FeCl3·6H2O-catalyzed mukaiyama-aldol type reactions of enolizable aldehydes and acetals

Article abstract of DOI:10.1021/jo501498a

Mukaiyama-aldol type reactions of acetals derived from enolizable aldehydes with FeCl₃·6H₂O, an eco-friendly, low-cost, and stable catalyst, lead to β-methoxycarbonyl compounds with nearly quantitative yields. The methodology is extended to the parent aldehydes as starting materials, leading to the corresponding aldols with lower yields, but efficiently. Different alkyl and aryl substituted acetals and aldehydes have been tested in the reaction with linear and cyclic silyl enol ethers. Reactions are carried out in an open air atmosphere, and additives are not required. Acetals can be considered activating groups of the carbonyl moiety rather than a protecting group in this type of FeCl₃·6H₂O-catalyzed condensation.

Full text of DOI:10.1021/jo501498a

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Article
FeCl3.6H2O Catalyzed Mukaiyama-aldol Type
Reactions of Enolizable Aldehydes and Acetals
Alejandra Rodríguez-Gimeno, Ana B Cuenca, Jesús Gil-Tomás,
Mercedes Medio-Simon, Andrea Olmos, and Gregorio Asensio
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/jo501498a • Publication Date (Web): 07 Aug 2014
Downloaded from http://pubs.acs.org on August 16, 2014
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FeCl3—6H2O Catalyzed Mukaiyamaꢀaldol Type Reactions of Enolizable
Aldehydes and Acetals
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Alejandra RodríguezꢀGimeno†, Ana B. Cuenca†, Jesús GilꢀTomás†, Mercedes
†,
‡
†
*
MedioꢀSimón , Andrea Olmos and Gregorio Asensio .
†Departamento de Química Orgánica, Universidad de Valencia, Avda. Vicente
Andrés Estellés, s/n 46100 Burjassot, Valencia, Spain.
‡Laboratorio de Catálisis Homogénea, Unidad Asociada al CSIC, CIQSOꢀCentro
de Investigación en Química Sostenible, Universidad de Huelva, Campus El
Carmen, 21007 Huelva (Spain)
Eꢀmail: mercedes.medio@uv.es
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Abstract: Mukaiyamaꢀaldol type reactions of acetals derived from enolizable
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aldehydes with FeCl3—6H2O, an ecoꢀfriendly, lowꢀcost and stable catalyst, leads to
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β
ꢀmethoxycarbonyl compounds with nearly quantitative yields. The methodology is
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extended to the parent aldehydes as starting materials leading to the
corresponding aldols with lower yields but efficiently. Different alkyl and aryl
substituted acetals and aldehydes have been tested in the reaction with linear and
cyclic silyl enol ethers. Reactions are carried out in an open air atmosphere and
additives are not required. Acetals can be considered activating groups of the
carbonyl moiety rather than a protecting group in this type of FeCl3—6H2O catalyzed
condensations.
Introduction
Aldol reactions are among the most important procedures for the formation of CꢀC
bonds.1 Numerous methods have been developed for this reaction and the
Mukaiyama approach emerged as one of the most effective routes in the formation
of
βꢀhydroxyketones, important synthetic intermediates for the preparation of a
wide variety of natural products and many other compounds. Since the discovery
of the reaction, more than 40 years ago, numerous methods are still being
developed to increase its efficiency and stereoselectivity.1a Despite all the work
done on this transformation, it still suffers from important restrictions. The majority
of the methods reported recognized an important reduction of the efficiency of the
reaction when enolizable aldehydes are used 2 or even a complete lack of reactivity
(Scheme 1).3 Only a few methods can be used with this type of starting materials
but they require complicated nonꢀcommercial catalysts4 or have serious structural
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and/or functional requirements well on the aldehyde5 or on the enol6 counterpart. A
typical solution for the preparation of aldols from enolizable aldehydes is the use of
acetals as their surrogates (Scheme 1).7 Acetals are typical carbonyl protecting
groups as well as synthetic equivalents of the carbonyl moiety. However, acetals
can act as strong electrophiles under acidic conditions by generating an oxonium
ion intermediate. Although this method of cleavage gives usually high yields, it
requires the use of strong Lewis acids as TMSOTf, Bu2BOTf or TMSI and strict
anhydrous conditions for the generation of the oxonium ion from the acetal.8 Other
strategy based on [Ir(COD)(PPh3)2]OTf as preꢀcatalyst has been developed but it
needs to be activated by hydrogen at temperatures of 70 οC.9 A further possibility is
the use of an ester with a reductant instead of the aldehyde.10 These precedents
prompted us to explore alternative methods to allow the use of enolizable
aldehydes or their surrogates in Mukaiyamaꢀaldol reactions.
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Scheme 1. Mukaiyamaꢀaldol reaction with enolizable aldehydes and the use
of their corresponding acetals as surrogates.
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Iron based catalysts11 have been discretely used in organic chemistry compared to
other transition metals although they are cheap, easily accessible, nonꢀtoxic and
stable. The principal use of iron in organic catalysis is related to oxo and hydride
transfer reactions although carbene, nitrene and carbanion transfer reactions have
also been catalyzed by iron.12 Another important use of iron as a catalyst profits of
its Lewis acid character. In this aspect, iron salts have often been reported as
efficient catalysts in DielsꢀAlder reactions,13 1,3ꢀdipolar cyclizations,14 FriedelꢀCraft
reactions15 or Mannich additions.16 Surprisingly, although the Mukaiyamaꢀaldol
reaction is traditionally catalyzed by a Lewis acid, few iron catalyzed reactions
have been described.17ꢀ20 Nevertheless, FeCl3 was already tested in the early
stages of the Mukaiyama transformation, although with very low efficiency.18
Recently, use of bipyridine17a phosphineoxazoline17b and bisoxazoline17c,d FeII
complexes have been successfully reported in the asymmetric version of this
process. However, only the bipyridineꢀiron complexe gave moderated results with
enolizable aldehydes but it required benzoic acid as an additive in combination with
the catalyst. The other two methods reported gave poor results with saturated
aldehydes. In addition, all three catalysts need the use of anoxic conditions to
avoid the oxidation of FeII to FeIII with subsequent loss of the catalytic activity. The
development of aldol reactions in water19 have brought about the possibility of
using water compatible catalysts as, for instance, FeCl3 or FeCl3—6H2O20 although
the reaction was mostly applied to aromatic or non enolizable aldehydes.
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Based on the above precedents we decided to assay FeCl3—6H2O to catalyze the
Mukaiyamaꢀaldol reaction of enolizable aldehydes due to the moderated Lewis
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acid character and a high air and water stability of this cheap, environmentally
friendly, stable and easy to handle salt.
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Results and Discussion
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Several FeIII salts were assayed to optimize the catalytic system (see Supporting
Information) and FeCl3—6H2O was selected to perform the Mukaiyamaꢀaldol
reaction of acetals 1 derived from enolizable aldehydes or their precursor
aldehydes 2 with silyl enol ethers 3. 2ꢀPhenylaldehyde dimethylacetal (1a),
selected as representative starting material, was treated with different silyl enol
ethers 3 (Figure 1) in the presence of 5 mol% of FeCl3—6H2O. The formation of the
Figure 1. Dimethyl acetals 1, enolizable aldehydes 2 and silyl enol ethers 3.
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corresponding
β
ꢀmethoxycarbonyl compounds 4 was efficiently promoted under
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these conditions (Table 1). Reactions were performed by adding the catalyst over a
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solution of 1a and the silyl enol ethers 3aꢀf in dichloromethane at 0 C. The
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resulting solution was stirred for 30 minutes at room temperature to yield the
corresponding products 4aaꢀ4af after evaporation of the residue and purification
through silica column
Table 1. FeCl3—6H2Oꢀcatalyzed Mukaiyamaꢀaldol type reaction of acetal 1a
with silyl enol ethers 3.a
Run
3
4
Yield (%)b
>99
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3a
4aa
4ab
4ac
4ad
4ae
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3
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5
3b
3c
3d
3e
>99c
97
>99d
44e
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3f
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aReaction conditions: 1.0 equiv 1a, 1.1 equiv 3aꢀf, 0.05 equiv FeCl3—6H2O, CH2Cl2 0.29 M, 30 min,
rt. bIsolated yields. cRelation syn:anti 55:45. dRelation syn:anti 60:40. eDesilylation of the ketone was
found.
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chromatography. Reactions were performed in an open atmosphere without any
special care to exclude the presence of moisture or air. Nearly quantitative isolated
yields were obtained in most cases for the silyl enol ethers 3 used, independently
of their structure or electronic character. Yield was slightly lower in the case of the
less reactive ketene silyl acetal 3f.8
a Acetone silyl enol ether 3e gave a lower yield
due to partial desilylation.
The influence of the structure of 1 in the reaction efficiency was explored. Acetals
1bꢀe (Figure 1) were subjected to react with a selection of silyl enol ethers 3aꢀ3c to
give the corresponding compounds 4 with satisfactory to quantitative yields.
αꢀ
Substituted acetals 1e and 1c did not experiment decrease in the reaction
efficiency. Completely saturated octanal dimethyl acetal (1d) gave also quantitative
conversion into the desired product with all the silyl enol ethers tested.
Table 2. Acetals 1 in FeCl3—6H2Oꢀcatalyzed Mukaiyamaꢀaldol type reaction
with silyl enol ethers 3.a
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4bb,95%d
4bc, 95%
4ca, 96%
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4cb, 70%d
4cc, 95%
4dc, 95%
4da, 90%
4db, 95%e
4ea, >99%c
aReaction conditions: 1.0 equiv 1bꢀe, 1.1 equiv 3aꢀc, 0.05 equiv FeCl3—6H2O, CH2Cl2 0.29 M, 30
min, rt. bIsolated yields. cRelation syn: anti 70:30. dRelation syn: anti 57:43. eRelation syn:anti 60:40.
It is remarkable that only compounds 4 containing a completely methylated
hydroxy group were obtained in all cases thus allowing their direct use for future
transformations. This behaviour is quite common, but not general in Mukaiyamaꢀ
aldol reactions which afford in some occasions to free aldols or their mixtures with
methylated products.8c,9 Compounds 4 were also stable under our reaction
conditions and did not led to
α,βꢀunsaturated carbonyl compounds even in the
presence of FeCl3—6H2O, an acid catalyst.8a,21
The synꢀdiastereoisomer always predominated and the value of the syn:anti ratio
ranged from 55:45 to 70:30 when two diastereoisomers could be obtained. With
the aim of increasing the diastereoselection, a number of reactions were performed
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at temperatures between ꢀ78 and 25 C (Table 3) but the syn:anti ratio remained
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unchanged. This observation and the fact that the diastereoselectivity found was in
all cases similar to that reported in reactions catalyzed by other Lewis acids,22 has
been interpreted previously based on dipolar, inductive and steric effects.23
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Table 3. Effect of temperature on the reaction diastereoselectivity.a
Run
1
Temperature (οC)
Yield (%)b
>99
syn:antic
70:30
25d
0e
2
>99
70:30
3
ꢀ40f
ꢀ78f
>99
70:30
4
>99
71:29
aReaction conditions: 1.0 equiv 1e, 1.1 equiv 3a, 0.05 equiv FeCl3—6H2O, CH2Cl2 0.29 M, t. bIsolated
yields. cRelation syn: anti determined by 1H NMR. d 30 min. e 1.15 h. f 2 h.
Encouraged by the excellent results obtained with acetals 1 derived from
enolizable aldehydes, we decided to explore the reactivity of the parent free
aldehydes. Non protected enolizable aldehydes 2aꢀ2d (Figure 1), selected by their
poor results under typical Mukaiyama reaction conditions, were exposed to react
with representative silyl enol ethers 3aꢀ3c in the same conditions as previously
employed by us in the condensation of acetals 1 (Table 4). The direct
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Table 4. Enolizable aldehydes 2 in FeCl3—6H2Oꢀcatalyzed Mukaiyamaꢀaldol
type reaction with silyl enol ethers 3.a
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5aa, 88%
5bb, 69%d
5cc, 41%c
5ab, 50%c,d
5bc, 41%
5db, 46%d
5ac, 83%
5cb, 89%e
5dc, 48%c
aReaction conditions: 1.0 equiv 2aꢀd, 1.1 equiv 3aꢀc, 0.05 equiv FeCl3—6H2O, CH2Cl2 0.29 M, rt.
bIsolated yields. cReaction carried out with 0.1 equiv FeCl3—6H2O. dRelation syn:anti 55:45.
ePurification by flash chromatography gave the elimination product.
condensation of enolizable aldehydes is known to afford poor results in the
Mukaiyamaꢀaldol condensation according to previous reports in the literature.2,3
Accordingly, we observed a decrease in the efficiency of the reaction but
satisfactory yields (see Table 4) were still obtained under our reaction conditions in
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the majority of the cases. Notably, our reactions proceeded in 1ꢀ4h a reaction time
shorter than that reported for typical aldol reactions which require 12ꢀ24 h or even
some days.24 Compounds 5 were less stable than their corresponding acetal
derivatives 4 giving rise in some cases to partial elimination of water in the
chromatographic purification process. In the reaction with unprotected aldehydes
the formation of the syn diastereoisomer was also prevalent.
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Scheme 2. Competition experiment between acetal 1a, aldehyde 2a and silyl
enol ether 3a.
The relative reactivity of compounds 1 and 2 was investigated in a competition
experiment between 1a and 2a in their condensation with 3a (Scheme 2). Acetal
1a reacted faster than the parent aldehyde 2a to afford a 2.3:1 mixture of
compounds 4aa and 5aa. Consequently, acetals can be considered activating
groups of the carbonyl moiety rather than a protecting group in the Mukaiyamaꢀ
aldol type condensation.
Conclusions
A robust and general method for the Mukaiyama type condensarion of
dimethylacetals derived from enolizable aldehydes catalyzed by FeCl3.6H2O has
been developed leading to
βꢀmethoxy ketones with excellent yields. This
methodology has been extended also to the parent enolizable aldehydes as
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starting materials with fair results although their reactivity was remarkably lower if
compared to that of their acetalꢀsurrogates. Due to the ecoꢀfriendly character, lowꢀ
cost and stability of the FeCl3.6H2O catalyst and the fact that reactions are
performed in an open air atmosphere in absence of additives our approach
becomes a method of choice for the CꢀC bond formation using Mukaiyama type
reactions.
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Experimental Section
General Methods. Chemicals were purchased from commercial suppliers and
used as delivered. All reactions were carried out in test tubes or Schlenk tubes.
Deuterated solvents were purchased and used without further purification. NMR
spectra were recorded at room temperature on 300MHz, 400MHz or 500MHz
spectrometers. Chemical shifts are given in ppm and coupling constants in Hz. In
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13
the H and C spectra chemical shifts are reported relative to deuterated solvents
(CDCl3: 7.26 / 77.2 ppm; CD2Cl2: 5.32 / 54.0 ppm). The following abbreviations
1
were used for HꢀNMR to indicate the signal multiplicity: s (singlet), d (doublet), t
(triplet), m (multiplet), br s (broad singlet). High Resolution Mass Spectra were
obtained with ESIꢀTOF analyzer equipment. Analytical thin layer chromatography
was carried out using commercial aluminium sheets preꢀcoated (0.2mm layer
thickness) with silica gel 60 F254, and visualization was effected with shorts
wavelength UV light (254nm). Product purification by flash chromatography was
performed using 230ꢀ400 mesh silica gel.
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Materials. Acetals (1a, 1d and 1e), aldehydes 2, silyl enol ethers 3, all the
commercial reagents and FeCl3—6H2O catalyst were commercially available and
were used without further purification.
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Synthesis of acetals. General procedure. To a magnetically stirred mixture of the
corresponding aldehyde (1 equiv, 5 mmol) and trimethyl orthoformate (1.2 equiv, 6
mmol) in methanol (1M), pꢀTsOH—H2O (0.01 equiv, 1 mol %) was added and the
mixture was stirred at room temperature until completion of the reaction (12ꢀ24h,
TLC). The mixture was extracted with H2O/Et2O. The combined Et2O extracts were
dried (Na2SO4) and concentrated under reduced pressure and the product was
obtained as colourless oil and used without purification
(3,3ꢀdimethoxypropyl)benzene (1b). Compound 1b was prepared according to the
general procedure and was obtained in >99% yield (0.9013 g, 5 mmol) as a
colourless oil. 1H NMR (300 MHz, CDCl3) δ 7.28 – 7.02 (m, 5H), 4.30 (t, J = 5.7 Hz,
1H), 3.26 (s, 6H), 2.60 (dd, J = 9.0, 7.0 Hz, 2H), 1.85 (ddd, J = 10.0, 8.0, 5.9 Hz,
2H).13C NMR (75 MHz, CDCl3) δ 141.8, 128.5, 126.0, 103.9, 52.9, 34.2, 31.0.The
spectral data match with reported in the literature.25
(2,2ꢀdimethoxyethaneꢀ1,1ꢀdiyl)dibenzene (1c). Compound 1c was prepared
according to the general procedure and was obtained in >99% yield (1.2116 g, 5
mmol) as a colourless oil. 1H NMR (300 MHz, CDCl3) δ 7.44 – 7.21 (m, 10H), 5.08
(d, J = 7.7 Hz, 1H), 4.32 (d, J = 7.7 Hz, 1H), 3.38 (s, 6H).13C NMR (75 MHz,
CDCl3) δ 141.2, 128.8, 128.5, 126.5, 106.6, 54.7, 54.1. The spectral data match
with reported in the literature.26
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General Procedure for FeCl3—6H2OꢀCatalyzed Mukaiyama Type Reaction.
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A schlenk with a Teflon stirring bar was charged with the corresponding acetal 1 or
aldehyde 2 (1 equiv, 0.5 mmol) and silyl enol ether 3 (1.1 equiv, 0.55 mmol) in
CH2Cl2 (0.29M) at 0οC. Subsequently, FeCl3—6H2O (0.05 equiv, 5 mol%) was
added. The reaction was stirred at room temperature until consumption of the
starting material (monitored by TLC). Next, the reaction was diluted with
dichloromethane (2ꢀ3 mL), and filtered over Aluminium oxide activated. The solvent
was removed under reduced pressure and the corresponding products (4 or 5)
were isolated by silica gel column chromatography.
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5ꢀmethoxyꢀ2,2ꢀdimethylꢀ6ꢀphenylhexanꢀ3ꢀone (4aa). Compound 4aa was
prepared according to the general procedure and was obtained in >99% yield
1
(117.2 mg, 0.5 mmol) as yellow oil. Eluents: hexane: ethyl acetate = 100:1. H
NMR (300 MHz, CDCl3) δ 7.41 – 7.33 (m, 2H), 7.29 ꢀ7.27 (m, 3H), 4.13 – 4.00 (m,
1H), 3.38 (s, 3H), 2.96 (dd, J = 14.0, 6.5 Hz, 1H), 2.91 – 2.80 (m, 2H), 2.50 (dd, J =
17.2, 5.0 Hz, 1H), 1.19 (s, 9H). 13C NMR (75 MHz, CDCl3) δ 214.2, 138.5, 129.6,
128.4, 126.3, 78.3, 57.7, 44.3, 41.1, 40.1, 26.2. HRMS (ESIꢀTOF) m/z: [M+Na]+
Calcd. for C15H22O2Na 257.1517; found 257.1515.
2ꢀ(1ꢀmethoxyꢀ2ꢀphenylethyl)cyclohexanꢀ1ꢀone (4ab). Compound 4ab was
prepared according to the general procedure and was obtained in >99% yield
(116.2 mg, 0.5 mmol) as a mixture of diastereoisomers in a 55:45 proportion
(syn/anti). Syn diastereoisomer: Eluents: Hexane: ethyl acetate = 100:1. Yellow oil.
1H NMR (300 MHz, CDCl3) δ 7.23 – 7.18 (m, 2H), 7.16 – 7.08 (m, 3H), 3.86 (td, J =
6.5, 4.3 Hz, 1H), 3.22 (s, 3H), 2.81 (dd, J = 13.7, 6.3 Hz, 1H), 2.67 (dd, J = 13.7,
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6.7 Hz, 1H), 2.36 – 2.25 (m, 1H), 2.21 – 2.05 (m, 3H), 1.98 – 1.91 (m, 1H), 1.89 –
1.78 (m, 1H), 1.68 – 1.45 (m, 3H).13C NMR (75 MHz, ) δ 211.8, 138.8, 129.5,
128.5, 126.3, 79.5, 58.5, 53.4, 42.5, 37.9, 27.5, 27.3, 24.9. HRMS (ESIꢀTOF) m/z:
[M+H]+ Calcd. for C15H21O2 233.1542; found 233.1537. Anti diastereoisomer:
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Eluents: hexane: ethyl acetate = 100:1. Yellow oil. H NMR (300 MHz, CDCl3) δ
7.23 – 7.11 (m, 5H), 3.74 (ddd, J = 8.2, 4.6, 3.4 Hz, 1H), 3.10 (s, 3H), 2.79 (dd, J =
13.8, 3.3 Hz, 1H), 2.61 – 2.49 (m, 2H), 2.39 – 2.23 (m, 2H), 2.08 (ddd, J = 12.1,
6.9, 3.8 Hz, 1H), 2.02 – 1.91 (m, 1H), 1.88 – 1.81 (m, 1H), 1.66 – 1.50 (m, 3H). 13C
NMR (75 MHz, CDCl3) δ 212.0, 139.9, 129.5, 128.3, 126.1, 81.7, 58.2, 53.2, 42.6,
37.9, 28.4, 27.6, 24.8. HRMS (ESIꢀTOF) m/z: [M+H]+ Calcd. for C15H21O2
233.1542; found 233.1537.
3ꢀmethoxyꢀ1,4ꢀdiphenylbutanꢀ1ꢀone (4ac). Compound 4ac was prepared
according to the general procedure and was obtained in 97% yield (123.4 mg, 0.5
mmol) as colourless solid (mp 54ꢀ56 οC). 1H NMR (300 MHz, CDCl3) δ 8.09 – 8.04
(m, 2H), 7.76 – 7.67 (m, 1H), 7.63 – 7.58 (m, 2H), 7.51 – 7.38 (m, 5H), 4.31 (dtd, J
= 7.3, 6.1, 4.9 Hz, 1H), 3.52 (s, 3H), 3.41 (dd, J = 16.6, 7.3 Hz, 1H), 3.18 ꢀ 3.00 (m,
3H). 13C NMR (75 MHz, CDCl3) δ 198.9, 138.3, 137.3, 133.2, 129.7, 128.7, 128.5,
128.2, 126.5, 78.7, 57.7, 42.9, 40.3. The spectral data match with that reported in
the literature.27
2ꢀ(1ꢀmethoxyꢀ2ꢀphenylethyl)ꢀ3,4ꢀdihydronaphthalenꢀ1(2H)ꢀone
(4ad).
Compound 4ad was prepared according to the general procedure and was
obtained in >99% yield (140.2 mg, 0.5 mmol) as a mixture of diastereoisomers in a
ο
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60:40 proportion (syn/anti). Syn diastereoisomer: Yellow solid (mp 61ꢀ63 C). H
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NMR (300 MHz, CDCl3) δ 8.05 (dd, J = 7.8, 1.3 Hz, 1H), 7.48 (td, J = 7.5, 1.5 Hz,
1H), 7.39 – 7.19 (m, 7H), 4.47 (ddd, J = 8.6, 6.5, 2.5 Hz, 1H), 3.33 (s, 3H), 3.18 –
3.09 (m, 1H), 3.09 – 2.88 (m, 2H), 2.80 (dd, J = 13.6, 8.1 Hz, 1H), 2.42 (ddd, J =
12.7, 4.5, 2.5 Hz, 1H), 2.33 (dt, J = 12.6, 4.1 Hz, 1H), 2.26 – 2.09 (m, 1H).13C NMR
(75 MHz, CDCl3) δ 198.6, 144.2, 138.7, 133.7, 133.0, 129.4, 128.7, 128.6, 127.6,
126.6, 126.5, 79.8, 58.7, 50.4, 38.0, 29.1, 22.2. Anti diastereoisomer: Yellow solid
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(mp 62ꢀ63 C). H NMR (300 MHz, CDCl3) δ 8.05 (dd, J = 7.9, 1.2 Hz, 1H), 7.48
(td, J = 7.5, 1.5 Hz, 1H), 7.36 – 7.27 (m, 5H), 7.25 – 7.17 (m, 2H), 4.20 (dt, J = 8.9,
3.4 Hz, 1H), 3.22 (s, 3H), 3.11 – 2.99 (m, 2H), 2.99 – 2.90 (m, 1H), 2.81 – 2.66 (m,
2H), 2.34 (dq, J = 12.6, 4.1 Hz, 1H), 2.12 – 1.98 (m, 1H). 13C NMR (75 MHz,
CDCl3) δ 199.0, 144.4, 140.1, 133.5, 133.2, 129.5, 128.9, 128.3, 127.4, 126.8,
126.2, 82.5, 58.1, 50.0, 38.1, 29.3, 23.6. The spectral data match with that reported
in the literature.28
4ꢀmethoxyꢀ5ꢀphenylpentanꢀ2ꢀone (4ae). Compound 4ae was prepared according
to the general procedure and was obtained in 44% yield (42.3 mg, 0.22 mmol) as
yellow oil. Eluents: hexane: ethyl acetate = 50:1. 1H NMR (300 MHz, CDCl3) δ 7.26
– 7.07 (m, 5H), 3.91 – 3.77 (m, 1H), 3.27 (s, 3H), 2.84 (dd, J = 13.7, 5.8 Hz, 1H),
2.68 – 2.51 (m, 2H), 2.34 (dd, J = 16.3, 4.4 Hz, 1H), 2.04 (s, 3H). 13C NMR (75
MHz, CDCl3) δ 207.6, 138.1, 129.6, 128.5, 126.5, 78.4, 57.5, 47.9, 39.9, 31.2.
HRMS (ESIꢀTOF) m/z: [M+H]+ Calcd. for C12H17O2 193.1223; found 193.1214.
methyl 3ꢀmethoxyꢀ2,2ꢀdimethylꢀ4ꢀphenylbutanoate (4af). Compound 4af was
prepared according to the general procedure and was obtained in 71% yield (83.9
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mg, 0.36 mmol) as yellow oil. Eluents: hexane: ethyl acetate = 50:1. H NMR (300
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MHz, CDCl3) δ 7.24 – 7.14 (m, 5H), 3.60 (s, 3H), 3.55 (dd, J = 8.7, 3.5 Hz, 1H),
2.94 (s, 3H), 2.68 – 2.51 (m, 2H), 1.19 (s, 3H), 1.13 (s, 3H).13C NMR (75 MHz,
CDCl3) δ 177.4, 139.9, 129.5, 128.4, 126.2, 88.1, 61.0, 51.9, 48.0, 38.0, 21.4, 20.8.
HRMS (ESIꢀTOF) m/z: [M+Na]+ Calcd. for C14H20O3Na 259.1310; found 259.1310.
2ꢀ(1ꢀmethoxyꢀ3ꢀphenylpropyl)cyclohexanꢀ1ꢀone (4bb). Compound 4bb was
prepared according to the general procedure and was obtained in 95% yield (117.0
mg, 0.48 mmol) as a mixture of diastereoisomers in a 57:43 proportion (syn/anti).
Syn diastereoisomer: Eluents: hexane: ethyl acetate = 30:1.Colourless oil. 1H NMR
(300 MHz, CDCl3) δ 7.39 – 7.32 (m, 2H), 7.31 – 7.25 (m, 3H), 3.83 (dt, J = 7.2, 5.1
Hz, 1H), 3.47 (s, 3H), 2.86 – 2.66 (m, 2H), 2.52 – 2.21 (m, 5H), 2.05 – 1.77 (m,
4H), 1.78 – 1.68 (m, 2H).13C NMR (75 MHz, CDCl3) δ 211.9, 142.2, 128.5, 125.9,
77.9, 58.5, 54.6, 42.4, 34.4, 32.0, 27.9, 27.4, 24.7. HRMS (ESIꢀTOF) m/z: [M+Na]+
Calcd. for C16H22O2Na 269.1512; found 269.1511. Anti diastereoisomer: Eluents:
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hexane: ethyl acetate = 30:1.Colourless oil. H NMR (500 MHz, CDCl3) δ 7.29 –
7.26 (m, 1H), 7.23 – 7.21 (m, 2H), 7.19 – 7.16 (m, 1H), 3.70 (ddd, J = 8.0, 4.8, 2.9
Hz, 1H), 3.36 (s, 3H), 2.83 – 2.80 (m, 1H), 2.71 – 2.62 (m, 2H), 2.43 – 2.36 (m,
1H), 2.34 – 2.28 (m, 1H), 2.10 – 2.10 (m, 1H), 2.05 – 1.98 (m, 1H), 1.93 – 1.86 (m,
1H), 1.85 – 1.79 (m, 1H), 1.70 – 1.61 (m, 4H). 13C NMR (126 MHz, CDCl3) δ 212.2,
142.5, 128.6, 128.4, 125.9, 79.2, 57.6, 52.7, 42.5, 33.1, 32.3, 27.9, 27.6, 24.8.
HRMS (ESIꢀTOF) m/z: [M+Na]+ Calcd. for C16H22O2Na 269.1512; found 269.1511.
3ꢀmethoxyꢀ1,5ꢀdiphenylpentanꢀ1ꢀone (4bc). Compound 4bc was prepared
according to the general procedure and was obtained in 95% yield (127.5 mg, 0.48
mmol) as yellow oil. 1H NMR (300 MHz, CDCl3) δ 8.06 – 8.00 (m, 2H), 7.66 – 7.59
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(m, 1H), 7.56 – 7.49 (m, 2H), 7.38 – 7.25 (m, 5H), 4.06 – 3.96 (m, 1H), 3.45 (s,
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3H), 3.44 – 3.35 (m, 1H), 3.05 (dd, J = 16.2, 5.7 Hz, 1H), 3.02 – 3.09 (m, 2H), 2.04
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– 1.94 (m, 2H). C NMR (75 MHz, CDCl3) δ 198.8, 142.0, 137.3, 133.2, 128.6,
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128.6, 128.6, 128.4, 128.4, 128.3, 128.3, 128.2, 125.9, 77.1, 57.3, 43.2, 36.3, 31.5.
The spectral data match with that reported in the literature.29
5ꢀmethoxyꢀ2,2ꢀdimethylꢀ6,6ꢀdiphenylhexanꢀ3ꢀone (4ca). Compound 4ca was
prepared according to the general procedure and was obtained in 96% yield (149.0
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mg, 0.48 mmol) as a white solid (mp 68ꢀ70 C). Eluents: hexane: ethyl acetate =
50:1. 1H NMR (300 MHz, CDCl3) δ 7.25 – 7.21 (m, 2H), 7.17 – 7.08 (m, 6H), 7.07 –
6.99 (m, 2H), 4.38 (ddd, J = 8.1, 7.2, 4.0 Hz, 1H), 3.86 (d, J = 8.1 Hz, 1H), 2.91 (s,
3H), 2.64 (dd, J = 17.5, 7.2 Hz, 1H), 2.34 (dd, J = 17.5, 4.0 Hz, 1H), 0.87 (s, 9H).
13C NMR (75 MHz, CDCl3) δ 214.7, 142.5, 142.0, 129.1, 128.7, 128.6, 128.4,
126.6, 126.6, 80.2, 59.3, 56.9, 44.4, 41.3, 26.2. HRMS (ESIꢀTOF) m/z: [M+Na]+
Calcd. for C21H26O2Na 333.1830; found 333.1834.
2ꢀ(1ꢀmethoxyꢀ2,2ꢀdiphenylethyl)cyclohexanꢀ1ꢀone (4cb). Compound 4cb was
prepared according to the general procedure and was obtained in 70% yield (107.9
mg, 0.35 mmol) as a mixture of diastereoisomers in a 57:43 proportion (syn/anti).
Syn diastereoisomer:. Eluents: hexane: ethyl acetate = 30:1. Pale yellow solid. (mp
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124ꢀ126 C). H NMR (500 MHz, CDCl3) δ 7.32 – 7.31 (m, 2H), 7.22 – 7.17 (m,
6H), 7.11 ꢀ 7.08 (m, 2H), 4.58 (dd, J = 9.6, 2.8 Hz, 1H), 3.95 (d, J = 9.6 Hz, 1H),
2.94 (s, 3H), 2.35 – 2.28 (m, 1H), 2.22 – 2.15 (m, 1H), 2.09 – 1.98 (m, 2H), 1.87
(m, 1H), 1.84 – 1.77 (m, 1H), 1.68 – 1.63 (m, 1H), 1.59 – 1.49 (m, 1H), 1.41 – 1.30
(m, 1H). 13C NMR (126 MHz, CDCl3) δ 212.0, 142.5, 142.4, 129.0, 128.8, 128.4,
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126.7, 126.5, 80.5, 60.5, 55.1, 52.7, 42.1, 26.5, 26.0, 24.7. HRMS (ESIꢀTOF) m/z:
[M+Na]+ Calcd. for C21H24O2Na 331.1669; found 331.1668. Anti diastereoisomer:
Eluents: hexane: ethyl acetate = 30:1. White solid. (mp 122ꢀ125 ºC). 1H NMR (500
MHz, CDCl3) δ 7.53 – 7.49 (m, 2H), 7.31 – 7.27 (m, 2H), 7.27 – 7.19 (m, 5H), 7.18
– 7.15 (m, 1H), 4.29 (d, J = 6.3 Hz, 1H), 4.02 (t, J = 6.3 Hz, 1H), 2.97 (s, 3H), 2.58
– 2.47 (m, 1H), 2.35 – 2.25 (m, 1H), 2.25 – 2.13 (m, 1H), 1.97 – 1.90 (m, 2H), 1.83
– 1.73 (m, 1H), 1.68 – 1.52 (m, 2H), 1.48 – 1.40 (m, 1H). 13C NMR (126 MHz,
CDCl3) δ 212.0, 142.7, 141.3, 129.8, 129.0, 128.5, 128.4, 126.6, 126.5, 85.1, 61.0,
54.6, 53.9, 42.8, 31.1, 27.9, 24.9. HRMS (ESIꢀTOF) m/z: [M+Na]+ Calcd. for
C21H24O2Na 331.1669; found 331.1668.
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3ꢀmethoxyꢀ1,4,4ꢀtriphenylbutanꢀ1ꢀone (4cc). Compound 4cc was prepared
according to the general procedure and was obtained in 95% yield (156.9 mg, 0.48
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mmol) as a yellow solid (mp 98ꢀ100 οC). Eluents: hexane: ethyl acetate = 30:1. H
NMR (300 MHz, CDCl3) δ 7.78 – 7.75 (m, 2H), 7.48 – 7.40 (m, 1H), 7.37 – 7.31 (m,
4H), 7.31 – 7.26 (m, 1H), 7.25 – 7.17 (m, 5H), 7.14 – 7.05 (m, 2H), 4.62 (td, J =
7.6, 3.9 Hz, 1H), 4.04 (d, J = 7.9 Hz, 1H), 3.19 (dd, J = 16.8, 7.4 Hz, 1H), 3.05 (s,
3H), 2.90 (dd, J = 16.8, 3.9 Hz, 1H). 13C NMR (75 MHz, CDCl3) δ 199.2, 142.4,
141.8, 137.3, 133.2, 129.2, 128.7, 128.7, 128.6, 128.5, 128.3, 126.7, 126.6, 80.5,
59.1, 57.0, 43.1. HRMS (ESIꢀTOF) m/z: [M+Na]+ Calcd. for C23H22O2Na 353.1512;
found 353.1509.
5ꢀmethoxyꢀ2,2ꢀdimethyldodecanꢀ3ꢀone (4da). Compound 4da was prepared
according to the general procedure and was obtained in 90% yield (109.1 mg, 0.45
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mmol) as colourless oil. H NMR (300 MHz, CDCl3) δ 3.69 (ddd, J = 11.9, 8.7, 5.3
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Hz, 1H), 3.29 (s, 3H), 2.78 (dd, J = 17.0, 6.9 Hz, 1H), 2.42 (dd, J = 17.0, 5.4 Hz,
1H), 1.36 – 1.17 (m, 12H), 1.12 (s, 9H), 0.90 – 0.80 (m, 3H).13C NMR (75 MHz,
CDCl3) δ 214.6, 77.3, 57.4, 44.5, 41.5, 34.3, 31.9, 29.8, 29.4, 26.3, 26.3, 25.4,
22.8, 14.2. The spectral data match with that reported in the literature.30
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2ꢀ(1ꢀmethoxyoctyl)cyclohexanꢀ1ꢀone (4db). Compound 4db was prepared
according to the general procedure and was obtained in 95% yield (114.2 mg, 0.48
mmol) as a mixture of diastereoisomers in a 60:40 proportion (syn/anti). Syn
diastereoisomer: Colourless oil. 1H NMR (300 MHz, CDCl3) δ 3.67 (dt, J = 10.4, 5.1
Hz, 1H), 3.32 (s, 3H), 2.43 – 2.17 (m, 3H), 2.15 – 1.58 (m, 7H), 1.33 – 1.16 (m,
11H), 0.85 (t, J = 6.7 Hz, 3H). 13C NMR (75 MHz, CDCl3) δ 212.0, 78.1, 58.3, 54.3,
42.4, 32.2, 31.9, 29.8, 29.4, 27.4, 27.2, 25.7, 24.7, 22.7, 14.2. Anti
diastereoisomer: Colourless oil. 1H NMR (300 MHz, CDCl3) δ 3.62 (m, 1H), 3.31 (s,
3H), 2.65 – 2.52 (m, 1H), 2.45 – 2.21 (m, 2H), 2.09 – 1.94 (m, 2H), 1.94 – 1.81 (m,
1H), 1.69 – 1.19 (m, 15H), 0.87 (t, J = 6.7 Hz, 3H).13C NMR (75 MHz, CDCl3) δ
212.3, 79.7, 57.6, 53.1, 42.4, 32.0, 31.1, 29.9, 29.4, 28.1, 27.6, 25.9, 24.7, 22.8,
14.2. The spectral data match with that reported in the literature.31
3ꢀmethoxyꢀ1ꢀphenyldecanꢀ1ꢀone (4dc). Compound 4dc was prepared according
to the general procedure and was obtained in 95% yield (125.9 mg, 0.48 mmol) as
colourless oil. 1H NMR (300 MHz, CDCl3) δ 8.04 – 7.95 (m, 2H), 7.59 (ddd, J = 6.4,
3.8, 1.3 Hz, 1H), 7.54 – 7.44 (m, 2H), 3.98 – 3.82 (m, 1H), 3.38 (s, 3H), 3.32 (dd, J
= 16.1, 6.9 Hz, 1H), 2.97 (dd, J = 16.1, 5.3 Hz, 1H), 1.66 – 1.24 (m, 12H), 0.92 (t, J
= 6.7 Hz, 3H). 13C NMR (75 MHz, CDCl3) δ 199.2, 137.5, 133.1, 128.7, 128.3, 77.7,
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57.3, 43.4, 34.5, 31.9, 29.8, 29.4, 25.3, 22.7, 14.2.The spectral data match with
that reported in the literature.30
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prepared according to the general procedure and was obtained in >99% yield
(124.2 mg, 0.5 mmol) as colourless oil mixture of diastereoisomers. Spectra of the
inseparable mixture of diastereoisomers in a 71:29 proportion (syn/anti). The
syn/anti assignment was determined in comparison with the spectra reported in the
literature.32 Syn diastereoisomer: 1H NMR (300 MHz, CDCl3) δ 7.34 – 7.15 (m, 5H),
3.91 (td, J = 7.3, 3.6 Hz,1H,), 3.34 (s, 3H), 2.91 – 2.82 (m, 1H), 2.79 – 2.59 (m,
1H), 2.37 – 2.23 (m, 1H), 1.34 – 1.29 (m, 3H), 1.07 – 1.04 (m, 9H). Anti
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diastereoisomer: H NMR (300 MHz, CDCl3) δ 7.34 – 7.15 (m, 5H), 3.91 (td, J =
7.3, 3.6 Hz, 1H,), 3.27 (s, 1H), 3.05 – 2.99 (m, 1H), 2.79 – 2.59 (m, 1H), 2.37 –
2.23 (m, 1H), 1.34 – 1.29 (m, 3H), 1.07 – 1.04 (m, 9H). 13C NMR (75 MHz, CDCl3)
δ 214.6, 214.5, 144.3, 143.4, 128.5, 128.4, 128.3, 128.0, 126.5, 126.4, 81.9, 81.7,
59.3, 58.7, 44.5, 44.4, 42.6, 40.4, 38.7, 26.3, 26.2, 17.3, 16.2.
5ꢀhydroxyꢀ2,2ꢀdimethylꢀ6ꢀphenylhexanꢀ3ꢀone (5aa). Compound 5aa was
prepared according to the general procedure and was obtained in 88% yield (96.9
mg, 0.44 mmol) as white dense oil in 1.5 h. Eluents: hexane: ethyl acetate = 50:1.
1H NMR (300 MHz, CDCl3) δ 7.49 – 7.19 (m, 5H), 4.62 – 4.27 (m, 1H), 3.03 – 2.50
13
(m, 4H), 1.21 (s, 9H). C NMR (75 MHz, CDCl3) δ 217.3, 138.2, 129.4, 128.5,
126.5, 68.9, 44.2, 42.9, 42.3, 26.3. The spectral data match with that reported in
the literature.33
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2ꢀ(1ꢀhydroxyꢀ2ꢀphenylethyl)cyclohexanꢀ1ꢀone (5ab). Compound 5ab was
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prepared according to the general procedure and was obtained in 50% yield (54.6
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9
ο
mg, 0.25 mmol) as white solid (mp 58ꢀ60 C) in 1 h. (eluents: Hexane: ethyl
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acetate = 5:1). Spectra of the inseparable mixture of diastereoisomers in a 55:45
proportion (syn/anti).Syn diastereoisomer: 1H NMR (500 MHz, CDCl3) δ 7.37 – 7.29
(m, 5H), 4.45 – 4.37 (m, 1H), 3.35 (br s, 1H,), 2.86 (dd, J = 13.7, 8.0 Hz,1H), 2.71
(dd, J = 13.7, 6.3 Hz, 1H), 2.47 – 2.25 (m, 3H), 2.21 – 1.96 (m, 4H), 1.85 – 1.62
1
(m, 2H). Anti diastereoisomer: H NMR (500 MHz, CDCl3) δ 7.28 – 7.22 (m, 5H),
3.99 (br s, 1H), 2.96 (dd, J = 13.8, 4.5 Hz, 1H), 2.78 (dd, J = 13.8, 8.1 Hz, 1H),
2.55 (s, 1H), 2.47 – 2.25 (m, 3H), 2.21 – 1.96 (m, 4H), 1.85 – 1.62 (m, 2H).13C
NMR (126 MHz, CDCl3) δ 215.5, 214.7, 138.9, 138.7, 129.6, 129.3, 128.7, 128.5,
126.6, 126.5, 73.0, 70.3, 55.0, 54.2, 43.1, 42.8, 40.5, 39.6, 31.2, 28.1, 27.9, 26.8,
25.1, 25.0. HRMS (ESIꢀTOF) m/z: [M+H]+ Calcd. for C14H19O2 219.1380; found
219.1380.
3ꢀhydroxyꢀ1,4ꢀdiphenylbutanꢀ1ꢀone (5ac). Compound 5ac was prepared
according to the general procedure and was obtained in 83% yield (99.7 mg, 0.42
ο
mmol) as yellow solid (mp 75ꢀ77 C) in 1 h. Eluents: hexane: ethyl acetate = 5:1.
1H NMR (400 MHz, CDCl3) δ 7.95 – 7.93 (m, 2H), 7.62 – 7.58 (m, 1H), 7.50 – 7.45
(m, 2H), 7.38 – 7.34 (m, 2H), 7.33 – 7.24 (m, 3H), 4.55 – 4.49 (m, 1H), 3.26 (br s,
1H), 3.22 – 3.08 (m, 2H), 3.01 (dd, J = 13.6, 7.1 Hz, 1H), 2.88 (dd, J = 13.6, 6.4
Hz, 1H). 13C NMR (101 MHz, CDCl3) δ 200.6, 138.2, 136.9, 133.6, 129.6, 128.8,
128.7, 128.2, 126.7, 69.1, 44.2, 43.1. The spectral data match with that reported in
the literature.34
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2ꢀ(1ꢀhydroxyꢀ3ꢀphenylpropyl)cyclohexanꢀ1ꢀone (5bb). Compound 5bb was
prepared according to the general procedure and was obtained in 69% yield (80.2
mg, 0.35 mmol) as colourless oil in 3.5 h. Eluents: hexane: ethyl acetate = 5:1.
Spectra of the inseparable mixture of diastereoisomers in a 55:45 proportion
(syn/anti).Syn diastereoisomer: 1H NMR (500 MHz, CDCl3) δ 7.19 – 7.22 (m, 1H),
7.17 – 7.07 (m, 5H), 3.74 – 3.63 (m, 1H), 2.67 – 2.53 (m, 1H), 2.34 – 2.19 (m, 2H),
2.01 (dd, J = 9.5, 3.9 Hz, 2H), 1.90 – 1.44 (m, 8H). Anti diastereoisomer: 1H NMR
(500 MHz, CDCl3) δ 7.19 – 7.22 (m, 1H), 7.17 – 7.07 (m, 5H), 4.05 (dt, J = 9.6, 3.0
Hz, 1H), 2.84 – 2.74 (m, 1H), 2.34 – 2.19 (m, 2H), 2.01 (dd, J = 9.5, 3.9 Hz, 2H),
1.90 – 1.44 (m, 8H). 13C NMR (126 MHz, CDCl3) δ 215.9, 215.0, 142.5, 142.2,
128.6, 128.6, 128.5, 128.5, 126.0, 125.9, 71.1, 68.7, 56.2, 55.4, 43.0, 42.8, 35.6,
34.9, 32.6, 31.7, 31.1, 30.9, 27.9, 27.8, 26.7, 25.1, 25.1. HRMS (ESIꢀTOF) m/z:
[M+H]+ Calcd. for C15H21O2 233.1536; found 233.1541.
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3ꢀhydroxyꢀ1,5ꢀdiphenylpentanꢀ1ꢀone (5bc). Compound 5bc was prepared
according to the general procedure and was obtained in 41% yield (52.1 mg, 0.21
mmol) as yellow oil in 4 h. Eluents: hexane: ethyl acetate = 5:1. 1H NMR (500 MHz,
CDCl3) δ 8.04 – 7.92 (m, 2H), 7.67 – 7.57 (m, 1H), 7.55 – 7.45 (m, 2H), 7.36 – 7.30
(m, 2H), 7.29 – 7.27 (m, 2H), 7.25 – 7.20 (m, 1H), 4.30 – 4.26 (m, 1H), 3.40 (d, J =
2.9 Hz, 1H), 3.20 (dd, J = 17.7, 2.8 Hz, 1H), 3.11 (dd, J = 17.7, 8.9 Hz, 1H), 2.93
(ddd, J = 14.7, 9.7, 5.3 Hz, 1H), 2.80 (ddd, J = 13.8, 9.5, 6.9 Hz, 1H), 2.05 – 1.93
(m, 1H), 1.93 – 1.79 (m, 1H).13C NMR (126 MHz, CDCl3) δ 201.0, 142.0, 136.8,
133.7, 128.8, 128.6, 128.5, 128.2, 126.0, 67.2, 45.2, 38.3, 32.0. The spectral data
match with that reported in the literature.9, 35
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(E)ꢀ2ꢀ(2,2ꢀdiphenylethylidene)cyclohexanꢀ1ꢀone (5cb). Compound 5cb was
prepared according to the general procedure and was obtained in 89% yield (123.0
mg, 0.45 mmol) as white solid (mp 78ꢀ81 οC) in 2 h. Eluents: hexane: ethyl acetate
= 100:1. 1H NMR (300 MHz, CDCl3) δ 7.35 – 7.19 (m, 10H), 7.13 (dt, J = 10.0, 2.2
Hz, 1H), 4.94 (d, J = 10.0 Hz, 1H), 2.63 (td, J = 6.5, 2.2 Hz, 2H), 2.49 (t, J = 6.7 Hz,
2H), 1.93 – 1.84 (m, 2H), 1.83 – 1.72 (m, 2H).13C NMR (75 MHz, CDCl3) δ 201.1,
143.0, 140.1, 136.2, 128.8, 128.4, 126.8, 48.9, 40.4, 27.1, 23.6, 23.3. HRMS (ESIꢀ
TOF) m/z: [M+H]+ Calcd. for C20H21O 277.1587; found 277.1584.
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3ꢀhydroxyꢀ1,4,4ꢀtriphenylbutanꢀ1ꢀone (5cc). Compound 5cc was prepared
according to the general procedure and was obtained in 41% yield (64.9 mg, 0.21
ο
mmol) as pale yellow solid (mp 126ꢀ128 C) in 1.5 h. Eluents: hexane: ethyl
1
acetate = 50:1. H NMR (300 MHz, CDCl3) δ 7.94 – 7.85 (m, 2H), 7.63 – 7.22 (m,
13H), 5.13 (ddd, J = 11.6, 7.4, 3.3 Hz, 1H), 4.13 (d, J = 9.1 Hz, 1H), 3.20 – 3.13
(m, 2H).13C NMR (75 MHz, CDCl3) δ 200.5, 142.2, 141.6, 136.9, 133.5, 128.9,
128.8, 128.7, 128.7, 128.4, 128.2, 126.9, 126.8, 70.1, 57.8, 43.6. The spectral data
match with that reported in the literature.36
2ꢀ(1ꢀhydroxyoctyl)cyclohexanꢀ1ꢀone (5db). Compound 5db was prepared
according to the general procedure and was obtained in 46% yield (52.1 mg, 0.23
mmol) as colourless oil in 2 h. Eluents: hexane: ethyl acetate = 20:1. Spectra of the
inseparable mixture of diastereoisomers in a 55:45 proportion (syn/anti). Syn
diastereoisomer.1H NMR (500 MHz, CDCl3) δ 3.72 (t, J = 7.2 Hz, 1H), 2.45 – 2.26
(m, 3H), 2.14 – 2.04 (m, 2H), 2.00 – 1.85 (m, 1H), 1.74 – 1.58 (m, 2H), 1.56 – 1.38
(m, 3H), 1.37 – 1.20 (m, 11H), 0.87 (t, J = 6.9 Hz, 3H). Anti diastereoisomer 1H
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NMR (500 MHz, CDCl3) δ 4.13 – 4.03 (m, 1H), 2.45 – 2.26 (m, 3H), 2.14 – 2.04 (m,
2H), 2.00 – 1.85 (m,1H), 1.74 – 1.58 (m, 2H), 1.56 – 1.38 (m, 3H), 1.37 – 1.20 (m,
11H), 0.87 (t, J = 6.9 Hz, 3H)..13C NMR (126 MHz, CDCl3) δ 216.0, 215.2, 71.7,
69.2, 56.1, 55.1, 43.0, 42.8, 33.7, 33.0, 32.0, 32.0, 30.9, 29.8, 29.7, 29.4, 29.4,
28.0, 27.8, 26.5, 26.3, 25.3, 25.1, 25.1, 22.8, 14.2. HRMS (ESIꢀTOF) m/z: [M+H]+
Calcd. for C14H27O2 227.2006; found 227.2009.
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3ꢀhydroxyꢀ1ꢀphenyldecanꢀ1ꢀone (5dc). Compound 5dc was prepared according
to the general procedure and was obtained in 48% yield (59.6 mg, 0.24 mmol) as
ο
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white solid (mp 40ꢀ43 C) in 1.5 h. Eluents: hexane: ethyl acetate = 20:1. H NMR
(500 MHz, CDCl3) δ 7.97 – 7.95 (m, 2H), 7.60 – 7.57 (m, 1H), 7.52 – 7.43 (m, 2H),
4.22 (br s, 1H), 3.26 – 3.12 (m, 2H), 3.04 (dd, J = 17.6, 9.1 Hz, 2H), 1.67 – 1.56 (m,
2H), 1.53 – 1.47 (m, 2H), 1.42 – 1.21 (m, 9H), 0.88 (t, J = 7.0 Hz, 3H). 13C NMR
(126 MHz, CDCl3) δ 201.2, 137.0, 133.7, 128.8, 128.2, 67.9, 45.2, 36.7, 32.0, 29.7,
29.4, 25.7, 22.8, 14.2. The spectral data match with that reported in the literature.37
HRMS (ESIꢀTOF) m/z: [M+H]+ Calcd. for C16H25O2 249.1849; found 249.1849.
Acknowledgements
This work was supported by the Spanish Ministerio de Ciencia e Innovación,
European Community Founds (FEDER), CTQ 2010ꢀ19999 and CTQ2011ꢀ28942ꢀ
C02ꢀ02 grants. A. O. thanks the Spanish government for a Juan de la Cierva
contract. We thank the SCSIE (Universidad de Valencia) for access to instrumental
facilities.
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Supporting Information
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Optimization Table and copies of H and 13C NMR spectra for all compounds. This
material is available free of charge via the Internet at http://pubs.acs.org.
References
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