Planar Chirality: Cycloadditions and Transannular Reactions of Optically Active Azoninones Bearing E-Olefins

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1 Copyright Wiley-VC Verlag Gmb, D-9451 Weinheim, Chem. Eur. J Planar Chirality: Cycloadditions and Transannular Reactions of ptically Active Azoninones Bearing E-lefins Alexander Sudau [a], Winfried Münch [a], Jan W. Bats [b] and Udo ubbemeyer [a] [a] [b] Dr. U. ubbemeyer, A. Sudau, W. Münch, Institut für Chemie - rganische Chemie, Freie Universität Berlin, Takustr. 3, D Berlin, Tel: +49 (30) , Fax. +49 (30) , udonubb@chemie.fu-berlin.de Dr. J. W. Bats, Institut für rganische Chemie, J. W. Goethe Universität Frankfurt, Marie-Curie-Str. 11, D-0439 Frankfurt/Main

2 1 Chemistry, A European Journal Alexander Sudau, Winfried Münch, Jan W. Bats and Udo ubbemeyer Title: Planar Chirality: Cycloadditions and Transannular Reactions of ptically Active Azoninones Bearing E-lefins Supporting Information: (-p-toluenesulfonylimino)-phenyl iodinane (modified procedure): A solution of K (0.7 g, 12.5 mmol, 2.5 mol-eq.) in Me (10 ml) was treated with p-toluenesulfone amide (0.8 g, 5 mmol). The resulting clear and colorless solution was stirred for 10 min at 0 C, then, a white precipitate of the potassium p-toluenesulfonates appeared. Diacetoxyiodosobenzene (1. g, 5 mmol) was added at 0 C. After 5-10 min of stirring at 0 C all solids were dissolved to result a clear yellow solution. After a further 30 min of stirring at 0 C a yellow precipitate of the (-(p-toluenesulfonyl)-imino)-phenyl iodinane occurred. Stirring was continued for 30 min at 0 C and 1h at rt. Work-up started by addition of 2 (25 ml, 0 C) and cooling for 45 min at 4 C. The solid product was filtered off and dried in vacuum to give pure (-(p-toluenesulfonylimino)-phenyl iodinane (0.85 g, 48%) as a pale yellow solid, m.p. 104 C (lit.: C). 1 -MR (270 Mz, DMS-D ) δ = (m, 9 ), 2.25 (s, 3 ). IR (KBr) ν = 12 (s, ν as S 2 ), 1132 (s, ν s S 2 ), 1081 (s), 989 (m), 8 (s) cm -1. IR of p-tosylamide : 1305 (s, ν as S 2 ), 1155 (s, ν s S 2 ) according Yamamoto et al.[10] (2R,S,8S,8aR)-2-(t-Butyldimethylsilyloxy)--phenyl-8-trimethylsilyloxy-5(8)-indolizidinone (20a, TMS ether): Reaction of epoxy azonanone 12a in a MR test tube scale with TMSBr. [α] 20 D = 70.3 (c = 0.3, C 3 ). 1 -MR (270 Mz, CD 3 ): δ = (m, 5 ), (m, 1 ), (ddd, J =11, 9, 4 z, 1 ), (dd, J = 11, 7 z,1 ), (m, 3 ), (ddd, J =12,, z, 1 ), (ddd, J = 11, 7, 4 z, 1 ), (ddd, J = 13, 11, 11 z,1 ), (ddd, J = 13, 10, 7 z, 1 ), 0.80 (s, 9 ), 0.01 (s, 3 ), 0.05 (s, 3 ). 13 C-MR (2.9 Mz, CD 3 ): δ = 18.7, 141.0, 128., 128.1, 12.7, 71.4, 9.2, 2.5, 53., 47.7, 40.7, 39.3, 25.7 (-C(C 3 ) 3 ), 17.9 (- C(C 3 ) 3 ), (-C 3 ). IR (KBr): ν = 2959 (s), 2930 (s), 141 (C=, s), 1472 (s) 145 (s), 1433 (s), 1253 (s) cm -1. MS (80 ev, EI, 130 C): m/z = 433 (0.5) [M + ], 432 (0.5) [M - + ], 418 (5) [M + - C 3 ], 37 (100) [M + - C 4 9 ], 304 (5), 28 (5) [M + - C 4 9 TMS]. RMS (80 ev, 130 C): C [M + -C 3 ]: Calcd Found (2R,R,8R,8aS)-2-(t-Butyldimethylsilyloxy)--chloro-8-trimethylsilyloxy-5(8)-indolizidinone (19c, TMS ether): Reaction with 11c (150 mg, 0.37 mmol) TMSI (1.0 eq.) without LiI following the standard transannular epoxide opening. Removal of 22c as the major side

3 2 product by acidic extraction with a 1:1 mixture of aqueous (10 %) and aqueous Ac (10 %). Chromatography: EtAc/n-hexane 1:4, R f = 0.4. Yield: 7 mg (0.17 mmol, 47 %) of 19c (TMS) as a colorless oil. [α] 20 D = (c = 1.7, C 3 ). 1 -MR (270 Mz, CD 3 ): δ = (dd, J = 4, 4 z, 1 ), (dd, J = 4, 4 z, 1 ), (ddd, J = 8, 8, 8 z, 1 ), (dd, J = 13, 4 z, 1 ), (ddd, J = 12, 9, 4 z, 1 ), (d, J = 13 z, 1 ), (m, 2 ), (dd, J = 12.5, 4 z, 1 ), (ddd, J = 12, 12, 4 z, 1 ), 0.83 (s, 9 ), 0.13 (s, 9 ), 0.03 (s, 3 ), 0.02 (s, 3 ). 13 C-MR (7.9 Mz, CD 3 ): δ = 14.1 (q), 8.5 (d), 7. (d), 2.2 (d), 5.3 (t), 53.9 (d), 41.5 (t), 40.8 (t), 25.7 (q, -C(C 3 ) 3 ), 17.9 (-C(C 3 ) 3 ), 0.0 (q, (C 3 ) 3 ), (q, -C 3 ). IR (KBr): ν = 2955 (s), 2928 (s), 2895 (s), 2857 (s), 14 (s, -C), 1449 (s), 135 (m), 1253 (m) cm -1. MS (70 ev, EI, 90 C): m/z = 391 (0.1) [M + + ], 37 (8) [M + - C 3 ], 35 (1) [M + - ], 334 (100) [M + - C 4 9 ]. RMS (80 ev, 90 C): C [M + -C 3 ]: Calcd Found (3S,5)-5-[(1S,4R)-2-Benzyl-4(t-butyldimethylsilyloxy)-2-pyrrolidinyl]-3-phenyl-3,4,5-trihydrofuran-2-one (22a): Spectral data: [α] 20 D = (c = 1.9, C 3 ). 1 -MR (270 Mz, CD 2 2 ): δ = (m, 10 ), (ddd, J = 10, 5, 4 z, 1 ), (m, 1 ), (d, J = 13 z, 1 ), (dd, J = 12.7, 9 z, 1 ), (ddd, J = 8, 8, 4 z, 1 ), (dd, J = 10, 5 z, 1 ), (ddd, J = 12.7, 9, z, 1 ), (dd, J = 10, z, 1 ), (ddd, J = 12.7, 12.7, 11 z, 1 ), (ddd, J = 13, 8, 4 z, 1 ), (ddd, J = 13, 7, 7 z, 1 ), 0.90 (s, 9 ), 0.0 (s, 3 ), 0.04 (s, 3 ). 13 C-MR (7.9 Mz, CD 3 ): δ = 17. (s), (s), 13.7 (s), (d), (d), (d), (d), (d), 12.8 (d), 80.5 (d), 70.9 (d), 4.0 (d), 2.4 (t), 1.3 (t), 47.0 (d), 37.0 (t), 33.7 (t), 25.7 (q, -C(C 3 ) 3 ), 17.9 (s, -C(C 3 ) 3 ), (q, - C 3 ). IR (KBr): ν = 2953 (s), 2927 (s), 2855 (s), 1773 (s, C), 1495 (m), 1471 (m), 1453 (m), 1388 (m), 131 (m), 1253 (m) cm -1. MS (80 ev, EI, 130 C): m/z = 451 (0.4) [M + ], 43 (1.2) [M + - C 3 ], 394 (0.5) [M + - C 4 9 ], 37 (0.3), 352 (0.5), 290 (100). RMS (80 ev, 130 C): C [M + ]: Calcd Found (3R,5R)-5-[(1S,4R)-2-Benzyl-4(t-butyldimethylsilyloxy)-2-pyrrolidinyl]-3-chloro-3,4,5- trihydrofuran-2-one (22c): MR-Test tube reaction, analytical scale, the epoxy azonanone 11c completely rearranged in presence of Lewis acid catalysis (Ti 4, BF 3 Et 2 ) to give 22c. [α] 20 D = (c = 1.5, C 3 ). 1 -MR (270 Mz, CD 3 ): δ = (m, 10 ), (dd, J = 11, 9 z, 1 ), (ddd, J = 10, 5, 4 z, 1 ), (m, 1 ), (d, J = 13.7 z, 1 ), (d, J = 13.7 z, 1 ), (ddd, J = 8, 8, 4 z, 1 ), (dd, J = 11, 5 z, 1 ), (ddd, J = 12.7, 9, 5 z, 1 ), (m, 2 ), (ddd, J = 12.7, 8, 4 z, 1 ), (m, 1 ), 0.90 (s, 9 ), 0.0 (s, 3 ), 0.04 (s, 3 ). 13 C-MR (2.9 Mz, CD 3 ): δ = (s), (s), 128. (d), (d), (d), 80.0 (d), 71.0 (d), 4.0 (d), 2.2 (t), 1.5 (t), 51.5 (d), 3.9 (t), 34.8

4 3 (t), 25.7 (-C(C 3 ) 3 ), 17.9 (-C(C 3 ) 3 ), (-C 3 ). IR (KBr): ν = 2953 (s), 2928 (s), 2885 (s), 285 (m), 1787 (C=, s), 1494 (m), 142 (m), 1471 (m), 1453 (m), 1387 (m), 131 (m), 1255 (m) cm -1. MS (70 ev, EI, 130 C): m/z = 409 (1) [M + ], 394 (1) [M + - C 3 ], 352 (1) [M + - C 4 9 ], 290 (100) [M + C ]. RMS (80 ev, 130 C): C [M + ]: Calcd Found (3S,5R)-5-[(1S,4R)-2-Benzyl-4(t-butyldimethylsilyloxy)-2-pyrrolidinyl]-3-phenyl-1-tosyl- 3,4,5-trihydro-pyrrolidin-2-one (23a): Epimino azonanone 9a rearranged to give 23a by storing at rt. [α] 20 D = (c = 1., C 3 ). 1 -MR (270 Mz, CD 3 ): δ = (m, 2 ), (m, 13 ), (dd, J = 8, 8 z, 1 ), (m, 2 ), (d, J = 13 z, 1 ), (d, J = 11 z, 1 ), (d, J = 13 z, 1 ), (dd, J = 11, 4 z, 1 ), (ddd, J = 12.7, 12.7, 8 z, 1 ), (m, 2 ), 2.40 (s, 3 ), (ddd, J = 12.7, 9, 3 z, 1 ), (ddd, J = 13, 8, z, 1 ), 0.90 (s, 9 ), 0.0 (s, 3 ), 0.04 (s, 3 ). 13 C-MR (7.9 Mz, CD 3 ): δ = (s), (s), (s), (s), 135. (s), (d), 128. (d), (d), (d), (d), 12. (d), 71.1 (d), 4.4 (d), 2.5 (t), 1.5 (t), 1.2 (d), 48.1 (d), 38.4 (t), 2.5 (t), 25.8 (q, - C(C 3 ) 3 ), 21. (q), 17.9 (s, -C(C 3 ) 3 ), (q, -C 3 ). IR (KBr): ν = 3027 (m), 2927 (s), 2854 (s), 1731 (C=, s), 1597 (m), 1494 (s), 1471 (s), 1453 (s), 131 (s), 1253 (m), 1210 (m), 11 (s) cm -1. MS (80 ev, EI, 150 C): m/z = 04 (0.3) [M + ], 589 (0.5) [M + - C 3 ], 547 (0.1) [M + - C 4 9 ], 449 (0.) [M + - Tos], 290 (100), 91 (18), 75 (11). RMS (80 ev,120 C): C S [M + ]: Calcd Found:

5 4 Crystallographic Data (Cambridge Data Centre Deposit o. in Brackets) Crystal structure of cyclopropano azonanone 5c (CCDC-14505) C7 C5 C4 C2 Crystal data for cyclopropano azonanone 5c: colorless, transparent prism crystallized from diethyl ether/n-hexane at -20 C C (Mr = 408.0); crystal dimensions 0.40 x 0.45 x 0.52 mm 3 ; monoclinic; P 21, a = (8), b = (2), c = 9.08(1) Å, Z = 4, V = Å 3 (3), ρ calc. = g/cm -3, T = 135 K, 2Θ max =.3 ; of the reflections measured, were 7240 independent reflections (R int = 0.027, ω R = and S = 1.50); emens-smart diffractometer, Mo-Kα radiation (λ = Å). The structure was determined by direct methods using program SELXS. The atoms were taken from a difference Fourier synthesis and were refined with isotropic thermal parameters. The non- atoms were refined with anisotropic thermal parameters. The structure was refined on F values using weighting scheme: w (F) = 4 * F 2 / [s 2 (F 2 ) + (0.03 * F 2 ) 2 ]. The final difference density was between and e/a 3. Discussion of the structure: The conformation of the bicyclo [7.1.0] decane ring differs considerably from similar rings found in other crystal structures (Mihailovic et al., Tetrahedron Lett., 1979, 4917). The C3-C4-C5-C torsion angle of 134.1(1) is slightly smaller than the value of about 143 found for a larger ring (Marsh et al., J. rg. Chem. 199, 1, 2743 ). Several C-C bonds deviate significantly from a gauche conformation. Thus the nine-membered ring appears considerably strained. Both the and C1 atoms deviate slightly from planarity: lies 0.07 Å outside the plane through C1, C8 and C9; C1 lies 0.04 Å outside the plane through, 1 and C2. The intramolecular 2...8B distance of 1.91(2) Å is very short and indicates a steric repulsion between those atoms. Another short intramolecular contact distance is found between 1 and 9B (2.28(1) Å). The crystal packing shows only very weak, intermolecular, electrostatic interactions:...9a: 3.04(2) Å (2-x, y-0.5, 1-z ), C: 2.59(2) Å (2-x, y-0.5, 1-z) and two C-...pi(phenyl) interactions with...pi distances of 2.99 and 3.13 Å.

6 5 Crystal structure of epoxy azonanone 11c (CCDC-1450) C7 C5 C4 C2 Crystal data epoxy azonanone 11c: colorless, transparent prism crystallized from diethyl ether/n-hexane at room temperature C (Mr = ); crystal dimensions 0.38 x 0.52 x 0.4 mm 3 ; orthorhombic; P , a = (12), b = (10), c = 1.000(2) Å, Z = 4, V = Å 3 (5), ρ calc. = g/cm -3, T = 13 K, 2Θ max =.3 ; of the reflections measured, were 8017 independent reflections (R int = 0.048, ω R = and S = 1.32); emens-smart diffractometer, Mo-Kα radiation (λ = Å). The structure was determined by direct methods using program SELXS. The atoms were taken from a difference Fourier synthesis and were refined with isotropic thermal parameters. The non- atoms were refined with anisotropic thermal parameters. The structure was refined on F values using weighting scheme: w (F) = 4 * F 2 / [s 2 (F 2 ) + (0.03 * F 2 ) 2 ]. The final difference density was between and e/a 3. Discussion of the structure: The conformation of the nine-membered ring is very similar to that found in the corresponding unsaturated compound. The largest difference (about 12 deg) is found for the torsion angle about the C-C7 bond. The title compound and the corresponding unsaturated compound have isomorphous crystal structures. Small differences between the title compound and the unsaturated compound are found for the relative orientations of the side chains: differences up to 14 deg are found for the torsion angles about the - bond. Differences up to deg are also found for the torsion angles about the -C9 and C9-C10 bonds. The molecule shows a short repulsive intramolecular distance of 1.9 Å between 2 and 8Å. The crystal packing only shows very weak, intermolecular electrostatic interactions:...17c: 3.09 Å (x, y-1, z) and B: 2.9 Å (1-x, y-0.5, 0.5-z). There are no other significant intra- or intermolecular contacts.

7 Crystal structure of epoxy azonanone 12c (CCDC-14507) C5 C7 C4 C2 Crystal data epoxy azonanone 12c: colorless, transparent prism crystallized from diethyl ether/n-hexane at room temperature C (Mr = ); crystal dimensions 0.5 x 0.5 x 0.52 mm 3 ; orthorhombic; P ,a = (13), b = (14), c = (2) Å, Z = 4, V = Å 3 (5), ρ calc. = g/cm -3, T = 13 K, 2Q max =.3 ; of the reflections measured were 7790 independent reflections (R int = , ω R = and S = 1.37); emens-smart diffractometer, Mo-Kα radiation (λ = Å). The structure was determined by direct methods using program SELXS. The atoms were taken from a difference Fourier synthesis and were refined with isotropic thermal parameters. The non- atoms were refined with anisotropic thermal parameters. The structure was refined on F values using weighting scheme: w (F) = 4 * F 2 / [s 2 (F 2 ) + (0.03 * F 2 ) 2 ]. The final difference density was between and +0.1 e/a 3. Discussion of the structure: The title compound and the corresponding unsaturated compound have isomorphous crystal structures. The conformation of the molecule is very similar to that of the corresponding unsaturated compound. Torsion angles about corresponding bonds agree within 4, except for the C3-C4-C5-C bond which has a torsion angle of (1) in the title compound and (2) in the unsaturated compound. The molecule shows a short repulsive intramolecular distance of 2.01 Å between 2 and 8B. The crystal packing only shows very weak, intermolecular electrostatic interactions:...17a: 3.05 Å (x, y-1, z),...19b: 3.03 Å (x-0.5, 0.5-y, -z), : 2.5 Å (1-x, y-0.5, 0.5-z), C: 2.0 Å (1-x, y-0.5, 0.5-z) and : 2.0 Å (x+1, y, z). There are no other significant intra- or intermolecular contacts.

8 7 Crystal structure of epoxy azonanone 12b (CCDC-14508) C7 C5 C4 C2 Crystal data epoxy azonanone 12b: colorless, transparent prism crystallized from diethyl ether/n-hexane at room temperature C (Mr = 481.9); crystal dimensions 0.5 x 0.2 x 0.22 mm 3 ; monoclinic; P 21, a = (2), b = (11), c = (1) Å, Z = 2, V = 13.9 Å 3 (3), ρ calc. = g/cm -3, T = 13K, 2Θ max =.3 ; of the reflections measured, were 8511 independent reflections (R int = , ω R = and S = 1.277); emens-smart diffractometer, Mo-Kα radiation (λ = Å). The structure was determined by direct methods using program SELXS. The atoms were taken from a difference Fourier synthesis and were refined with isotropic thermal parameters. The non- atoms were refined with anisotropic thermal parameters. The structure was refined on F values using weighting scheme: w (F) = 4 * F 2 / [s 2 (F 2 ) + ( 0.03 * F 2 ) 2 ]. The final difference density was between and e/a 3. Discussion of the structure: The conformation of the nine-membered ring is very similar to that found in the corresponding chloride. The molecule shows short repulsive intramolecular distances of 1.98 Å between 2A and 8A and of 2.03 Å between 7 and 9B. The crystal packing shows weak, intermolecular electrostatic C-... and C-...pi(phenyl) interactions: D A - A D A symmetry [Å] [deg] C x, y-1/2, 1-z C2-2A x, y+1/2, 2-z C13-13 pi(c10-c15) x, y-1/2, 1-z C28-28A pi(c23-c28) x, y-1/2, 2-z

9 8 Crystal structure of 8-hydroxy-indolizidin-5-one 20b (CCDC-14509) Crystal data of the indolizidinone 20b: colorless, transparent prism crystallized from diethyl ether/n-hexane at room temperature C (Mr = ); crystal dimensions 0.7 x 0.50 x 0.34 mm 3 ; monoclinic; P 21, a = (14), b = (10), c = (14) Å, Z = 2, V = Å 3 (3), ρ calc. = g/cm -3, T = 200 K, 2Θ max =.3 ; of the reflections measured, were 837 independent reflections (R int = , ω R = and S = 1.491); emens-smart diffractometer, Mo-Kα radiation (λ = Å). The t-butyl-dimethyl-silyl group was found to be disordered. Two possible orientations were found for this group. The occupancy factor of the group labeled, C1, C17, C18, C19, C20 and C21 was 0.494(). The occupancy factor of the group labeled ', C1', C17', C18', C19', C20' and C21' was 0.50(). Even the split atoms had very large displacement parameters. atoms were placed at calculated positions and were treated as riding atoms. The atom of the hydroxyl group was taken from a difference Fourier synthesis and was refined with isotropic thermal parameters. The structure was refined on F 2 values using program SELXL-9. The absolute configuration of the structure was confirmed by a refinement of the Flack x - parameter [ x = -0.05(20)]. The final difference density was between and e/a 3. Below about 85 C additional reflections appear with indices h+-0.50, k+-0.39, l+-0.50, corresponding to a modulated phase. The structure remains modulated upon cooling to at least 170 C, which is the lowest temperature reachable with our low temperature device. Discussion of the structure: The five-membered ring approximately has an envelope conformation with atom C 0.57 Å outside the plane of C5,, C8 and C7. The saturated sixmembered ring approximately has an unsymmetrical twist (half-chair) conformation with atoms C3 and C and 0.48 Å in opposite directions outside the plane of C2, C1, and C5. The hydroxyl group is in a pseudo-equatorial position with respect to this ring. Conformations for the 2-oxo-1-azabicyclononane group similar to that in the title compound have been observed by Polyak and Lubell (J. rg. Chem. 1998, 3, 5937) and Lindemann et al. (Tetrahedron 1998, 54, 2529). Slightly different conformations were found by Austin et al. (Tetrahedron 1987, 43, 3095) and ua et al. (Acta Cryst., C51, 1995, 2301). Very different conformations for this group were reported by Lindemann et al. (Tetrahedron Asymmetry 1998, 9, 4459), Fox et al. (J. Am. Chem. Soc. 1991, 113, 252), Colombo et al. (Tetrahedron

10 9 1998, 54, 5325), Lombart and Lubell (J. rg. Chem. 199, 1, 9437) and Lynch et al. (Acta Cryst., C , 908). The molecules are connected by an intermolecular hydrogen bond to infinite chains in the a - direction. A weak, intermolecular C-... interaction also contributes to this chain formation. There are no other significant intra- or intermolecular contacts.

11 Supplementary material: Crystallographic structure of [5c] A. Sudau, W. Muench, U. ubbemeyer, J. W. Bats

12 Supplementary material: Crystallographic structure of [11c] A. Sudau, W. Muench, U. ubbemeyer, J. W. Bats

13 Supplementary material: Crystallographic structure of [12b] A. Sudau, W. Muench, U. ubbemeyer, J. W. Bats

14 Supplementary material: Crystallographic structure of [12c] A. Sudau, W. Muench, U. ubbemeyer, J. W. Bats

15 Supplementary material : EDS-Data for [9a], [9c], [12a], [11a], [5c], [11c] [9a] [12c] TBS Tos TBS 2.5 TBS Bn [11a] [5c] TBS [11c] TBS [9c] TBS Tos

16 Supplementary material : EDS-Data for [10c], [8c], [17a], [17c] TBS 5 3 Tos TBS Tos TBS Et 2 C 3.5 C 2 Et main rotamer (70%) of [10c] possible minor rotamer (30%) of [10c] main rotamer [8c] TBS 3.5 Et 2 C Et 2 C possible minor rotamer [8c] TBS [17a] TBS TBS [17c]

17 Supplementary material : EDS-Data for [19c-TMS], [20b], [22c], [20a-TMS], [22a], [23a] TMS TBS [19c-TMS] TBS [20b] TMS TBS [20a-TMS] TBS [22a] TBS S p-tol [23a] TBS [22c] 5 1

18 Supplementary material : EDS-Data for [20a], [21a] 17 TBS R [20a] [21a]

19 18 solvent: CD 3 [5c]

20 19 solvent: CD 3 [c]

21 20 solvent: CD 3 Et 2 C C 2 Et [7c]

22 21 solvent: CD 3 Et 2 C C 2 Et [8c]

23 22 solvent: CD 3 S [9a]

24 23 solvent: CD 3 S [9c]

25 24 solvent: CD 3 Tos TBS [10c]

26 25 solvent: CD 3 TBS [11a]

27 2 solvent: CD 3 [11c]

28 27 solvent: CD 3 [12a]

29 28 solvent: CD 3 Bn [12b]

30 29 solvent: CD 3 [12c]

31 30 solvent: C D [15c]

32 31 Solvent: CD Mz, 23K Ac Ac [1c]

33 32 Solvent: CD 2 2 [17a]

34 33 solvent: CD 2 2 [17c]

35 Solvent: CD Mz, 25 K [18c]

36 35 Lsgsmittel : CD 2 2 [19a]

37 [19c] (ppm) solvet: CD 3 0 3

38 37 solvent: CD 2 2 [19c]-TMS

39 38 solvent: CD 3 [20a]

40

41 40 Solvent: CD 3 TBS [20b]

42 41 solvent: CD 3 [21a]

43 42 solvent: CD 3 [22a]

44

45 44 solvent: CD 3 S [23a]