616
Helvetica Chimica Acta – Vol. 95 (2012)
Table 4. Comparison of NDC with Other Reagents Used for the Oxidative Deamination of Benzylamine
Entry
Reagents or catalyst
Time
Yield [%]
Ref.
1
2
NDC, MeCN, r.t.
–a)
10 min
98
79
–b)
[7a]
Riboflavin tetraacetate (10 mol-%), air,
D2O/(D6)DMSO 24 : 1, LED 440 nm
5% Pd/C, PEG-400, microwave, 1708
Ascorbic acid, CuI-3-methylsalicylate, DMAc), 508
30% aq. H2O2 soln. (5 equiv.), toluene, 608
KMnO4 (1.25 equiv.), H2O, tBuOH
3
4
5
6
3 h
2 h
2 – 3 h
10 min
68
82
69
61
[7b]
[7c]
[7d]
[7e]
a) Reaction occurred immediately. b) Present work. c) N,N-Dimethylacetamide.
We are thankful to the Birjand University Research Council for its support of this work.
Experimental Part
Oxidation of Amines to Aldehydes and Ketones: General Procedure. NDC (1 mmol) was added to the
soln. of amine (1 mmol) in MeCN (2 ml) and stirred for the appropriate time at r.t. (Table 2). The
resulting heterogeneous mixture was then filtered, and the filter cake was washed with Et2O (2 ꢁ 10 ml).
In most cases, evaporation of the filtrate yielded the desired pure product. If further purification was
required, the crude product was purified by column chromatography (silica gel, hexane/AcOEt 3 :1).
Oxidation of Aminophosphonates: General Procedure. A mixture of aminophosphonate (5 mmol)
and NDC (10 mmol) in MeCN (10 ml) was stirred under reflux conditions for the time given in Table 3.
The resulting heterogeneous reaction mixture was cooled and filtered. The filter cake was washed with
Et2O (2 ꢁ 10 ml). The solvent was evaporated to give the crude product. The pure product was obtained
by vacuum distillation in 85 – 97% yield (Table 3).
Diethyl P-Benzoylphosphonate (1): IR (neat): 1660 (C¼O), 1250 (P¼O). 1H-NMR (CDCl3): 1.39 (t,
3J(H,H) ¼ 7.1, 2 MeCH2O); 4.22 (qt, 3J(P,H) ¼ 3J(H,H) ¼ 7.1, 2 MeCH2O); 7.28 – 7.6 (m, 3 arom. H); 8.23
(d, 3J(H,H) ¼ 7.7, 2 arom. H). 13C-NMR (CDCl3): 16.6 (d, 3J(C,P) ¼ 5.7, MeCH2O); 64.3 (d, 2J(C,P) ¼ 7.5,
MeCH2O); 129.1, 130.1, 135.0, 136.3 (Ph); 199.1 (d, 1J(C,P) ¼ 177.5, C¼O). MS (70 eV): 242 (Mþ), 105
([M ꢀ P(O)(OEt)2]þ).
Diethyl P-(4-Methoxybenzoyl)phosphonate (2): IR (neat): 1655 (C¼O), 1265 (P¼O). 1H-NMR
(CDCl3): 1.20 (t, 3J(H,H) ¼ 7.1, 2 MeCH2O); 3.80 (s, MeO); 4.00 (qt, 2J(P,H) ¼ 3J(H,H) ¼ 7.1,
2 MeCH2O); 6.84 – 6.90 (m, 2 H); 7.42 – 7.50 (m, 2 H). 13C-NMR (CDCl3): 16.7 (d, 3J(C,P) ¼ 5.7,
2
MeCH2O); 55.6 (MeO); 63.5 (d, J(C,P) ¼ 7.5, MeCH2O); 114.0, 128.8, 129.2, 159.8 (C6H4); 198.01 (d,
1J(C,P) ¼ 176.2, C¼O). MS (70 eV) : 272 (Mþ), 135 ([M ꢀ P(O)(OEt)2]þ).
Diethyl P-(4-Methylbenzoyl)phosphonate (3): IR (neat): 1650 (C¼O), 1261 (P¼O). 1H-NMR
(CDCl3): 1.32 (t, 3J(H,H) ¼ 7.1, 2 MeCH2O); 2.35 (s, Me); 4.14 (qt, 2J(P,H) ¼ 3J(H,H) ¼ 7.1, 2 MeCH2O);
7.12 – 7.21 (m, 2 arom. H); 8.04 – 8.07 (m, 2 arom. H). 13C-NMR (CDCl3): 16.7 (d, 3J(C,P) ¼ 5.7,
MeCH2O); 22.2 (Me); 64.2 (d, 2J(C,P) ¼ 7.5, MeCH2O); 127.3, 129.9, 130.3, 146.4 (C6H4); 198.5 (d,
1J(C,P) ¼ 176.6, C¼O). MS: 256 (Mþ), 119 ([M ꢀ P(O)(OEt)2]þ).
Diethyl P-(4-Chlorobenzoyl)phosphonate (5): IR (neat): 1650 (C¼O), 1260 (P¼O). 1H-NMR
(CDCl3): 1.39 (t, 3J(H,H) ¼ 7.1, 2 MeCH2O); 4.28 (qt, 2J(P,H) ¼ 3J(H,H) ¼ 7.1, 2 MeCH2O); 7.49 (d,
3
3
3J(H,H) ¼ 7.8, 2 H); 8.23 (d, J(H,H) ¼ 8.0, 2 H). 13C-NMR (CDCl3): 16.7 (d, J(C,P) ¼ 5.7, MeCH2O);
64.5 (d, 2J(C,P) ¼ 7.5, MeCH2O); 129.6, 131.6, 133.7, 141.8 (C6H4); 198.1 (d, 1J(C,P) ¼ 180.0, C¼O). MS
(70 eV): 277 (Mþ), 279 ([M þ 2]þ), 139 ([M ꢀ P(O)(OEt)2]þ).
Diethyl P-(3-Chlorobenzoyl)phosphonate (6): IR (neat): 1650 (C¼O), 1267 (P¼O). 1H-NMR
(CDCl3): 1.28 – 1.34 (m, 2 MeCH2O); 4.22 (qt, 2J(P,H) ¼ 3J(H,H) ¼ 6.9, 2 MeCH2O); 7.22 – 7.53 (m, 3 H);
7.96 (s, 1 H). 13C-NMR (CDCl3): 18.4 (d, 3J(C,P) ¼ 5.7, MeCH2O); 66.4 (d, 2J(C,P) ¼ 7.4, MeCH2O);