomer (when not obscured by major
Following the general procedure, a solution of the trans-
phenylcyclopropylprop-2(E)-enoic acid (200 mg, 1.1 mmol) in
dichloromethane (15 ml) was treated with tributylphosphine
(400 ll, 1.6 mmol) and N-phenylselenophthalimide (480 mg,
1.6 mmol). The crude product was purified by chromatog-
raphy on silica using petroleum ether–diethyl ether (9 : 1)
as eluent to give the selenyl ester (140 mg, 40%) as a pale
1
isomer): H NMR (250 MHz, CDCl3) d 9.35 (1H, t, J 2.5 Hz,
=
CHO), 5.53 (1H, br. t, J 5.0 Hz, CH2CH C), 1.61 (3H, s, CH3);
13C NMR (67.8 MHz, CDCl3) d 202.5 (s), 53.7 (t), 36.2 (2 ×
t), 30.9 (q); (iii), 6-phenyl-3-methylcyclohex-2-en-1-one (14 mg,
51%) (eluted last) as a colourless oil; mmax(film)/cm−1 1661 (lit.12
1
yellow oil; mmax(film)/cm−1 1692, 1613, 1580, 1496; H NMR
1
mmax(CCl4)/cm−1 1675); H NMR (250 MHz, CDCl3) d 7.29–
(270 MHz, CDCl3) d 7.73–7.11 (10H, m, ArH), 6.61 (1H, dd,
=
=
7.07 (5H, m, ArH), 5.96 (1H, br. s, CH C), 3.45 (1H, app.
J 9.1 and 14.3 Hz, CHCH CH), 6.30 (1H, d, J 14.3 Hz,
CH CHCOSePh), 2.27 (1H, m, cyclopropyl CH), 1.92 (1H,
=
t, J 8.6 Hz, PhCHC(O)), 2.41–2.15 (4H, m, 2 × CH2), 1.93
(3H, s, CH3); 13C NMR (67.8 MHz, CDCl3) d 199.5 (s), 162.6 (s),
141.2 (s), 128.9 (d), 128.7 (d), 127.5 (d), 127.3 (d), 52.7 (d), 31.1
(t), 24.8 (q); m/z (EI) found 186.1035 (M+), C13H14O requires
186.1045.
m, cyclopropyl CH), 1.54 (1H, m, cyclopropyl CHH), 1.39 (1H,
m, cyclopropyl CHH); 13C NMR (67.8 MHz, CDCl3) d 189.3 (s),
149.1 (d), 140.2 (s), 135.9 (2 × d), 129.2 (2 × d), 129.1 (s), 128.9
(2 × d), 127.4 (d), 126.3 (d), 125.7 (2 × d), 27.5 (d), 27.2 (d),
18.2 (t); m/z (FAB) found 329.0435 (M+ + H), C18H16O80Se
requires 329.0445; found 327.0448, C18H16O78Se requires
327.0452.
Phenyl 3-cyclopropylprop-2E-enyl selenoate 17
Following the general procedure, a solution of 3-cyclopro-
pylprop-2(E)-enoic acid13 (80 mg, 0.7 mmol) in dichloromethane
(15 ml) was treated with N-phenylselenophthalimide (430 mg,
1.4 mmol) and tributylphosphine (360 ll, 1.4 mmol). The
crude product was purified by chromatography on silica using
petroleum ether–diethyl ether (10 : 1) as eluent to give the selenyl
ester (75 mg, 42%) as a pale yellow oil; mmax(film)/cm−1 1693,
1614; 1H NMR (270 MHz, CDCl3) d 7.67–7.32 (5H, m, ArH),
6-Phenylcyclohex-3-en-1-one 19
A solution of tributyltin hydride (72 ll, 0.2 mmol) and AIBN
(2 mg) in dry degassed benzene (2 ml) was added over 8 h
via syringe pump to a stirred solution of the selenyl ester 18
(60 mg, 0.18 mmol) and AIBN (2 mg) in benzene (60 ml)
under reflux in an atmosphere of argon. The mixture was stirred
under reflux for 4 h, then cooled to room temperature and the
solvent was evaporated in vacuo. The residue was purified by
chromatography on silica using petroleum ether–diethyl ether
(10 : 1 then 5 : 1) as eluent to give: (i), 6-phenylhex-2-en-1-al
(14 mg, 45%) (eluted first) as a pale yellow oil; mmax(film)/cm−1
=
6.47–6.27 (2H, m, CH CH), 1.61 (1H, m, cyclopropyl CH),
1.09 (2H, m, cyclopropyl CH2), 0.78 (2H, m, cyclopropyl CH2);
13C NMR (67.8 MHz, CDCl3) d 191.4 (s), 152.8 (d), 136.8 (2 ×
d), 130.1 (2 × d), 129.7 (d), 128.0 (d), 127.2 (s), 15.8 (d), 10.2
(2 × t); m/z (FAB) found 253.0110 (M+ + H), C12H13O80Se
requires 253.0132; found 251.0113, C12H13O78Se requires
251.0139.
1
1692; H NMR (400 MHz, CDCl3) d 9.51 (1H, d, J 7.9 Hz,
CHO), 7.32–7.18 (5H, m, ArH), 6.85 (1H, dt, J 6.8, 15.6 Hz,
=
=
CH CHCHO), 6.14 (1H, dd, J 7.9, 15.6 Hz, CH CHCHO),
2.69 (2H, t, J 7.3 Hz, PhCH2CH2), 2.37 (2H, app. q, J 7.3 Hz,
Phenyl trans-3-(2-phenylcyclopropyl)-prop-2E-enyl selenoate 18
=
CH2CH2CH ), 1.87 (2H, app. qn, J 7.3 Hz, CH2CH2CH2);
Following the general procedure, a solution of trans-2-phenyl-
cyclopropyl carboxaldehyde14 (1.0 g, 6.8 mmol) in THF (3.6 ml)
was treated with sodium hydride (60% dispersion in oil, 550 mg,
14 mmol) and triethyl phosphonoacetate (2.9 ml, 15 mmol) in
THF (7.2 ml). The crude product was purified by chromato-
graphy on silica using petroleum ether–diethyl ether (5 : 1) as
eluent to give the E-isomer of the (phenylcyclopropyl)prop-2-
enoate (1.2 g, 84%), as a colourless oil; (found: C, 77.8; H,
7.6; C14H16O2 requires C, 77.7; H, 7.5%); kmax(EtOH)/nm 247
(11 400); mmax(film)/cm−1 1713, 1644, 1604; 1H NMR (270 MHz,
CDCl3) d 7.54–7.16 (5H, m, ArH), 6.66 (1H, dd, J 9.6, 15.2 Hz,
13C NMR (67.8 MHz, CDCl3) d 198.6 (d), 162.7 (d), 137.7 (d),
132.9 (2 × d), 132.8 (2 × d), 131.2 (s), 130.5 (d), 39.7 (t), 36.6
(t), 33.9 (t); (ii), 6-phenylcyclohex-3-en-1-one (6 mg, 20%) (eluted
second) as a colourless oil; mmax(film)/cm−1 1716, 1680; 1H NMR
(250 MHz, CDCl3) d 7.49–7.17 (5H, m, ArH), 6.04–5.95 (1H,
=
=
m, C(O)CH2CH CH), 5.84–5.77 (1H, m, CH CHCH2CH),
3.85 (1H, t, J 7.8 Hz, PhCHC(O)), 2.99 (2H, br. AB, app. q, J
=
21.7 Hz, CH2C(O)), 2.84–2.79 (2H, m, CHCH2CH ); m/z (EI)
found 172.0894 (M+), C12H12O requires 172.0888.
Ethyl trans-3-[2,2-dimethyl-3-(2-methylprop-1-enyl)-
cyclopropyl]but-2E-enoate 23a
=
=
CH CHCO2Et), 5.96 (1H, d, J 15.2 Hz, CH CHCO2Et), 4.26
(2H, q, J 6.9 Hz, OCH2CH3), 2.21 (1H, m, cyclopropyl CH),
1.86 (1H, m, cyclopropyl CH), 1.50 (1H, m, cyclopropyl CH),
1.35 (4H, t, J 6.9 Hz, OCH2CH3 + obs. cyclopropyl CH); 13C
Following the modified general procedure, a solution of the
cyclopropyl ketone15 (1.5 g, 9.0 mmol) in THF (3.2 ml), was
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 3 2 8 – 3 3 9
3 3 3

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treated with sodium hydride (60% dispersion in oil, 1.1 g,
27 mmol) and triethyl phosphonoacetate (4.5 ml, 25.0 mmol)
in THF (9.5 ml) and the mixture was heated at reflux overnight.
The crude product was purified by chromatography on silica
using petroleum ether–diethyl ether (20 : 1) as eluent to give
the E-a,b-unsaturated ester (1.0 g, 47%) as a colourless oil;
(found: C. 76.1; H, 10.3; C15H24O2 requires C, 76.2; H, 10.3%);
mmax(film)/cm−1 1714, 1643; 1H NMR (250 MHz, CDCl3) d 5.60
mixture was concentrated in vacuo and the residue was then
partitioned between water (25 ml) and diethyl ether (25 ml). The
separated aqueous layer was extracted with diethyl ether (3 ×
25 ml) and the combined organic extracts were washed with
brine (25 ml), dried (MgSO4) and concentrated under reduced
pressure. The residue was purified by chromatography on silica
using petroleum ether–diethyl ether (9 : 1) as eluent to give the
E-a,b-unsaturated ester 23b (500 mg, 67%) as a colourless oil;
mmax(film)/cm−1 1718, 1645; 1H NMR (250 MHz, CDCl3) d 5.67–
=
=
(1H, br. s, CHCO2Et), 4.90 (1H, d, J 7.6 Hz, CHCH), 4.15
(2H, q, J 7.2 Hz, OCH2CH3), 2.21 (3H, s, CH3C ), 1.72 (6H, s,
=
= =
5.53 (2H, m, CH3C CH + CH CH2), 5.13 (1H, d, J 18.8 Hz,
=
=
=
2 × CH3C ), 1.61 (1H, m, cyclopropyl CH), 1.29 (4H, m,
CH CHH), 5.00 (1H, d, J 10.3 Hz, CH CHH), 4.15 (2H, q,
=
OCH2CH3 + cyclopropyl CH), 1.15 (3H, s, CH3), 0.99 (3H, s,
CH3); 13C NMR (67.8 MHz, CDCl3) d 166.8 (s), 158.5 (s), 133.9
(s), 122.4 (d), 114.8 (d), 59.3 (t), 42.8 (d), 28.4 (d), 26.1 (s), 25.4
(q), 22.7 (q), 20.7 (2 × q), 18.4 (q), 14.2 (q); m/z (EI) found
235.1684 (M+ − H), C15H23O2 requires 235.1698.
J 7.0 Hz, OCH2CH3), 2.22 (3H, s, CH C(CH3)), 1.63 (1H,
=
app. t, J 6.2 Hz, cyclopropyl CHCH ), 1.43 (1H, d, J 6.2 Hz,
cyclopropyl CH), 1.29 (3H, t, J 7.0 Hz, OCH2CH3), 1.18 (3H, s,
CH3), 0.99 (3H, s, CH3); 13C NMR (67.8 MHz, CDCl3) d 167.2
(s), 157.9 (s), 136.9 (d), 115.4 (d), 114.9 (t), 55.5 (t), 41.5 (d), 33.2
(d), 26.4 (s), 22.2 (q), 20.7 (q), 14.3 (q); m/z (EI) found 208.1473
(M+), C13H20O2 requires 208.1463.
Phenyl trans-3-[2,2-dimethyl-3-(2-methylprop-1-enyl)-
cyclopropyl]but-2E-enyl selenoate 24a
Following the general procedure, a solution of the a,b-
unsaturated ester 23b (900 mg, 4.3 mmol) in ethanol (10 ml)
and water (1 ml) was treated with sodium hydroxide (900 mg) to
give a 1 : 4 mixture of Z- and E-isomers of the corresponding car-
boxylic acid (600 mg, 77%) as a pale yellow oil; mmax(film)/cm−1
3174 (br), 2640, 1694, 1642; 1H NMR (250 MHz, CDCl3) d 5.88–
Following the general procedure, a solution of the ester 23a
(170 mg, 0.7 mmol) in refluxing EtOH (5.0 ml) and water
(0.5 ml) was treated with sodium hydroxide (170 mg) to give the
corresponding carboxylic acid (130 mg, 89%) as a pale yellow
oil; mmax(film)/cm−1 3439, 2919, 1713, 1682, 1632; 1H NMR
=
=
5.53 (2H, m, CH3C CH + CH CH2), 5.15 (1H, d, J 17.1 Hz,
=
=
=
(250 MHz, CDCl3) d 5.61 (1H, br. s, CHCO2H), 4.89 (1H,
CH CHH), 5.05 (1H, d, J 10.1 Hz, CH CHH), 2.23 (3H, s,
=
=
=
app. d, J 7.6 Hz, CH C), 2.21 (3H, s, CH3C(O)), 1.73 (6H, s,
CH C(CH3)), 1.68 (1H, app. t, J 6.0 Hz, cyclopropyl CHCH ),
1.46 (1H, d, J 6.0 Hz, cyclopropyl CH), 1.19 (3H, s, CH3), 0.99
(3H, s, CH3); 13C NMR (67.8 MHz, CDCl3) major isomer: d
172.4 (s), 161.1 (s), 136.6 (d), 115.2 (t), 114.8 (d), 41.8 (d), 33.5
(d), 26.9 (s), 22.2 (q), 21.1 (q), 20.5 (q); minor isomer: d 177.2 (s),
161.1 (s), 137.5 (d), 114.7 (d), 114.5 (t), 37.4 (d), 33.0 (d), 25.4
(s), 21.9 (q), 21.1 (q), 20.5 (q); m/z (EI) found 180.1150 (M+),
C11H16O2 requires 180.1150.
=
2 × CH3C ), 1.69 (1H, m, cyclopropyl CH), 1.33 (1H, d, J
7.0 Hz, cyclopropyl CH), 1.17 (3H, s, CH3), 0.99 (3H, s, CH3);
13C NMR (67.8 MHz, CDCl3) d 172.5 (s), 162.4 (s), 134.2 (s),
122.2 (d), 114.0 (d), 43.1 (d), 28.7 (d), 26.8 (s), 25.4 (q), 22.5 (q),
20.7 (2 × q), 18.3 (q); m/z (EI) found 195.1225 (M+ − CH3),
C12H17O2 requires 193.1229.
Following the general procedure, a solution of the carboxylic
acid (77 mg, 0.37 mmol) in dichloromethane (8 ml) was
treated with tributylphosphine (100 ll, 0.41 mmol) and N-
phenylselenophthalimide (220 mg, 0.74 mmol). The crude prod-
uct was purified by chromatography on silica using petroleum
ether–diethyl ether (9 : 1) as eluent to give the selenyl ester (92 mg,
72%) as a pale yellow oil; mmax(film)/cm−1 1697, 1605, 1580; 1H
NMR (250 MHz, CDCl3) d 7.57–7.38 (5H, m, ArH), 5.99 (1H, s,
Following the general procedure, a solution of the trans-
cyclopropyl-but-2-enoic acid (250 mg) in dichloromethane
(30 ml) was treated with N-phenylselenophthalimide (840 mg,
2.8 mmol) and tributylphosphine (690 ll, 2.8 mmol). The
crude product was purified by chromatography on silica using
petroleum ether–diethyl ether (9 : 1) as eluent to give the selenyl
ester (310 mg, 70%) as a pale yellow oil; (found: C, 63.9, H,
6.5; C17H21OSe requires C, 63.9, H, 6.3%); kmax(EtOH)/nm 224
(8190), 260 (5280) 300 (2430); mmax(film)/cm−1 1704, 1634, 1607;
major (E) isomer: 1H NMR (400 MHz, CDCl3) d 7.63–7.34 (5H,
=
=
CHCOSePh), 4.92 (1H, d, J 7.6 Hz, CHCH C), 2.16 (3H, s,
=
=
=
CH3C ), 1.74 (3H, s, CH3C ), 1.71 (3H, s, CH3C ), 1.62 (1H,
m, cyclopropyl CH), 1.23 (1H, d, J 7.0 Hz, cyclopropyl CH),
1.18 (3H, s, CH3), 1.03 (3H, s, CH3); 13C NMR (67.8 MHz,
CDCl3) d 189.3 (s), 157.4 (s), 135.7 (2 × d), 134.7 (s), 129.2 (2 ×
d), 128.7 (d), 127.4 (s), 123.3 (d), 122.0 (d), 42.8 (d), 29.1 (d),
27.6 (s), 25.5 (q), 22.7 (q), 22.3 (q), 20.9 (q), 18.6 (q).
=
=
m, ArH), 6.00 (1H, br. s, CH C), 5.63 (1H, m, CH CH2), 5.24
=
=
(2H, m, CH CH2), 2.14 (3H, s, CH C(CH3)), 1.65 (1H, dd,
=
J 6.2, 6.4 Hz, cyclopropyl CHCH ), 1.42 (1H, d, J 6.2 Hz,
cyclopropyl CH), 1.19 (3H, s, CH3), 1.02 (3H, s, CH3); 13C
NMR (67.8 MHz, CDCl3) d 189.3 (s), 156.2 (s), 136.3 (d), 135.8
(2 × d), 129.3 (2 × d), 128.8 (d), 127.3 (s), 123.7 (d), 115.7 (t),
41.4 (d), 33.7 (d), 27.5 (s), 22.3 (q), 21.9 (q), 120.8 (q); minor (Z)
Phenyl trans-3-[2,2-dimethyl-3-(eth-1-enyl)-
cyclopropyl]but-2-enyl selenoate 24b
1
isomer (where observed): H NMR (400 MHz, CDCl3) d 1.14
Methyllithium (1.5 mol dm−3 in THF, 6.2 ml, 9.3 mmol) was
added dropwise over 10 min to a stirred solution of 2,2-dimethyl-
3-(eth-1-enyl)cyclopropylcarboxylic acid16 (1 : 9 cis : trans,
500 mg, 3.6 mmol) in diethyl ether (1 ml) at 0 ◦C. The mixture was
stirred at room temperature for 5 h then poured onto ice–water
and the separated aqueous layer was then extracted with diethyl
ether (3 × 10 ml). The combined organic layers were washed with
water (1 × 10 ml) and brine (1 × 10 ml), then dried (MgSO4) and
the volume of the solution was reduced to provide a 5 ml solution
of the corresponding methyl ketone. A solution of triethyl
phosphonoacetate (3.2 ml, 16 mmol) in THF (2 ml) was added
dropwise over 30 min to a stirred suspension of sodium hydride
(60% dispersion in oil, 720 mg, 18 mmol) in THF (4 ml) at room
temperature. The mixture was stirred at room temperature for
1 h, then a solution of the methyl ketone (3.6 mmol) in diethyl
ether (5 ml) was added in one portion. The mixture was heated
to reflux for 30 min then allowed to stir at room temperature
overnight before saturated NH4Cl solution was added. The
(3H, s, CH3), 1.00 (3H, s, CH3); 13C NMR (67.8 MHz, CDCl3)
d 197.3 (s), 139.3 (s), 137.3 (d), 135.8 (2 × d), 129.3 (2 × d),
128.8 (d), 128.6 (d), 127.3 (s), 114.6 (t), 37.4 (d), 33.2 (d), 25.5
(s), 22.3 (q), 21.9 (q), 20.8 (q); m/z (FAB) found 321.0745 (M+ +
H), C17H21O80Se requires 321.0758; found 319.0719; C17H21O78Se
requires 319.0765.
3,5,5-Trimethyl-6-ethenylcyclohex-2-en-1-one 25
A solution of tributyltin hydride (64 ll, 0.17 mmol) and AIBN
(2 mg) in dry degassed benzene (2 ml) was added over 2 h
via syringe pump to a stirred solution of the selenyl ester 24b
(50 mg, 0.15 mmol) and AIBN (2 mg) in benzene (60 ml)
under reflux in an atmosphere of argon. The mixture was
stirred under reflux for 2 h then cooled to room temperature
and the solvent was evaporated in vacuo. The residue was
purified by chromatography on silica using petroleum ether–
diethyl ether (5 : 1) as eluent to give the cyclohex-2-en-1-one
3 3 4
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 3 2 8 – 3 3 9

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(14 mg, 55%) as a colourless oil; mmax(film)/cm−1 1661; 1H NMR
CH), 1.36 (1H, dd, J 4.9, 10.7 Hz, cyclopropyl CH), 1.22 (3H, s,
CH3), 1.14 (3H, s, CH3); 13C NMR (67.8 MHz, CDCl3) d 177.7
(s), 154.0 (d), 134.4 (s), 121.4 (d), 118.3 (d), 37.6 (d), 35.7 (d),
28.4 (s), 22.4 (q), 21.9 (q), 20.8 (2 × q); m/z (EI) found 194.1309
(M+), C12H18O2 requires 194.1307.
=
(400 MHz, CDCl3) d 5.91 (1H, br. s, C(O)CH C), 5.73 (1H, dt,
J 7.0, 10.9 Hz, CH CH2), 5.26 (1H, d, J 7.0 Hz, CH CHH),
=
=
=
5.18 (1H, d, J 10.9 Hz, CH CHH), 2.72 (1H, d, J 7.0 Hz,
=
C(O)CHCH ), 2.21 (2H, app. d, J 6.3 Hz, CH2), 1.96 (3H, s,
CHC (CH3)), 1.04 (3H, s, CH3), 0.98 (3H, s, CH3); 13C NMR
Following the general procedure, a solution of the carboxylic
acid (100 mg, 0.5 mmol) in dichloromethane (6 ml) was
treated with N-phenylselenophthalimide (230 mg, 7.6 mmol)
and tributylphosphine (200 ll, 7.6 mmol). The crude product
was purified by chromatography on silica using petroleum
ether–diethyl ether (9 : 1) as eluent, to give the selenyl ester
(100 mg, 60%) as a colourless oil; kmax(EtOH)/nm 205 (8060),
=
(67.8 MHz, CDCl3) d 201.8 (s), 158.6 (s), 133.8 (d), 125.9 (d),
120.3 (t), 62.5 (d), 30.2 (t), 29.5 (s), 28.8 (q), 24.8 (q), 23.1 (q).
6-(2-Methylprop-2-enyl)-3,5,5-trimethylcyclohex-2-en-1-one and
6-(2-methylprop-2-enyl)-3,5,5-trimethylcyclohex-3-en-1-one 26
1
A solution of tributyltin hydride (60 ll, 0.17 mmol) in dry
degassed benzene (1.0 ml) was added over 2 h via syringe pump
to a stirred solution of the selenyl ester 24c (30 mg, 0.82 mmol)
and AIBN (14 mg, 0.08 mmol) in benzene (28 ml) under reflux in
an atmosphere of argon. The mixture was stirred under reflux for
a further 2 h, then cooled to room temperature and the solvent
was evaporated in vacuo. The residue was purified by chro-
matography on silica using petroleum ether–diethyl ether (5 : 1)
as eluent to give: (i), the cyclohex-3-enone (2 mg, 12%) (eluted
first); mmax(film)/cm−1 1709; 1H NMR (400 MHz, CDCl3) d 5.40
250 (4050); mmax(film)/cm−1 1693, 1603; H NMR (250 MHz,
CDCl3) d 7.57–7.37 (5H, m, ArH), 6.73 (1H, dd, J 10.6, 15.0 Hz,
=
=
CH CHCOSePh), 6.26 (1H, d, J 15.0 Hz, CH CHCOSePh),
=
=
4.92 (1H, br. d, J 8.0 Hz, CH C), 1.73 (3H, s, CH3C ), 1.69
=
(3H, s, CH3C ), 1.73–1.69 (1H, obs. cyclopropyl CH), 1.32
(1H, dd, J 4.8, 10.6 Hz, cyclopropyl CH), 1.23 (3H, s, CH3),
1.15 (3H, s, CH3); 13C NMR (67.8 MHz, CDCl3) d 188.7 (s),
148.6 (d), 135.9 (2 × d), 134.3 (s), 129.2 (2 × d), 128.9 (d), 128.7
(d), 128.1 (s), 121.3 (d), 38.0 (d), 36.2 (d), 29.0 (s), 25.6 (q),
22.7 (q), 22.1 (q), 18.5 (q); m/z (FAB) found 335.0919 (M+
+
(1H, br. s, CH C), 5.26 (1H, br. d, J ∼10 Hz, CHC ), 3.15
H), C18H23O80Se requires 335.0914; found 333.0888, C18H23O78Se
=
=
(1H, d, J ∼10 Hz, CHC(O)), 2.81 (1H, d, J 16.0 Hz, CCHH),
requires 333.0922 (M + H+).
=
=
=
2.71 (1H, d, J 16.0 Hz, CCHH), 1.78 (3H, s, CH3C ), 1.72
=
=
=
(3H, s, CH3C ), 1.66 (3H, s, CH3C ), 1.03 (3H, s, CH3C ),
Bis(methyl 5,5,8-trimethylnona-3,6-dien-8-yloate) 29
=
0.92 (3H, s, CH3C ); (ii), the cyclohex-2-enone (9 mg, 52%)
(eluted second); mmax(film)/cm−1 1656; 1H NMR (400 MHz,
A solution of tributyltin hydride (81 ll, 0.3 mmol) and AIBN
(25 mg) in dry degassed benzene (1 ml) and methanol (0.1 ml)
was added over 1.5 h via syringe pump to a stirred solution
of the selenyl ester 27 (58 mg, 0.17 mmol) and AIBN (3 mg)
in dry degassed benzene (90 ml) and methanol (9 ml), under
reflux in an atmosphere of argon. The mixture was stirred
under reflux for 4 h then cooled to room temperature and the
solvent was evaporated in vacuo. The residue was purified by
chromatography on silica using petroleum ether–diethyl ether
(10 : 1 then 3 : 1), as eluent to give the dimeric ester (20 mg,
=
CDCl3) d 5.85 (1H, br. s, CHC(O)), 5.08 (1H, d, J 9.9 Hz,
CHCH ), 2.96 (1H, d, J 9.9 Hz, C(O)CHCH ), 2.28 (1H, d,
=
=
=
=
J 18.5 Hz, CCHH), 2.12 (1H, d, J 18.5 Hz, CCHH), 1.93
=
=
=
(3H, s, CH3C ), 1.78 (3H, s, CH3C ), 1.69 (3H, s, CH3C ),
1.02 (3H, s, CH3CCH2), 0.97 (3H, s, CH3CCH2); 13C NMR
(67.8 MHz, CDCl3) d 202.1 (s), 136.9 (s), 128.5 (s), 125.1 (d),
118.6 (d), 56.8 (d), 36.9 (s), 29.7 (t), 28.1 (q), 26.2 (q), 24.6
(q), 24.3 (q), 18.6 (q); m/z (EI) found 192.1507 (M+), C13H20O
requires 192.1514.
1
63%) as a colourless oil; mmax(film)/cm−1 1731, 1601; H NMR
=
(250 MHz, CDCl3) d 5.56–5.32 (4H, m, 2 × CH CH), 5.43
Phenyl trans-3-[2,2-dimethyl-3-(2-methylprop-1-enyl)-
cyclopropyl]prop-2E-enyl selenoate 27
=
(2H, d, J 17.5 Hz, 2 × CCH CHC), 5.25 (2H, d, J 17.5 Hz, 2 ×
=
CCH CHC), 3.69 (6H, s, 2 × CH3), 3.03 (4H, d, J 6.3 Hz, 2 ×
=
Following the general procedure, trans-2,2-dimethyl-3(2-
methylprop-1-enyl)cyclopropyl carboxaldehyde17 (400 mg,
2.6 mmol) was treated with sodium hydride (60% dispersion in
oil, 170 mg, 4.2 mmol) and triethyl phosphonoacetate (590 mg,
2.6 mmol) in THF (4 ml). Purification by chromatography on
silica using petroleum ether–diethyl ether (5 : 1) as eluent gave a
1 : 3 mixture of Z- and E-isomers of ethyl 3-(2,2-dimethyl-3-(2-
methylprop-1-enyl)cyclopropyl)prop-2-enoate (380 mg, 65%),
as a colourless oil; (found: C, 76.0; H, 10.4; C14H22O2 requires
C, 75.6; H, 10.0%); kmax(EtOH)/nm 254 (6030); mmax(film)/cm−1
CHCH2CO2Me), 1.08 (12H, s, 4 × CH3), 0.91 (12H, s, 4 ×
CH3); 13C NMR (67.8 MHz, CDCl3) d 173.7 (2 × s), 144.3 (2 ×
d), 135.8 (2 × d), 134.8 (2 × d), 128.4 (2 × d), 118.1 (2 × d),
52.2 (2 × q), 40.8 (2 × s), 38.9 (2 × s), 38.5 (2 × t), 28.1 (4 × q),
23.5 (4 × q); m/z (FAB) found 209.1558 (M+), C13H21O2 requires
209.1542.
Se-Phenyl (2E,4E,Z)-5,9-dimethyl-2,4,8-decatrieneselenoate 31
Tri-n-butylphosphine (0.4 ml, 1.65 mmol) was added dropwise
over 3 min to a stirred solution of (2E,4E)-5,9-dimethyl-2,4,8-
decatrienoic acid18 (212 mg, 1.09 mmol) in dry CH2Cl2 (5.2 ml)
at −30 ◦C under a nitrogen atmosphere. The mixture was stirred
at −30 ◦C for 20 min and then NPSP (495 mg, 1.6 mmol)
was added. The mixture turned yellow, and it was stirred at
−28 ◦C to −35 ◦C for 1.75 h, and then allowed to warm to room
temperature. Diethyl ether (25 ml) was added and the mixture
was then washed with water (2 × 12 ml). The separated aqueous
phase was extracted with ether (15 ml) and the combined organic
extracts were then washed with brine and dried. Evaporation
of the solvents, followed by chromatography on silica using
petroleum ether–diethyl ether (99 : 1) as eluent gave a 2 : 1
mixture of E- and Z- C-4 isomers of the seleno ester (274 mg,
75%) as a yellow oil. No satisfactory microanalytical data could
be obtained; kmax(EtOH)/nm 293 (8000); mmax(film)/cm−1 1691,
1623, 1581; 1H NMR (2E,4E) isomer: (360 MHz, CDCl3) d 1.61
1
1714, 1638, 1449; H NMR (250 MHz, CDCl3) d 6.75 (1H,
=
dd, J 10.5, 15.3 Hz, CH CHCO2Et), 5.87 (1H, d, J 15.3 Hz,
CH CHCO2Et), 4.92 (1H, br. d, J 8.1 Hz, CH C), 4.17
=
=
=
(2H, q, J 7.2 Hz, OCH2CH3), 1.72 (3H, s, CH3C ), 1.68
(3H, s, CH3C ), 1.62 (1H, m, cyclopropyl CH), 1.31 (1H, m,
=
cyclopropyl CH), 1.28 (3H, t, J 7.2 Hz, OCH2CH3), 1.21 (3H, s,
CH3), 1.12 (3H, s, CH3); 13C NMR (67.8 MHz, CDCl3) d 166.1
(s), 150.4 (d), 134.5 (s), 121.7 (d), 119.4 (d), 59.8 (t), 37.3 (d),
35.0 (d), 27.7 (s), 25.6 (q), 22.5 (q), 22.0 (q), 18.3 (q), 14.2 (q);
m/z (EI) found 222.1630 (M+), C14H22O2 requires 222.1620.
Following the general procedure, a solution of the a,b-
unsaturated ester (370 mg, 1.7 mmol) in ethanol (4.1 ml) and
water (0.3 ml) was treated with sodium hydroxide (370 mg)
to give the corresponding carboxylic acid (280 mg, 86%), as a
yellow oil; kmax(EtOH) 250 (10 500) nm; mmax(film)/cm−1 3363
(br), 1708, 1650; 1H NMR (400 MHz, CDCl3) d 6.87 (1H,
=
=
=
dd, J 10.7, 15.3 Hz, CH CHCO2H), 5.88 (1H, d, J 15.3 Hz,
(3H, s, C(CH3)CH3), 1.69 (3H, s, C(CH3)CH3), 1.90 (3H, s,
C(CH3)CH2), 2.15–2.20 (4H, m, CH2CH2), 5.05–5.15 (1H, m,
CHCH2), 5.97 (1H, d, J 11.6 Hz, CH2(CH3)C CH), 6.13 (1H,
=
=
=
CH CHCO2H), 4.93 (1H, br. d, J 8.0 Hz, CH C), 1.73 (3H, s,
=
=
=
=
CH3C ), 1.69 (3H, s, CH3C ), 1.73–1.69 (1H, obs. cyclopropyl
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 3 2 8 – 3 3 9
3 3 5

View Article Online
=
d, J 14.8 Hz, CHCOSePh), 7.35–7.40 (3H, m, 3 × ArH), 7.53
d, J 6.5 Hz, CHCH3), 1.17 (3H, s, CH3), 1.32 (1H, dd, J 13.0,
6.0 Hz, MeCCHH), 1.35–1.45 (1H, m, CHMe2), 1.60–1.70 (2H,
m, CHCHMe2, MeCCH2CHH), 1.92 (1H, dd, J 13.0, 6.4 Hz,
=
(1H, dd, J 14.8, 11.6 Hz, CH CHCOSePh), 7.50–7.55 (2H, m,
=
2 × ArH); (2E,4Z) isomer: 1.61 (3H, s, C(CH3)CH3), 1.68
=
=
=
(3H, s, C(CH3)CH3), 1.90 (3H, s, C(CH3)CH2), 2.10–2.20
MeCCHH), 2.93 (1H, dm, J 6.7 Hz, CHCH), 6.22 (1H, dd,
=
=
=
(2H, m, CHCH2), 2.30–2.35 (2H, m, C(CH3)CH2), 5.05–5.15
(1H, m, CHCH2), 5.97 (1H, d, J 11.6 Hz, CH2(CH3)C CH),
J 5.8 and 1.7 Hz, CHCO), 7.61 (1H, dd, J 5.8 and 2.6 Hz,
CH CHCO); 13C NMR a-epimer: d 21.3 (q), 21.6 (q), 22.6 (q),
=
=
=
=
6.10 (1H, d, J 14.8 Hz, CHCOSePh), 7.35–7.40 (3H, m, 3 ×
31.3 (t), 32.4 (d), 34.9 (t), 51.6 (d), 54.6 (s), 60.0 (d), 130.5 (d),
166.4 (d), 215.1 (s); b-epimer: d 22.0 (q), 22.2 (q), 22.5 (q), 28.8
(t), 30.2 (d), 37.0 (t), 50.5 (d), 54.1 (s), 56.4 (d), 134.9 (d), 163.9
(d), 215.7 (s); m/z (EI) found 178.1360 (M+), C12H18O requires
178.1358.
=
ArH), 7.51 (1H, dd, J 14.8, 11.6 Hz, CH CHCOSePh), 7.50–
7.55 (2H, m, 2 × ArH); 13C NMR (2E,4E) isomer d 17.6 (q),
25.6 (q), 26.1 (t), 40.5 (t), 123.0 (d), 123.1 (d), 126.5 (s), 127.0 (d),
128.6 (d), 129.1 (2 × d), 132.3 (s), 135.7 (2 × d), 137.5 (d), 153.3
(s), 190.5 (s); (2E,4Z) isomer d 17.6 (q), 24.7 (q), 25.6 (q), 26.7
(q), 33.1 (t), 122.9 (d), 124.0 (d), 126.5 (s), 126.7 (d), 128.6 (d),
129.1 (2 × d), 132.8 (s), 135.8 (2 × d), 137.5 (d), 153.4 (s), 190.6
(s); m/z (ES) found 335.0893 (M+ + H), C18H22OSe requires
335.0914.
Methyl (E,Z)-7-methyl-3E-propenylocta-2,6-dienoate 37
Diisopropylamine (3.15 ml, 22.5 mmol) was added dropwise
over 10 min to a stirred solution of n-butyllithium (1.6 M in
hexanes; 11.5 ml, 18.4 mmol) in dry THF (45 ml), at 0 ◦C under
a nitrogen atmosphere, and the mixture was stirred at 0 ◦C for
30 min, then at room temperature for 30 min. The mixture was
cooled to −78 ◦C and methyl (trimethylsilyl)acetate (3.30 ml,
20.1 mmol) was added dro◦pwise over 10 min. The resulting
mixture was stirred at −78 C for 1 h, and then a solution of
(E)-8-methylnona-2,7-dien-4-one20 (1.25 g, 8.2 mmol) in THF
(9 ml) was added dropwise over 15 min. The mixture was stirred
at −78 ◦C for a further 1.75 h then quenched with water,
and extracted with ether. The combined organic extracts were
washed with brine and dried. The solvents were evaporated
and the residue was purified by chromatography on silica using
petroleum ether–diethyl ether as eluent to give: (i), the E-methyl
ester (230 mg) as a colourless oil, and (ii), an 8 : 5 mixture
of 2E- and 2Z-isomers (1.18 g); (found, C, 75.2%; H, 9.7%;
C13H20O2 requires C, 75.0%; H, 9.7%); mmax(film)/cm−1 1715,
Se-Phenyl (2E,4E/Z,6E)-3,7,11-trimethyldodeca-2,4,6,10-
tetraeneselenoate 32
Tri-n-butylphosphine (0.40 ml, 1.61 mmol) was added drop-
wise over 3 min to a stirred solution of (2E,4E/Z,6E)-
trimethyldodeca-2,4,6,10-tetraenoic acid19 (2E,4E,6E : 2E,4Z,
◦
6E, 5 : 3; 253 mg, 1.08 mmol) in dry CH2Cl2 (5 ml) at −30 C
under a nitrogen atmosphere. After 5 min, NPSP (490 mg,
1.62 mmol) was added in one portion, and the mixture was
stirred at −30 ◦C for a further 20 min. Ether (10 ml) was
added, and the mixture was washed with water (12 ml), then
dried, and the solvents were removed under reduced pressure.
Chromatography on silica using graduated petroleum ether–
diethyl ether as eluent gave a complex mixture of double bond
isomers of the selenyl ester (400 mg, 97%) as a yellow oil; (found,
C, 67.3%; H, 7.1%; C21H26OSe requires C, 67.6%; H, 7.0%);
1
1640, 1604; H NMR 2E isomer: (360 MHz, CDCl3) d 1.62
mmax(film)/cm−1 1692, 1629, 1588, 1557; H NMR (360 MHz,
(3H, s, C(CH3)CH3), 1.69 (3H, s, C(CH3)CH3), 1.86 (3H,
1
=
=
=
=
CDCl3) d 1.58–2.29 (m, 16H, 4 × CH3, CH2CH2), 5.01–5.17
d, J 6.6 Hz, CHCH3), 2.11–2.18 (2H, m, CHCH2), 2.76–
=
=
(m, 1H, CHCH2), 5.93–6.15 (m, 3H), 6.90–7.04 (1H, m,
2.80 (2H, m, CHCH2CH2), 3.70 (3H, s, CO2CH3), 5.20 (1H,
tm, J 7.3 Hz, CHCH2), 5.65 (1H, s, CHCO2Me), 6.03 (1H,
d, J 15.6 Hz, CH3CH CH), 6.18 (1H, dq, J 15.6, 6.6 Hz,
CHCH3); 2Z isomer: 1.60 (3H, s, C(CH3)CH3), 1.69 (3H, s,
=
=
=
=
CHCH CH), 7.33–7.43 (3H, m, 3 × ArH), 7.50–7.60 (2H,
m, 2 × ArH); 13C NMR d 15.0 (q), 17.2 (q), 17.6 (q), 20.4 (q),
24.4 (q), 25.6 (q), 26.2 (t), 26.3 (t), 26.7 (t), 32.9 (t), 40.2 (t), 123.3
(d), 123.4 (2 × d), 123.8 (2 × d), 125.0 (d), 125.6 (2 × d), 125.7
(d), 125.9 (d), 126.5 (d), 127.4 (s), 127.6 (d), 128.2 (d), 128.5 (2 ×
d), 129.1 (d), 131.3 (d), 131.9 (s), 132.2 (d), 132.3 (s), 132.4 (s),
132.5 (d), 133.8 (d), 134.0 (d), 134.9 (d), 135.0 (d), 135.6 (d),
145.5 (s), 145.7 (s), 145.9 (s), 146.1 (s), 148.7 (s), 150.1 (s), 150.2
(s), 188.5 (s), 188.6 (s), 189.3 (s); m/z (EI) found 374.1154 (M+),
C21H26OSe requires 374.1149.
=
=
=
=
=
C(CH3)CH3), 1.90 (3H, d, J 6.7 Hz, CHCH3), 2.13–2.21
=
=
(2H, m, CHCH2), 2.32–2.36 (2H, m, CHCH2CH2), 3.70
=
(3H, s, CO2CH3), 5.12 (1H, tm, J 7.1 Hz, CHCH2), 5.59
=
=
(1H, s, CHCO2Me), 6.15–6.26 (1H, m, CHCH3), 7.50 (1H,
d, J 16.0 Hz, CH3CH CH); 13C NMR 2E isomer: d 17.5 (q),
=
18.6 (q), 25.6 (q), 27.8 (t), 28.2 (t), 50.8 (q), 116.4 (d), 123.9
(d), 131.7 (d), 131.9 (s), 133.7 (d), 157.1 (s), 167.1 (s); 2Z
isomer: d 17.6 (q), 19.0 (q), 25.6 (q), 27.8 (t), 34.4 (t), 50.8
(q), 114.3 (d), 123.2 (d), 128.0 (d), 132.4 (s), 133.2 (d), 155.3
(s), 167.0 (s); m/z (EI) found 208.1457 (M+), C13H20O2 requires
208.1463.
4-Isopropyl-6a-methyl-4,5,6,6a-tetrahydro-3aH-pentalen-1-
one 34
A solution of tributyltin hydride (245 ll, 0.91 mmol) and AIBN
(6 mg, 37 lmol) in dry benzene (5 ml), was added dropwise
over 4.5 h via syringe pump to a stirred, refluxing solution of the
phenyl selenyl ester 31 (2E,4E : 2E,4Z, 2 : 1; 253 mg, 0.76 mmol)
and AIBN (6 mg, 37 lmol) in dry, degassed benzene (210 ml),
under an argon atmosphere. The mixture was heated for a further
6 h, then allowed to cool to room temperature. The solvent was
evaporated under reduced pressure to leave an oil, which was
purified by column chromatography on silica using graduated
petroleum ether–diethyl ether as eluent to give an approximately
1 : 1 mixture of the diastereoisomers of the diquinane (93 mg,
69%), as a pale yellow oil. Repeated chromatography gave
clean samples of each compound; mmax(film)/cm−1 1710, 1586;
1H NMR (360 MHz, CDCl3) a-epimer: d 0.92 (3H, d, J
6.6 Hz, CHCH3), 1.02 (3H, d, J 6.6 Hz, CHCH3), 1.19
(3H, s, CH3), 1.35–1.45 (1H, m, CHCHMe2), 1.50–1.80 (5H,
m, MeCCH2CH2, MeCCH2, CHMe2), 2.65 (1H, dm, J 5.7 Hz,
Se-Phenyl (E,Z)-7-methyl-3E-propenylocta-2,6-
dieneselenoate 38
A solution of the ester 37 (2E : 2Z, 1.6 : 1; 1.18 g, 5.7 mmol)
in THF–water (3 : 1; 24 ml) was heated under reflux with
lithium hydroxide monohydrate (490 mg, 11.7 mmol) for 43 h.
2 N HCl was added to acidify the mixture, and it was then
extracted with ether. The combined extracts were washed with
water and brine, then dried. The solvents were evaporated to
leave an oil, which was again heated under reflux in THF–water
(3 : 1; 24 ml) with lithium hydroxide monohydrate (490 mg,
11.7 mmol) for a further 43 h. The mixture was acidified with
2 N HCl, and then extracted with ether. The combined organic
extracts were washed with brine and dried. Evaporation of the
solvents left an 8 : 5 mixture of 2E- and 2Z-isomers of the
corresponding carboxylic acid (1.04 g, 94%) as a colourless
solid. No satisfactory microanalytical data could be obtained;
=
=
CHCH), 5.96 (1H, dd, J 5.7, 1.7 Hz, CHCO), 7.52 (1H,
dd, J 5.7, 2.8 Hz, CH CHCO); b-epimer: d 0.90 (3H, d, J
6.5 Hz, CHCH3), 0.90–0.96 (1H, m, MeCCH2CHH), 1.08 (3H,
mmax(film)/cm−1 (nujol) 3500–2300 (br), 1685, 1637, 1600; H
1
=
=
NMR (360 MHz, CDCl3) d 1.63 (3H, s, C(CH3)CH3, 2Z),
3 3 6
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 3 2 8 – 3 3 9

View Article Online
=
=
1.65 (3H, s, C(CH3)CH3, 2E), 1.73 (3H, s, C(CH3)CH3,
2E and 3H, C(CH3)CH3, 2Z), 1.91 (3H, dm, J 6.7 Hz,
40.7 (d), 122.7 (d), 128.3 (d), 132.9 (s), 180.9 (s), 212.8 (s); M+
not observed in EI or FAB.
=
=
=
CHCH3, 2E), 1.94 (3H, dm, J 6.8 Hz, CHCH3, 2Z), 2.12–
=
=
2.26 (2H, m, CHCH2, 2E and 2H, CHCH2, 2Z), 2.36–2.43
(E,Z)-5-(2,6-Dimethylhepta-1,5-dienyl)-3-methylcyclopent-2-
enone 47
=
=
(2H, m, CHCH2CH2, 2Z), 2.78–2.84 (2H, m, CHCH2CH2,
=
2E), 5.13 (1H, tm, J 7.0 Hz, CHCH2, 2Z), 5.20 (1H, tm,
J 7.4 Hz, CHCH2, 2E), 5.61 (1H, s, CHCO2H, 2Z), 5.68
(1H, s, CHCO2H, 2E), 6.07 (1H, dm, J 15.6 Hz, CH3CH CH,
=
=
A solution of tributyltin hydride (90 ll, 0.33 mmol) and AIBN
(cat.) in dry, degassed benzene (3.5 ml) was added dropwise
over 5.25 h via syringe pump to a stirred, refluxing solution
of the phenyl selenyl ester 32 (100 mg, 0.27 mmol) and
AIBN (cat.) in dry, degassed benzene (85 ml) under an argon
atmosphere. The mixture was heated for an additional 3.5 h,
and then allowed to cool to room temperature. The benzene
was evaporated under reduced pressure, and the residue was
purified by chromatography on silica using petroleum ether–
diethyl ether as eluent to give the Z- and the E-isomers of the
cyclopentenone (each 23 mg, 38%), as pale yellow oils; E-isomer:
kmax(EtOH)/nm 223 (13 200); mmax(film)/cm−1 1704, 1625; 1H
=
=
=
=
2E), 6.19–6.32 (1H, m, CHCH3, 2E and 1H, CHCH3, 2Z),
7.48 (1H, dm, J 16.0 Hz, CH3CH CH, 2Z); 13C NMR 2E
=
isomer: d 17.5 (q), 18.7 (q), 25.7 (q), 28.1 (t), 28.3 (t), 116.3
(d), 123.8 (d), 132.2 (s), 132.8 (d), 133.7 (d), 159.5 (s), 172.5
(s); 2Z isomer: d 17.7 (q), 19.1 (q), 25.6 (q), 27.9 (t), 34.6 (t),
114.1 (d), 123.1 (d), 128.0 (d), 132.6 (s), 134.1 (d), 157.6 (s),
171.5 (s); m/z (EI) found 194.1307 (M+), C12H18O2 requires
194.1307.
Tri-n-butylphosphine (0.20 ml, 0.80 mmol) was added to a
stirred solution of the propenylocta-2,6-dienoic acid (2E : 2Z,
8 : 5; 105 mg, 0.54 mmol) in dry CH2Cl2 (2.2 ml) at −30 ◦C
under a nitrogen atmosphere. The mixture was stirred at ca.
=
NMR (500 MHz, CDCl3) d 1.60 (3H, s, C(CH3)CH3), 1.68
(3H, s, C(CH3)CH3), 1.72 (3H, s, C(CH3)CH2), 1.98–2.15
=
=
◦
=
(4H, m, CH2CH2), 2.12 (3H, s, CH3C CHCO), 2.30 (1H,
−30 C for 15 min, and then NPSP (230 mg, 0.76 mmol) was
d, J 18.5 Hz, CHHCHCO), 2.90 (1H, dd, J 18.5, 6.9 Hz,
CHHCHCO), 3.27–3.34 (1H, m, CH2CHCO), 5.00 (1H, d, J
added in one portion. The resulting bright yellow mixture was
stirred at −30 ◦C for a further 30 min, then the cooling bath
was removed and ether (25 ml) was added. The mixture was
washed with water, then brine, and dried. The solvents were
removed under reduced pressure to leave a residue which was
purified by chromatography on silica using petroleum ether–
diethyl ether as eluent to give a 3 : 2 mixture of 2E- and
2Z-isomers of the selenyl ester (100 mg, 56%) as a bright
yellow oil; (found, C, 65.0%; H, 6.8%; C18H22OSe requires C,
=
=
8.7 Hz, CHCHCO), 5.05–5.12 (1H, m, CHCH2), 5.93 (1H, s,
CHCO); 13C NMR d 16.9 (q), 17.7 (q), 19.3 (q), 25.7 (q), 26.5
=
(t), 39.4 (t), 41.5 (t), 46.6 (d), 121.7 (d), 124.0 (d), 129.7 (d),
139.6 (s), 151.6 (s), 177.1 (s), 210.6 (s); m/z found 218.1676 (M+),
C15H22O requires M+, 218.1671). Z-isomer: kmax(EtOH)/nm 223
(7700); mmax(film)/cm−1 1704, 1625; 1H NMR d 1.63 (3H, s,
=
=
C(CH3)CH3), 1.70 (3H, s, C(CH3)CH3), 1.76 (3H, d, J
64.9%; H, 6.7%); mmax(film)/cm−1 1693, 1633, 1570; H NMR
(360 MHz, CDCl3) d 1.58 (3H, s, C(CH3)CH3, 2E), 1.62 (3H, s,
C(CH3)CH3, 2Z), 1.67 (3H, s, C(CH3)CH3, 2E), 1.73 (3H, s,
C(CH3)CH3, 2Z), 1.83 (3H, dm, J 6.8 Hz, CHCH3, 2Z),
1.88 (3H, dd, J 6.8, 1.5 Hz, CHCH3, 2E), 2.07–2.16 (2H, m,
CHCH2, 2E), 2.16–2.24 (2H, m, CHCH2, 2Z), 2.28–2.35
(2H, m, CHCH2CH2, 2Z), 2.64–2.71 (2H, m, CHCH2CH2,
1
=
1.3 Hz, C(CH3)CH2), 2.05–2.21 (4H, m, CH2CH2), 2.12 (3H, s,
=
=
CH3C CHCO), 2.30 (1H, dm, J 18.5 Hz, CHHCHCO), 2.86
(1H, dd, J 18.5, 7.0 Hz, CHHCHCO), 3.32 (1H, ddd, J 9.2, 7.0,
=
=
=
=
=
2.7 Hz, CH2CHCO), 5.00 (1H, dd, J 9.2, 1.3 Hz, CHCHCO),
=
=
=
5.10–5.18 (1H, m, CHCH2), 5.90–5.92 (1H, m, CHCO); 13C
NMR d 17.7 (q), 19.3 (q), 23.3 (q), 25.7 (q), 26.7 (t), 32.5 (t), 41.5
(t), 46.6 (d), 122.4 (d), 124.1 (d), 129.7 (d), 131.8 (s), 139.7 (s),
177.1 (s), 210.5 (s); m/z found 218.1666 (M+), C15H22O requires
218.1671.
=
=
=
=
=
=
2E), 5.09–5.17 (1H, m, CHCH2, 2E and 1H, CHCH2, 2Z),
=
5.95 (1H, s, CHCOSePh, 2Z), 5.99 (1H, dm, J 15.6 Hz,
=
=
CH3CH CH, 2E), 6.04 (1H, s, CHCOSePh, 2E), 6.27–6.39
=
=
Phenyl o-vinylbenzoselenoate 48
(1H, m, CHCH3, 2E and 1H, CHCH3, 2Z), 7.31 (1H, dm,
=
J 15.9 Hz, CH3CH CH, 2Z), 7.37–7.43 (3H, m, 3 × ArH, 2E
N-Phenylselenophthalimide (1.6 g, 5.4 mmol) was added in one
portion to a stirred solution of tributylphosphine (0.6 g, 3 mmol)
and o-vinylbenzoic acid21 (0.4 g, 2.7 mmol) in dichloromethane
(30 ml) at −30 ◦C, and the bright yellow mixture was then
stirred at −30 ◦C for 4 h. The mixture was diluted with
dichloromethane, and then washed successively with water, 5%
NaHCO3 and brine. The separated organic extract was dried
and concentrated under reduced pressure to leave an oil which
was purified by chromatography on silica using petroleum ether–
diethyl ether (9 : 1) as eluent to give the selenyl ester (430 mg,
56%) as a pale yellow oil; mmax(film)/cm−1 1694; 1H NMR
and 3H, 3 × ArH, 2Z), 7.52–7.58 (2H, m, 2 × ArH, 2E and
2H, 2 × ArH, 2Z); 13C NMR d 17.7 (q), 17.8 (q), 19.0 (q), 19.1
(q), 25.6 (q), 25.7 (q), 27.8 (t), 28.1 (t), 29.0 (t), 34.0 (t), 122.9
(d), 123.6 (d), 124.9 (d), 127.4 (s), 128.6 (d), 128.7 (d), 129.1 (d),
129.2 (4 × d), 132.1 (s), 132.8 (s), 133.2 (d), 135.2 (d), 135.7 (2 ×
d), 135.8 (2 × d), 136.2 (d), 152.1 (s), 154.0 (s), 188.9 (s), 189.4
(s); m/z (EI) found 177.1270 (M+ − SePh), C18H22OSe requires
177.1279.
5-Methyl-3-(4-methylpent-3-enyl)cyclopent-2-enone 40
=
(360 MHz, CDCl3) d 5.38 (1H, dd, J 11.0, 1.1 Hz, CH CH),
A solution of tributyltin hydride (75 ll, 0.28 mmol) and AIBN
(6 mg, 37 lmol) in dry, degrassed benzene (6 ml) was added
dropwise over 6 h via syringe pump to a stirred, refluxing solution
of the selenyl ester 38 (77 mg, 0.23 mmol) and AIBN (4 mg,
24 lmol) in dry, degassed benzene (70 ml) under an argon
atmosphere. The mixture was heated under reflux for a further
3 h and then evaporated to dryness. The residue was purified
by chromatography on silica using 0–10% petroleum ether–
diethyl ether as eluent to give the cyclopentenone (23 mg, 70%),
based on unreacted starting material (11 mg), as a colourless oil;
mmax(film)/cm−1 1704, 1616; 1H NMR (360 MHz, CDCl3) d 1.17
(3H, d, J 7.5 Hz, CH3CH), 1.62 (3H, s, C(CH3)CH3), 1.69 (3H, s,
C(CH3)CH3), 2.18 (1H, dm, J 18.4 Hz, CHHCHCH3), 2.27
=
5.75 (1H, dd, J 17.4, 1.1 Hz, CH CHH), 7.20 (1H, dd, J
=
17.4, 11.0 Hz, CH CH2), 7.41–7.47 (4H, m, arom. CH), 7.4–
7.5 (1H, m, arom. CH), 7.62–7.67 (3H, m, arom. CH), 7.90
(1 H, dd, J 7.8, 1.2 Hz, arom. CH); 13C NMR d 117.4 (t),
126.9 (s), 127.1 (d), 127.7 (d), 128.4 (d), 129.0 (d), 129.0 (d),
129.4 (d), 132.3 (d), 134.5 (d), 135.7 (s), 136.0 (d), 137.5 (s),
195.4 (s).
Phenyl 3-(o-vinylphenyl)-2E-propeneselenoate 52
A mixture of methyltriphenylphosphonium bromide (0.72 g,
2 mmol) and potassium t-butoxide (0.22 g, 2 mmol) in benzene
(40 ml) was stirred at room temperature for 1 h, then cooled
◦
to 0 C and a solution of ethyl o-formylcinnamate22 (0.2 g,
=
(2H, app. q, J 7.0 Hz, CHCH2), 2.37–2.47 (3H, m, CH3CH,
CHCH2CH2), 2.82 (1H, ddm, J 18.4, 6.7 Hz, CHHCHCH3),
=
1 mmol) in dry benzene (5 ml) was added dropwise over
30 min. The mixture was heated at 45–50 ◦C for 1 h, then
cooled, diluted with water (50 ml) and extracted with ether. The
=
=
5.09 (1H, tm, J 7.0 Hz, CHCH2), 5.89–5.93 (1H, m CHCO);
13C NMR d 16.4 (q), 17.7 (q), 25.6 (q), 25.6 (t), 33.5 (t), 40.4 (t),
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 3 2 8 – 3 3 9
3 3 7

View Article Online
combined organic extracts were washed with brine, then dried
and evaporated under reduced pressure. The residue was purified
by chromatography on silica using petroleum ether–diethyl ether
(9 : 1) as eluent to give ethyl o-vinyl-E-cinnamate (96 mg,
47%) as a pale yellow oil; mmax(film)/cm−1 1713, 1633; 1H NMR
(360 MHz, CDCl3) d 1.32 (3H, t, J 7.1 Hz, OCH2CH3), 4.25 (2H,
evaporated to dryness under reduced pressure. The residue was
purified by chromatography on silica using petroleum ether–
diethyl ether (95 : 5) as eluent to give 1-indanone (44 mg, 56%),
which was identical with a commercial sample.
=
q, J 7.1 Hz, OCH2CH3), 5.41 (1H, dd, J 11.0, 1.3 Hz, HHC ),
5,6-Dihydrobenzocyclohepten-7-one 54
5.62 (1H, dd, J 17.1, 1.3 Hz, HHC), 6.33 (1H, d, J 15.8 Hz,
Phenyl 3-(o-vinylphenyl)-2-propeneselenoate 52 (60 mg,
0.19 mmol) was treated with Bu3SnH–AIBN and AIBN accord-
ing to the usual procedure and gave the benzocyclohepten-7-one
(21 mg, 70%) as a pale yellow oil, which displayed spectroscopic
data identical with those previously reported.23
=
CHCO2Et), 7.05 (1H, dd, J 17.1, 11.0 Hz, ArCH CH2), 7.26–
7.37 (2H, m, arom. CH), 7.47 (1H, dd, J 7.7, 1.5 Hz, arom. CH),
7.51 (1H, dd, J 7.6, 1.3 Hz, arom. CH), 8.01 (1H, d, J 15.8 Hz,
13
=
ArCH CHCO2Et); C NMR d 14.3 (q), 60.4 (t), 117.9 (t), 120.2
(d), 126.8 (d), 126.9 (d), 127.8 (d), 129.9 (d), 132.4 (s), 134.1 (d),
137.9 (s), 142.2 (d), 166.7 (s).
A solution of the cinnamate ester (40 mg, 0.2 mmol), and
potassium carbonate (138 mg, 1.0 mmol) in water (460 mg,
25 mmol) and ethanol (7 ml) was heated under reflux for 14 h,
then cooled and evaporated under reduced pressure. Water
(50 ml) was added to the residue followed by concentrated
HCl (2 ml), and the mixture was then extracted with ether.
The combined organic extracts were treated with 5% NaOH
(50 ml), and the separated aqueous layer was then treated with
concentrated HCl (2 ml) and extracted with ether. Evaporation
of the dried ether extracts under reduced pressure left the
corresponding cinnamic acid (30 mg, 86%) which recrystallised
from ethanol–water 1 : 1) as colourless needles; mmax(film)/cm−1
References
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1
3168, 1692, 1631; H NMR (360 MHz, CDCl3) d 5.38 (1H,
d, J 10.9 Hz, HHC), 5.56 (1H, d, J 17.0 Hz, HHC), 6.30
(1H, d, J 15.8 Hz, CHCO2H), 6.99 (1H, dd, J 17.0, 10.9 Hz,
=
ArCH CH2), 7.17–7.33 (2H, m, arom. CH), 7.42 (1H, d, J
7.6 Hz, arom. CH), 7.49 (1H, d, J 7.6 Hz, arom. CH), 8.09 (1H,
d, J 15.8 Hz, ArCH CHCO2H); 13C NMR d 118.8 (t), 119.5
=
(d), 127.5 (d), 128.3 (d), 130.8 (d), 132.3 (s), 134.4 (d), 138.6 (s),
145.2 (d), 172.8 (s); m/z (EI) found 174.0680 (M+), C11H10O2
requires 174.0681.
Triethylamine (35 mg, 0.34 mmol) was added to a solution of
the cinnamic acid (60 mg, 0.34 mmol) in dry dichloromethane
(2 ml) at −35 ◦C and the mixture was stirred at room temperature
for 5 min under a nitrogen atmosphere. The solvent was
evaporated under reduced pressure and the oily residue was dried
under vacuum for 30 min, and then dissolved in tetrahydrofuran
(2 ml). Tributylphosphine (0.14 g, 0.7 mmol) was added to the
cooledsolution at −35 ◦C under anitrogen atmosphere followed,
after 10 min, by phenylselenyl chloride (0.13 g, 0.69 mmol). The
mixture was allowed to warm to room temperature, then stirred
at this temperature for a further 1.5 h, diluted with ether (30 ml)
and washed with 5% NaHCO3 (20 ml). The separated organic
layer was dried and evaporated under reduced pressure to leave
a residue which was purified by chromatography on silica using
petroleum ether–diethyl ether (9 : 1) as eluent to give the selenyl
ester (60 mg 56%) as a pale yellow oil; mmax(CHCl3)/cm−1 1692,
1605; 1H NMR (360 MHz, CDCl3) d 5.52 (1H, dd, J 11.0, 1.1 Hz,
4 (a) D. L. Boger and R. J. Mathvink, J. Org. Chem., 1988, 53, 3377–
3379; (b) J. Pfenninger, C. Heuberger and W. Graf, Helv. Chim. Acta,
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=
=
CHH CHAr), 5.70 (1H, dd, J 17.3, 1.1 Hz, CHH CHAr),
=
6.74 (1H, d, J 15.6 Hz, ArCH CHCOSe), 7.09 (1H, dd, J,
=
17.3, 11.0 Hz, ArCH CH2), 7.3–7.4 (2H, m, arom. CH), 7.40–
7.50 (3H, m, arom. CH), 7.53 (1H, d, J 7.7 Hz, arom. CH),
7.61 (1H, d, J 7.8 Hz, arom. CH), 7.64 (1H, d, J 7.1 Hz, arom.
CH), 7.65 (1H, d, J 7.9 Hz, arom. CH), 8.03 (1H, d, J 15.6 Hz,
ArCH CHCOSe); 13C NMR d 118.8 (t), 126.3 (s), 127.1 (d),
=
127.3 (d), 128.0 (d), 129.0 (d), 129.4 (d), 130.6, (2 × d), 131.9 (s),
134.0 (d), 135.7 (s), 135.9 (d), 138.9 (d), 190.8 (s).
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1-Indanone 51
11 A. J. Birch, J. Chem. Soc., 1947, 1270.
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over 6 h, under an argon atmosphere, to a refluxing solution of
the selenyl ester 48 (172.3 mg, 0.60 mmol) and AIBN (4.9 mg,
0.03 mmol) in argon-degassed benzene (60 ml). The mixture
was heated under reflux for a further 10 h, then cooled and
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3 3 8
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 3 2 8 – 3 3 9

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O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 3 2 8 – 3 3 9
3 3 9