6380
V. A. Soloshonok et al. / Tetrahedron 57,2001) 6375±6382
3.1.4. Ni(II)-complex of the Schiff base of (S)-15 with (S)-
20,60-dimethylphenylalanine (S,a-S)-9b. Mp 122±1248C.
*s, 2H), 6.39 *d, 1H, J7.0 Hz), 6.53±6.59 *m, 2H), 6.69
*s, 2H), 7.05±7.08 *m, 1H), 7.11±7.17 *m, 2H), 7.20±7.22
*m, 1H), 7.30±7.33 *m, 3H), 7.24±7.43 *m, 6H), 8.08±
8.11*m, 3H). 13C NMR *CDCl3, DRX500) d 21.9, 23.8,
27.8, 30.5, 42.0, 57.8, 63.6, 69.6, 70.1, 80.4, 115.0, 120.3,
123.2, 125.8, 126.7, 127.2, 127.4, 127.8, 127.9, 128.1,
128.5, 128.8, 128.9, 130.3, 131.5, 131.9, 133.4, 134.0,
136.9, 137.1, 140.6, 141.9, 157.3, 171.6, 180.1, 180.4.
HRMS *FAB) [M1H]1 calcd for C44H43N3O4Ni
736.2685, found 736.2695.
25
Rf0.35 *acetone/hexanes, 1:1). [a]D 12437* c 0.02002,
1
CHCl3). H NMR *CDCl3) d 2.08±2.12 *m, 1H), 2.14 *s,
6H), 2.27±2.33 *m, 1H), 2.57±2.66 *m, 1H), 2.76±2.80 *m,
1H), 3.51±3.57*m, 2H), 3.53 *d, 1H, J12.9 Hz), 3.91±
3.97*m, 1H), 4.11 *dd, 1H, J10.5, 14.0 Hz), 4.30 *dd,
1H, J4.0, 10.5 Hz), 4.46 *d, 1H, J12.5 Hz), 5.55 *d,
1H, J7.4 Hz), 6.41±6.43 *m, 2H), 6.56±6.60 *m, 1H),
6.82 *d, 2H, J7.6 Hz), 6.93±7.00 *m, 2H), 7.06±7.16
*m, 3H), 7.28±7.38 *m, 4H), 8.07 *d, 2H, J7.1 Hz), 8.22
*d, 1H, J8.7Hz). 13C NMR *CDCl3) d 20.0, 24.2, 30.6,
37.5, 57.1, 63.0, 70.3, 70.4, 120.6, 123.2, 126.0, 126.9,
127.4, 128.1, 128.3, 128.6, 128.8, 128.9, 129.0, 131.4,
132.3, 132.4, 133.1, 133.3, 133.8, 137.8, 142.3, 171.0,
178.8, 180.0. HRMS *FAB) [M1H]1 calcd for
C36H35N3O3Ni 616.2110, found 616.2100.
3.1.8. Ni(II)-complex of the Schiff base of (S)-15 with (R)-
O-benzyl-a,20,60-trimethyltyrosine (S,a-R)-24a. Mp
25
1
243±2458C. [a]D 2372.8 *c 0.01725, CHCl3). H NMR
*CDCl3) d 1.06 *s, 3H), 1.61±1.69 *m, 2H), 2.13±2.17*m,
1H), 2.28 *s, 6H), 2.40±2.45 *m, 1H), 2.48±2.53 *m, 1H),
3.20 *d, 1H, J14.5 Hz), 3.32 *d, 1H, J14.5 Hz), 3.46±
3.52 *m, 1H), 3.57*d, 1H, J13.5 Hz), 3.96 *d, 1H,
J13.5 Hz), 4.01±4.05 *m, 1H), 4.93 *d, 1H, J11.5 Hz).
5.00 *d, 1H, J11.5 Hz), 6.63±6.69 *m, 2H), 6.81 *s,
2H), 6.78±6.81 *m, 1H), 7.17±7.22 *m, 2H), 7.33±7.47
*m, 11H, 7.62±7.63 *m, 2H), 8.21 *d, 1H, J8.5 Hz). 13C
NMR *CDCl3) d 21.8, 23.5, 28.5, 30.9, 42.5, 56.8, 61.2,
69.4, 69.5, 80.2, 114.9, 120.6, 123.7, 126.8, 127.2, 127.3,
127.4, 127.6, 127.8, 127.9, 128.5, 128.6, 128.7, 128.8,
129.1, 129.8, 131.8, 131.9, 133.0, 133.9, 137.0, 137.4,
141.0, 142.1, 157.4, 172.1, 180.4, 180.9. HRMS *FAB)
[M1H]1 calcd for C44H43N3O4Ni 736.2685, found
736.2695.
3.1.5. Ni(II)-complex of the Schiff base of (S)-15 with (R)-
20,60-dimethylphenylalanine (S,a-R)-10b. Mp 295±
25
2978C. Rf0.47*acetone/hexanes, 1:1). [ a]D 21481*c
1
0.0280, CHCl3). H NMR *CDCl3) d 1.85±1.94 *m, 1H),
1.98 *s, 6H), 2.22±2.30 *m, 1H), 2.87±2.92 *m, 1H), 3.34
*dd, 1H, J13.0 Hz, J214.0 Hz), 3.43 *d, 1H, J13.0 Hz),
3.94 *d, part of AB, 1H, JAB9.0 Hz), 4.02 *t, 1H,
J13.6 Hz), 4.29 *dd, 1H, J3.5, 10.5 Hz), 4.29 *dd, 1H,
J3.5, 10.5 Hz), 4.34 *d, 1H, J12.0 Hz), 5.41 *d, 1H,
J6.5 Hz), 6.54±6.56 *d, 1H, J8.5 Hz), 6.62±6.65 *m,
1H), 6.81 *d, 2H, J7.5 Hz), 6.92±6.95 *m, 1H), 6.98±
7.01 *m, 1H), 7.11±7.12 *m, 1H), 7.22±7.23 *m, 1H),
7.31±7.33 *m, 2H), 7.46±7.49 *m, 1H), 7.52±7.55 *m,
2H), 7.92 *d, 1H, J7.5 Hz), 8.61 *d, 1H, J9.0 Hz). 13C
NMR *CDCl3) d 19.7, 22.7, 29.6, 36.7, 58.6, 60.0, 68.5,
70.4, 120.6, 123.1, 125.7, 126.8, 127.1, 128.1, 128.5,
128.6, 128.9, 129.1, 129.2, 131.9, 132.5, 132.6, 133.2,
133.4, 134.1, 138.3, 142.7, 171.5, 179.0, 181.1. HRMS
*FAB) [M1H]1 calcd for C36H35N3O3Ni 616.2110, found
616.2105.
3.1.9. Ni(II)-complex of the Schiff base of (S)-15 with (S)-
a,20,60-trimethylphenylalanine (S,a-S)-23b. Mp 224±
25
2258C. Rf0.46 *acetone/hexanes, 1:1). [a]D 12253 *c,
1
0.01988, CHCl3). H NMR *CDCl3) d 0.94 *s, 3H), 1.95±
2.00 *m, 1H), 2.06±2.11 *m, 1H), 2.38 *s, 6H), 2.44±2.51
*m, 1H), 2.55±2.58 *m, 1H), 3.10±3.15 *m, 1H), 3.37±3.41
*m, 1H), 3.44±3.49 *m, 1H), 3.53 *d, 1H, J12.5 Hz), 3.68
*d, 1H, J14.0 Hz), 3.96 *d, 1H, J14.5 Hz), 4.47*d, 1H,
J12.5 Hz), 6.29 *d, 1H, J8.0 Hz), 6.58±6.52 *m, 2H),
7.02±7.18 *m, 6H), 7.21±7.22 *m, 1H), 7.30±7.33 *m,
2H), 7.36±7.39 *m, 2H), 8.08 *d, 2H, J7.5 Hz), d 8.11
*d, 1H, J9.0 Hz). 13C NMR *CDCl3) d 21.6, 23.8, 27.8,
30.5, 42.5, 57.3, 63.5, 70.1, 80.4, 120.4, 123.2, 126.7, 127.1,
127.2, 127.8, 128.1, 128.8, 128.9, 130.3, 131.6, 131.9,
133.2, 133.4, 134.0, 136.8, 139.2, 141.9, 171.7, 180.1,
180.4. HRMS *FAB) [M1H]1 calcd for C37H37N3O3Ni
630.2267, found 630.2262.
3.1.6. Reaction of the Ni(II)-complex (S,a-S/R)-22 with
bromides 7a and 7b. A 100 mL round-bottom ¯ask with
5.121 g *10 mmol, 1 equiv.) of 22 and 4.0 g *100 mmol,
10 equiv.) of NaOH was purged with Ar and 20 mL of
anhydrous DMF was added to dissolve the complex and
the base. Upon formation of a greenish enolate solution,
11 mmol *1.1 equiv.) of either bromides 7a or 7b, dissolved
in 20 mL of anhydrous DMF, was added to the solution by
syringe. The reaction mixture was stirred under Ar and the
reaction progress was monitored by TLC. Upon completion,
the reaction was quenched by addition of 500 mL of ice-
water and the precipitated material was ®ltered and then
dried in vacuo. The diastereomerically pure products *S,a-
S) and *S,a-R) were isolated by column chromatography on
silica-gel.
3.1.10. Ni(II)-complex of the Schiff base of (S)-15 with
(R)-a,20,60-trimethylphenylalanine (S,a-R)-24b. Rf0.36
25
*acetone/hexanes, 1:1). Mp 230±2328C. [a]D 2228.0 *c
1
0.06058, CHCl3). H NMR *CDCl3) d 1.11 *s, 3H), 1.71±
1.69 *m, 1H), 1.79±1.72 *m, 1H), 2.22±2.18 *m, 1H), 2.28
*s, 6H), 2.53±2.45 *m, 2H), 3.26 *d, 1H, J14.4 Hz), 3.41
*d, 1H, J14.3 Hz), 3.50 *dd, 1H, J3.8, 9.6 Hz), 3.54 *d,
1H, J13.4 Hz), 3.97*d, 1H, J13.3 Hz), 4.00±4.02 *m,
1H), 6.63±6.66 *m, 1H), 6.68 *d, 2H, J7.4 Hz), 7.08 *d,
2H, J7.5 Hz), 7.14±7.21 *m, 3H), 7.30±7.45 *m, 5H), 7.70
*d, 2H, J7.3 Hz), 8.20 *d, 1H, J8.5 Hz). 13C NMR
*CDCl3) d 21.4, 23.3, 28.2, 30.7, 42.6, 56.8, 61.1, 69.2,
79.8, 120.4, 123.6, 127.0, 127.2, 127.6, 127.7, 128.5,
128.7, 129.0, 129.5, 131.6, 131.8, 132.9, 133.6, 134.1,
137.1, 139.2, 141.9, 172.2, 180.2, 180.7. HRMS *FAB)
3.1.7. Ni(II)-complex of the Schiff base of (S)-15 with (S)-
O-benzyl-a,20,60-trimethyltyrosine (S,a-S)-23a. Mp 108±
25
1108C, [a]D 11666.7* c 0.0099, CHCl3), 1H NMR
*CDCl3, DRX500) d 0.92 *s, 3H), 1.92±1.97*m, 1H),
2.06±2.12 *m, 1H), 2.34 *s, 6H), 2.43±2.49 *m, 1H),
2.53±2.61 *m, 1H), 3.08±3.13 *m, 1H), 3.41±3.47*m,
2H), 3.52 *d, 1H, J12.5 Hz),3.64 *d, H, J14.5 Hz),
3.84 *d, 1H, J14.5 Hz), 4.47*d, 1H, J14.5 Hz), 5.02