Supporting Information

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1 Supporting Information A Domino Pericyclic Route to Polysubstituted Salicylic Acid Derivatives: Four Sequential Processes from Enynones and Ketene Silyl Acetals Toshiyuki Hamura, Shin Iwata, and Keisuke Suzuki * Department of Chemistry, Tokyo Institute of Technology, and SRST JST, -okayama, guro-ku, Tokyo , Japan Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, and PREST, Japan Science and Technology Agency (JST) 2- Gakuen, Sanda, Hyogo , Japan ksuzuki@chem.titech.ac.jp General Experimental Procedures All experiments dealing with air- and moisture-sensitive compounds were conducted under an atmosphere of dry argon. For thin-layer chromatography (TLC) analysis, rck pre-coated plates (silica gel 60 F 254, Art 575, 0.25 mm) were used. For flash column chromatography, silica gel 60 (rck Art 7734, mesh) was used. Silica gel preparative TLC (PTLC) was performed on rck silica gel 60 PF 254 (Art 7747). lting point (mp) determinations were performed by using a Yanako MP-S3 instrument and are uncorrected. H NMR and 3 C NMR were measured on a JEL JNM lambda-400, a JEL JNM ECA-300, a JEL JNM ECA-400, and a Bruker DRX-500 spectrometer. Infrared (IR) spectra were recorded on a Jasco IR-Report-00, and a Horiba FT-70 spectrometer. Attenuated Total Reflectance Fourier Transformation Infrared (ATR-FTIR) spectra were recorded on a Perkin Elmer 600 FTIR. Elementary analyses were performed by using Perkin Elmer series II S

2 Preparation of dienone 22: LiAlH 4 H TPAP, NM H THF, 0 C CH 2 Cl 2 87% 2 i 83% ii Li Et 2, 78 C 8% H iii TPAP, NM CH 2 Cl 2 85% 22 Synthesis of cyclobutene i: To a solution of cyclobutene 2 ) (50 mg, 0.39 mmol) in THF (5.0 ml) was added LiAlH 4 (20 mg, 0.53 mmol) at 0 C. After 5 min, the reaction was quenched by adding sat. aq. NaHC 3. The products were extracted with EtAc ( 3), and the combined organic extracts were washed with brine, dried (Na 2 S 4 ), and concentrated in vacuo. The residue was purified by PTLC (hexane/etac = 7/3) to give cyclobutene i (06 mg, 87.4%) as a colorless oil. H cyclobutene i H NMR (acetone-d 6, δ) 0.7 (s, 6H), 0.92 (s, 9H), 3.35 (s, 3H), 3.47 (s, 6H), (m, H), (m, 2H), (m, 3H), 7, (m, 2H); 2.90, 2.89, 9.0, 26.3, 52.2, 52.7, 55.7, 07.4, 09.8, 28.9, 29.0, 29.4, 33.9, 45.8, 48.4; 3448, 3056, 2937, 2856, 2834, 656, 573, 494, 463, 274, 253, 2, 78, 39, 085, 002, 993, 92, 892, 869, 836, 779 cm ; Anal. Calcd for C 20 H 32 5 Si: C, 63.2; H, Found: C, 62.90; H, Synthesis of aldehyde ii: To a stirred mixture of allyl alcohol i (24.4 mg, mmol), NM (8.0 mg, 0.54 mmol), and 4 Å molecular sieves (60 mg) in CH 2 Cl 2 (2.0 ml) was added TPAP (3.8 mg, 0.0 mmol) at room temperature. After stirred for 2 h, the reaction mixture was filtered through celite pad. The filtrate was purified by PTLC (hexane/etac = 7/3) to afford ii (20.2 mg, 83.2%) as a colorless oil. ) Iwata, S.; Hamura, T.; Matsumoto, T. Suzuki, K. Chem. Commun. 200, 22, S2

3 H aldehyde ii H NMR (acetone-d 6, δ) 0.4 (s, 3H), 0.8 (s, 3H), 0.93 (s, 9H), 3.40 (s, 3H), 3.42 (s, 3H), 3.48 (s, 3H), (m, 3H), (m, 2H), 0. (s, H); 3 C NMR (acetone-d 6, δ) 3.4, 3.0, 9., 26.3, 52.3, 52.6, 53.2, 06.4, 09.7, 29.6, 30.3, 32.0, 32.3, 42.7, 59., 87.7; 2943, 2856, 679, 572, 492, 359, 26, 23, 6, 060, 00, 990, 89, 835, 804, 779 cm ; Anal. Calcd for C 20 H 30 5 Si: C, 63.46; H, Found: C, 63.22; H, Synthesis of alcohol iii: To a solution of 2-bromo-cis-2-butene (86 mg, 96% purity, 0.6 mmol) in Et 2 (.2 ml) was slowly added t-buli (.48 M in pentane, 0.47 ml, 0.70 mmol) at 78 C, and the reaction mixture was further stirred for h; to the stirred solution was added aldehyde ii (05 mg, mmol) in Et 2 (2.0 ml). After 0 min, the reaction was quenched with water. The products were extracted with EtAc (X3), and the combined organic extracts were washed with brine, dried (Na 2 S 4 ), and concentrated in vacuo. The residue was purified by PTLC (hexane/etac = 97/3) to give less polar product iii (47.6 mg, 39.5%) and more polar product iii (49.8 mg, 4.3%). H alcohol iii (less polar) H NMR (acetone-d 6, δ) 0.2 (s, 3H), 0.22 (s, 3H), 0.95 (s, 9H),.56 (d, 3H, J = 6.4 Hz),.63 (s, 3H), 3.30 (s, 3H), 3.4 (s, 3H), 3.46 (s, 3H), 4.03 (d, H, J = 4.2 Hz), 5.00 (d, H, J = 4.2 Hz), 5.67 (q, H, J = 6.4 Hz), (m, 3H), (m, 2H); 2.6, 2.5, 3., 3.3, 9.2, 26.6, 5.9, 52.6, 52.9, 73.3, 08.0, 09.6, 22.2, 28.6, 28.9, 29.9, 33.9, 37., 45.3, 49.9; 3468, 2936, 494, 47, 387, 360, 248, 20, 7, 080, 029, 992, 894, 835, 805, 778 cm ; Anal. Calcd for C 24 H 38 5 Si: C, 66.32; H, 8.8. Found: C, 66.4; H, H alcohol iii (more polar) H NMR (acetone-d 6, δ) S3

4 0.7 (s, 3H), 0.20 (s, 3H), 0.9 (s, 9H),.53 (d, 3H, J = 6.9 Hz),.58 (s, 3H), 3.32 (s, 3H), 3.42 (s, 3H), 3.54 (s, 3H), 4.8 (d, H, J = 4.6 Hz), 4.87 (d, H, J = 4.6 Hz), 5.66 (q, H, J = 6.9 Hz), (m, 3H), (m, 2H); 2.5, 3., 3.3, 8.9, 26.5, 5.8, 52.7, 53.2, 73., 08.0, 09.7, 22.3, 28.4, 28.9, 30.2, 33.7, 36.7, 46., 49.3; 3479, 2937, 2856, 493, 47, 387, 360, 247, 208, 72, 080, 039, 99, 885, 835, 808, 777 cm ; Anal. Calcd for C 24 H 38 5 Si: C, 66.32; H, 8.8. Found: C, 66.2; H, Synthesis of dienone 22: To a stirred mixture of alcohol iii (33.3 mg, mmol), NM (23.0 mg, 0.96 mmol), and 4 Å molecular sieves (72 mg) in CH 2 Cl 2 (2.0 ml) was added TPAP (5.2 mg, 0.05 mmol) at room temperature. After stirred for 0 h, the reaction mixture was filtered through celite pad. The filtrate was purified by PTLC (hexane/etac = 7/3) to afford 22 (28.2 mg, 85.%) as a colorless oil. dienone 22 H NMR (acetone-d 6, δ) 0.05 (s, 3H), 0.6 (s, 3H), 0.90 (s, 9H),.76 (qd, 3H, J =.0, J 2 = 6.9 Hz),.79.8 (m, 3H), 3.43 (s, 3H), 3.44 (s, 3H), 3.52 (s, 3H), 6.88 (qq, H, J =.4, J 2 = 6.9 Hz), (m, 5H); 3 C NMR (acetone-d 6, δ) 3., 2.8, 0.3, 5., 9.0, 26.5, 52.3, 52.5, 53.7, 08.8, 09.3, 28.9, 29.3, 30., 32.8, 39.0, 45.4, 46.4, 48.3, 94.7; 2937, 2855, 633, 493, 47, 390, 360, 246, 206, 7, 082, 060, 028, 994, 887, 835, , 752 cm ; Anal. Calcd for C 24 H 36 5 Si: C, H, Found: C, 66.68; H, Preparation of dinone 24: H ii 2) Li H TPAP, NM Et 2, 78 C CH 2 Cl 2 83% 82% iv 24 S4

5 H alcohol iv (less polar) 2) H NMR (acetone-d 6, δ) 0.22 (s, 3H), 0.25 (s, 3H), 0.96 (s, 9H), (m, 2H), 2.63 (t, 2H, J = 7.9 Hz), 3.32 (s, 3H), 3.43 (s, 3H), 3.50 (s, 3H), 3.97 (d, H, J = 5.8 Hz), 5.67 (d, H, J = 5.8 Hz), 6.36 (t, H, J = 4.8 Hz), (m, 6H), (m, 3H); 2.5, 2.4, 9.2, 23.8, 26.6, 28.5, 5.9, 52.7, 53.2, 68.4, 08.2, 09.6, 24.6, 27.0, 27.6, 28.2, 28.7, 28.9, 29.5, 29.7, 34.0, 34.3, 37.4, 37.6, 45.6, 50.2; 3594, 2933, 2855, 2833, 49, 462, 387, 360, 248, 20, 7, 080, 034, 990, 923, 890, 835, 806, 778, 746, 732 cm ; Anal. Calcd for C 30 H 40 5 Si: C, 70.83; H, Found: C, 70.69; H, H alcohol iv (more polar) H NMR (acetone-d 6, δ) 0.4 (s, 3H), 0.2 (s, 3H), 0.9 (s, 9H), (m, 2H), (m, 2H), 3.34 (s, 3H), 3.4 (s, 3H), 3.6 (s, 3H), 4.3 (d, H, J = 5.3 Hz), 5.57 (d, H, J = 4.0 Hz), 6.30 (t, H, J = 4.6 Hz), (m, 3H), (m, 3H), 7.52 (d, H, J = 7.2 Hz), (m, 2H); 2.6, 2.5, 9.0, 23.7, 26.6, 28.4, 5.9, 52.7, 53.4, 66.7, 08., 09.8, 24.4, 26.8, 27.4, 28., 28.2, 28.4, 28.9, 30.0, 33.7, 34.4, 36.7, 37.4, 47.4, 49.2; 3460, 2936, 2884, 2855, 490, 470, 449, 388, 359, 248, 209, 74, 083, 00, 935, 887, 838, 779, 735 cm ; Anal. Calcd for C 30 H 40 5 Si: C, 70.83; H, Found: C, 70.78; H, ) Vinyllithium A was generated by halogen lithium exchange of iodoalkene a, i) prepared from -tetralone. I Li t-buli a Et 2, 78 C i) Lee, K.; Wiemer, D. F. Tetrahedron Lett. 993, 34, A S5

6 dienone 24 H NMR (acetone-d 6, δ) 0. (s, 3H), 0.22 (s, 3H), 0.93 (s, 9H), (m, 2H), 2.62 (t, 2H, J = 7.9 Hz), 3.43 (s, 3H), 3.46 (s, 3H), 3.58 (s, 3H), 7.2 (t, H, J = 4.9 Hz), (m, 6H), (m, 2H), (m, H); 3.8, 3.6, 8.2, 23.6, 25.7, 26.6, 5.5, 5.6, 53.0, 07.8, 08.5, 26.0, 26.2, 27.6, 27.8, 28.3, 28.4, 29.4, 30.5, 32.0, 36.5, 37.6, 45.0, 45.4, 50.0, 92.; 2938, 2855, 2834, 646, 597, 573, 49, 423, 388, 248, 20, 7, 088, 02, 000, 938, 89, 836, 82, 780, 735 cm ; Anal. Calcd for C 30 H 38 5 Si: C, 7.; H, Found: C, 7.29; H, Domino pericyclic reaction of dienones to salicylic acid derivatives; Synthesis of benzene 9 starting from dienone 6 (thod A): A solution of dienone 6 (48.0 mg, 0.8 mmol) in mesitylene (3.0 ml) and 2,6-lutidine (0.5 ml) was heated at 65 C for 0 h. After evaporation of the solvent, the residue was purified by PTLC (hexane/etac = 9/) to give 9 (35.4 mg, 80.%) as a colorless oil. Synthesis of benzene 9 by reaction of enynone 5 and KSA 2a (thod B): A mixture of ynone 5 (37.0 mg, mmol) and KSA 2a (70.2 mg, mmol) was heated at 60 C for h. After diluted in mesitylene (2.4 ml), the mixture was heated at 65 C for 4 h. The crude product was purified by PTLC (hexane/ch 2 Cl 2 /Et 2 = 6/2/2) to give 9 (66.4 mg, 75.2%) as a colorless oil. C 2 benzene 9 H NMR (acetone-d 6, δ) 0.2 (s, 6H),.0 (s, 9H), 3.79 (s, 3H), 3.84 (s, 3H), 6.90 (s, H), (m, 4H), (m, 2H); 4.2, 8.8, 26.0, 52.0, 56.3, 4.4, 22.6, 24.3, , 30., 36.3, 38., 49.6, 5.4, 66.9; 3055, 3026, 295, 293, 2896, 2857, 733, 63, 558, 508, 484, 464, 433, 393, 323, 259, 2, 83, 086, 044, 03, 989, 946, 894, 882, 840, 825, 8, 782, 744 cm ; Anal. Calcd for C 2 H 28 4 Si: C, 67.7; H, Found: C, 67.80; H, S6

7 C 2 C 2 ester 7 H NMR (acetone-d 6, δ) 0.20 (s, 3H),.06 (s, 9H), 3.48 (s, 2H), 3.62 (s, 3H), 3.68 (s, 3H), 7.07 (d, H, J = 6.2 Hz), (m, 3H), (m, 2H), 8. (d, H, J = 6.2 Hz); 3.2, 9., 26.3, 33.7, 5.7, 5.9, 0.9, 24.4, 28., 29.72, 29.77, 36.3, 37.0, 60.5, 68.3, 72.; 3025, 2952, 2932, 2887, 2859, 743, 70, 626, 58, 569, 463, 434, 32, 285, 259, 9, 69, 6, 055, 975, 933, 84, 828, 80, 784, 756 cm ; Anal. Calcd for C 2 H 30 5 Si: C, 64.58; H, Found: C, 64.79; H, C 2 cyclohexadiene 8 H NMR (acetone-d 6, δ) 0.2 (s, 6H), 0.90 (s, 9H), 3.09 (s, 3H), 3.25 (s, 3H), 3.77 (s, 3H), 3.8 (d, H, J = 6.6 Hz), 5.28 (d, H, J = 6.6 Hz), 6.24 (s, H), (m, 3H), (m, 2H); 4.6, 4.5, 8.6, 26.0, 49.3, 49.52, 49.54, 52.3, 00.5, 2.6, 27.7, 28.9, 29.6, 34.9, 35.5, 39., 44.5, 66.5; 2952, 2858, 737, 482, 379, 256, 23, 076, 053, 893, 840, 78 cm ; Anal. Calcd for C 22 H 32 5 Si: C, 65.3; H, Found: C, 65.52; H, 8.8. Synthesis of benzene 3: According to the general procedure of 9 (thod B), ynone 0 (37.5 mg, mmol) and KSA 2a (3 mg, mmol), after purification by PTLC (hexane/etac = 8/2), gave 3 (79.8 mg, 70.9%) as a colorless oil. C 2 benzene 3 H NMR (CDCl 3, δ) 0.0 (s, 6H),.05 (s, 9H), 2.4 (s, 3H), 2.5 (s, 3H), 3.80 (s, 3H), 3.85 (s, 3H), 7.05 (s, H); 3 C NMR (CDCl 3, δ) 4.4, 2.7, 4.0, 8.3, 25.8, 5.8, 55.7, 09.3, 20.3, 30.8, 3.6, 46.3, 5.6, 68.3; S7

8 2950, 2858, 729, 60, 578, 432, 409, 36, 335, 266, 227, 95, 73, 4, 093, 00, 963, 882, 84, 827, 84, 778, 73 cm ; Anal. Calcd for C 7 H 28 4 Si: C, 62.92; H, Found: C, 63.3; H, Synthesis of benzene 4: According to the general procedure of 9 (thod B), ynone (38.4 mg, mmol) and KSA 2a (06 mg, mmol), after purification by PTLC (hexane/etac = 8/2), gave 4 (65.4 mg, 66.%) as a colorless oil. C 2 benzene 4 H NMR (CDCl 3, δ) 0.05 (s, 6H),.03 (s, 9H), (m, 4H), (m, 4H), 3.79 (s, 3H), 3.84 (s, 3H), 6.97 (s, H); 3 C NMR (CDCl 3, δ) 4.0, 8.4, 22.0, 22.3, 23.7, 25.0, 25.8, 5.7, 55.4, 08.0, 9.5, 3.9, 32.3, 46.3, 5.4, 68.3; 2932, 2857, 730, 60, 577, 463, 448, 432, 4, 332, 27, 250, 224, 88, 62, 03, 083, 063, 989, 960, 939, 895, 882, 84, 827, 83, 788, 778, 728 cm ; Anal. Calcd for C 9 H 30 4 Si: C, 65.0; H, Found: C, 65.23; H, Synthesis of cyclohexadiene 5: A mixtuere of dienone 5 (48.0 mg, mmol) and KSA 2b (98.7 mg, mmol) was heated at 60 C for h. After diluted in xylene (3.0 ml), the reaction was heated at 40 C for 3 h. Evaporation of the solvents gave the crude product, which was purified by PTLC (hexane/ch 2 Cl 2 /Et 2 = 70/5/5) to give 5-cis (84.7 mg, 73.6%) and 5-trans (4. mg, 2.2%). C 2 cyclohexadiene 5-cis (colorless oil) H NMR (acetone-d 6, δ) 0.9 (s, 3H), 0.20 (s, 3H), 0.93 (s, 9H), 3.25 (s, 3H), 3.73 (s, 3H), 3.84 (dd, H, J = 5.4, J 2 = 7.8 Hz), 4.28 (dd, H, J = 3.4, J 2 = 7.8 Hz), 5.24 (d, H, J = 5.4 Hz), 6.45 (d, H, J = 3.4 Hz) (m, 5H); 5.3, 7.8, 25., 43., 5.2, 56.5, 77.5, 07.9, 26.6, 27.8, 29.4, 3.4, 36., 38., 46.5, 65.5; 2962, 2903, 2858, 734, 647, 599, 26, 09, 09, 799 cm Anal. Calcd for C 2 H 30 3 Si: C, 67.34; H, Found: C, 67.55; H, S8

9 # The stereochemistry of 5-cis was determined on the basis of the observed NE shown below. C 2 H a C(H b ) 3 H a : 3.84 ppm, H b : 7.33 ppm. NE C 2 cyclohexadiene 5-trans H NMR (acetone-d 6, δ) 0.28 (s, 3H), (s, 3H),.00 (s, 9H), 2.55 (dd, H, J = 5.6, 8.3 Hz), 3.27 (s, 3H), 3.28 (dd, H, J = 2.2, 8.3 Hz), 3.69 (s, 3H), 4.38 (dd, H, J = 2.2, 5.6 Hz), 6.39 (s, H), (m, 3H), (m, 2H); 3.9, 3.8, 8.9, 26., 28.9, 5., 55.5, 73.0, 05.0, 25.8, 26.8, 29.3, 29.6, 39.2, 44.0, 55.6, 67.5; 2930, 2858, 73, 637, 580, 435, 372, 297, 25, 209, 65, 087, 075, 994, 946, 99, 884, 833, 782 cm ; Anal. Calcd for C 2 H 30 3 Si: C, 67.34; H, Found: C, 67.45; H, 8.3. #2 The stereochemistry of 5-trans was determined on the basis of the observed NE shown below. C 2 H a H b H d C(H c ) 3 H a : 7.6 ppm, H b : 2.55 ppm, H c : 3.27 ppm, H d : 3.28 ppm. NE Synthesis of cyclohexadiene 6: According to the general procedure of 5, ynone 5 (32.3 mg, mmol) and KSA 2c (63.2 mg, 0.32 mmol), after purification by PTLC (hexane/etac = 8/2), gave 6 (46. mg, 62.2%) as a colorless oil. S9

10 C 2 Et cyclohexadiene 6 H NMR (acetone-d 6, δ) 0.96 (s, 3H), 0.99 (s, 3H), 0.94 (s, 9H),.26 (t, 3H, J = 7.0 Hz), 2.35 (ddd, H, J = 4.6, J 2 =.7, J 3 = 7.3 Hz), 2.57 (ddd, H, J = 4.6, J 2 = 8.0, J 3 = 7.3 Hz), 3.69 (ddd, H, J = 4., J 2 = 8.0, J 3 =.7 Hz), 4.6 (q, 2H, J = 7.0 Hz), 5.07 (d, H, J = 4. Hz), 6.56 (t, H, J = 4.6 Hz), (m, 5H); 4.5, 4.4, 4.5, 8.7, 26.0, 32.9, 40.2, 60.9, 08.9, 27.3, 28.2, 29.3, 32.7, 35.8, 45.6, 47.6, 65.9; 2955, 293, 2896, 2858, 729, 643, 60, 472, 382, 363, 276, 25, 24, 073, 932, 840, 780, 756, 700 cm ; Anal. Calcd for C 2 H 30 3 Si: C, 70.35; H, Found: C, 70.25; H, 8.4. Synthesis of cyclohexadiene 7: According to the general procedure of 5, ynone 0 (34.7 mg, 0.32 mmol) and KSA 2b (89.7 mg, 0.4 mmol), after purification by PTLC (hexane/ch 2 Cl 2 /Et 2 = 70/5/5), gave 7 (58.8 mg, 56.%) as a colorless oil. C 2 cyclohexadiene 7 H NMR (acetone-d 6, δ) 0.03 (s, 3H), 0.06 (s, 3H), 0.83 (d, 3H, J = 7.0 Hz), 0.93 (s, 9H),.72 (s, 3H), 2.38 (dquint, H, J =.7, J 2 = 7.0 Hz), 3.34 (s, 3H), 3.68 (s, 3H), 4.23 (dd, H, J = 2.2, J 2 = 7.0 Hz), 6.30 (dd, H, J =.7, J 2 = 2.2 Hz); 4.5, 4.7, 8.3, 5.0, 8.5, 26.0, 37.8, 5.7, 56.5, 79.6, 2.5, 30.8, 37.3, 40.0, 66.3; 295, 2930, 2899, 2857, 734, 650, 603, 472, 462, 435, 377, 366, 330, 298, 258, 95, 30, 00, 065, 054, 04, 98, 94, 890, 840, 785, 743 cm ; Anal. Calcd for C 7 H 30 4 Si: C, 62.54; H, Found: C, 62.75; H, #3 The stereochemistry of 7 was determined on the basis of the observed NE shown below. S0

11 TBDMS C 2 NE (H b ) 3 C (H a ) 3 C H a : 3.34 ppm, H b : 0.83 ppm. Synthesis of cyclohexadiene 8: According to the general procedure of 5, ynone (28.0 mg, mmol) and KSA 2b (2 mg, 0.53 mmol), after purification by PTLC (hexane/ch 2 Cl 2 /Et 2 = 8//), gave 8 (36.6 mg, 49.8%) as a colorless oil. C 2 cyclohexadiene 8 H NMR (acetone-d 6, δ) 0.02 (s, 3H), 0.03 (s, 3H), 0.94 (s, 9H),.4.52 (m, 3H),.7.85 (m, 4H), (m, H), (m, H), 3.3 (s, 3H), 3.69 (s, 3H), 3.93 (dd, H, J = 4., J 2 = 7.6 Hz), 6.40 (d, H, J = 4. Hz); 3 C NMR (acetone-d 6, δ) 4.8, 4.6, 8.6, 25.95, 26.04, 26., 27.3, 27.8, 42.4, 5.8, 56.7, 75.3, 23.7, 32.0, 33.0, 37.6, 67.0; 2930, 2858, 735, 646, 588, 472, 462, 435, 362, 254, 204, 098, 840, 780 cm ; Anal. Calcd for C 9 H 32 4 Si: C, 64.73; H, 9.5. Found: C, 64.43; H, Synthesis of cyclohexadiene 9: According to the general procedure of 5, ynone 2 (36.6 mg, mmol) and KSA 2b (00 mg, mmol), after purification by PTLC (hexane/etac = 8/2), gave 9 (66. mg, 59.8%) as a colorless oil. C 2 cyclohexadiene 9 H NMR (CDCl 3, δ) 0.0 (s, 3H), 0.3 (s, 3H), 0.89 (s, 9H), 0.94 (s, 3H),.08 (s, 3H), 3.40 (s, 3H), 3.73 (s, 3H), 3.74 (d, H, J = 2.6 Hz), 4.79 (s, H), 6.59 (d, H, J = 2.6 Hz); 3 C NMR (CDCl 3, δ) 4.8, 4.6, 8.0, 9.7, 25.6, 27.3, 37.4, 5.8, 57.7, 84.3, 7.3, 30.4, 37.8, 43.7, 66.; 2853, 2932, 2859, 734, 642, 274, 437, 363, 257, 72, 04, 004, 95, 883, 840, 783 cm ; S

12 Anal. Calcd for C 7 H 30 4 Si: C, 62.54; H, Found: C, 62.33; H, Synthesis of benzene 23: According to the general procedure of 9 (hod A), dienone 22 (44. mg, 0.02 mmol), after purification by PTLC (hexane/etac = 8/2), gave 23 (3.6 mg, 77.4%) as a colorless oil. C 2 benzene 23 H NMR (CDCl 3, δ) 0. (s, 6H),.02 (s, 9H), 2.8 (s, 3H), 2.24 (s, 3H), 3.23 (s, 3H), 3.40 (s, 3H), (m, 5H); 3 C NMR (CDCl 3, δ) 3.8, 3.3, 4.4, 8.4, 25.9, 5.5, 60.3, 24.8, 27.0, 27.7, 29.2, 29.4, 3.7, 33.4, 36.8, 45.9, 50.0, 67.9; 2949, 2930, 2895, 2858, 732, 563, 452, 402, 339, 294, 257, 24, 69, 090, 02, 970, 933, 900, 837, 828, 87, 782, 755 cm ; Anal. Calcd for C 23 H 32 4 Si: C, 68.96; H, Found: C, 69.03; H, 8.0. Synthesis of benzene 25: According to the general procedure of 9 (hod A), dienone 24 (36.5 mg, mmol), after purification by PTLC (hexane/etac = 8/2), gave 25 (24.0 mg, 70.2%) as a colorless oil. C 2 benzene 25 H NMR (CDCl 3, δ) 0.3 (s, 6H), 0.93 (s, 9H), (m, 4H), 3.26 (s, 3H), 3.45 (s, 3H), (m, 8H), (m, H); 3 C NMR (CDCl 3, δ) 4.4, 8., 23., 25.9, 28.9, 5.5, 60.5, 26., 27.2, 27.3, 27.4, 28.5, 28.9, 29.4, 33., 33.3, 35.6, 36.5, 38.3, 45.8, 48.9, 67.8; 2948, 2930, 2857, 733, 544, 499, 472, 46, 444, 36, 39, 303, 275, 20, 76, 25, 063, 032, 09, 97, 88, 84, 78, 769 cm ; Anal. Calcd for C 29 H 34 4 Si: C, 73.38; H, Found: C, 73.9; H, S2

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18 S8

19 S9

20 S20

21 S2