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Syntheses of Bisoxazolidinesand MorpholonesVÍCtor Santes a , Aurelio Ortíz a , Rosa Santillan a ,Atilano Gutiérrez b & Norberto Farfán aa Departamento de Química, Centro de Investigatióny de Estudios Avanzados del, IPN , Apdo. Postal14-740, 07000, México, D.F., México E-mail:b Lab. de RMN, Universidad AutónomaMetropolitana, Av. Michoacán y la Purisima s/n , Col.Vicentina, 09340 Ixtapalapa, México, D. F., MéxicoPublished online: 17 Sep 2007.

To cite this article: VÍCtor Santes , Aurelio Ortíz , Rosa Santillan , Atilano Gutiérrez& Norberto Farfán (1999) Syntheses of Bisoxazolidines and Morpholones, SyntheticCommunications: An International Journal for Rapid Communication of SyntheticOrganic Chemistry, 29:8, 1277-1286, DOI: 10.1080/00397919908086103

To link to this article: http://dx.doi.org/10.1080/00397919908086103

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SYNTHETIC COMMUNICATIONS, 29(8), 1277-1286 (1999)

SYNTHESES OF BISOXAZOLIDINES AND MORPHOLONES

Victor Santes,” Aurelio Ortiz,” Rosa Santillan,” Atilano Gutitrrezb and Norbert0 Fa r fha*

“Departamento de Quimica, Centro de Investigacih y de Estudios Avanzados del IPN, Apdo. Postal 14-740,07000 Mexico D.F., Mexico,

Email Jfarfan@mail.cinvestav.mx. bLab. de RMN, Universidad Aut6noma Metropolitana, Av. Michoach y la

Purisima s/n, Col. Vicentina, 09340 Ixtapalapa, Mtxico D. F., Mtxico.

Abstract: The preparation of two new bisoxazolidines, two N-(2-hydroxyethyl)- N-alkylglycine derivatives and two morpholones is described. The structure of

(5S,6R)-N-isopropylJ-methyl-6-phenyl-l,4-oxazin-2-one was established by X- ray crystallographic analysis.

In previous studies we have reported that the reaction of secondary aminoalcohols with glyoxal provides a route to aminoacids,’ oxazino-oxazines and bisoxazolidines,’ while secondary anilines afford indol derivative^.^ In contrast, the reaction of primary aminoalcohols with 1 ,Zdiketones yield heteropropellane~~ and 2-hydroxy-5,6-dihydro-2H-[ 1,4]-oxazines: or bi(benzothiazoly1) and benzothiazino-benzothiazine, if o-aminothiophenol is reacted with gyoxaL6 Recently we have applied this sequence to the preparation of 1,4-piperazines by reaction of the N,N’-bis-(n0rephedrine)ethylendiamine derivatives with 1 ,Zdiketones and subsequent reduction with diborane.’

* To whom correspondence should be addressed

1277

Copyright 0 1999 by Marcel Dekker, Inc www,dekker .com

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1278 SANTES ET AL.

In continuing with our interest in this type of reactions we report herein the condensation of four N-alkylnorephedrines (la-ld) with glyoxal. The alkylnorephedrine derivatives (la-lc) were prepared by reaction of (-)-

norephedrine with the corresponding alkylbromide,8 while compound Id was obtained by reaction of pivaloyl chloride with (-)-norephedrine and subsequent reduction with borane THF.’

Unequivocal ‘H and I3C spectral assignment for compounds 2a-2d was achieved by 2D ‘H and I3C correlated experiments. Reaction of l a and l b with glyoxal afforded [5R,5’R,4S,4’S,2R,2’R]-5,5’-diphenyl-4,4’-dimethyl-N,N’- diethyl-2,2’ -bisoxazolidine (2a) and [ 5R,5 ’R,4S ,4’S ,2R,2’S]-5,5 ’ -diphen y l-4,4' - dimethyl-N,N’-dibenzyl-2,2’-bisoxazolidine (2b), respectively (Scheme l), as established by NMR experiments. The ‘H and I3C NMR spectra of 2a show signals for half of the molecule due the existence of a C, symmetry axis in the molecule. Determination of the bisoxazolidine type structure for 2a was based on

measurement of the I3C satellite coupling constants’ for H-2 (6=4.53 ppm JCH= 154

Hz, ’JH,=3.66 Hz) and the NOESY spectrum which shows through space interaction between H-2 and CH,-6, thus allowing to establish the configuration for C-2 as R. In contrast, the ‘H NMR spectrum of 2b shows a different coupling

pattern since the protons at the ring fusion give rise to an AE? system at 6=4.69

ppm and 4.55 ppm (,JHH=5.6 Hz) for H-2 and H-2,’ respectively, thus evidencing that the new stereogenic centers are different. Complete assignment of the ’H NMR spectra for both compounds was based on the COSY and NOESY experiments. The NOESY spectrum shows interaction between H-2’ and H-2, H-4’, H-4, the AB system due to the methylene at the position 7’, H-5’ and H-5; in addition, H-2 shows interaction with the Al3 ascribed to H,-7 and H-2’, establishing the configuration at the C2 and C2’ ring fusion carbons are R and S, respectively. This in turn allowed assignment of the I3C NMR spectrum based on the HETCOR spectrum.

Reaction of compounds l c and Id with glyoxal afforded morpholones 2c

and 2d, respectively (Scheme 1) as evidenced by the I3C NMR signal at 6=169.1

and k168 .8 ppm for the carbonyl group of 2c and 2d, respectively. The ’H NMR

spectra show the characteristic AB system for the diastereotopic protons alpha to

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BISOXAZOLIDINES AND MORPHOLONES 1279

la R = q C H , lb R = C E & E , l c R=CH(CE.,), Id R=CE&XCE&

I

2c R=CH(CHs), 2d R=CH,C(CIi&

Scheme 1

the carbonyl group at 6=3.79 and 6=3.34 pprn for 2c and 6=3.69 and 6=3.54 ppm

for 2d.

The structure of 2d was established by X-ray crystallografic analysis (Figure 1) which shows that the morpholone has a pseudochair conformation, the phenyl and neopentyl groups occupy pseudoequatorial positions and the methyl group occupies a pseudoaxial position. Unit cell parameters and basic information about data collection and structure refinement are summarized in the experimental section." Selected interatomic bond lengths and angles are summarized in the Table.

Upon standing in ethanolkhoroform solution 2a and 2b hydrolyze to glycine derivatives 3a and 3b (Scheme 1 ) . The infrarred spectra show the characteristic bands at 3 196 and 3268 cm-' for the OH groups, and the carbonyl groups at 1628 and 1624 cm-' for 3a and 3b, respectively. The 'H NMR spectrum of 3a shows an

AB system for the H-4 methylene group at 6=3.59 ppm and 3.33 ppm (2J,,=1 6.1

Hz), while that of 3b is shifted to 6=3.37 ppm and 3.31 ppm (*J,,=17.5 Hz).

Complete I3C spectral assignment was based on HETCOR experiments.

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1280 SANTES ET AL.

FIG. 1 Molecular perspective view for morpholone 2d.

Table. Selected interatomic bond lengths and angles.

Interatomic bond lengths (A) for 26

O( 1) - C(2) 1.323(5) O( 1) - (76) 1.450(5)

O(2) - C(2) 1.193 (6) N(4) - C(3) 1.427(7) N 4 ) - (35) 1.458(6) N(4) - C( 14) 1.461(6) C(2) - C(3) 1.486(7) ( 3 5 ) - C(6) 1.5 14(6) C(5) - C( 13) 1.522(7) C(6) - (37) 1.491(7)

Bond angles (deg) for 2d

C(2) - O( 1) - C(6) 1 2 1.5(4) C(3) - N(4) - C(5) 110.9(4)

C(3) - N(4) - C(14) 114.3(4) C(5) - N(4) - C(14) 114.8(4) O( 1) - C(2) - O(2) 118.7(5) O( 1) - C(2) - C(3) 119.4(5) O(2) - C(2) - C(3) 121.9(5) N(4) - C(3) - C(2) 116.0(4) N(4) - C(5) - C(6) 106.8(4) N(4) - C(5) - C(13) 115.2(4)

It can be concluded that the reaction of N-alkylnorephedrines leads to bisoxazolidine type structures when the alkyl substituents are not bulky, however, bisoxazolidines containing ethyl and benzyl groups slowly hydrolize to the thermodynamically more stable glycine derivatives. A steric effect is supported by the fact that bisoxazolidines containing isopropyl and neopentyl groups were not

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BISOXAZOLIDINES AND MORPHOLONES 1281

obtained, the major product being the morpholone derivatives which showed good stability in methanol solution, under the same reaction conditions.

EXPERIMENTAL

'H and 13C NMR spectra were recorded on Jeol Eclipse +400 and Jeol-270 spectrometers. Chemical shifts (ppm) are relative to (CH,),Si. Coupling constants are quoted in Hz. The HETCOR and COSY standard pulse sequence, which incorporates quadrature detection in both domains, was used. NOESY experiments were recorded on a Bruker DMXSOO. Infrared spectra were recorded on a Perkin Elmer 16F spectrophotometer. Mass spectra were obtained with an HP 5989A mass spectrometer. Melting points were obtained on a Gallenkamp MFB-595 apparatus and are uncorrected. Elemental microanalyses were performed by Oneida Research Services, Whitesboro, NY 13492. Data for X-ray crystal structure determination of

2d was collected on an Enraf Nonius CAD4 diffractometer, h (MoKa)=0.7 1069 A,

monochromator: graphite, T= 293 K, o / 28 scan, range 1" < 0 < 25".

(5R,5 'R,4S,4' S,2R,2'R)-N,Nt-diethyl-5,5'-diphenyl-4,4'-dimethyl-2,2'- bisoxazolidine (2a). To a solution of l a (1.0 g, 5.6 mmol) in THF (40 ml) a 40 wt. % solution of glyoxal in water (0.41 g, 3.90 mmol) was added and the reaction mixture was stirred at room temperature for 6 h. The solution was concentrated under vacuum, ethyl ether was added and the resulting white precipitated was filtered off and dried

to give 2a (1.2 g, 56%); mp 149-151 "C; 'H NMR (399.78 MHz, CDCl,) 6: 7.40

(2H, d, J=7.3 Hz, H-0), 7.33 (2H, t, J=7.3 Hz, H-m), 7.26 (IH, t, J=7.3Hz, H-p), 5.48 (lH, d, J=2.6 Hz, H-5), 4.53 (lH, S , H-2), 3.47 (IH, dq, 5 ~ 2 . 6 , 6.6 Hz, H-4), 2.94 (lH, dq, J=7.2, 12.5 Hz, H-7a), 2.36 (lH, dq, J=7.2, 12.5 Hz, H-7b), 1.00 (3H, dd, J=7.2 Hz, H-8), 0.74 (3H, d, J=6.6 Hz, H-6) ppm; I3C

NMR (100.54 MHz, CDCl,) 6: 140.05 (C-i), 128.02 (C-m), 126.8 (C-p), 126.23

(C-0), 12.26 (C-8), 5.46 8 1.93 (C-2), 72.70 (C-5), 54.54 (C-4), 42.1 1 (C-7), (C-6) ppm; MS m/z (%): M' -C,H, 303 (25), 288 (loo), 273 (27), 243 (24), 165

(41), 136 (4.9, 91 (13), 65 (31); IR v,,(KBr): 3330, 1470, 1450, 1445, 1088, 1034, 630, 622,590, 538, 520 cm:' Elemental analysis: Calc.: C, 75.78; H, 8.42; N, 7.36. Found: C, 75.85; H, 8.49; N, 7.29.

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1282 SANTES ET AL.

(5R,5’R,4S,4’S,2R,2’S)-N,N’-dibenzyl-5,5’-diphenyl-4,4’-dimethyl-2,2’- bisoxazolidine (2b). To a solution of l b (2.5 g, 10.4 mmol) in ethanol (40 ml) a 40 % wt. solution of glyoxal in water (0.30 g, 5.18 mmol) was added, the reaction mixture was refluxed for 2 h and cooled to room temperature. The solvent was removed under vacuum, ethyl ether was added and the resulting white precipitate was filtered off and dried to

give 2b (1.07 g, 41%); mp 134-135 “C; ‘H NMR (270 MHz, CDCl,) 6: 7.19-7.49

(20 H, m, H-arom.), 5.40 (lH, d, J=4.6 Hz, H-5), 5.04 (lH, d, J=4.7 Hz, H-5’), 4.69 and 4.55 (2H, AB, J=5.6 Hz, H-2 and H-2’), 4.49 and 3.84 (2H, AB, J=3.9 Hz, H-7), 4.28 and3.88 (2H, AB, J=13.8 Hz, H-7’), 3.51 (lH, dq, J=4.6, 6.6 Hz, H-4), 3.21 (lH, dq, 5~4.7 , 5.6 Hz, H-4’), 0.60 (3H, d, J=6.6 Hz, H-6),

0.53 (3H, d, J=5.6 Hz, H-6’) ppm; I3C NMR (67.8 MHz, CDCI,) 6: 139.9 (C-8),

139.6 (C-12), 138.9 (C-87, 138.5 (C-l2’), 129.0, 128.2, 128.1, 127.9, 127.1, 126.8 and 126.1 ( C-10, C-9, C-14, C-13, C-lo’, C-9’, C-14’ and C-13’), 128.6, 128.0, 127.0 and 126.5 (C-11, C-15, C-11’ and C-15’), 97.7 (C-2’), 95.1 (C-2),

(C-6’), 8.7 (C-6) ppm; MS, m/z (%): 254 (3), 253 (33), M+/2 252 (loo), 225 (3),

224 (15), 120 (3), 118 (6), 92 (3), 91 (34); IR vm(IU3r): 3334, 1464, 1034,

1010, 636, 620, 602, 556 cm:’ Elemental analysis: Calc.: C, 80.95; H, 7.14; N, 5.55. Found: C, 80.54; H, 7.24; N, 5.45.

81.5 (C-5), 80.9 (C-5’), 61.7 (C-4’), 58.7 (C-7’), 57.5 (C-4), 50.9 (C-7), 17.7

(5S, 6R)- 6-phenyl-5-methyl-N-isopropyl- 1 ,4-oxazin-2-one (2c).

To a solution of l c (1.0 g, 5.2 mmol) in ethanol (40 ml) a 40 % wt. solution of glyoxal in water (0.30 g, 5.2 mmol) was added, the reaction mixture was refluxed for 2 h and cooled to room temperature. Removal of the solvent under vacuum yielded morpholone 2c as a yellow oil (1.15 g, 95%); bp 100 “C/300mm (dec.); ‘H

NMR (270 MHz, CDCl,) 6: 7.25-7.39 (5H, m, H-arom.), 5.60 (lH, d, J=3.1 Hz,

H-5), 2.70 (lH, heptet, J=6.3 Hz, CH-8), 1.12 (3H, d, J=6.3 Hz, CH,-9), 1.10 (3H, d, J=6.3 Hz, CH,-9’), 0.70 (3H, d, J=6.6 Hz, H-7) ppm; I3C NMR (67.8

MHz, CDCI,) 6: 169.1 (C=O), 136.9 (C-i), 128.4 (C-m), 128.0 (C-p), 125.8

H-6), 3.79 and 3.34 (2H, AB, 5~18.1 Hz, H-3), 3.40 (IH, dq, 5 ~ 3 . 1 , 6.6 Hz,

(CO), 83.8 (C-6), 52.6 (C-5), 50.8 (CH-8), 48.0 (C-3), 20.7 and 19.5 (CH,-9’

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BISOXAZOLIDINES AND MORPHOLONES 1283

and CH,-9), 5.7 (C-7) ppm; MS m/z (%): M+, 233 (32), 118 (47), 99 (loo), 91(27), 86 (66),85 (65), 84 (5% 83 (72), 77 (45), 56 (93), 44 (43), 28 (28); IR

v, (film, NaCl): 2972, 1732, 1682 (CO), 1634, 1456, 1258, 1002, 916, 700

cm:'

(5S, 6R)-6-phenyl-5-methyl-N-neopentyl- lt4-oxazin-2-one (2d). To a solution of Id (1.0 g, 4.5 mmol) in ethanol (40 ml) a 40% wt. solution of glyoxal in water (0.26 g, 4.5 mmol) was added and the reaction mixture was refluxed for 2 h and cooled to room temperature. Removal of the solvent under vacuum afforded morpholone 2d as a white solid (0.7 g, 63%); mp 106-108 "C;

'H NMR (270 MHz, CDCl,) 6: 7.26-7.39 (5H, m, H-arom.), 5.76 (IH, d, J=3.3

Hz, H-6), 3.69 and 3.54, (2H, AB, J=18.8 Hz, H-3), 3.09 (lH, dq, J=3.3 Hz, 6.6 Hz, H-5), 2.40 and 2.10 (2H, AB, J=13.8 Hz, CH,-8), 0.93 (9H, S ,

CH3-10), 0.75 (3H, d, J=6.6 Hz, H-7) ppm; I3C NMR (67.8 MHz, CDCl,) 6:

168.8 (C=O), 136.9 (C-i), 128.4 (C-m), 127.9 (C-p), 125.4 (C-o), 83.5 (C-6), 67.1 (CH,-8), 58.1 (C-5), 52.2 (C-3), 33.5 (C-9), 27.7 (CH3-lo), 5.3 (C-7) ppm. MSd. (%):M+,261 ( l l ) , 246 (7), 205 (14), 204 (IOO), 146 (13), 117 (8), 112 (48), 77 (3, 71 (25), 56 (20), 43 (14), 42 (84), 41 (16), 29 ( l l ) , 28 (5); IR

v ,,,ax(KBr): 2976, 2950,2918,2864, 1740 (CO), 1380, 1372, 1288, 1258, 1240,

1136, 1004,738,704 cm"; Elemental analysis: calc.: C, 73.56; H, 8.81; N, 5.36. Found: C, 73.75; H, 8.98; N, 5.34.

N-ethyl-N-( 1 -(S)-2-(R)-phenyl-2-hydroxyethyl)glycine (3a). Compound 2a hydrolyzed in chloroforrdmethanol solution to give 3a. The same compound was obtained when la was heated with glyoxal in ethanol for 8 h, white

solid mp 163-165 "C; 'H NMR (399.78 MHz, DMSO-d,) 6: 7.37 (2H, d, J=7.3

Hz, H-o), 7.32 (2H, t, J=7.3 Hz, H-m), 7.22 (lH, t, J=7.3 Hz, H-p), 5.05 ( lH, d, J=1.8 Hz, H-I), 3.59 and 3.33 (2H, AB, J=16.1 Hz, H-4), 3.26 (lH, dq, J=1.8, 6.6 Hz, H-2), 3.00 (2H, m, CH,-7), 1.09 (3H, t, J=7.1 Hz, H-8), 0.94

(3H, d, J=6.6 Hz, H-6) ppm; I3C NMR (100.54 MHz, DMSO-d,) 6: 169.7 (C-5),

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1284 SANTES ET AL.

143.7 (C-i), 128.4 (C-m), 127.4 (C-p), 126.4 (C-o), 71.8 (C-I), 63.7 (C-2), 53.2 (C-4), 48.4 (C-7), 11.6 (C-8), 8.4 (C-6) ppm; MS m/z (%): [M+ -H,O, 219 (0.5)],

192 (0.3), 130 (IOO), 105 (8), 85 (20), 77 (30), 58 (46), 56 (82), 28 (18); IR v,,

(KBr): 3196 (OH), 3022,2852, 1628 (CO), 1388, 1330, 1062, 1044, 1004, 750, 706 cm:' Elemental analysis: calc.: C, 65.82; H, 8.01; N, 5.90. Found: C, 65.85; H, 8.03; N, 5.78.

N-benzyl-N-( I -(S)-2-(R)-phenyl-2-hydroxyethyl)glycine (3b). Compound 2b was allowed to stand in chloroform for three weeks giving 3b as

white solid mp 155-157 "C; 'H NMR (270 MHz, DMSO-d,) 6: 7.26-7.21 (lOH,

m, H-arom), 4.81 (IH, d, J=3.9 Hz, H-I), 3.82 and 3.73 (2H, AB, J=14.0 Hz, CH,-7), 3.37 and 3.31 (2H, AB, J=17.5 Hz, H-4), 2.83 (lH, dq, J=3.9, 6.7 Hz,

H-2), 0.92 (3H, d, J=6.7 Hz, H-6) ppm; I3C NMR (67.8 MHz, DMSO-d,) 6:

173.7 (C-5), 145.4 (C-i), 140.1 (C-i ' ) , 129.0, 128.6, 128.2 and 126.6 (C-m, C-m', C-0' and C-o), 127.3 and (126.9 (C-p' and C-p), 74.2 (C-1), 61.2 (C-2), 55.8 (CH,-7), 52.1 (C-4), 9.9 (C-6) ppm; MS, m/z (%): [M' -H,O, 281 (12)], 192

(47), 147 (43), 91 (87), 56 (loo), 29 (46 ); IR v ,,,ax(KBr): 3268 (OH), 3064,

2998, 1624 (CO), 1458. 1450, 1390, 1344, 1328, 764, 748 and 704 cm." Elemental analysis: calc.: C, 72.24; H, 7.02; N, 4.68. Found: C, 71.87; H, 7.00; N, 4.62.

Acknowledgment. Financial support from CONACYT is acknowledged.

REFERENCES AND NOTES

1 . Farfin, N., CuCllar, L., Aceves, J. M. and Contreras, R., Synthesis, 1987, 927. a) Farfin, N., Santillan, R. L., Castillo, D., Cruz, R., Joseph-Nathan, P. and Daran, J. C., Can. J . Chem., 1992, 70, 2664; c) Farfrin, N., Santillan,

2.

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BISOXAZOLIDINES AND MORPHOLONES 1285

3.

4.

5.

6.

7.

8.

9. 10.

R., Guzmin, J.B., Castillo, B., Ortiz, A., Daran, J. C., Robert, F. and Halut, S., Tetrahedron, 1994, 50, 9951. Farfin, N., Hernindez, J. M., Joseph-Nathan, P. and Contreras, R.,

J.Heterocyclic Chem., 1990, 27, 1745. Ortiz, A., Carrasco, J., Hopfl, H., Santillan, R. and N. Farfin Synth. Commun., 1998, 28, 1293. Ortiz, A., Farfin, N., Santillan, R., Rosales, M. J., Garcia-BaCz, E., Daran, J. C. and Halut, S., Tetrahedron Asymmetry, 1995, 6, 2715. Farfin, N., Santillan, R., Castillo, B., Carretero, P., Rosales, M. de J., Garcia-Biez, E., Flores-Vela, A,, Daran, J. C. and Halut, S., J. Chem. Res.(S), 1994, 458, (M), 1994, 2521. Ortiz, A., Farfin, N., Hopfl, H., Santillan, R. and GutiCrrez A., Tetrahedr0n:Asymmetry , 1998 (in press). Chaloner, P. A., Langadianou, E. and Renuka Perera S. A., J . Chem. SOC. Perkin Trans. 1,1991, 273 1 . Tlihuext, H. and Contreras, R., Tetrahedron: Asymmetry, 1992, 3, 727. Crystal data for compound 2d: Colourless crystals, C,,H,,NO, (M=261.36

gmol-I), crystallized in the orthorrombic space group P 2,2,2,, a=8.390(4),

b=10.404(5), ~=17.467(4) A, V=1524(1) Z=4, Pcalcd= 0.70 Mgm.-3 A total of

1572 reflections was measured of which 155 1 were independent, absorption correction: DIFABS (min: 0.82, max: 1.20), corrections were made for Lorentz and polarization effects. Solution and refinement: direct methods (SHELXS-86) for structure solution. Nonhydrogen atoms were refined anisotropically, hydrogen atoms were found by difference Fourier maps and refined with an overall isotropic thermal parameter, least squares refinements were carried out by minimizing the function ~W(~F,I-IF,I>~, where F, and F, are the observed and calculated structure factors. Unit weight was used. Models reached convergence with R=~(IIF,I-IF,lI)/~IF,I and RW=[~W(~F,I-IF,I)~/~W(F,)~]”~ with values R= 0.040,

Rw= 0.037 from 847 reflections with F>3o(F) for 173 variables against IF/,

w= 1.0, s= 1.87. Largest residual electron density peak / hole in the final difference

map: ~max=O.18, Pmin= -0.36 e - / A3. (CRYSTALS, Program for Refinement of

Crystal Structures, D. J. Watkin, J. R Caruthers, P.V. Betteridge, Univ. Oxford, version 9, 1994).

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1286 SANTES ET AL.

Supplementary Material available: Tables of atomic coordinates, thermal parameters, bond lengths and angles and observed and calculated structure factors have been deposited at the Cambridge Crystallographic Data Center.

(Received in the USA 06 October 1998)

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