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β,γ-Unsaturated α-aminophosphonates: synthesis and reactivity
Tetrahedron Letters 41 (2000) 6045±6048
b,g-Unsaturated a-aminophosphonates: synthesis and reactivity A. Atmani,a,* J.-C. Combret,a C. Malhiaca and J. Kajima Mulengib a
b
Laboratoire d'HeÂteÂrochimie Organique, Universite de Rouen, B.P.118/76.134, Mont-St Aignan, France Laboratoire de SyntheÁse Organique, Institut de Chimie, Universite de Tlemcen, B.P. 119, Tlemcen 13000, Algeria Received 22 April 2000; accepted 1 June 2000
Abstract Vinylogous iminium salts from g-aminoenamines react with triethylphosphite to aord amino phosphonates in moderate to good yields. The latter are easily converted to a-substituted aminoallylphosphonates that can yield a-substituted aminoallylphosphonates on reaction with butyllitium and a series of electrophiles. # 2000 Elsevier Science Ltd. All rights reserved.
a-Aminophosphonic acids and their esters represent an interesting class of chemical compounds as they are endowed with interesting biological and chemical properties.1ÿ4 The synthesis of the title substances of type 1 has received little attention since preparative methods already described in the literature start generally from unsaturated imines.5,6
In this work we deal with a new synthetic way leading to a-amino b,g-ethylenic phosphonates starting from unsaturated iminiums salts 2.7 We describe, for the ®rst time, the use of such unsaturated compounds as a source of carbanions and the reaction of the latter with a series of electrophiles. Iminium salts were quantitatively prepared by the reaction of an acid chloride such as acetyl chloride with g-aminoenamines or by the reaction of methyl iodide with the same enamines (Scheme 1). * Corresponding author. 0040-4039/00/$ - see front matter # 2000 Elsevier Science Ltd. All rights reserved. PII: S0040-4039(00)00922-9
6046
Scheme 1.
This procedure is advantageous, compared to that of BoÈhme et al.8 The reaction takes place under mild working conditions and the isolation and puri®cation of salts 2 just requires their ®ltration and washing with the appropriate solvent. However, when R1 is a methyl group, the iminium salt cannot be isolated and it is engaged in situ in the synthesis of the aminophosphonate. In each case, we have investigated the reaction of 2 with alkylphosphites. The reaction aorded a-dialkylamino b,g-ethylenic phosphonates 1 in good yields (Scheme 2).
Scheme 2.
Hetero-substituted phosphonates have been extensively used as a source of carbanions in the Wittig±Horner or Horner±Wadsworth±Emmons reactions.9,10 However, the ease of carbanion formation is not always clear and some discrepancies are found in the literature.11ÿ15 In recent years, b,g-unsaturated phosphonates have been used as a source of carbanions.16ÿ18 To our best knowledge, b,g-ethylenic a-aminophosphonates 1 have not been tried for the same target yet. Scheme 3 shows our results on the treatment of 1 with butyllithium and the reaction of the resulting carbanions with a series of electrophiles to aord a-substituted b,g-unsaturated aminophosphonates 2.
Scheme 3. R1=CH3, C2H5; i=R0 CHO, PhCH2Br, CH3I; R0 =CH3, Ph, (CH3)2CH, Furyl
1. Experimental 1
H, 13C and 31P NMR spectra were recorded at 200 MHz on an AC 200 Bruker or a WP 80 Bruker (80 MHz) instrument using TMS as an internal standard for 1H and 13C analyses; phosphoric acid was used for 31P spectra. Chemical shifts are expressed in ppm. Mass spectra were recorded by coupling a HP 5890 Hewlett Packard gas chromatography instrument with a 70 eV electronic impact HP 5970 mass spectrometer. All commercial solvents were puri®ed and dried prior to use.
6047
1.1. Iminium salts: general procedure (example: 2a) 1,3-dimorpholino 3-phenylpropene (14.4 g, 50 mmol) was dissolved in dry ether (250 ml) and the resulting solution was cooled at ^5 C. Acetyl chloride (3.9 g, 50 mmol) in dry ether (100 ml) was slowly added with stirring to the propene solution keeping the temperature at ^5 C during the addition. Stirring was maintained for 30 min during which the temperature rose to room temperature. The solid 2a was ®ltered and washed several times with dry ether in order to get rid of acetmorpholide and was ®nally dried. Yield 96%. mp 180 C. 1H NMR (80 MHz,CD3CN): 2.3±3 (m, 6H, Hb, Hb0 , Hc), 3.4±3.7 (m, 4H, Ha, Ha0 ), 7.5±8 (m, 2H, Hb, Hg), 8.7 (d, J=11 Hz, 1H, Ha). IR: 1650 cm^1. Other salts were prepared from piperidine with XCl (yield 95%, mp 185 C, Ha=8.8, J=11 Hz); from morpholine with XI (yield 95%, mp 210 C, Ha=8.7, J=10 Hz); from dimethylamine with XI (yield 95%, mp 194 C, Ha=8.8, J=10 Hz). 1.2. -Aminophosphonates: general procedure Iminium salt (5 mmol) in dry acetonitrile (10 ml) was placed in a 50-ml three-necked ¯ask under dry nitrogen. Freshly distilled trialkylphosphite (5.1 mmol) was then added and the mixture was stirred overnight. After removal of the solvent, the residue was dissolved in ether (20 ml) and washed with 2 M HCl (10 ml). The organic layer was washed with further 2 M HCl (35 ml). The aqueous phase was adjusted at pH 11 with a 5 M NaOH solution and extracted with ether. The combined organic phases were dried over magnesium sulfate and the solvent was removed to aord the phosphonate as an oil. 1a: Yield: 40%. MS (EI, 70 eV): m/z 247 (6) M+, 138 (100), M-109. 31P NMR (200 MHz, CDCl3): 24.2. 1H NMR (200 MHz, CDCl3): 1.34 (m, 2H, Hc), 1.46±1.52 (m, 4H, Hb),1.71(d, 3H, J=4.6 Hz, CH3ÿCH), 2.46±2.75 (m, 4H, Ha), 3.30 (dd, J=8, 18 Hz, 1H, CHÿCHÿP), 3.67± 3.78 [2d, J=9.33, 9.90 Hz, 6H, P(OCH3)2], 5.63 (m, 2H, CH3ÿCHCH). 13C NMR (200 MHz, CDCl3): 18(s), 23.3(s, c), 26.5(s, b, b0 ), 51.5 (d, J=8.4 Hz, a, a0 ), 52.5 [d, J=7.3 Hz, (CH3O)2P], 53 [d, J=7.1 Hz, (CH3O)2P], 67.5 (d, J=156.6 Hz, CHÿCHÿCH3), 121 (s, CHÿCH), 132 (d, J=15.5 Hz, CH3ÿCH). 1b: Yield: 87%. MS(EI): 269(4), M+, 160 (100), M-109. 31P NMR (200 MHz, CDCl3): 23.6; 1H NMR (200 MHz, CDCl3): 2.5 (s, 6H, N(CH3)2), 3.50 (dd, J=8.8, 17.7 Hz, 1H, CHÿCHÿP) 3.75, (d, J=11 Hz, 3H, P(OCH3)2), 3.85 (d, J=11 Hz, 3H, P(OCH3)2), 6.35 (ddd, J=6.7, 9.8, 15 Hz, 1H, CH=CH), 6.7 (dd, J=2.8, 16 Hz, 1H, CH=CH), 7.4 (m, 5H, C6H5). 13C NMR (200 MHz, CDCl3): 43 [d, J=9.1 Hz, N(CH3)2], 52 (m, P(OCH3)2) 65 (d, J=159.4 Hz, CHÿCHÿP), 120 (s, CHCH), 138 (d, J=15.4 Hz, CHCH), 126, 128, 136 (Ph). 1c: Yield 84%. MS (EI): m/z 339 (4) M+, 202 (100), M-137. 31P NMR (200 MHz, CDCl3): 20.3. 1 H NMR (200 MHz, CDCl3): 1.28 [dt, J=6, 16 Hz, 6H, P(OCH2CH3)2], 2.62±2.94 (m, 4H, Ha), 3.45 (dd, J=8, 20 Hz, 1H, CHÿCHÿP), 3.66±3.70 (m, 4H, Hb), 4.11 [(m, 4H, P(OCH2CH3)2], 6.20 (dd, J=3, 12, 16 Hz, 1H, PhÿCHCH), 6.50 (dd, J=4, 16 Hz, 1H, C6H5ÿCHCH), 7.20 (m, 5H, C6H5ÿ). 13C NMR (200 MHz, CDCl3): 18 [m, P(OCH2CH3)2], 52 (d, J=8.2 Hz, a, a0 ), 62 [2d, J=7 Hz, P(OCH2CH3)2], 65 (d, J=157.9 Hz, CHÿCHÿP), 120 (s, C6H5ÿCHCH), 126, 127, 128, 136 (Ph), 138 (d, J=15 Hz, PhCH). 1d: Yield: 89%, MS (EI): 295 (7) M+, 186 (100), M-109. 1H NMR (200 MHz, CDCl3): 1.72 (m, 4H, Hb), 2.74 (m, 4H, Ha), 3.71 and 3.73 [2d, J=7.31, 6H, P(OCH3)2], 3.59 (dd, J=9.93, 13.4 Hz, 1H, CHÿCHÿP), 6.29 (dd, J=4, 6, 16 Hz, 1H, PhCHCH), 6.58 (dd, J=5, 15 Hz, 1H, PhCHCH), 7.32 (m, 5H, Ph).
6048
1.3. Alkylation of , -unsaturated -aminophosphonates: general procedure To a cooled solution (^78 C) of 1 (5 mmol) in THF (5 ml) was added butyllithium in THF (5 mmol), dropwise under argon, and the resulting solution was stirred for 1 h. A solution of the required aldehyde (5 mmol) in THF(5 ml) was then added. After 30 min stirring, Me3SiCl (5 mmol) was added and stirring was continued for a further 2 h. At the end, the solvent was removed under reduced pressure and the residue was dissolved in CH2Cl2. The resulting solution was washed with a saturated aqueous solution of NH4Cl (35 ml) and dried over MgSO4. After removal of the solvent, the residue was puri®ed on a silica gel column chromatography eluted with ether/methanol (9:1). All compounds gave satisfactory analytical data. 2a: R1C2H5, R2CH3. Yield 80%. MS(EI, 70 eV), m/z: 353 (20) M+, 322 (100). 31P NMR: 14.5. 1H NMR (200 MHz,CDCl3) 1.10 (s,3H, CÿCH3), 1.30 (dt, J=7.48, 14.18 Hz, 6H, P[(OCH2CH3)2], 2.80 (m, 4H, Ha, Ha0 ), 3.69 (m, 4H, Hb, Hb0 ), 4.03 (m, 4H, P[(OCH2CH3)2]), 6.40±6.54 (2d, J=11.89, 12.43 Hz, 2H, PhCHCH), 7.18 (m, 5H, C6H5). 2f: R1i-C3H7CHOTMS. Yield 85%. MS (EI, 70eV), m/z: 483, M+, 411 (7) M-73, 338 (100). 31P NMR: 14.1. 1H NMR (200 MHz,CDCl3) 0.06 (s, 6H, OSiMe3), 0.89 (d, J=2.9 Hz, 6H, [(H3C)2CH]), 1.28 (dt, J=3.7, 7.17 Hz, 6H, [(OCH2CH3)2]), 1.50 (m, 1H, [CH3)2CH]), 2.60±2.80 (m, 4H, Ha), 4.08 (m, 4H, P[(0CH2CH3)2]), 6.75 (d, J=10 Hz, 1H, PhCHCH), 6.80 (d, J=10 Hz, 1H, PhCH) 7.18 (m, 5H, C6H5). References 1. Kase, K.; Yamamoto, M.; Koguchi, T.; Okachi, R.; Kasai, M.; Shirata, K.; Kawamoto, I.; Shuto, K.; Karasawa, A. Eur. Pat. Appl., Ep 61, 172, 1982., Chem. Abstr. 1983, 98, 107793. 2. (a) Maier, L. Phosphorus, Sulfur and Silicon 1990, 53, 43±46. (b) Dhawan, B.; Redmore, D. Phosphorus, Sulfur and Silicon 1987, 32, 119. (c) Jacobson, N. E.; Bartlett, P. A. J. Am. Chem. Soc. 1981, 103, 654±657. (d) Lukszo, J.; Tyka, R. Synthesis 1977, 239±240. (e) Pudovik, A. N.; Konovalova, I. V. Synthesis 1979, 81±93. (f) Bartlett, P. A.; Hanson, J. E.; Giannousis, P. P. J. Org. Chem. 1990, 55, 6268±6274. 3. Kabachnik, M. I.; Medved, T. Y.; Dyatlova, N. M.; Arkhipova, O. G.; Rudomino, M. V. Chem. Abstr. 1969, 7c, 20101g. Usp. Khim. 1968, 37, 1161±1191. 4. Wadsworth, W. S.; Emmons, W. D. J. Am. Chem. Soc. 1961, 83, 1733±1738. 5. Sobanov, A. A.; Bathtiyarova, I. V.; Badeeva, E. K.; Zimin, M. G.; Pudovik, A. N. Zh. Obsch. Khim. 1985, 55, 22±26. 6. (a) Afarinkia, K.; Cadogan, J. I. G.; Rees, C. W. Synlett 1992, 123. (b) Afarinkia, K.; Cadogan, J. I. G.; Rees, C. W. Tetrahedron 1990, 46, 7175±7196. 7. Jahn, U.; Andersch, J.; Schroth, W. Synthesis 1997, 573±588. 8. BoÈhme, H.; Viehe, H. G. Iminium Salts in Organic Chemistry. Adv. Org. Chem.; Taylor, E. C., Ed. Vol 9. John Wiley: New York, 1975±1979; pp. 107±223. 9. (a) Martin, S. F.; Gomper, R. J. Org. Chem. 1974, 39, 2814±2815. (b) Martin, S. F. J. Org. Chem. 1976, 41, 3337± 3338. (c) Martin, S. F.; Chou, F. S.; Payne, C. W. J. Org. Chem. 1977, 42, 2520±2523. 10. Ahlbrecht, H.; Farnung, W. Synthesis 1977, 336±338. 11. Broekhof, N. J.; Van der Gen, A. Tetrahedron Lett. 1980, 21, 2671±2674. 12. Zimmer, H.; Bercz, J. P. Liebigs Ann. Chem. 1965, 686, 107±114. 13. Gross, H.; Costisella, B. Angew. Chem. 1968, 80, 364±365. 14. Schindler, N.; PloÈger, W. Chem. Ber. 1971, 104, 2021±2022. 15. Fukuda, M.; Kan, K.; Okamoto, Y.; Sakurai, H. Bull. Chem. Soc. Jpn. 1975, 2103±2105. 16. Gerber, J. P.; Modro, T. A. Phosphorus, Sulfur and Silicon 1994, 88, 99±111. 17. Gross, H.; Costisella, W. Angew. Chem., Int. Ed. 1968, 7, 391±392. 18. (a) Ahlbrecht, H.; Farnung, W. Chem. Ber. 1984, 117, 1±22. (b) Ahlbrecht, H.; Farnung, W.; Simon, H. Chem. Ber. 1984, 117, 2622±2643.
b,g-Unsaturated a-aminophosphonates: synthesis and reactivity A. Atmani,a,* J.-C. Combret,a C. Malhiaca and J. Kajima Mulengib a
b
Laboratoire d'HeÂteÂrochimie Organique, Universite de Rouen, B.P.118/76.134, Mont-St Aignan, France Laboratoire de SyntheÁse Organique, Institut de Chimie, Universite de Tlemcen, B.P. 119, Tlemcen 13000, Algeria Received 22 April 2000; accepted 1 June 2000
Abstract Vinylogous iminium salts from g-aminoenamines react with triethylphosphite to aord amino phosphonates in moderate to good yields. The latter are easily converted to a-substituted aminoallylphosphonates that can yield a-substituted aminoallylphosphonates on reaction with butyllitium and a series of electrophiles. # 2000 Elsevier Science Ltd. All rights reserved.
a-Aminophosphonic acids and their esters represent an interesting class of chemical compounds as they are endowed with interesting biological and chemical properties.1ÿ4 The synthesis of the title substances of type 1 has received little attention since preparative methods already described in the literature start generally from unsaturated imines.5,6
In this work we deal with a new synthetic way leading to a-amino b,g-ethylenic phosphonates starting from unsaturated iminiums salts 2.7 We describe, for the ®rst time, the use of such unsaturated compounds as a source of carbanions and the reaction of the latter with a series of electrophiles. Iminium salts were quantitatively prepared by the reaction of an acid chloride such as acetyl chloride with g-aminoenamines or by the reaction of methyl iodide with the same enamines (Scheme 1). * Corresponding author. 0040-4039/00/$ - see front matter # 2000 Elsevier Science Ltd. All rights reserved. PII: S0040-4039(00)00922-9
6046
Scheme 1.
This procedure is advantageous, compared to that of BoÈhme et al.8 The reaction takes place under mild working conditions and the isolation and puri®cation of salts 2 just requires their ®ltration and washing with the appropriate solvent. However, when R1 is a methyl group, the iminium salt cannot be isolated and it is engaged in situ in the synthesis of the aminophosphonate. In each case, we have investigated the reaction of 2 with alkylphosphites. The reaction aorded a-dialkylamino b,g-ethylenic phosphonates 1 in good yields (Scheme 2).
Scheme 2.
Hetero-substituted phosphonates have been extensively used as a source of carbanions in the Wittig±Horner or Horner±Wadsworth±Emmons reactions.9,10 However, the ease of carbanion formation is not always clear and some discrepancies are found in the literature.11ÿ15 In recent years, b,g-unsaturated phosphonates have been used as a source of carbanions.16ÿ18 To our best knowledge, b,g-ethylenic a-aminophosphonates 1 have not been tried for the same target yet. Scheme 3 shows our results on the treatment of 1 with butyllithium and the reaction of the resulting carbanions with a series of electrophiles to aord a-substituted b,g-unsaturated aminophosphonates 2.
Scheme 3. R1=CH3, C2H5; i=R0 CHO, PhCH2Br, CH3I; R0 =CH3, Ph, (CH3)2CH, Furyl
1. Experimental 1
H, 13C and 31P NMR spectra were recorded at 200 MHz on an AC 200 Bruker or a WP 80 Bruker (80 MHz) instrument using TMS as an internal standard for 1H and 13C analyses; phosphoric acid was used for 31P spectra. Chemical shifts are expressed in ppm. Mass spectra were recorded by coupling a HP 5890 Hewlett Packard gas chromatography instrument with a 70 eV electronic impact HP 5970 mass spectrometer. All commercial solvents were puri®ed and dried prior to use.
6047
1.1. Iminium salts: general procedure (example: 2a) 1,3-dimorpholino 3-phenylpropene (14.4 g, 50 mmol) was dissolved in dry ether (250 ml) and the resulting solution was cooled at ^5 C. Acetyl chloride (3.9 g, 50 mmol) in dry ether (100 ml) was slowly added with stirring to the propene solution keeping the temperature at ^5 C during the addition. Stirring was maintained for 30 min during which the temperature rose to room temperature. The solid 2a was ®ltered and washed several times with dry ether in order to get rid of acetmorpholide and was ®nally dried. Yield 96%. mp 180 C. 1H NMR (80 MHz,CD3CN): 2.3±3 (m, 6H, Hb, Hb0 , Hc), 3.4±3.7 (m, 4H, Ha, Ha0 ), 7.5±8 (m, 2H, Hb, Hg), 8.7 (d, J=11 Hz, 1H, Ha). IR: 1650 cm^1. Other salts were prepared from piperidine with XCl (yield 95%, mp 185 C, Ha=8.8, J=11 Hz); from morpholine with XI (yield 95%, mp 210 C, Ha=8.7, J=10 Hz); from dimethylamine with XI (yield 95%, mp 194 C, Ha=8.8, J=10 Hz). 1.2. -Aminophosphonates: general procedure Iminium salt (5 mmol) in dry acetonitrile (10 ml) was placed in a 50-ml three-necked ¯ask under dry nitrogen. Freshly distilled trialkylphosphite (5.1 mmol) was then added and the mixture was stirred overnight. After removal of the solvent, the residue was dissolved in ether (20 ml) and washed with 2 M HCl (10 ml). The organic layer was washed with further 2 M HCl (35 ml). The aqueous phase was adjusted at pH 11 with a 5 M NaOH solution and extracted with ether. The combined organic phases were dried over magnesium sulfate and the solvent was removed to aord the phosphonate as an oil. 1a: Yield: 40%. MS (EI, 70 eV): m/z 247 (6) M+, 138 (100), M-109. 31P NMR (200 MHz, CDCl3): 24.2. 1H NMR (200 MHz, CDCl3): 1.34 (m, 2H, Hc), 1.46±1.52 (m, 4H, Hb),1.71(d, 3H, J=4.6 Hz, CH3ÿCH), 2.46±2.75 (m, 4H, Ha), 3.30 (dd, J=8, 18 Hz, 1H, CHÿCHÿP), 3.67± 3.78 [2d, J=9.33, 9.90 Hz, 6H, P(OCH3)2], 5.63 (m, 2H, CH3ÿCHCH). 13C NMR (200 MHz, CDCl3): 18(s), 23.3(s, c), 26.5(s, b, b0 ), 51.5 (d, J=8.4 Hz, a, a0 ), 52.5 [d, J=7.3 Hz, (CH3O)2P], 53 [d, J=7.1 Hz, (CH3O)2P], 67.5 (d, J=156.6 Hz, CHÿCHÿCH3), 121 (s, CHÿCH), 132 (d, J=15.5 Hz, CH3ÿCH). 1b: Yield: 87%. MS(EI): 269(4), M+, 160 (100), M-109. 31P NMR (200 MHz, CDCl3): 23.6; 1H NMR (200 MHz, CDCl3): 2.5 (s, 6H, N(CH3)2), 3.50 (dd, J=8.8, 17.7 Hz, 1H, CHÿCHÿP) 3.75, (d, J=11 Hz, 3H, P(OCH3)2), 3.85 (d, J=11 Hz, 3H, P(OCH3)2), 6.35 (ddd, J=6.7, 9.8, 15 Hz, 1H, CH=CH), 6.7 (dd, J=2.8, 16 Hz, 1H, CH=CH), 7.4 (m, 5H, C6H5). 13C NMR (200 MHz, CDCl3): 43 [d, J=9.1 Hz, N(CH3)2], 52 (m, P(OCH3)2) 65 (d, J=159.4 Hz, CHÿCHÿP), 120 (s, CHCH), 138 (d, J=15.4 Hz, CHCH), 126, 128, 136 (Ph). 1c: Yield 84%. MS (EI): m/z 339 (4) M+, 202 (100), M-137. 31P NMR (200 MHz, CDCl3): 20.3. 1 H NMR (200 MHz, CDCl3): 1.28 [dt, J=6, 16 Hz, 6H, P(OCH2CH3)2], 2.62±2.94 (m, 4H, Ha), 3.45 (dd, J=8, 20 Hz, 1H, CHÿCHÿP), 3.66±3.70 (m, 4H, Hb), 4.11 [(m, 4H, P(OCH2CH3)2], 6.20 (dd, J=3, 12, 16 Hz, 1H, PhÿCHCH), 6.50 (dd, J=4, 16 Hz, 1H, C6H5ÿCHCH), 7.20 (m, 5H, C6H5ÿ). 13C NMR (200 MHz, CDCl3): 18 [m, P(OCH2CH3)2], 52 (d, J=8.2 Hz, a, a0 ), 62 [2d, J=7 Hz, P(OCH2CH3)2], 65 (d, J=157.9 Hz, CHÿCHÿP), 120 (s, C6H5ÿCHCH), 126, 127, 128, 136 (Ph), 138 (d, J=15 Hz, PhCH). 1d: Yield: 89%, MS (EI): 295 (7) M+, 186 (100), M-109. 1H NMR (200 MHz, CDCl3): 1.72 (m, 4H, Hb), 2.74 (m, 4H, Ha), 3.71 and 3.73 [2d, J=7.31, 6H, P(OCH3)2], 3.59 (dd, J=9.93, 13.4 Hz, 1H, CHÿCHÿP), 6.29 (dd, J=4, 6, 16 Hz, 1H, PhCHCH), 6.58 (dd, J=5, 15 Hz, 1H, PhCHCH), 7.32 (m, 5H, Ph).
6048
1.3. Alkylation of , -unsaturated -aminophosphonates: general procedure To a cooled solution (^78 C) of 1 (5 mmol) in THF (5 ml) was added butyllithium in THF (5 mmol), dropwise under argon, and the resulting solution was stirred for 1 h. A solution of the required aldehyde (5 mmol) in THF(5 ml) was then added. After 30 min stirring, Me3SiCl (5 mmol) was added and stirring was continued for a further 2 h. At the end, the solvent was removed under reduced pressure and the residue was dissolved in CH2Cl2. The resulting solution was washed with a saturated aqueous solution of NH4Cl (35 ml) and dried over MgSO4. After removal of the solvent, the residue was puri®ed on a silica gel column chromatography eluted with ether/methanol (9:1). All compounds gave satisfactory analytical data. 2a: R1C2H5, R2CH3. Yield 80%. MS(EI, 70 eV), m/z: 353 (20) M+, 322 (100). 31P NMR: 14.5. 1H NMR (200 MHz,CDCl3) 1.10 (s,3H, CÿCH3), 1.30 (dt, J=7.48, 14.18 Hz, 6H, P[(OCH2CH3)2], 2.80 (m, 4H, Ha, Ha0 ), 3.69 (m, 4H, Hb, Hb0 ), 4.03 (m, 4H, P[(OCH2CH3)2]), 6.40±6.54 (2d, J=11.89, 12.43 Hz, 2H, PhCHCH), 7.18 (m, 5H, C6H5). 2f: R1i-C3H7CHOTMS. Yield 85%. MS (EI, 70eV), m/z: 483, M+, 411 (7) M-73, 338 (100). 31P NMR: 14.1. 1H NMR (200 MHz,CDCl3) 0.06 (s, 6H, OSiMe3), 0.89 (d, J=2.9 Hz, 6H, [(H3C)2CH]), 1.28 (dt, J=3.7, 7.17 Hz, 6H, [(OCH2CH3)2]), 1.50 (m, 1H, [CH3)2CH]), 2.60±2.80 (m, 4H, Ha), 4.08 (m, 4H, P[(0CH2CH3)2]), 6.75 (d, J=10 Hz, 1H, PhCHCH), 6.80 (d, J=10 Hz, 1H, PhCH) 7.18 (m, 5H, C6H5). References 1. Kase, K.; Yamamoto, M.; Koguchi, T.; Okachi, R.; Kasai, M.; Shirata, K.; Kawamoto, I.; Shuto, K.; Karasawa, A. Eur. Pat. Appl., Ep 61, 172, 1982., Chem. Abstr. 1983, 98, 107793. 2. (a) Maier, L. Phosphorus, Sulfur and Silicon 1990, 53, 43±46. (b) Dhawan, B.; Redmore, D. Phosphorus, Sulfur and Silicon 1987, 32, 119. (c) Jacobson, N. E.; Bartlett, P. A. J. Am. Chem. Soc. 1981, 103, 654±657. (d) Lukszo, J.; Tyka, R. Synthesis 1977, 239±240. (e) Pudovik, A. N.; Konovalova, I. V. Synthesis 1979, 81±93. (f) Bartlett, P. A.; Hanson, J. E.; Giannousis, P. P. J. Org. Chem. 1990, 55, 6268±6274. 3. Kabachnik, M. I.; Medved, T. Y.; Dyatlova, N. M.; Arkhipova, O. G.; Rudomino, M. V. Chem. Abstr. 1969, 7c, 20101g. Usp. Khim. 1968, 37, 1161±1191. 4. Wadsworth, W. S.; Emmons, W. D. J. Am. Chem. Soc. 1961, 83, 1733±1738. 5. Sobanov, A. A.; Bathtiyarova, I. V.; Badeeva, E. K.; Zimin, M. G.; Pudovik, A. N. Zh. Obsch. Khim. 1985, 55, 22±26. 6. (a) Afarinkia, K.; Cadogan, J. I. G.; Rees, C. W. Synlett 1992, 123. (b) Afarinkia, K.; Cadogan, J. I. G.; Rees, C. W. Tetrahedron 1990, 46, 7175±7196. 7. Jahn, U.; Andersch, J.; Schroth, W. Synthesis 1997, 573±588. 8. BoÈhme, H.; Viehe, H. G. Iminium Salts in Organic Chemistry. Adv. Org. Chem.; Taylor, E. C., Ed. Vol 9. John Wiley: New York, 1975±1979; pp. 107±223. 9. (a) Martin, S. F.; Gomper, R. J. Org. Chem. 1974, 39, 2814±2815. (b) Martin, S. F. J. Org. Chem. 1976, 41, 3337± 3338. (c) Martin, S. F.; Chou, F. S.; Payne, C. W. J. Org. Chem. 1977, 42, 2520±2523. 10. Ahlbrecht, H.; Farnung, W. Synthesis 1977, 336±338. 11. Broekhof, N. J.; Van der Gen, A. Tetrahedron Lett. 1980, 21, 2671±2674. 12. Zimmer, H.; Bercz, J. P. Liebigs Ann. Chem. 1965, 686, 107±114. 13. Gross, H.; Costisella, B. Angew. Chem. 1968, 80, 364±365. 14. Schindler, N.; PloÈger, W. Chem. Ber. 1971, 104, 2021±2022. 15. Fukuda, M.; Kan, K.; Okamoto, Y.; Sakurai, H. Bull. Chem. Soc. Jpn. 1975, 2103±2105. 16. Gerber, J. P.; Modro, T. A. Phosphorus, Sulfur and Silicon 1994, 88, 99±111. 17. Gross, H.; Costisella, W. Angew. Chem., Int. Ed. 1968, 7, 391±392. 18. (a) Ahlbrecht, H.; Farnung, W. Chem. Ber. 1984, 117, 1±22. (b) Ahlbrecht, H.; Farnung, W.; Simon, H. Chem. Ber. 1984, 117, 2622±2643.