Synthesis of new 4,6-disubstituted-1,3-oxazinan-2-one analogues

Article abstract of DOI:10.1007/s12039-013-0508-5

1,3-Oxazinan-2-one analogues are important heterocyclic compounds having significant biological activities. This study reports the synthesis of eight new 4,6-disubstituted -1,3-oxazinan-2-one analogues from corresponding homoallylic carbamates. Homoallyli

Full text of DOI:10.1007/s12039-013-0508-5

J. Chem. Sci. Vol. 125, No. 6, November 2013, pp. 1503–1510. ꢀc Indian Academy of Sciences.
Synthesis of new 4,6-disubstituted-1,3-oxazinan-2-one analogues
∗
ARUN JYOTI BORAH and PRODEEP PHUKAN
Department of Chemistry, Gauhati University, Guwahati 781 014, India
e-mail: pphukan@yahoo.com
MS received 2 August 2012; revised 17 August 2013; accepted 21 August 2013
Abstract. 1,3-Oxazinan-2-one analogues are important heterocyclic compounds having significant biologi-
cal activities. This study reports the synthesis of eight new 4,6-disubstituted -1,3-oxazinan-2-one analogues
from corresponding homoallylic carbamates. Homoallylic carbamates were synthesized via a three-component
reaction of aldehyde, allyltrimethylsilane and benzyl carbamate in presence of iodine as catalyst. In the
next step, homoallylic carbamates were subjected to Sharpless dihydroxylation (racemic) to produce 3,4-
dihydroxybutylcarbamate derivatives. This product was then treated with NaH in tetrahydrofuran (THF) to
produce the desired 6-(hydroxymethyl)-1,3-oxazinan-2-one in high yield.
Keywords. 1,3-Oxazinan-2-one; homoallylic carbamates; Sharpless dihydroxylation; iodine; heterocyclic
compound.
1
. Introduction
There are very limited approaches to the synthesis
19
of 1, 3-oxazinan-2-one in literature. Lohray devel-
oped a method for enantiospecific synthesis of 6-
substituted N-aryl-1,3-oxazinan-2-ones using aspartic
acid as starting material. A quicker synthesis of the
same was carried out by reductive amination of 2-
deoxy-D-ribose followed by cyclization of aryl chlo-
Heterocyclic compounds containing nitrogen and oxy-
gen in the skeleton are important building blocks in
the synthesis of biologically active compounds. 1,3-
1
Oxazinan-2-one skeleton is one of such important com-
pounds, used as building block for the synthesis of
new heterocycles of biological significance. These 6-
memebered cyclic carbamates derivatives are found in
many biologically important natural products such as
maystansine, maystanprine, colubrinol and maytanbu-
20
roformate derivatized amine. Other methods include
1
5b,c,21–30
halogen-mediated cyclization reactions,
rear-
31
rangement from cyclic sulphates, selenium-mediated
cyclization of amino alcohols with carbon monoxide,3
2
2–4
33
tine. 1, 3-Oxazinan-2-one derivatives exhibit a variety
asymmetric dihydroxylation of homoallylic amine,
tethered aminohydroxylation, Hofmann rearrange-
ment of primary amide and intramolecular Michael
addition. Cyclization of 1, 3-aminoalcohol is one of
the versatile methods in the synthesis of cyclic carba-
5
34
of biological activities such as antibacterial, anti-
6
7
35
inflammatory and antithrombotic properties. These
molecules are used in treating asthma, allergies, ulcers,
arthritis and diabetes.4 In addition, they are also being
36
b
8
9
10
20,37–40
used as anticonvulsant, penetration enhancer, sedative,
mate.
A method used for the synthesis of oxazi-
11
and analgesic. Some 6-phenyl-1, 3-oxazinan-2-one
derivatives have phosphodiesterase IV inhibitor pro-
perty and are used as remedies for inflammatory
diseases and anti-asthmatics.1 1,3-Oxazinan-2-one
derivatives have also been used as key intermediates
nanones via intramolecular diazocarbonyl insertion
reaction of activated diazoketone catalysed by metal
41
triflates was reported by Avery et al.
2
in the synthesis of several biologically important com- 2. Experimental
13
pounds such as L-ristosamine, L-daunosamine, (± )-
2.1 Synthesis of homoallylic carbamate (1)42
14
15
7
negamycin erythromycin A and thrombolytics.
Besides being important bulding blocks in the prepara-
tion of complex synthetic targets, they are also used for
Benzyl carbamate (2.55 mmol, 1.05 equiv) and
allyltrimethylsilane (2.5 mmol, 1 equiv) were added
to a solution of aldehyde (2.5 mmol, 1 equiv) and
iodine (10 mol%) in acetonitrile at room temperature.
The reaction was completed within 10–20 min. After
completion of the reaction thin layer chromatography
16,17
the synthesis of amino alcohols
devices.
and liquid crystal
18
∗
For correspondence
1503

1504
Arun Jyoti Borah and Prodeep Phukan
(
TLC), sodium thiosulphate was added to reaction 2.1e Benzyl 1-(naphthalene-6-yl)but-3-enylcarbamate 1e:
◦
mixture. The mixture was extracted with EtOAc. The Yield: 65% (colourless solid); mp: 73–75 C; IR (KBr,
organic extract was washed with brine and dried over cm ): 3365, 3049, 2970, 1686, 1528, 1323, 1250,
anhydrous sodium sulphate. Evaporation of solvent and 1122, 1036, 751; H NMR (CDCl , 300 MHz): δ 7.86–
−1
1
3
purification of the crude product using flash chromatog- 7.27 (m, 12H), 5.79–5.65 (m, 1H), 5.30 (m, 1H),
13
raphy on silica gel (230–400 mesh) with petroleum 5.18–5.01 (m, 5H), 2.65 (br, 2H); C NMR (CDCl3,
ether-EtOAc (10–20%) as eluent gave the pure product 75 MHz): δ 155.6, 139.2, 136.3, 133.6, 133.2, 132.7,
(yield 50–82%).
128.4, 128.4, 128.1, 127.8, 127.5, 126.1, 125.7, 124.8,
24.4, 118.5, 66.8, 54.5, 40.9.
1
2
.1a Benzyl 1-(4-chlorophenyl)but-3-enylcarbamate
◦
2.1f Benzyl 1-(4-flurophenyl)but-3-enylcarbamate 1f:
1a: Yield: 70% (colourless solid); mp: 68–70 C; IR
−1
−1
Yield: 71% (yellowish liquid); IR (KBr, cm ): 3445,
(KBr, cm ): 3342, 3064, 2950, 1678, 1534, 1489,
1
1
1697, 1604, 1540, 1349, 1224, 1159, 1041, 736; H
1
3
5
346, 1263, 1119, 1035, 752; H NMR (CDCl3,
00 MHz): δ 7.35–7.19 (m, 9H), 5.72–5.57 (m, 1H),
.15–5.02 (m, 5H), 4.71 (br, 1H), 2.50 (br, 2H);
NMR (CDCl , 400 MHz): δ 7.33–7.00 (m, 9H), 5.66–
3
13
5.63 (m, 1H), 5.12–5.05 (m, 5H), 4.77 (br, 1H), 2.50 (br,
C
13
s, 2H); C NMR (CDCl , 100 MHz): δ 163.1, 160.7,
3
NMR (CDCl , 75 MHz): δ 155.6, 140.5, 136.2, 133.2,
3
1
1
55.6, 137.1, 136.3, 133.4, 128.5, 128.1, 127.8, 127.8,
18.7, 115.4, 115.2, 66.8, 53.8, 41.3.
1
4
33.0, 128.7, 128.5, 128.2, 127.6, 118.9, 66.9, 53.9,
0.9.
2
.1g Benzyl (1-phenylhex-5-en-3-yl)carbamate 1g:
2
.1b Benzyl 1-(4-bromophenyl)but-3-enylcarbamate
◦
Yield: 70% (colourless solid); mp: 70–71 C; IR (Nujol,
cm ): 3065, 1696, 1534, 1451, 1243, 1045, 739; H
NMR (CDCl , 400 MHz): δ 7.32–7.16 (m, 7H), 7.13–
◦
1b: Yield: 75% (colourless solid); mp: 87–88 C; IR
−1
1
−1
(KBr, cm ): 3345, 3087, 2950, 1684, 1592, 1533,
3
1
1455, 1347, 1264, 1119, 1034, 751; H NMR (CDCl ,
3
7
4
2
.06 (m, 3H), 5.77–5.60 (m, 1H), 5.10–4.95 (m, 4H),
.54 (d, J = 7.8 Hz, 1H), 3.79–3.63 (m, 1H), 2.68–
.50 (m, 2H), 2.29–2.09 (m, 2H), 1.83–1.70 (m, 1H);
4
00 MHz): δ 7.44 (d, J = 8.1Hz, 2H), 7.40–7.25
(m, 5H), 7.13 (d, J = 7.7 Hz, 2H), 5.72–5.54 (m,
1
H), 5.22–4.96 (m, 5H), 4.82–4.65 (m, 1H), 2.60–2.36
13
C NMR (CDCl , 100 MHz): δ 156.2, 141.7, 136.6,
3
13
(
m, 2H); C NMR (CDCl , 100 MHz): δ 155.6, 141.0,
3
1
5
33.9, 128.5, 128.4, 128.3, 128.1, 125.9, 118.1, 66.6,
0.5, 39.5, 36.5, 32.3.
1
6
36.2, 133.2, 131.6, 128.5, 128.2, 127.9, 121.1, 118.9,
6.9, 53.9, 40.8.
2
.1h Benzyl 1-(2-methoxyphenyl)but-3-enylcarbamate 1h:
2
7
3
1
7
4
.1c Benzyl 1-p-tolylbut-3-enylcarbamate 1c: Yield:
2% (colourless solid); mp: 70–71 C; IR (KBr, cm ):
◦
Yield: 80% (colourless solid); mp: 88–90 C; IR
◦
−1
−1
(KBr, cm ): 3333, 3060, 2942, 1685, 1600, 1537,
357, 3058, 2958, 1692, 1590, 1526, 1457, 1350, 1263,
1
1
4
5
468, 1352, 1264, 1121, 1035,754; H NMR (CDCl ,
00 MHz): δ 7.30–6.83 (m, 9H), 5.63–5.61 (m, 2H),
.04–4.98 (m, 5H), 3.80 (s, 3H), 2.52 ( br, s, 2H); C
3
1
143, 1044, 732; H NMR (CDCl , 300 MHz): δ 7.35–
3
.16 (m, 9H), 5.75–5.62 (m, 1H), 5.14–5.07 (m, 5H),
13
13
.78 (m, 1H), 2.56–2.62 (m, 2H), 2.34 (s, 3H);
C
NMR (CDCl ,100 MHz): δ 156.8, 155.6, 136.5, 134.7,
3
NMR (CDCl , 75 MHz): δ 155.6, 138.8, 136.9, 136.4,
3
1
6
29.3, 128.4, 128.3, 128.2, 128.1, 120.5, 117.4, 110.8,
6.6, 55.2, 52.8, 39.7.
1
4
33.8, 129.2, 128.4, 128.1, 126.1, 118.2, 66.6, 54.2,
0.9, 30.9.
2
.2 Synthesis of 3,4-dihydroxybutylcarbamate
43
2
.1d Benzyl 1-(4-methoxyphenyl)but-3-enylcarbamate 1d: derivative (2)
◦
Yield: 75% (colourless solid); mp: 70–71 C; IR (KBr,
−1
cm ): 3362, 3067, 2950, 1685, 1597, 1528, 1454, A flask was charged with K
CO
(4.5 mmol) in a mixture of BuOH and
00 MHz): δ 7.41–7.29 (m, 5H), 7.19 (d, J = 7.8 Hz, water (1:1). The mixture was stirred for 5–10 min and a
OsO (OH) (0.006 mmol) was
(4.5 mmol) and
2
3
1
t
1
4
2
5
2
1
1
346, 1243, 1116, 1032, 748; H NMR (CDCl3,
K Fe(CN)
3 6
H), 6.86 (d, J = 8.6 Hz, 2H), 5.77–5.58 (m, 1H), drop of pyridine and K
2
2
4
.20–5.00 (m, 5H), 4.80–4.70 (m, 1H), 3.79 (s, 3H), added to the mixture and stirred for another 5 min.
.60–2.54 (m, 2H); 13C NMR (CDCl , 100 MHz): δ Thereafter, homoalylic carbamate, 1 (1.5 mmol) was
3
58.7, 155.6, 136.4, 133.9, 128.4, 128.0, 127.3, 118.2, added to the reaction mixture and stirred for 24 h. The
13.8, 86.7, 55.2, 53.9, 40.9.
reaction was then quenched with sodium sulphite and

Synthesis of new 4,6-disubstituted-1,3-oxazinan-2-one analogues
1505
the reaction mixture was stirred for another half an hour. 66.5, 66.4, 53.3, 51.8, 39.7, 39.7, 21.1, 20.9; MS (m/z):
+
The reaction mixture was then extracted with EtOAc. 338.2 (8) (M + Na), 339.0 (15), 179.5 (55); Anal.
The organic extract was washed with brine and dried calcd. for C H NO (%): C, 69.28; H, 7.04; N, 4.25;
19
23
4
over anhydrous sodium sulphate. The solvent was eva- Found: C, 69.18; H, 6.95; N, 4.20.
porated under reduced pressure to get the crude mix-
ture. The crude product was purified by flash col-
2
.2d Benzyl-3, 4-dihydroxy-1-(4-methoxyphenyl)butyl-
umn chromatography using petroleum ether and ethyl
acetate (1:1) as eluent to get the desired diol as a insep-
arable mixture of two diastereomers (yield: 70–95%).
carbamate 2d: Yield: 75% (colourless solid); mp: 67–
◦
−1
70 C; IR (KBr, cm ): 3421, 3352, 3038, 2940, 1690,
1
1606, 1528, 1459, 1346, 1243, 1096, 1047, 753; H
NMR (CDCl , 400 MHz): δ 7.27–6.79 (m, 18H), 5.22
3
(
m, 2H), 5.07–4.94 (m, 4H), 4.90–4.85 (m, 1H), 4.77–
.67 (m, 1H), 3.72 (s, 6H), 3.57–3.50 (m, 2H), 3.46–
.33 (m, 2H), 2.10–2.08 (br, 2H), 1.92–1.66 (m, 4H);
2
.2a Benzyl 1-(4-chlorophenyl)-3, 4-dihydroxybutyl-
4
3
carbamate 2a: Yield: 72% (colourless solid); mp:
◦
−1
103–105 C; IR (KBr, cm ): 3429 (br), 2930, 1684,
13
C NMR (CDCl , 75 MHz): δ 158.9, 156.9, 156.1,
1
3
1593, 1539, 1454, 1350, 1261, 1094, 1013,758; H
1
1
5
36.2, 136.1, 133.4, 128.5, 128.4, 128.2, 128.1, 127.9,
NMR (CDCl , 400 MHz): δ 7.27–7.13 (m, 18H), 5.54
3
27.6, 127.4, 114.1, 69.9, 68.7, 67.1, 66.8, 66.5, 66.4,
(
d, J = 8 Hz, 2H), 5.06–4.94 (m, 4H), 3.68 (br,
+
5.2, 55.2, 51.5, 51.5, 39.7; MS (m/z): 368.1 (M +
s, 2H), 3.56–3.48 (m, 2H), 3.42–3.31 (m, 2H), 2.36
Na, 100), 369.1 (15); Anal. calcd. for C H NO (%):
C, 66.07; H, 6.71; N, 4.06; Found: C, 66.10; H, 6.80;
N, 4.10.
19
23
5
(
br, s, 2H), 1.84–1.75 (m, 2H), 1.68–1.63 (m, 2H);
1
3
C NMR (CDCl , 75 MHz): δ 156.6, 155.9, 140.1,
3
1
1
5
36.1, 135.9, 133.1, 128.8, 128.5, 128.4, 128.2, 128.1,
27.9, 127.7, 127.6, 69.8, 69.8, 68.6, 67.1, 66.9, 66.4,
1.6, 39.5, 39.2; MS (m/z): 372.1 (M + Na), 373.1;
+
2
.2e Benzyl-3, 4-dihydroxy-1-(naphthalene-6-yl)butyl-
carbamate 2e: Yield: 93% (colourless solid); mp: 87–
8
1
Anal. calcd. for C H ClNO (%): C, 61.80; H, 5.76;
18
20
4
◦
−1
9 C; IR (KBr, cm ): 3336, 3054, 2944, 1684, 1601,
N, 4.00; Found: C, 61.75; H, 5.90; N, 4.10.
1
631, 1455, 1331, 1258, 1097, 1045, 742; H NMR
(
8
(
1
1
CDCl , 400 MHz): δ 7.78–7.27 (m, 24H), 5.75 (d, J =
3
2
.2b Benzyl 1-(4-bromophenyl)-3, 4-dihydroxybutyl-
Hz, 2H), 5.17–5.01 (m, 4H), 4.09–4.04 (m, 1H), 3.77
carbamate 2b: Yield: 74% (colourless solid); mp:
br, 1H), 3.52–3.46 (m, 4H), 2.96–2.80 (m, 2H), 2.15–
◦
−1
13
123–125 C; IR (KBr, cm ): 3362, 3058, 2950, 1686,
.81 (m, 4H); C NMR (CDCl , 100 MHz): δ 156.9,
3
1
1593, 1525, 1455, 1346, 1269, 1097, 1049, 754; H
56.1, 133.2, 128.6, 128.5, 128.4, 128,2, 128.1, 127.6,
NMR (CDCl , 400 MHz): δ 7.41–7.09 (m, 18H), 5.52–
3
126.2, 67.2, 66.9, 66.6, 66.5, 53.8, 52.3, 39.7, 39.4,
3
calcd. for C H NO (%): C, 72.31; H, 6.34; N, 3.83;
Found: C, 72.25; H, 6.30; N, 3.87.
+
5
3
1
2
1
1
6
4
.46 (m, 2H), 5.07–4.91 (m, 4H), 3.69 (br, 1H), 3.57–
.51 (m, 3H), 3.44–3.32 (m, 2H), 2.07–2.04 (m, 1H),
.95–1.93 (m, 1H), 1.86–1.77 (m, 2H), 1.70–1.59 (m,
0.9; MS (m/z): 388.2 (M +Na, 39), 372.2 (8); Anal.
22
23
4
13
H); C NMR (CDCl , 75 MHz): δ 156.7,155.8, 140.3,
3
36.1, 135.9, 131.8, 131.8, 128.5, 128.5, 128.3, 128.2,
28.1, 127.9, 124.3, 121.4, 121.3, 69.9, 68.5, 67.2,
6.9, 66.5, 66.4, 53.5, 51.7, 39.5, 39.2 ; MS (m/z):
16.1 (M + Na), 418.0 (M +2+ Na); Anal. calcd.
2
.2f Benzyl 1-(4-flurophenyl)-3, 4-dihydroxybutylcar-
bamate 2f: Yield: 95% (colourless solid); mp: 79–
◦
−1
8
1
6
4
3
7
2 C; IR (KBr, cm ): 3445, 2925, 1697, 1593, 1350,
+
+
1
226, 1054, 735; H NMR (CDCl , 400 MHz): δ 7.28–
3
for C H BrNO (%): C, 54.84; H, 5.11; N, 3.55;
18
20
4
.93 (m, 18H), 5.43–5.34 (m, 2H), 5.04–4.94 (m, 4H),
.76 (br, 1H), 3.71 (br, s, 1H), 3.59–3.52 (m, 2H), 3.45–
Found: C, 54.90; H, 5.15; N, 3.55.
13
.34 (m, 2H), 2.00–1.66 (m, 6H); C NMR (CDCl3,
5 MHz): δ 163.6, 160.3, 156.7, 155.9, 137.7, 137.2,
2.2c Benzyl 3, 4-dihydroxy-1-p-tolylbutylcarbamate
◦
136.1, 135.9, 128.5, 128.4, 128.3, 128.2, 128.1, 128.0,
127.9, 115.7, 115.4, 69.9, 68.6, 67.2, 66.9, 66.5, 66.4,
2c: Yield: 84% (colourless solid); mp: 102–104 C;
−1
IR (KBr, cm ): 3345, 3283, 3055, 2928, 1697, 1538,
+
1
53.1, 51.5, 39.7, 39.5 MS (m/z): 356.1 (M + Na, 100),
1
4
5
3
2
1
1
456, 1350, 1257, 1100, 1014, 737; H NMR (CDCl ,
3
3
38.2 (10); Anal. calcd. for C H FNO (%): C, 64.85;
18 20 4
00 MHz): δ 7.57–7.35 (m, 18H), 5.68–5.59 (m, 2H),
.33–5.18 (m, 4H), 4.05–4.00 (m, 1H), 3.89–3.78 (m,
H), 3.74–3.61 (m, 2H), 2.82 (br, s, 2H), 2.55 (s, 6H),
H, 6.05; N, 4.20; Found: C, 64.80; H, 6.10; N, 4.25.
.20–1.95 (m, 4H); 13C NMR (CDCl , 75 MHz): δ 2.2g Benzyl (5,6-dihydroxy-1-phenylhexan-3-yl)car-
56.8, 155.9, 138.4, 137.2, 136.2, 135.9, 129.4, 128.4, bamate 2g: Yield: 75% (colourless solid); mp: 73–
28.4, 128.2, 128.1, 126.2, 126.1, 69.9, 68.7, 67.1, 66.7, 76 C; IR ( KBr, cm ): 3426, 3335, 2924, 1687, 1599,
3
◦
−1

1506
Arun Jyoti Borah and Prodeep Phukan
1
1
4
4
4
541, 1454, 1352, 1253, 1051, 750; H NMR (CDCl , s, 1H), 7.46–7.42 (m, 4H), 7.36–7.33 (m, 4H), 5.00–
3
00 MHz): δ 7.32–7.05 (m, 20 H), 5.06–5.04 (m, 4H), 4.93 (m, 2H), 4.70–4.69 (m, 1H), 4.60 (dd, J = 12 Hz,
.74 (br, 1H), 4.61 (d, J = 12 Hz, 1H), 3.86–3.68 (m, 4 Hz, 1H), 4.34–4.30 (m, 1H), 3.97–3.92 (m, 1H), 3.52–
H), 3.59–3.57 (m, 1H), 3.51–3.48 (m, 1H), 3.42–3.38 3.44 (m, 2H), 2.13–2.05 (m, 2H), 1.89–1.86 (br, m,
13
(
m, 2H), 2.70–2.55 (m, 4H), 1.81–1.64 (m, 4H), 1.60– 1H), 1.59–1.50 (m, 1H); C NMR (DMSO,100 MHz):
3
1
7
1
1
4
3
6
.51 (m, 2H), 1.27–1.19 (m, 2H); 1 C NMR (CDCl3, δ 153.2, 152.9, 142.3, 141.3, 132.0, 131.7, 128.5, 128.4,
5 MHz): δ 157.6, 156.5, 141.3, 141.1, 136.3, 136.1, 128.1, 128.0, 76.7, 73.4, 62.8, 62.7, 53.1, 50.5, 32.9,
+
+
28.6, 128.5, 128.5, 128.4, 128.3, 128.2, 128.1, 128.0, 30.4; MS (m/z): 264.1 (M +Na), 266.1 (M +2+ Na);
27.9, 126.0, 125.9, 70.1, 68.3, 67.2, 66.8, 66.5, 66.4, Anal. calcd. for C H ClNO (%): C, 54.67; H, 5.00; N,
11
12
3
9.3, 47.9, 39.8, 38.9, 37.5, 37.4, 32.6, 32.1; MS (m/z): 5.80; Found: C, 54.60; H, 4.95; N, 5.70.
+
66.0 (M + Na); Anal. calcd. for C H NO (%): C,
2
0
25
4
9.95; H, 7.34; N, 4.08; Found: C, 69.90; H, 7.30;
2
.3b 4-(4-Bromophenyl)-6-(hydroxymethyl)-1, 3-oxa-
zinan-2-one (3b + 4b): Yield: 82% (colourless solid);
mp: 173–175 C; IR (KBr, cm ): 3418, 3293, 3126,
.2h Benzyl-3, 4-dihydroxy-1-(2-methoxyphenyl)butyl- 2936, 1710, 1592, 1538, 1459, 1341, 1292, 1086, 1057,
N, 4.12.
◦
−1
2
1
carbamate 2h: Yield: 70% (colourless solid); mp: 768; H NMR (DMSO, 400 MHz): δ 7.72 (d, J =
◦
−1
1
1
10–113 C; IR (KBr, cm ): 3430, 3338, 2927, 1686, 4 Hz, 1H), 7.61–7.55 (m, 5H), 7.29–7.26 (m, 4H), 4.98–
1
597, 1543, 1469, 1351, 1259, 1101, 1051, 755; H 4.94 (m, 2H), 4.68–4.66 (m, 1H), 4.58 (dd, J =
NMR (CDCl , 400 MHz): δ 7.30–6.81 (m, 18H), 5.98 12 Hz, 4Hz, 1H), 4.33–4.30 (m, 1H), 3.96–3.92 (m,
3
(
d, J = 8 Hz, 1H), 5.81 (br, s, 1H), 5.04–4.96 (m, 6H), 1H), 3.50–3.45 (m, 2H), 2.12–2.04 (m, 2H), 1.88–1.85
13
3
2
.78 (s, 6H), 3.53–3.50 (m, 2H), 3.44–3.37 (m, 2H), (br, m, 1H), 1.58–1.49 (m, 1H); C NMR (DMSO,
.25 (br, 2H), 1.93–1.81 (m, 3H), 1.61–1.54 (m, 1H); 100 MHz): δ 153.2, 152.9, 142.7, 141.7, 131.4, 131.3,
1
3
C NMR (CDCl , 100 MHz): δ 157.4, 156.9, 156.7, 128.5, 128.3, 120.5, 120.2, 76.7, 73.3, 62.8, 62.7, 53.2,
3
+
1
1
6
56.0, 136.4, 136.2, 128.9, 128.8, 128.7, 128.6, 128.5, 50.6, 32.9, 30.3; MS (m/z): 308.0 (M + Na), 310.0
+
28.3, 128.1, 121.1, 120.9, 111.1, 111.0, 70.2, 68.7, (M +2+ Na); Anal. calcd. for C11
H12BrNO (%): C,
3
7.2, 66.8, 66.7, 66.4, 55.4, 55.3, 51.3, 51.1, 39.3, 39.0; 46.18; H, 4.23; N, 4.90; Found: C, 46.25; H, 4.30;
+
+
MS (m/z): 368.1 (M + Na, 100), 369.1(M +1+ Na N, 4.85.
,
18); Anal. calcd. for C H NO (%): C, 66.07; H, 6.71;
19
23
5
N, 4.06; Found: C, 66.10; H, 6.75; N, 4.10.
2
(
.3c 6-(Hydroxymethyl)-4-p-tolyl-1, 3-oxazinan-2-one
3c + 4c): Yield: 73% (colourless solid); mp: 124–
125 C; IR (KBr, cm ): 3372, 3272, 2969, 2917, 1707,
.3 Synthesis of 1, 3-oxazinan-2-one (3)44
◦
−1
2
1
1592, 1538, 1464, 1353, 1294, 1090, 1052; H NMR
The diol (2, 1 mmol, 1 equiv) was dissolved in dry (DMSO, 400 MHz): δ 7.66 (m, 1H), 7.50 (br, s, 1H),
THF (3–4 mL) under N atmosphere. The mixture was 7.20–7.15 (m, 8H), 4.97–4.91 (m, 2H), 4.63 (m, 1H),
2
then cooled in an ice water bath and NaH (1.4 mmol, 4.52 (dd, J = 12 Hz, 4Hz, 1H), 4.32–4.29 (m, 1H),
1
.4 equiv) was added to the mixture. The reaction mix- 3.96–3.94 (m, 1H), 3.50–3.43 (m, 2H), 2.29 (s, 6H),
◦
ture was then allowed to stir at 0–5 C for appropriate 2.08–2.02 (m, 2H), 1.86–1.83 (m, 1H), 1.59–1.49 (m,
time (TLC). The reaction was then quenched with aq. 1H); C NMR (DMSO,100 MHz): δ 153.5, 153.3,
13
NH Cl solution and extracted with EtOAc. The organic 140.3, 139.3, 136.9, 136.4, 129.2, 129.1, 126.1, 125.9,
4
extract was then dried over anhydrous sodium sulphate. 76.9, 73.5, 63.0, 62.8, 53.7, 50.9, 40.1, 39.9, 33.2, 30.7,
+
The solvent was evaporated under reduced pressure to 20.7, 20.7; MS (m/z): 244.1 (M + Na, 100), 245.2
+
get the crude reaction mixture. The crude product was (M + 1+ Na, 28); Anal. calcd. for C H CNO (%):
12
15
3
purified by flash column chromatography to get the C, 65.14; H, 6.83; N, 6.33; Found: C, 65.10; H, 6.88;
1, 3-oxazinan-2-one as a inseparable diastereomeric N, 6.29.
mixture (yield 70–85%).
2.3d 6-(Hydroxymethyl)-4-(4-methoxyphenyl)-1, 3-oxa-
2
2
1
1
.3a 4-(4-Chlorophenyl)-6-(hydroxymethyl)-1, 3-oxazinan- zinan-2-one (4d): Yield: 70% (light brown solid); mp:
◦
−1
-one (3a + 4a): Yield: 75% (colourless solid); mp: 132–135 C; IR (KBr, cm ): 3450, 3254, 3097, 2930,
◦
−1
58–160 C; IR (KBr, cm ): 3515, 3283, 3058, 2938, 1655, 1587, 1508, 1459, 1351, 1297, 1253, 1081, 1023,
1
1
714, 1541, 1492, 1340, 1291, 1087, 1056, 766; H 767; H NMR (DMSO, 400 MHz): δ 7.65 (m, 1H),
NMR (DMSO, 400 MHz) δ 7.73 (br, m, 1H), 7.61 (br, 7.20 (d, J = 12 Hz, 2H), 6.94 (d, J = 8 Hz, 2H),

Synthesis of new 4,6-disubstituted-1,3-oxazinan-2-one analogues
1507
1
4
3
1
1
3
.93 (br, m. 1H), 4.62 (br, m, 1H), 3.99–3.96 (m, 1H), 1092, 677; H NMR (DMSO, 400 MHz): δ 7.38–7.37
.74 (s, 3H), 3.45–3.44 (m, 1H), 2.08–2.00 (m, 1H), (m, 1H), 7.30 (m, 1H), 7.28–7.15 (m, 10 H), 4.98
.86–1.82 (br, m, 1H); C NMR (DMSO,100 MHz): δ (br, 2H), 4.30–4.24 (m, 1H), 4.19–4.13 (m, 1H), 3.49–
58.4, 153.0, 135.1, 127.1, 113.3, 73.4, 62.8, 55.1, 50.5, 3.48 (m, 4H), 2.67–2.54 (m, 4H), 2.04–2.00 (m, 1H),
13
+
0.8; MS (m/z) 260.8 (M + Na, 100); Anal. calcd. for 1.87–1.74 (m, 4H), 1.72–1.59 (m, 2H), 1.41–1.32
13
C H NO (%): C, 60.75; H, 6.37; N, 5.90; Found: C, (m, 1H); C NMR (DMSO, 100 MHz): δ 153.2, 152.9,
12
15
4
60.71; H, 6.34; N, 5.85.
141.6, 141.6, 128.3, 128.3, 128.3, 128.3, 125.8, 125.8,
7
2
6.9, 74.2, 63.1, 62.8, 49.4, 47.1, 37.9, 37.4, 31.1, 30.3,
+
9.1, 26.8; MS (m/z): 258.0 (M + Na, 21), 241.6
2.3e 6-(Hydroxymethyl)-4-(naphthalene-6-yl)-1, 3-oxa-
(41); Anal. calcd. for C H NO (%): C, 66.36; H, 7.28;
13 17 3
zinan-2-one (3e + 4e): Yield: 76% (colourless solid);
N, 5.95; Found: C, 66.38; H, 7.31; N, 5.92.
◦
−1
mp: 170–172 C; IR (KBr, cm ): 3443, 3249, 3129,
1
2
931, 1702, 1507, 1425, 1336, 1155, 1073, 762; H
2
.3h 6-(Hydroxymethyl)-4-(2-methoxyphenyl)-1, 3-oxazi-
nan-2-one (3h + 4h): Yield: 71% (colourless solid);
mp: 154–155 C; IR (KBr, cm ): 3373, 3244, 3107,
939, 1690, 1597, 1344, 1294, 1246, 1106, 1081, 759;
NMR (DMSO, 400 MHz): δ 7.95–7.46 (m, 16H), 5.00–
4
4
2
.93 (br, m, 2H), 4.85 (br, m, 1H), 4.77–4.73 (m, 1H),
.41–4.38 (m, 1H), 4.03–4.01 (m, 1H), 3.53–3.46 (m,
H), 2.20–2.12 (m, 2H), 2.01–1.98 (m, 1H), 1.74–1.63
◦
−1
2
1
13
H NMR (DMSO, 300 MHz): δ 7.55–7.54 (m, 1H),
(
m, 1H); C NMR (DMSO, 75 MHz): δ 153.3, 153.1,
7
.43 (br, s, 1H), 7.32–7.18 (m, 4H), 7.04–6.96 (m, 4H),
.93–4.87 (m, 2H), 4.85–4.82 (m, 2H), 4.34–4.30 (m,
H), 3.94–3.87 (m, 1H), 3.81 (s, 3H), 3.79 (s, 3H),
.49–3.48 (m, 2H), 2.15 (dd, J = 15 Hz, 6 Hz, 1H),
.05–1.96 (m, 1H), 1.88–1.83 (br, m, 1H), 1.51–1.39
1
1
1
3
2
5
40.9, 139.7, 132.8, 132.7, 132.5, 132.2, 128.2, 127.8,
27.7, 127.5, 127.5, 126.4, 126.3, 126.0, 124.7, 124.6,
24.5, 125.4, 76.8, 73.3, 62.9, 62.7, 53.9, 51.2, 33.0,
4
1
3
2
+
0.3; MS (m/z): 280.1 (M + Na, 100), 279.2 (12),
64.0 (5); Anal. calcd. for C H NO (%): C, 70.02; H,
15
15
3
13
(
m, 1H); C NMR (DMSO, 75 MHz): δ 156.1, 155.5,
.88; N, 5.44; Found: C, 69.98; H, 5.91; N, 5.41.
1
1
4
1
6
53.7, 153.4, 130.5, 129.8, 128.5, 128.5, 126.6, 125.9,
20.6, 120.1, 110.9, 110.9, 76.7, 73.5, 62.9, 55.5, 55.4,
2
2
1
1
4
7
3
1
1
6
.3f 4-(4-Flurophenyl)-6-(hydroxymethyl)-1, 3-oxazinan-
+
7.8, 46.7, 31.0, 28.3; MS (m/z): 260.8 (M + Na,
-one (4f): Yield:70% (colourless solid); mp: 102–
00); Anal. calcd. for C H NO (%): C, 60.75; H,
12
15
4
◦
−1
05 C; IR (KBr, cm ): 3298, 2919, 1708, 1603, 1509,
.37; N, 5.90; Found: C, 60.78; H, 6.40; N, 5.92.
1
433, 1351, 1293, 1156, 1052, 767; H NMR (DMSO,
00 MHz): δ 7.71 (m, 1H), 7.36–7.32 (m, 2H), 7.23–
.19 (m, 2H), 4.97 (br, 1H), 4.70–4.67 (m, 1H), 3.99–
.93 (m, 1H), 3.46–3.45 (m, 1H), 2.11–2.04 (m, 1H),
.89–1.85 (m, 1H); 13CNMR (DMSO, 100 MHz): δ
62.5, 153.0,139.4, 128.0, 127.9, 115.2, 115.0, 73.4,
3
. Results and discussion
Although a number of methods are available for the
synthesis of 1,3-oxazinan-2-one, development of new
simple and efficient synthetic pathways for prepara-
tion of such compounds are quite interesting for a
synthetic chemist. Due to the wide biological acti-
vity of oxazinanones, synthesis of new analogues and
a study of their biological properties is essential. We
+
2.7, 50.5, 30.6; MS (m/z): 248.1 (M +Na, 100);
Anal. calcd. for C H FNO (%): C, 58.66; H, 5.37; N,
11
12
3
6.22; Found: C, 58.63; H, 5.34; N, 6.19.
2.3g 6-(Hydroxymethyl)-4-(2-phenylethyl)-1, 3-oxazinan- report the synthesis of some new analogues of 1,3-
2
-one (3g + 4g): Yield: 85% (yellowish oily liquid); oxazinan-2-ones starting from homoallylic carbamate
−1
IR (KBr, cm ): 3445, 1701, 1593, 1351, 1455, 1335, (scheme 1).
O
O
NHCbz
NHCbz
OH
HN
O
OH
OH
a
b
c
H
R
R
R
R
1
2
3/4
R = Cl, Br, F, Me, OMe, etc.
Reagent and condition: (a) Allyltrimethylsilane, benzyl carbamate, I , CH CN, rt;
2
3
(
b) K OsO (OH) , K Fe(CN) , K CO , pyridine, tBuOH:H O (1:1); (c) NaH, THF, 0°C
2 2 4 3 6 2 3 2
Scheme 1. Synthetic pathway for 1,3-oxazinan-2-one.

1508
Arun Jyoti Borah and Prodeep Phukan
We have synthesized some new 4,6-disubstituted prepared from 4-chloro benzaldehyde. The com-
1,3-oxazinan-2-one using homoallyl amine via Sharp- pound 1a was prepared by adding benzyl carba-
less dihydroxylation and cyclization strategy. In our mate (1.05 equiv) and allyltrimethylsilane (1 equiv)
approach, we have used Cbz-protected homoallyl amine to a solution of 4-chloro benzaldehyde (1 equiv)
1
as the staring material which was prepared by a three- and iodine (10 mol%) in acetonitrile at room tem-
42a
component condensation reaction of aromatic aldehyde, perature.
The protected homoallyl amine 1a was
43
benzyl carbamate and allyltrimethylsilane, developed then subjected to Sharpless dihydroxylation. The
in our laboratory.42 Initially, the synthesis (scheme 1) reaction was carried out using standard dihydroxy-
was carried out with homoallylic carbamate 1a, lation reaction condition in presence of a small
Table 1. Synthesis of 4,6-disubstituted 1,3-oxazinan-2-one derivatives.
Homoallylic carbamate 3,4-dihydroxybutylcarbamate
1,3-oxazinan-2-one
a
Yield dr (4/3)a
a
Sl. No.
1
2
Yield
3 (cis)
4 (trans)
O
O
NHCbz
NHCbz
OH
HN
O
HN
O
OH
OH
OH
1
72
75
82
2:1
2:1
Cl
Cl
Cl
Cl
(
1a)
(2a)
(3a)
(4a)
O
O
NHCbz
NHCbz
OH
HN
O
HN
O
OH
OH
OH
2
74
Br
Br
Br
Br
(
1b)
(2b)
(3b)
(4b)
O
O
NHCbz
HN
O
HN
O
NHCbz
OH
OH
OH
OH
3
4
5
84
75
93
73
70
76
2:3
>99
2:3
(
1c)
(2c)
(3c)
(4c)
O
O
NHCbz
NHCbz
OH
HN
O
HN
O
OH
OH
OH
MeO
MeO
MeO
MeO
(
1d)
(2d)
(3d)
(4d)
O
O
NHCbz
NHCbz
OH
HN
O
HN
O
OH
OH
OH
(
(
1e)
(2e)
(3e)
O
(4e)
O
NHCbz
NHCbz
HN
O
HN
O
OH
OH
OH
6
7
OH
95
75
70
85
>99
F
F
F
F
1f)
(2f)
(3f)
(4f)
O
O
NHCbz
HN
O
HN
O
NHCbz
OH
OH
OH
OH
3:2
(
1g)
(2g)
(3g)
O
(4g)
O
HN
O
HN
O
NHCbz
NHCbz
OH
OH
OH
8
OH
OMe
70
71
2:1
OMe
OMe
OMe
(
1h)
(2h)
(3h)
(4h)
aisolated yield after chromatographic purifications

Synthesis of new 4,6-disubstituted-1,3-oxazinan-2-one analogues
1509
amount of pyridine to produce corresponding 3,4- oxazinan-2-one derivatives starting from a homoal-
dihydroxybutylcarbamate derivative 2a. The product lylic amine. Although, in most of the cases, a mixture
was found to be an inseparable mixture of two diastereo- of diostereomers is formed, 6-(hydroxymethyl)-4-(4-
mers. The 3,4-dihydroxybutylcarbamate derivative 2a methoxyphenyl)-1,3-oxazinan-2-one and 4-(4-fluro-
◦
was then treated with NaH in THF at 0 C. This base- phenyl)-6-(hydroxymethyl)-1,3-oxazinan-2-one were
induced intramolecular cyclization reaction44 resulted formed predominantly with only trans diastereomer.
in the formation of a diastereomeric mixture of 6-
membered 1, 3-oxazinan-2-one (3a + 4a) in 75% yield.
Supplementary information
The nuclear magnetic resonance (NMR) studies indi-
cate the presence of two diastereomers in the final prod-
uct. In this case also, it was not possible to separate the
diastereomers using column chromatography and was
isolated as a mixture of cis and trans products. Rela-
For 1H NMR and 13NMR spectra as supporting infor-
mation see www.ias.ac.in/chemschi: website.
tive stereochemistry of the products has been assigned Acknowledgements
by comparison of the chemical shifts of −CH OH pro-
2
Financial support from the Council of Scientific and
tons with data on similar skeleton already reported in
30
Industrial Research, New Delhi (Grant no. 01(1933)/
04/EMR-II) is gratefully acknowledged. AB thanks
DST-JBNSTS for providing a visiting studentship to
work in the Department of Organic Chemistry, Indian
Institute of Science (IISc), Bangalore. We also thank
Prof. K R Prasad (IISc, Bangalore) for extending his
laboratory facilities during the initial stage of this study.
literature. Diastereomeric ratio (cis : trans) was cal-
1
1
culated using H NMR and found to be 1:2. In the H
NMR spectrum, one of the −CH OH protons appear as
2
two different multiplets at 4.34–4.30 δ (for cis isomer)
and 3.97–3.92 δ (for trans isomer) with a ratio of 1:2.
The other proton in the same group, appears at 3.52–
3.44 δ as multiplet (for both diastereomers). In a similar
way, one proton of 5-CH group appears as a multiplet
2
at 1.89–1.86 δ (trans isomer), while the same proton in
the other diastereomer appears at 1.59–1.50 δ (cis iso- References
mer) with a ratio of 2:1 (trans:cis). The other proton for
1
. (a) Wang G, Ella-Menye J R and Sharma V 2006 Bioorg.
both diastereomers comes at 2.13–2.05 δ as multiplet.
After optimizing the synthetic strategy, we have
expanded the scope of the process using a number of
homoallylic carbamates prepared with different aro-
matic aldehydes. Results are presented in table 1.
In general, this strategy works well for a vari-
ety of aldehydes to produce the corresponding 4,6-
disubstituted-1,3-oxazinan-2-one derivatives in high
yield. All the products were characterized through IR,
NMR and mass apectral data. Integration ratio of pro-
Med. Chem. Lett. 16 2177; (b) Ullrich T, Baumann K,
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J G and Weitz-Schmidt G 2004 Bioorg. Med. Chem. Lett.
1
4 2483; (c) Zanatta N, Borchhardt D M, Alves S H,
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1
ton in H NMR spectra of the cyclic carbamate reveals
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for the entries (1, 2, 8); while 1:1.5 (cis : trans) selecti-
vity was observed for entry 7. However for the entries 3
and 5, the cis-isomer was found to be dominant over the
trans-isomer with diasteromeric ratio 1.5:1 (cis : trans).
Interestingly for the entries 4 and 6 (table 1), only trans-
isomers 4d and 4f, respectively, were formed predomi-
nantly. This may be due to strong resonance effect of
substituents on the aromatic ring.
3. Gormley Jr G, Chan Y Y and Fried J 1980 J. Org. Chem.
5 1447
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. (a) Larson G M, Schaneberg B T and Sneden A T 1999
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Camenisch G, Meingassner J G and Weitz-Schmidt G
4
. Conclusion
2004 Bioorg. Med. Chem. Lett. 14 2483
In conclusion, we have developed an efficient syn-
thetic strategy for the synthesis of 4,6-disubstituted 1,3-
. Jin F 2000 Confalone P N PCT Int. Appl. WO0000481,
119; Chem. Abstr. 132 78560

1510
Arun Jyoti Borah and Prodeep Phukan
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