One-pot synthesis of α-formyloxy ketones from enolizable ketones

Article abstract of DOI:10.1080/00397910701767049

One-pot synthesis of α-formyloxy tones as well as α-acetoxy ketones from enolizable ketones and [hydroxy(tosyloxy) iodo] benzene (HTIB)/polymer supported [hydroxy(tosyloxy) iodo] benzene (PSHTIB) in N,N-dimethylformamide (DMF)/N, N-dimethylacetamide (DMA)

Full text of DOI:10.1080/00397910701767049

Synthetic Communicationsw, 38: 338–345, 2008
Copyright # Taylor & Francis Group, LLC
ISSN 0039-7911 print/1532-2432 online
DOI: 10.1080/00397910701767049
One-Pot Synthesis of a-Formyloxy Ketones
from Enolizable Ketones
Sunil Kumar, Ashok Kumar, Rakesh K. Gupta,
and Devinder Kumar
Department of Chemistry, Guru Jambeshwar University of Science and
Technology, Hisar, Haryana, India
Abstract: One-pot synthesis of a-formyloxy tones as well as a-acetoxy ketones from
enolizable ketones and [hydroxy(tosyloxy) iodo] benzene (HTIB)/polymer supported
[hydroxy(tosyloxy) iodo] benzene (PSHTIB) in N,N–dimethylformamide (DMF)/
N, N–dimethylacetamide (DMA) in high yields is described.
Keywords: a-acetoxy ketones, a-formyloxy ketones, [hydroxyl(tosyloxy)iodo]ben-
zene, polymer-supported [hydroxyl(tosyloxy)iodo]benzene
The a-formyloxy ketones are useful intermediates for synthesizing (oxodiox-
olenyl) methylcarbamate as novel nonchiral bioreversible prodrug moieties
for chiral amino functional drugs.[1,2] a-Formyloxy/acetoxy indane-1,3-
dione derivatives are effective as allergy inhibitors.[3,4] The formate and
acetate groups also serve as good protective groups for the hydroxyl
function in a-hydroxy ketones,[5] the moiety that is present in many biologi-
cally active natural products.[6] The a-acetoxy ketones find applications for
biotransformation to optically active 1,2-diols, which are important intermedi-
ates in organic synthesis and for staining biologically active compounds.[7]
There are various protocols for synthesizing a-acetoxy ketones.[8–12]
Received in India July 12, 2007
Address correspondence to Devinder Kumar, Department of Chemistry, Guru
Jambeshwar University of Science and Technology, Hisar 125001, Haryana, India.
E-mail: dk_ic@yahoo.com
338

a-Formyloxy Ketones
339
Scheme 1. R1 ¼ aryl, 2-thienyl, naphthyl; R2 ¼ H, Me, cycloakyl; and R3 ¼ H, Me.
Table 1. Physical data of a-formyloxy and a-acetoxy ketones (5)a
a-Formyloxy ketone a-Acetoxy ketone
Yield
(%)
Mp (8C)
(lit. mp)
Yield
(%)
Mp (8C)
(lit. mp)
Entry
1
Reactants
C6H5COCH3
75
50
78
45
(50–52)[12]
Liquid[12]
65–67
2
3
4-CH3C6H4COCH3
4-CH3OC6H4COCH3
70
75
76
74
Liquid[9]
69
(84.5)[10]
55
62
4
5
2-CH3OC6H4COCH3
4-CIC6H6COCH3
65
78
48
82
72
80
(82–85)[12]
90
69
(70.3)[10]
7010]
6
7
4-BrC6H4COCH3
4-FC6H4COCH3
C6H5COCH2CH3
1-Indanone
80
75
85
80
68
70
70
80
42[10]
8
85
Liquid
Liquid[10]
Liquid
9
66–67
70
78
10
11
2-Acetylthiophene
1-Acetylnaphthalene
62
Liquid
Liquid
aThe elemental analysis of unknown compounds was found be satisfactory (0.4%),
and in IR, the carbonyl band appeared at 1732 + .8, 1701 + .8 cm21 in all compounds
besides other bands.

340
S. Kumar et al.
Table 2. Spectroscopic data of a-formyloxy ketones (5)
Entry
1
1H NMR (CDCl3)
13C NMR (CDCl3)
5.44 (s, 2H, CH2), 7.47–7.51
(m, 2H, H3 and H5), 7.59–7.64
(m, 1H, H4), 7.90–7.93
(m, 2H, H2 and H6), 8.25
(s, 1H, OCHO)
65.3 (CH2), 127.7 (C-3 and C-5),
128.9 (C-2 and C-6), 133.8
(C-1), 134.0 (C-4), 160.0
(OC55O), 191.1 (C55O)
2
3
4
2.34 (s, 3H, CH3), 5.34 (s, 2H,
CH2), 7.21 (d, J ¼ 8 Hz, 2H,
H3 and H5), 7.74 (d, J ¼ 8 Hz,
2H, H2 and H6), 8.17 (s, 1H,
OCHO)
21.8 (CH3), 65.3 (CH2), 127.9
(C-2 and C-6), 129.6 (C-3 and
C-5), 131.4 (C-1), 145.1 (C-4),
160.1 (OC55O), 190.7 (C55O)
3.87 (s, 3H, OCH3), 5.40 (s, 2H,
CH2), 6.96 (dd, J ¼ 6.9,
55.5 (OCH3), 65.0 (CH2), 114.1
(C-3 and C-5), 126.8 (C-1),
130.1 (C-2 and C-6), 160.1
(OC55O), 164.1(C-4), 189.5
(C55O)
2.0 Hz, 2H, H3 and H5), 7.89
(dd, J ¼ 6.9, 2.0 Hz, 2H, H2
and H6), 8.25 (s, 1H, OCHO)
3.96 (s, 3H, OCH3), 5.34 (s, 2H,
CH2), 7.00 (d, J ¼ 8.4 Hz, 1H,
H3), 7.05 (t, J ¼ 7.4 Hz, 1H,
H4), 7.54 (1 H, dt, J ¼ 7.8,
1.6 Hz, H5), 7.97 (1 H, dd,
J ¼ 7.6, 1.6 Hz, H6), 8.24 (1
H, s, OCHO).
55.7 (OCH3), 69.4 (CH2), 111.5
(C-3), 121.1 (C-5), 124.0 (C-
1), 131.2 (C-6), 135.2 (C-4),
159.6 (C-2), 160.4 (OC55O),
191.9(C55O)
5
6
7
5.32 (s, 2H, CH2), 7.37–7.41
(m, 2H, H3 and H5), 7.76–7.80
(m, 2H, H2 and H6), 8.16
(s, 1H, OCHO)
65.4 (CH2), 128.8 (C-3 and C-5),
130.0 (C-2 and C-6), 135.5
(C-1), 138.2 (C-4), 160.0
(OC55O), 190.3 (C55O)
65.1 (CH2), 129.3 (C-2 and C-6),
129.4 (C-4), 132.3 (C-3 and
C-5), 132.6 (C-1), 160.0
5.40 (s, 2H, CH2), 7.63–7.66
(m, 2H, H3 and H5), 7.77–7.80
(m, 2H, H2 and H6), 8.25
(s, 1H, OCHO)
(OC55O), 190.3 (C55O)
65.1 (CH2), 116.2
5.41 (2 H, s, CH2), 7.15–7.21
(m, 2H, H3 and H5), 7.93–7.98
(m, 2H, H2 and H6), 8.25
(s, 1H, OCHO)
(d, JCF ¼ 22 Hz, C-3 and C-5),
130.4 (d, JCF ¼ 2.8 Hz, C-1),
130.5 (d, JCF ¼ 9.00 Hz, C-2
and C-6), 160.0 (OC55O),
166.0 (d, JCF ¼ 255.0 Hz,
C-4), 189.6 (C55O)
8
1.57 (d, J ¼ 7.04 Hz, 3H, CH3),
6.12 (q, J ¼ 7.04,1H, CH),
7.47–7.52 (m, 2H, H3 and H5),
7.59–7.63 (m, 1H, H4), 7.92–
7.96 (m, 2H, H2 and H6), 8.13
(s, 1H, OCHO)
17.2 (CH3), 69.3 (CH), 128.5
(C-3 and C-5), 128.8 (C-2 and
C-6), 133.8 (C-4), 134.0 (C-1),
160.1 (OC55O), 195.8 (C55O).
(continued)

a-Formyloxy Ketones
Table 2. Continued
341
Entry
9
1H NMR (CDCl3)
13C NMR (CDCl3)
3.10 (dd, J ¼ 17.0, 4.8 Hz, 1H),
3.70 (dd, J ¼ 17.0, 8.0 Hz,
1H), 5.54–5.57 (m, 1H),
33.2 (C-3), 73.5 (C-2), 124.6
(C-6), 126.7 (C-4), 128.3
(C-7), 134.2 (C-7a), 136.1
(C-5), 150.2 (C-3a), 160.2
(OC55O), 199.8 (C55O)
7.42–7.48 (m, 2H), 7.65–7.69
(m, 1H), 7.81 (d, J ¼ 7.76 Hz,
1H), 8.23 (s, 1H, OCHO)
10
11
5.33 (s, 2H, CH2), 7.18 (dd,
J ¼ 4.84, 3.96 Hz, 1H, H4),
7.40 (dd, J ¼ 4.9, 0.8 Hz, 1H,
H5), 7.77 (dd, J ¼ 3.8, 0.8 Hz,
1H, H3) 7.73–7.77 (m, 2H),
8.24 (s, 1H, OCHO)
65.0 (CH2), 128.4 (C-4), 132.1
(C-3), 134.7 (C-5), 140.0
(C-2), 160.0 (OC55O), 184.3
(C55O)
5.39 (s, 2H, CH2), 7.47–7.62
(m, 3H, H3, H6 and H7), 7.81–
7.87 (m, 2H, H2 and H5), 8.01
(d, J ¼ 8.2 Hz, 1H, H4), 8.26
(s, 1H, OCHO), 8.63
66.7 (CH2), 124.2 (C-3), 125.4
(C-8), 126.8 (C-6), 127.6 (C-
7), 128.5 (C-5), 128.7 (C-2),
130.2 (C-8a), 131.9 (C-4a),
133.8 (C-4), 133.9 (C-1),
(d, J ¼ 8.0 Hz, 1H, H8)
160.1 (OC55O), 194.8 (C55O)
However, there exist only two reports (i.e., aniodic oxidation of enol
carbonate[13] and a thallium(III)triflate[14]) for furnishing a-formyloxy
ketones. Keeping in view the importance of a-formyloxy and a-acetoxy
ketones, we report herein a smooth conversion of enolizable ketones to
a-formyloxy and a-acetoxy ketones using fhydoxy(tosyloxy) iodogbenzene
(HTIB) as well as polymer-supported [hydoxy(tosyloxy)iodo]benzene
(PSHTIB) in DMF and DMA solvent with high yields.
The enolizable ketones (I) are first converted to corresponding
a-tosyloxy ketones (2) using HTIB or PSHTIB.[15] The reaction of 2 with
3 (R55H, DMF and R55CH3, DMA) as solvent generated iminium salt inter-
mediate (4), which on subsequent treatment with water cleanly afforded
a-formyloxy ketones and a-acetoxy ketones (5), respectively, within 15–
45 min. (Scheme 1). The products were purified by percolation through a
column of silica gel using hexane–ethyl acetate as eluent. The structure of
the products was established through their physical and spectroscopic
(FTIR and NMR) data. The physical data are presented in Table 1. The spec-
troscopic data of a-formyloxy ketones and a-acetoxy ketones are presented
in Tables 2 and 3, respectively.
Further, we also examined the reaction of 1 with diacetoxyiodobenzene in
the presence of trifluoromethane sulphonic acid which resulted in the desired
product (5), but the HTIB-mediated reaction was much cleaner. The reaction
was extended to a variety of substrate to afford 5 for generalization. The

342
S. Kumar et al.
Table 3. Spectroscopic data of a-acetoxy ketones (5)
Entry
1
1H NMR (CDCl3)
13C NMR (CDCl3)
2.22 (s, 3H, CH3), 5.34 (s, 2H,
CH2), 7.46–7.51 (m, 2H, H3
and H5), 7.58–7.63 (m, 1H,
H4), 7.90–7.93 (m, 2H, H2
and H6)
20.6 (CH3), 66.0 (CH2), 127.8
(C-3 and C-5), 128.9 (C-2 and
C-6), 133.9 (C-4), 134.2 (C-1),
170.5 (OC55O), 192.2 (C55O)
2
3
2.22 (s, 3H, CH3), 2.41 (s, 3H,
CH3), 5.31 (s, 2H, CH2), 7.26–
7.28 (m, 2H, H3 and H5),
7.80–7.82 (m, 2H, H2 and H6)
20.6 (CH3), 21.7 (CH3), 66.0
(CH2), 127.9 (C-2 and C-6),
129.5 (C-3 and C-5), 131.8
(C-1), 144.9 (C-4), 170.5
(OC55O), 191.7(C55O)
2.22 (s, 3H, CH3), 3.88 (s, 3H,
OCH3), 5.29 (s, 2H, CH2),
6.95 (dd, J ¼ 6.96, 2.00 Hz,
2H, H3 and H5), 7.90 (dd,
J ¼ 6.96, 2.00 Hz, 2H, H2
and H6)
20.6 (CH3), 55.5 (OCH3), 65.8
(CH2), 114.1 (C-3 and C-5),
127.3 (C-1), 130.1 (C-2 and
C-6), 164.1 (C-4), 170.5
(OC55O), 190.6(C55O)
4
2.19 (s, 3H, CH3), 3.92 (s, 3H,
OCH3), 5.22 (s, 2H, CH2),
6.96–7.05 (m, 2H, H3 and H5),
7.48–7.54 (m, 1H, H4), 7.91
(dd, J ¼ 7.8, 1.8 Hz, 1H, H6)
2.22 (s, 3H, CH3), 5.29 (s, 2H,
CH2), 7.45–7.48 (m, 2H, H3
and H5), 7.83–7.87 (m, 2H, H2
and H6)
20.6 (CH3), 56.0 (OCH3), 65.9
(CH2), 114.0 (C-3), 120.7
(C-5), 123.0 (C-1), 129.6
(C-6), 133.9 (C-4), 162 (C-2),
170.5 (OC55O), 191.2 (C55O)
20.5 (CH3), 65.9 (CH2), 129.2
(C-3 and C-5), 129.3 (C-2 and
C-6), 132.6 (C-1), 140.4 (C-4),
170.4 (OC55O), 191.1 (C55O)
20.6 (CH3), 65.8 (CH2), 129.2
(C-4), 129.3 (C-3 and C-5),
132.3 (C-3 and C-5), 132.9
(C-1) 170.4 (OC55O), 191.3
(C55O)
5
6
2.22 (s, 3H, CH3), 5.28 (s, 2H,
CH2), 7.63 (d, 2H, J ¼ 8.6 Hz,
H3 and H5), 7.78 (d, 2H,
J ¼ 8.6 Hz, H2 and H6)
7
2.22 (s, 3H, CH3), 5.30 (s, 2H,
CH2), 7.14–7.19 (m, 2H, H3
and H5), 7.93–7.97 (m, 2H)
20.6 (CH3), 65.8 (CH2), 116.2
(d, J ¼ 32 Hz, C-3 and C-5),
130.6 (d, J ¼ 10.00 Hz, C-2
and C-6), 130.7 (d, J ¼ 3.00 Hz,
C-1), 166.0 (d, J ¼ 255.0 Hz,
C-4), 170.4 (OC55O), 190.7
(C55O)
8
1.52 (d, J ¼ 7.0 Hz, 3H, CH3),
2.13 (s, 3H, CH3), 5.96 (q, 1H,
CH), 7.45–7.48 (m, 2H, H3
and H5), 7.55–7.60 (m, 1H,
H4), 7.91–7.95 (m, 2H, H2
and H6)
17.0 (CH3), 20.6 (CH3), 71.3
(CH), 128.3 (C-3 and C-5),
128.7 (C-2 and C-6), 133.5
(C-4), 134.2 (C-1), 170.3
(OC55O), 196.8 (C55O)
(continued)

a-Formyloxy Ketones
Table 3. Continued
343
Entry
9
1H NMR (CDCl3)
13C NMR (CDCl3)
2.19 (s, 3H, CH3), 3.04 (dd,
J ¼ 16.92, 4.88 Hz, 1H, H3),
3.66 (dd, J ¼ 16.92, 8.00 Hz,
20.6 (CH3), 33.4 (C-3), 74.0
(C-2), 124.5 (C-6), 126.6
(C-4), 128.1 (C-7), 134.4
(C-7a), 135.9 (C-5), 150.4
0
1H, H3 ), 5.42 (dd, J ¼ 8.0,
4.8 Hz, 1H, H2), 7.40–7.66
(m, 4H, H4, H5, H6 and H7)
2.22 (s, 3H, CH3), 5.22 (s, 2H,
CH2), 7.16 (dd, J ¼ 4.96,
3.8 Hz, 1H, H4), 7.71 (dd,
J ¼ 4.9, 0.8 Hz, 1H, H5), 7.75
(dd, J ¼ 3.8, 1.0 Hz, 1H, H3)
2.23 (s, 3H, CH3), 5.30 (s, 2H,
CH2), 7.46–7.62 (m, 3H, H3,
H6 and H7), 7.82–7.87 (m, 2H,
H2 and H5), 8.01 (d, J ¼ 8.2 Hz,
1H, H4), 8.62 (d, J ¼ 8.4 Hz,
1H, H8)
(C-3a), 170.5 (OC55O), 200.7
(C55O)
10
11
20.5 (CH3), 65.7 (CH2), 128.3
(C-4), 132.0 (C-3), 134.3
(C-5), 140.3 (C-2), 170.3
(OC55O), 185.4 (C55O)
20.6 (CH3), 67.5 (CH2), 124.2
(C-3), 125.5 (C-8), 126.8
(C-6), 127.5 (C-7), 128.4
(C-5), 128.5 (C-2), 130.2
(C-8a), 132.3 (C-4a), 133.5
(C-4), 133.9 (C-1), 170.6
(OC55O), 196.1 (C55O)
synthetically useful a-formyloxy and a-acetoxy ketone (5) may be depro-
tected to get a-hydroxy ketone, the moiety that is present in many naturally
occurring products and drugs. The a-formyloxy and a-acetoxy ketones (5)
were also obtained in one pot starting from enolizable ketone (1) to first
generate the a-tosyloxy ketones in situ, followed by subsequent removal of
acetonitrile, reflux in DMF/DMA, and addition of water.
In conclusion, this simple, efficient, and economic transformation is
superior to the previously described method for the synthesis of
a-formyloxy ketones utilizing the reaction of ketones with toxic thalliu-
m(III)acetate and costly trifluoromethanesulphonic acid.[14] Further,
PSHTIB utilized in these reactions can be regenerated by treatment of the
recovered iodopolystyrene with peracetic acid followed by p-toluenesulpho-
nic acid.
EXPERIMENTAL
Melting points were determined in open capillaries and are uncorrected. FTIR
spectra were obtained in KBr on Perkin-Elmer Spectrum RX1 instruments and
1
are reported in centimeters21. H and 13C NMR spectra were determined on
Bruker Avance II 400-MHz and 100-MHz NMR spectrometers,
respectively, in CDCl3 and are expressed as parts per million (ppm) with

344
S. Kumar et al.
respect to TMS. Elemental analysis was carried out on a Perkin-Elmer 2400
instrument.
Synthesis of a-Formyloxy and a-Acetoxy Ketones (5): General
Procedure
HTIB (2.2 mmol, 758 mg) was added to a solution of enolizable ketone
(1, 2 mmol) in acetonitrile (20 ml). The reaction mixture was refluxed for
2–3 h. After the completion of the reaction, most of the acetonitrile was
removed under vaccum, and 10 ml of dry DMF/DMA was added. The
solution was further refluxed for 30–45/15–25 min, respectively. The
reaction mixture was cooled, and 2–3 ml of water was added. It was stirred
for 15 min, extracted with dichloromethane thrice, and washed with
saturated aq. sodium bicarbonate and water. The combined extract was
dried over anhydrous sodium sulphate, and the excess of dichloromethane
was distilled off. The residue was chromatographed over silica gel
(60–120 mesh) using hexane–ethyl acetate (95:5) as eluant to afford 5.
Alternatively, 5 can also be prepared utilizing polymer-supported [hydox-
y(tosyloxy) iodo]benzene (PSHTIB) instead of HTIB. The only difference was
that the reaction mixture containing 1 and PSHTIB was refluxed and filtered to
remove iodopolystyrene followed by removal of acetonitrile.
ACKNOWLEDGMENT
The authors are thankful to Council of Scientific and Industrial Research
(CSIR) and University Grants Commission (UGC), New Delhi, for financial
support.
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