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Synlett 2002(9): 1459-1462
DOI: 10.1055/s-2002-33533
LETTER
© Georg Thieme Verlag Stuttgart · New York

Addition Reactions of Tertiary Silylphosphanes with Acetylenic Ketones and Aldehydes

Martin Reisser, Alexandra Maier, Gerhard Maas*
Abteilung Organische Chemie I, Universität Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany
Fax: +49(731)5022803; e-Mail: gerhard.maas@chemie.uni-ulm.de;
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Publication History

Received 18 June 2002
Publication Date:
17 September 2002 (online)

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Abstract

(Trimethylsilyl)phosphanes Me3Si-PR2 (PR2 = PPh2, PEt2, 1-phospholanyl) add smoothly across the C≡C bond of acetyl­enic ketones RCOC≡CPh to form (Z)-3-phosphanyl-2-(trimethyl­silyl)prop-2-en-1-ones 3 (3,4-addition). Thermal isomerization of the latter yields the corresponding 3-(trimethylsilyl)oxy-allenylphosphane 6, formally the product of a 1,4-addition. Mainly 1,2-addition occurs with propiolic aldehydes leading to (1-[(trimethyl­silyl)oxy]propargyl)phosphanes 4. Desilylation reactions of 3b yield either (3-oxopropyl)phosphanoxide 7 or (3-oxopropen­yl)phosphanoxide 8.

Key words

organophosphorus(III) compounds - organosilicon compounds - nucleophilic addition at alkynones - enones - siloxy-allenes

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(Z)-3-(Diphenylphosphanyl)-1,3-diphenyl-2-(trimethyl-silyl)prop-2-en-1-one(3a); general procedure: A solution of 1,3-diphenylprop-2-yn-1-one (2a, 3.1 g, 15.0 mmol) in THF (100 mL) was cooled at 0 °C and diphenyl(trimethyl-silyl)phosphane (1a, 3.87 g, 15.0 mmol) was added. The reaction mixture was kept with stirring at 0 °C for 2 h, then at 20 °C for 12 h. The solvent was evaporated at 15 mbar and the solid residue was recrystallized from CH3CN to furnish 3a as colorless crystals (5.22 g, 75%), mp 127-128 °C. IR (KBr): 1663 s, 1243 s, 1233 s, 858 s, 842 s cm-1. 1H NMR (CDCl3, 500.14 MHz): δ = 0.51 (d, 5 J H,P = 1.2 Hz, 9 H, SiMe3), 6.3-7.8 (20 HPh). MS (EI, 70 eV): m/z (%) = 466 (9), 465 (33), 464 (100) [all M+].
3b: From 1b and 2a; large pale-yellow crystals, 69% yield, mp 100 °C. IR (KBr): 1655 s, 1237 s, 844 s, 703 m cm-1.
1H NMR (CDCl3, 500.14 MHz, 233 K): δ = 0.35 (d, 5 J H,P = 1.6 Hz, 9 H, SiMe3), 1.0-1.4 (m, 10 Hethyl), 6.6-7.6 (10 HPh). 29Si NMR (CDCl3, 99.37 MHz): δ = -8.5 (d, 3 J Si,P = 11.4 Hz). MS (EI, 70 eV): m/z (%) = 370 (5), 369 (10), 368 (39) [all M+], 279 (100). C22H29OSiP (368.53): calcd C 71.70, H 7.93; found C 71.38, H 8.12.
3c: From 1c and 2a; pale-yellow crystals, 69% yield, mp 99 °C. IR (KBr): 1667/1650 vs, 1230 vs, 1174 vs, 702 vs
cm-1. 1H NMR (CDCl3, 500.14 MHz): δ = 0.35 (d, 5 J H,P = 1.5 Hz, 9 H, SiMe3), 1.08-1.25 (m, coalescing, 2 H), 1.35-1.45 (m, 2 H), 1.65-1.90 (m, 4 H), 6.7-7.7 (10 HPh). MS (EI, 70 eV): m/z (%) = 368 (2), 367 (7), 366 (25) [all M+], 279 (100). C22H27OPSi (366.51): calcd C 72.10, H 7.42; found C 71.80, H 7.55.
3d: From 1a and 2b; 70% yield, amorphous solid, mp 149 °C. IR (KBr): 1629 vs, 1413 s, 1261 s, 1246 s, 846 vs, 743 vs, 725 s, 702 vs cm-1. 1H NMR (CDCl3, 500.14 MHz):
δ = 0.44 (s, 9 H, SiMe3), 6.4-7.5 (18 Harom). MS (EI, 70 eV): m/z (%) = 472 (13), 471 (36), 470 (100) [all M+], 469 (39). C28H27OPSSi (470.64): calcd C 71.46, H 5.78; found C 71.52, H 5.62.
3e: From 1b and 2c, malodorous colorless oil, isolated by bulb-to-bulb distillation at 80-100 °C/0.0001 mbar; 76% yield. IR (KBr): 1687 s, 1245 s, 1187 s, 841 s cm-1. 1H NMR (CDCl3, 500.14 MHz): δ = 0.49 (d, 5 J H,P = 1.5 Hz, 9 H, SiMe3), 1.19 (dt, 6 H, CH2CH 3), 1.35 (m, 4 H, PCH2), 1.86 (d, 5 J H,P = 1.4 Hz, COCH3), 6.90-7.00 (m, 2 HPh), 7.32-7.43 (m, 3 HPh). MS (EI, 70 eV): m/z (%) = 308 (2), 307 (9), 306 (43) [all M+], 217 (100). C17H27OPSi (306.46): calcd C 66.63, H 8.88; found C 67.31, H 8.25.

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Crystal data for 3b: Triclinic, space group P1, a = 9.432 (3), b = 9.611 (2), c = 12.548 (3) Å, α = 98.82 (3), β = 102.21 (3), γ = 101.69 (3); Z = 2, D calc = 1.149 g·cm-3. Crystallographic data have been deposited at the Cambridge Crystallographic Data Centre as supplementary publication no. CCDC-187712. These data can be obtained free of charge via www.ccdc.cam.ac.uk/conts/retrieving.html (or from the Cambridge Crystallographic Data Centre, 12, Union Road, Cambridge CB2 1EZ, UK; fax: +44(1223)336033).

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Yield of crude 4a,b: ˜90%; since both compounds are extremely malodorous oils, we refrained from further purification. Data for 4a: 1H NMR (CDCl3, 500.14 MHz): δ = 0.17 (s, SiMe3), 5.33 (d, 2 J H,P = 1.2 Hz, HCC≡C), 7.23-7.70 (m, 5 HPh). 13C{1H} NMR (CDCl3, 50.32 MHz): δ = 0.2 (s, SiMe3), 64.4 (s, HCC≡C), 88.21 (d, J C,P = 10.6 Hz) and 88.63 (d, J C,P = 5.0 Hz) (C≡C). This product was isolated as a 6.2:1 mixture (31P NMR) with 5a [δ(1H) = 0.43 (d, 5 J H,P = 1.5, SiMe3); δ(13C) = 1.8 (d, 4 J C,P = 9.1, SiMe3), 198.0 (3 J C,P = 17.4, CHO); δ(31P) = 3.4].
Data for 4b: IR (film): 1679 m, 1599 m, 1251 vs, 1065 vs, 868 vs, 844 vs, 754 m cm-1. 1H NMR (CDCl3, 200.13 MHz): δ = 0.16 (s, 9 H, SiMe3), 0.90-1.15 (dt, 6 H, CH2CH 3), 1.30-1.70 (m, 4 H, PCH2), 4.78 (d, J H,P = 5.0 Hz, HCC≡C), 7.15-7.40 (m, 5 HPh). 13C{1H} NMR (CDCl3, 50.32 MHz): δ = 0.09 (s, SiMe3), 9.85 and 9.95 (each d, J C,P = 15.1 Hz, CH2CH3), 16.4 (d, J C,P = 15.1 Hz, PCH2), 16.7 (d, J C,P = 14.1 Hz, PCH2), 61.9 (d, J C,P = 11.6 Hz, HCC≡C), 87.2 (s) and 87.9 (d, J C,P = 4.0 Hz) (C≡C). This product was isolated as a 94:6 mixture (31P NMR) with 5b [δ(1H) = 0.32 (d, 5 J H,P = 1.6 Hz, SiMe3); δ(13C) = 2.3 (d, 4 J C,P = 10.7 Hz, SiMe3)].

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Allene 6 was obtained as an oil (˜97% purity by 31P NMR) which could not be purified further by chromatography or vacuum distillation without decomposition. 1H NMR (CDCl3, 500.14 MHz): δ = 0.21 (s, 9 H, SiMe3), 1.04 and 1.42 (each dt, 3 H, PCH2CH3), 1.58-1.74 (m, 4 H, PCH2), 7.24-7.38 (m, 6 HPh), 7.61 (dd, 2 HPh), 7.64 (dd, 2HPh).

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7: colorless crystals, mp 89 °C. IR (KBr): 1688 (s, C=O), 1266 m, 1158 (s, P=O) cm-1. 1H NMR (CDCl3, 400.13 MHz): δ = 1.01 (dt, 3 J P,H = 17.0 Hz, 3 J H,H = 7.7 Hz, 3 H, CH2CH 3), 1.23 (dt, 3 J P,H = 17.2 Hz, 3 J H,H = 7.7 Hz, 3 H, CH2CH 3), 1.49-1.74 (m, 2 H, PCH2), 1.84-2.05 (m, 2 H, PCH2), 3.80 (mc, 2 H, COCH2), 3.95 (mc, 1 H, PCH), 7.26-7.55 (m, 8 Harom), 7.96 (dd, 2 Harom). 13C{1H} NMR (CDCl3, 100.61 MHz): δ = 5.88/5.92 (2 d, J P,C = 44.3/44.3 Hz, PCH2 CH3), 18.51/19.25 (2 overlapping d, PCH2), 38.6 (s, COCH2), 39.1 (d, J P,C = 61.4 Hz, CHPOEt2), 127.2-137.5 (CPh), 196.9 (d, J P,C = 10.2 Hz, CO). 31P (CDCl3): δ = 54.8. C19H23O2P (314.36): calcd C 72.59, H 7.37; found C 72.82, H 7.51.

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(Z)-8: Colorless oil. IR(film): 1669 (s, C=O), 1225 (s), 1174 (s, P=O) cm-1. 1H NMR (CDCl3, 400.13 MHz): δ = 1.14 (dt, 3 J P,H = 17.4 Hz, 3 J H,H = 7.7 Hz, 6 H, PCH2CH 3), 1.80-1.97 (m, 4 H, POCH2), 7.24 (d, 3 J P,H = 30.5 Hz, 1 H, COCH=), 7.35-7.60 (3 m, 8 Harom), 7.97-8.00 (dd, 2 Harom). 13C{1H} NMR (CDCl3, 100.61 MHz): δ = 5.67 (d, J P,C = 5.3 Hz, PCH2 CH3), 21.9 (d, J P,C = 69.1 Hz, PCH2), 128.1-128.8 (several C), 133.8 (CH), 137.0, 138.8 (d, J P,C = 9.1 Hz), 142.3 (J P,C = 5.4 Hz, COCH=), 145.8, 146.5, 192.9 (d, J P,C = 4.9 Hz, C=O). 31P: δ = 46.4. C19H21O2P (312.35): calcd C 73.06, H 6.78; found C 72.68, H 6.94. (E)-8: Colorless crystals, mp 80 °C. IR (solid, ATR): 1659 (s, C=O), 1254 (s), 1188 (s, P=O) cm-1. 1H NMR (CDCl3, 400.13 MHz): δ = 1.25 (dt, 3 J P,H = 16.9 Hz, 3 J H,H = 7.6 Hz, 6 H, PCH2CH 3), 1.67-1.86 (m, 4 H, POCH2), 7.09-7.52 (4 m, 8 Harom), 7.82 (d, 3 J P,H = 17.8 Hz, 1 H, COCH=), 7.87 (dd, 2 Harom). 13C{1H} NMR (CDCl3, 100.61 MHz): δ = 5.42 (d, J P,C = 5.7 Hz, PCH2 CH3), 19.6 (d, J P,C = 69.8 Hz, PCH2), 127.6-128.9 (several C), 133.5 (CH), 134.9 (d, J P,C = 9.1 Hz), 136.6, 140.3 (J P,C = 5.7 Hz, COCH=), 145.8, 146.5, 191.9 (d, J P,C = 14.8 Hz, C=O). 31P: δ = 44.2. C19H21O2P (312.35): calcd C 73.06, H 6.78; found C 73.11, H 6.83.