(R = Et)

[57584-86-8]  · C10H15NSe  · N,N-Diethylbenzeneselenenamide  · (MW 228.22) (R = Me)

[57584-85-7]  · C8H11NSe  · N,N-Dimethylbenzeneselenenamide  · (MW 200.16) (NR2 = morpholino)

[82737-08-4]  · C10H13NOSe  · N-Phenylselenomorphine  · (MW 242.24)

(reagent for a-selenenylation of aldehydes2 and b-dicarbonyl compounds;3 areneselenenamides are electrophilic selenium agents for enamines,4 silyl enol ethers,4 and a,b-unsaturated carbonyl compounds,2 and have a more basic character than arenesulfenamides5)

Alternate Name: N-phenylseleno-N,N-diethylamine.

Physical Data: bp 75 °C/0.1 mmHg.

Solubility: sol aprotic solvents; hydrolyzed in water; reacts with alcohols.

Form Supplied in: pale yellow oil, often with diphenyl diselenide as impurity.

Analysis of Reagent Purity: 1H NMR (CDCl3)6 7.56 (m, 2H) 7.2 (m, 3H) 3.0 (q, J = 7 Hz, 4H) 1.2 (t, J = 7 Hz, 6H). 13C NMR7 131.0, 128.5, 126.9, 53.8, 14.6, 3.0.

Preparative Methods: from Benzeneselenenyl Chloride and diethylamine (eq 1).3 Benzeneselenenyl Bromide, formed from Diphenyl Diselenide and Bromine, can also be used.6 The more stable morpholino analog is obtained by the same procedure.4,9 Optically active areneselenenamides have been prepared from chiral amines.10,11 Selenenamides are also obtained from N-(trimethylsilyl)dialkylamines (eq 2)7a,12 and used without purification.7a

Handling, Storage, and Precautions: can be stored for several weeks below 0 °C in the absence of moisture; like its morpholino analog N-phenylselenomorpholine,8 it can be prepared just before use. Use in a fume hood.

a-Selenenylation of Carbonyl Compounds.

PhSeNEt2,2 like its morpholino analog,4,8 reacts with aldehydes to give a-phenylseleno aldehydes (eq 3). Linear aldehydes react very quickly (5 min). The reaction has been used in natural products synthesis.6,9,13 With the morpholino analog, (phenylseleno)acetaldehyde gives a bis(phenylseleno)enamine, which is hydrolyzed to bis(phenylseleno)acetaldehyde; this is then converted into tris(phenylseleno)acetaldehyde (eq 4).4a,b PhSeNEt23 and N-phenylselenomorpholine8 react also with 1,3-dicarbonyl compounds (eqs 5 and 6).

Using PhSeNMe2, a reverse Claisen reaction sometimes occurs.3 Ketones and selenenamides lead to mixtures. Chiral selenenamides and 4-alkylcyclohexanones produce a-phenylselenocyclohexanones in refluxing solvent (THF, benzene) in poor yields (20-52%) and modest enantiomeric excess.10 2-Phenyl-2-(p-chlorophenylseleno)propionaldehyde is prepared from 2-phenylpropionaldehyde and the p-chlorobenzeneselenenamide derived from S-methyl prolinate, in optically pure form.11 a-Oxo esters react also, under the same conditions (eq 7).4b

Reactions with Enamines and Silyl Enol Ethers.

Selenenamides add to enamines with elimination of an amine (eqs 4 and 8).4b Silyl enol ethers give a-phenylseleno ketones (eq 9)4b and conjugated dienoxysilanes allow access to g-phenylseleno-a,b-unsaturated carbonyl compounds (eq 10).4b

Additions to Electron-Deficient Alkenes.

PhSeNEt2, formed with the PhSeOH resulting from a syn-elimination reaction of a-phenylseleninyl ketones, adds to the newly created double bond to give a-phenylseleno enones (eq 11).3

PhSeNMe2 reacts also with a-alkylated enones (eq 12). The adduct is isolated and oxidized to an a-aminomethyl enone, which is the major product.3 Selenenamides add to conjugated enals to give a-phenylseleno enals (eq 13).4b A demethylation occurs on a 6-methylenemisotane by treatment with N-phenylselenomorpholine and also when the 6-methyl-6-(phenylseleno)misotane is oxidized and treated with a secondary amine. PhSeOH, liberated during the elimination step, is transformed into a selenenamide which adds to the double bond. A retro-Mannich reaction explains the demethylation.14

PhSeNMe2 and Dimethyl Acetylenedicarboxylate give a mixture of isomers. The maleate kinetic product (1) partially isomerizes to the fumarate form (2) (eq 14).15 The sulfenamides add only under forcing conditions.15 Selenenamides react with butynone and Methyl Propiolate.4b

Related Reagents.

N-Phenylselenophthalimide; N-Phenylthiophthalimide.

1. (a) Sonoda, N.; Ogawa, A. In The Chemistry of Organic Selenium and Tellurium Compounds; Patai, S.; Rappoport, Z. Eds.; Wiley: New York, 1986; Vol. 1, pp 640-641. (b) Organoselenium Chemistry; Liotta, D., Ed.; Wiley: New York, 1987. (c) Paulmier, C. Selenium Reagents and Intermediates in Organic Synthesis; Pergamon: Oxford, 1986.
2. Jefson, M.; Meinwald, J. TL 1981, 22, 3561.
3. Reich, H. J.; Renga, J. M. JOC 1975, 40, 3313.
4. (a) Paulmier, C.; Lerouge, P. TL 1982, 23, 1557. (b) Lerouge, P.; Paulmier, C. BSF(2) 1985, 1219.
5. Kice, J. L.; Kutateladze, A. G. JOC 1993, 58, 917.
6. Keck, G. E.; Cressman, E. N. K.; Enholm, E. J. JOC 1989, 54, 4345.
7. (a) Tomoda, S.; Takeuchi, Y.; Nomura, Y. S 1985, 212. (b) Paulmier, C.; Lerouge, P.; Outurquin, F.; Chapelle, S.; Granger, P. MRC 1987, 25, 955.
8. Lerouge, P.; Paulmier, C. TL 1984, 25, 1983.
9. Kuwahara, S.; Mori, K. T 1990, 46, 8075.
10. Hiroi, K.; Sato, S. S 1985, 635.
11. Paulmier, C.; Outurquin, F.; Plaquevent, J.-C. TL 1988, 29, 5889.
12. Back, T. G.; Kerr, R. G. CJC 1986, 64, 308.
13. Kuehne, M. E.; Seaton, P. J. JOC 1985, 50, 4790.
14. Arai, H.; Kanda, Y.; Kasai, M. JOC 1993, 58, 892.
15. Reich, H. J.; Renga, J. M.; Trend, J. E. TL 1976, 2217.

Claude Paulmier

Université de Rouen, Mont-Saint-Aignan, France

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