Novel phosphoryloxylactonisation of pentenoic acids mediated by ammonium iodide

Article abstract of DOI:10.3184/174751914X14117493538131

Using ammonium iodide as a catalyst and m-chloroperbenzoic acid as the oxidant, a novel and efficient procedure has been developed for phosphoryloxylactonisation of alkenoic acids in CH3CN at room temperature, which provides the corresponding phosphoryloxylactones in good yields. In this protocol, it is proposed that ammonium iodide catalyst is first oxidised to hypoiodous acid, which reacts with the alkenoic acid to afford the corresponding iodolactone. Then, the iodolactone is further transformed into a hypervalent iodine intermediate by continuing oxidation, and finally the in situ generated active iodine species reacts with a diaryl phosphate to furnish the phosphoryloxylactone end product.

Full text of DOI:10.3184/174751914X14117493538131

630 RESEARCH PAPER
VOL. 38 OCTOBER, 630–633
JOURNAL OF CHEMICAL RESEARCH 2014
Novel phosphoryloxylactonisation of pentenoic acids mediated by
ammonium iodide
Zhong-Shi Zhoua* and Xue-Han Heb
aCollege of Biological and Environmental Sciences, Zhejiang Shuren University, Hangzhou 310015, P.R. China
bZhejiang Institute of Geology and Mineral Resource Laboratory, Hangzhou 310007, P.R. China
Using ammonium iodide as a catalyst and m‑chloroperbenzoic acid as the oxidant, a novel and efficient procedure has been
developed for phosphoryloxylactonisation of alkenoic acids in CH3CN at room temperature, which provides the corresponding
phosphoryloxylactones in good yields. In this protocol, it is proposed that ammonium iodide catalyst is first oxidised to
hypoiodous acid, which reacts with the alkenoic acid to afford the corresponding iodolactone. Then, the iodolactone is further
transformed into a hypervalent iodine intermediate by continuing oxidation, and finally the in situ generated active iodine
species reacts with a diaryl phosphate to furnish the phosphoryloxylactone end product.
Keywords: phosphoryloxylactonisation, hypervalent iodine intermediate, ammonium iodide, catalytic cyclisation, pentenoic acids
Hypervalent iodine reagents have found broad application
in organic chemistry and are frequently used in synthesis as
they are non-metallic oxidation reagents and avoid the issues
of toxicity of many transition metals commonly involved in
such processes.1–10 Using hypervalent iodine reagents, some
special compounds such as phosphoryloxylactones which
are important in organic chemistry as well as biochemistry
have been prepared. In 1988, Koser’s group utilised a novel
hypervalent iodine reagent, [hydroxyl((bis(phenyloxy)
phosphoryl)oxy)iodo]-benzene, to react with pent-4-enoic acids
and prepared some new phosphoryloxylactones.11 However, as
this method was a two-step procedure and the yields are low,
the number of prepared phosphoryloxylactones is only three.
Other methods for synthesis of phosphoryloxylactones, except
direct phosphorylation of sugar lactones, are less.12,13 In order
to develop more efficient procedures for the preparation of
phosphoryloxylactones, we recently improved Koser’s method
using (diacetoxyiodo)benzene and phosphates in place of
In order to extend the scope of hypervalent iodine
reagents for organic synthesis, we have developed a method
for phosphoryloxylactonisation of alkenoic acids using
iodobenzene as catalyst, and a series of phosphoryloxylactones
has been prepared.24 Based on this success, we have now
investigated the more environmentally benign catalytic
phosphoryloxylactonisation of alkenoic acids in the presence of
a sub-stoichiometric amount of ammonium iodide (NH4I), and
obtained the desired phosphoryloxylactones in good yields. We
now report this novel phosphoryloxylactonisation of alkenoic
acids catalysed by NH4I.
Firstly, we examined the reaction of equivalent amounts of
pent-4-enoic acid, diphenyl phosphate and m-chloroperbenzoic
acid (mCPBA) in the presence of 0.1 equiv. of NH4I in CH3CN
at room temperature and found that this reaction occurred
readily and provided the desired product 5-(bis(phenyloxy)
phosphory)oxy-4-pentanolactone (Table 1). Encouraged by
the result, the reaction conditions were optimised. As shown
in Table 1, solvent influenced the reaction greatly and CH3CN
was superior to other solvents (entries 1–6). 2.0 Equiv. of
mCPBA and 1.2 equiv. of diphenyl phosphate were optimal
for the reaction (entries 5, 7–13). The amount of NH4I was
also investigated, and 0.1 equiv. of it was optimal (entries 11,
14–15). However, if NH4I was absent, no desired product was
observed (entry 16). The reaction was completed in several
hours and 8 h was selected as the best suitable reaction time
(entries 11, 17–19). Other oxidants, such as Oxone, NaBO3 and
Na2S2O8, when they were in place of mCPBA, usually resulted
in bad yields (entries 20–22).
[hydroxy((bis(phenyloxy)phosphoryl)oxy)iodo]benzene
and
reported a “one pot” procedure.14
The catalytic utilisation of hypervalent iodine reagents as
catalysts has been increasing in importance, with growing
interest in the development of environmentally benign
synthetic transformations.15–19 In these reactions, a sub-
stoichiometric amount of an iodine-containing compound
together with a stoichiometric amount of oxidant are used.
Recently, Togo and co-workers have investigated a new method
for the α‑tosyloxylation of ketones using molecular iodine as
catalyst, which has been shown to involve a hypervalent iodine
intermediate. 20 This method avoids the need for expensive aryl
iodides and gives good yields. It is well known that molecular
iodine can be easily accessed from iodides, but the use of
the one-pot reaction mediated by hypervalent iodine species
generated in situ from iodides, especially inorganic iodides, a
method which is more environmentally benign has been quite
limited.21–23
Under the optimal reaction conditions, we investigated the
phosphoryloxylactonisation of 1.0 equiv. of a range of alkenoic
acids (1), 1.2 equiv. of a selection of diarylphosphate (2) and
2.0 equiv. of mCPBA with 0.1 equiv. of NH4I in CH3CN at room
temperature in 8 h (Scheme 1). The results are summarised in
Table 2.
O
R1
NH4I
mCPBA
O
R3
R2
O
O
R2
+
HOP(OR)2
O
OH
CH3CN, RT
R3
R1
OP(OR)2
1
2
3
Scheme 1
* Correspondent. E-mail: zhoushan63@163.com
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JOURNAL OF CHEMICAL RESEARCH 2014 631
Table 1 Optimisation of the NH4I catalysed phosphoryloxylactonisation of pent‑4‑enoic acid
O
O
NH4I
mCPBA
O
O
+
HOP(OPh)2
O
OH
RT
OP(OPh)2
Solvent
Entry
NH4I/equiv.
Oxidant/equiv.b Diphenyl phosphate/equiv.
Time/h
Yield/%a
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.2
0.05
0
1.5
1.5
1.5
1.5
1.5
1.5
2.0
2.5
1.2
1.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.2
1.5
2.0
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.2
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
4
THF
CH3OH
DMF
21
25
3
CF3CH2OH
CH3CN
CH2Cl2
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
54
61
32
68
65
45
34
71
72
73
72
52
0
0.1
0.1
0.1
0.1
0.1
0.1
55
73
74
24
5
12
15
8
8
8
2.0
(2.0)c
(2.0)d
(2.0)e
13
aIsolated yield.
bmCPBA unless otherwise indicated: cOxone; dNaBO3; eNa2S2O8.
Table 2 shows that the studied alkenoic acids readily reacted
with phosphates (2a and 2b) catalysed by NH4I, to provide
To support the proposed mechanism, pent-4-enoic acid was
firsttreatedwithHOI,25 whichprovidedtheiodolactoneinnearly
quantitative yield. Then, the reaction of this iodolactone with
phosphate was examined. In the absence of oxidant mCPBA,
the desired product 5-phosphoryloxy-4-pentanolactone was
not observed even after a long reaction time. However, when
mCPBA was added to the reaction mixture, the desired product
the
corresponding
5-phosphoryloxy-4-pentanolactones
were obtained in moderate to good yields (Table 2, entries
1–7). Phosphoryloxylactones 3b, 3c and 3f were mixtures
of diastereoisomers, the ratios were 2.8:1 for 3b, 1:1 for 3c
and 2.4:1 for 3f respectively, which were determined by
examination of the 1H NMR spectra of phosphoryloxylactones.
Bis(4-nitrophenyl)phosphate (2c) also reacted with pent-4-
enoic acid, but the product (3h) was unstable and decomposed
during purification; the yield was measured on the crude
product by 1H NMR (entry 8). In order to prepare the related six-
membered and four-membered phosphoryloxylactones, hex-5-
enoic acid and but-3-enoic acid were treated under the same
conditions, but neither of the desired phosphoryloxylactones
were obtained. It may be that they were not formed or
were unstable and decomposed during purification, which
was as we have observed before.11,14,24 Therefore, our new
method is only suitable for preparation of five-membered
phosphoryloxylactones.
A plausible reaction pathway for the present reaction is
shown in Scheme 2, which is different from that we reported
previously.24 Thus, NH4I is first oxidised by mCPBA to
HOI, which reacts with the alkenoic acid to afford the
iodolactone.25 Then, this is transformed into the hypervalent
iodine intermediate in situ by continuing oxidation.26,27 The
hypervalent iodine intermediate is generally highly unstable
and when it reacts with phosphate, the phosphoryloxylactone is
formed by nucleophilic substitution.2–4
O
H
O
O
OH
I
O
HOI
O
O
I
mCPBA
mCPBA
O
NH I
4
I(III)
HOPO(OPh)2
O
O
O
OP(OPh)
2
Scheme 2
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632 JOURNAL OF CHEMICAL RESEARCH 2014
Table 2 The catalytic phosphoryloxylactonisation of alkenoic acids
Entry
Alkenoic acids (1) Phosphates (2)
Phosphoryloxylactones (3)
Yield/%a
71
O
R1, R2, R3=H
R=Ph
1
3a
O
O
1a
2a
OP(OPh)2
Me
O
R1=Me
R2, R3=H
1b
2
3
4
5
6
2a
2a
2a
3b
74
63
74
71
68
O
O
OP(OPh)2
O
R2=Me
R1, R3=H
1c
3cb
Me
O
O
OP(OPh)2
Me
O
R1, R2=Me
R3=H
1d
Me
3d
OP(OPh)2
O
O
O
O
R=Bn
2b
1a
1b
3e
3f
O
OP(OBn)2
Me
O
2b
2b
O
O
OP(OBn)2
Me
O
Me
7
8
1d
1a
3g
76
O
O
OP(OBn)2
O
R=C6H4NO2‑p
2c
3h
OP(OC6H4NO2-p)2
47c
O
O
aIsolated yields.
bSee text (diastereoisomeric mixture).
c
1H NMR analysis.
NH4I catalytic phosphoryloxylactonisation of alkenoic acids; typical
procedure
was obtained in good yield. Therefore, an in situ generated
hypervalent iodine intermediate is responsible for effecting the
reaction.
To CH3CN (5 mL), pent-4-enoic acid (0.030 g, 0.3 mmol), diphenyl
phosphate (0.090 g, 0.36 mmol), mCPBA (75%, 0.138 g, 0.60 mmol)
and NH4I (0.0043 g, 0.030 mmol) were added. The mixture was
stirred at room temperature for 8 h. Then H2O (5 mL), sat.aq Na2S2O3
(2 mL) and sat. aq Na2CO3 (2 mL) were added. The mixture was
extracted with CH2Cl2 (3×5 mL) and the combined organic extract
was dried over anhydrous Na2SO4, filtered, and concentrated under
reduced pressure. The residue was purified on silica gel plate using
(3:2 hexane-ethyl acetate) as eluent to afford 5-(bis(phenyloxy)
phosphoryl)oxy-4-pentanolactone in 71% yield.
In summary, we have developed a novel and efficient
procedure for phosphoryloxylactonisation of alkenoic acids
using a sub-stoichiometric amount of NH4I with mCPBA
in CH3CN at room temperature. The results highlight the
advantageous role of inorganic iodide as the catalyst as a
replacement for expensive aryl iodides. Moreover, it extends
the scope of hypervalent iodine reagents in organic synthesis,
as well as being more environmentally benign.
Experimental
5-(Bis(phenyloxy)phosphoryl)oxy-4-pentanolactone (3a): White solid,
m.p. 77–78 °C (lit.14 77–78 °C). 1H NMR (500 MHz, CDCl3): δ 7.37–7.34
(m, 4H), 7.23–7.20 (m, 6H), 4.72–4.70 (m, 1H), 4.47–4.43 (m, 1H),
4.32–4.27 (m, 1H), 2.49–2.45 (m, 2H), 2.33–2.26 (m, 1H), 2.10–2.03 (m,
1H). 13C NMR (125 MHz, CDCl3): δ 176.2, 150.3 (dd, J=6.3, 2.5 Hz),
129.9, 125.6, 120.0 (d, J=5.0 Hz), 77.3, 69.2 (d, J=5.0 Hz), 27.9, 23.2.
31P NMR (202 MHz, CDCl3): δ –12.1. IR (neat, cm–1): 1771, 1593, 1489,
1293, 1221, 1189, 1044, 947. MS (EI, m/z, %): 348 (M+, 62.3), 249 (100).
HRMS: m/z [M]+ calcd for C17H17O6P: 338.0763; found: 348.0751.
Melting points were determined on a digital apparatus and were
not corrected. IR spectra were recorded on a Thermo-Nicolet 6700
instrument, NMR spectra were measured on a Bruker Avance III
1
(500 MHz) spectrometer using TMS as internal standard for H and
13C spectra and 80% phosphoric acid as standard for 31P spectra. Mass
spectra were determined on a Thermo-ITQ 1100 mass spectrometer.
Alkenoic acids, phosphates, mCPBA, NH4I and solvents were
commercially available.
JCR1402737_FINAL.indd 632
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JOURNAL OF CHEMICAL RESEARCH 2014 633
5-(Bis(phenyloxy)phosphoryl)oxy-2-methyl-4-pentanolactone
135.5 (d, J=6.3 Hz), 128.7, 128.6 (d, J=3.8 Hz), 128.0 (d, J=2.5 Hz),
75.6 (d, J=7.5 Hz), 75.1 (d, J=7.5 Hz), 69.6 (d, J=5.0 Hz), 68.2 (d,
J=6.3 Hz), 67.5 (d, J=5.0 Hz), 35.1, 33.6, 31.9, 31.5, 16.0, 15.1. IR (neat,
cm–1): 3034, 1774, 1597, 1456, 1278, 1171, 1012. MS (EI, m/z, %): 390
(M+, 18.8), 277 (100). HRMS: m/z [M]+ calcd for C20H23O6P: 390.1232;
found: 390.1201.
1
(3b) (2:8:1 diastereoisomeric mixture):24 Light yellow oil. H NMR
(500 MHz, CDCl3): δ 7.38–7.34 (m, 4H), 7.24–7.19 (m, 6H), 4.68–4.65
(m, 0.26H), 4.59–4.54 (m, 0.74H), 4.48–4.40 (m, 1H), 4.31–4.26 (m,
1H), 2.73–2.63 (m, 0.74H), 2.59–2.54 (m, 0.26H), 2.45–2.39 (m,
0.74H), 2.33–2.28 (m, 0.26H), 2.01–1.95 (m, 0.26H), 1.71–1.61 (m,
0.74H), 1.23 (d, J=7.5 Hz, 2.22H), 1.21 (d, J=7.5 Hz, 0.78H). 13C NMR
(125 MHz, CDCl3): δ 179.1, 178.3, 150.3 (dd, J=7.5, 3.8 Hz), 129.8 (d,
J=5.0 Hz), 125.5, 120.0 (dd, J=7.5, 3.8 Hz), 75.4 (d, J=7.5 Hz), 74.9 (d,
J=8.8 Hz), 69.5 (d, J=5.0 Hz), 68.5 (d, J=5.0 Hz), 35.1, 33.6, 31.8, 31.4,
16.0, 15.0. 31P NMR (202 MHz, CDCl3): δ –12.1, –12.0. IR (neat, cm–1):
3070, 1775, 1590, 1489, 1294, 1190, 1024, 955. MS (EI, m/z, %): 362
(M+, 34.8), 249 (100). HRMS: m/z [M]+ calcd for C18H19O6P: 362.0919;
found: 362.0901.
5-(Bis(benzoyloxy)phosphoryl)oxy-2,2-dimethyl-4-pentanolactone
1
(3g):24Yellow oil. H NMR (500 MHz, CDCl3): δ 7.37–7.35 (m, 10H),
5.10–5.02 (m, 4H), 4.53–4.49 (m, 1H), 4.16–4.12 (m, 1H), 4.01–3.96
(m, 1H), 2.03–1.99 (m, 1H), 1.85–1.80 (m, 1H), 1.24 (s, 6H). 13C NMR
(125 MHz, CDCl3): δ 181.0, 135.6 (d, J=6.3 Hz), 128.7 (d, J=3.8 Hz),
128.1 (d, J=2.5 Hz), 74.3 (d, J=7.5 Hz), 69.6 (d, J=5.0 Hz), 67.8 (d,
J=5.0 Hz), 39.9, 38.3, 24.8 (d, J=8.8 Hz). IR (neat, cm–1): 1764, 1460,
1267, 1024, 991. MS (EI, m/z, %): 404 (M+, 50.1), 277 (100). HRMS:
m/z [M]+ calcd for C21H25O6P: 404.1389; found: 404.1377.
5-(Bis(phenyloxy)phosphoryl)oxy-3-methyl-4-pentanolactone
(3c) (1:1 diastereoisomeric mixture):24 Light yellow oil. 1H NMR
(500 MHz, CDCl3): δ 7.38–7.34 (m, 4H), 7.23–7.20 (m, 6H), 4.63–4.60
(m, 0.5H), 4.48–4.43 (m, 1H), 4.41–4.37 (m, 0.5H), 4.34–4.29 (m,
0.5H), 4.23–4.20 (m, 0.5H), 2.77–2.72 (m, 0.5H), 2.66–2.55 (m, 1H),
2.46–2.40 (m, 0.5H), 2.22–2.14 (m, 1H), 1.15 (d, J=7.0 Hz, 1.5H), 1.09
(d, J=7.5 Hz, 1.5H). 13C NMR (125 MHz, CDCl3): δ 175.7, 175.4, 150.2
(d, J=7.5 Hz), 129.9, 125.6, 120.0 (d, J=5.0 Hz), 83.9 (d, J=7.5 Hz),
79.7 (d, J=7.5 Hz), 67.8 (d, J=6.3 Hz), 67.1 (d, J=6.3 Hz), 36.2 (d,
J=23.8 Hz), 31.8, 31.3, 18.0, 13.5. IR (neat, cm–1): 3068, 1786, 1592,
1489, 1293, 1190, 1029, 956. MS (EI, m/z, %): 362 (M+, 11.2), 249 (100).
HRMS: m/z [M]+ calcd for C18H19O6P: 362.0919; found: 362.0893.
5-(Bis(phenyloxy)phosphoryl)oxy-2,2-dimethyl-4-pentanolactone
Received 26 June 2014; accepted 21 September 2014
Paper1402737 doi: 10.3184/174751914X14117493538131
Published online: 17 October 2014
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