mmax(thin film, cm−1) 1776 [CO endocyclic], 1710 [CO exo-
[C(CH3)2 (12)], 27.0, 27.1 [C(CH3)2 (11)], 54.1 [NCH2 (12)], 54.2
[NCH2 (11)], 70.7 [CH(OH) (12)], 71.7 [CH(OH) (11)], 72.6 and
73.1 [2 × CHOCH2Ph (11)], 72.8 and 74.3 [2 × CHOCH2Ph
(12)], 74.1 [CH(OTBDMS) (11)], 77.0 [CH(OTBDMS) (12)],
77.7 [CO.CHOCH2Ph (11)], 78.5 [CO.CHOCH2Ph (12)], 79.2
[C(CH3)2 (11)], 79.3 [C(CH3)2 (12)], 82.0 [CHOCH2Ph.CHPh
(11)], 82.4 [CHOCH2Ph.CHPh (12)], 127.3, 128.0 [p-Ph (11)],
127.1, 127.9, 128.2, 128.3 [m/o-Ph (11)], 127.6, 127.7, 128.1,
128.2 [p- and m/o-Ph (12)], 137.3, 138.5, 141.2 [i-Ph (11)],
137.2, 138.7, 141.6 [i-Ph (12)], 152.1 [CO endocyclic (11)],
152.6 [CO endocyclic (12)], 171.0 [CO exocyclic (12)], 171.7
[CO exocyclic (11)]; mmax(thin film, cm−1) 3471 [O–H], 1780
[CO endocyclic], 1711 [CO exocyclic]; HRMS C36H51N2O7Si
[MNH4+]requires651.3466, found651.3471; m/zLD+ (MALDI)
656, 657, 658 [100%, 40%, 15%, MNa+].
+
cyclic]; HRMS C43H57N2O7Si [MNH4 ] requires 741.3935, found
741.3934; [a]2D5 +130.4 (c = 1.05, CHCl3); m/z LD+ (MALDI)
746.29, 747.25, 748.21 [100%, 50%, 15%, MNa+].
Preparation of (2R,3S,4R,4R,5R)-4-benzyl-3-[2,4-bis-
benzyloxy-5-(tert-butyl-dimethyl-silanyloxy)-3-hydroxy-
5-phenyl–pentanoyl]-5,5-dimethyl–oxazolidin-2-one
(2R,3S,4R,4R,5R)-14. Following representative procedure
1, CF3SO3H (0.12 mL, 1.36 mmol), Et3B (1.36 mL, 1.36 mmol),
(R)-4 (400 mg, 1.13 mmol), i-Pr2NEt (0.28 mL, 1.58 mmol) and
8 (400 mg, 1.14 mmol) in CH2Cl2 (15 mL) furnished 14 (442 mg,
0.61 mmol, 54%) as a white solid after column chromatography.
14: Rf 0.25 [1:1 pentane–Et2O]; mp 142–144 °C [pentane–
Et2O]; dH (400 MHz, CDCl3) −0.15 [3H, s, Si(CH3)A(CH3)B],
0.01 [3H, s, Si(CH3)A(CH3)B], 0.890 [9H, s, SiC(CH3)3], 1.31
[3H, s, C(CH3)A(CH3)B], 1.343 [3H, s, C(CH3)A(CH3)B],
2.86 [1H, dd, J 14.4, 9.6, CHCHAHBPh], 2.89 [1H, d, J 7.3,
CH(OH)], 3.14 [1H, dd, J 14.4, 3.8, CHCHAHBPh], 3.69 [1H,
dd, J 8.9, 2.6, CH(OCH2Ph).CH(OTBDMS)], 4.00–4.05 [1H,
m, CH(OH)], 4.09 [1H, d, J 11.7, CHOCHAHBPh], 4.16 [1H, d,
J 11.0, CHOCHCHDPh], 4.25 [1H, d, J 11.7, CHOCHAHBPh],
4.44 [1H, d, J 11.0, CHOCHCHDPh], 4.47 [1H, dd, J 9.6,
3.8, CHCH2Ph], 5.05 [1H, d, J 2.6, CH(OTBDMS)], 5.55
[1H, d, J 2.0, CO.CHOCH2Ph], 7.19–7.42 [20H, m, PhH];
dC (100 MHz, CDCl3) −4.9, −4.7 [Si(CH3)2], 18.2 [C(CH3)3],
22.1, 28.1 [C(CH3)2], 25.9 [C(CH3)3], 35.3 [CHCH2Ph], 64.0
[CHCH2Ph], 71.5 [CH(OH)], 72.3, 73.3 [2 × CHOCH2Ph],
74.1 [CH(OTBDMS)], 77.6 [CO.CHOCH2Ph], 81.9
[CHOCH2Ph.CH(OTBDMS)], 83.1 [C(CH3)2], 126.7, 127.0,
127.2, 127.4, 127.6, 127.8, 128.1, 128.3, 128.4, 128.5, 128.6,
129.1 [p- and m/o-Ph], 137.0, 137.3, 138.5, 141.3 [i-Ph], 152.1
[CO endocyclic], 171.2 [CO exocyclic]; mmax(KBr disc, cm−1)
1782 [CO endocyclic], 1702 [CO exocyclic]; C43H53NO7Si
requires C 71.3, H 7.4, N 1.9%, found C 71.3, H 7.4, N 2.0%;
[a]2D0 +14.6 (c = 1.0, CHCl3); m/z LD+ (MALDI) 746, 747, 748
[100%, 45%, 15%, MNa+].
Preparation of (2S,3R,4S,4R,5R)-4-benzyl-3-[2,4-bis-
benzyloxy-5-(tert-butyl-dimethyl-silanyloxy)-3-hydroxy-5-phenyl-
pentanoyl]-5,5-dimethyl-oxazolidin-2-one (2S,3R, 4S,4R,5R)-
15 and (2S,3S,4S,4R, 5R)-4-benzyl-3-[2, 4-bis-benzyloxy-
5-(tert-butyl-dimethyl-silanyloxy)-3-hydroxy-5-phenyl-penta-
noyl]-5,5-dimethyl-oxazolidin-2-one (2S,3S,4S,4R,5R)-16.
Following representative procedure 1, CF3SO3H (0.29 mL,
3.24 mmol), Et3B (3.24 mL, 3.24 mmol), (S)-4 (950 mg,
2.70 mmol), i-Pr2NEt (0.61 mL, 3.51 mmol) and 8 (1.00 g,
2.70 mmol) in CH2Cl2 (20 mL) furnished a 57:43 ratio of 15:16
which after purification by column chromatography gave 15
(690 mg, 0.95 mmol, 35%) and 16 (667 mg, 0.92 mmol, 34%)
as white solids.
15: Rf 0.14 [5:1 pentane–Et2O]; mp 124–125 °C [pentane–
Et2O]; dH (400 MHz, CDCl3) −0.16 [3H, s, Si(CH3)A(CH3)B],
0.077 [3H, s, Si(CH3)A(CH3)B], 0.92 [9H, s, SiC(CH3)3], 0.94
[3H, s, C(CH3)A(CH3)B], 1.12 [3H, s, C(CH3)A(CH3)B], 2.70
[1H, dd, J 14.4, 9.6, CHCHAHBPh], 3.09 [1H, dd, J 14.4, 2.5,
CHCHAHBPh], 3.23 [1H, d, J 7.4, CH(OH)], 3.74–3.78 [2H,
m, CHOCH2Ph.CH(OTBDMS) and CHCH2Ph], 4.04–4.10
[2H, m, CH(OH) and CHOCHAHBPh], 4.47 [2H, app. t, J 11.9,
CHOCH2Ph], 4.76 [1H, d, J 11.4, CHOCHAHBPh], 5.07 [1H,
d, J 3.7, CH(OTBDMS)], 5.31 [1H, d, J 1.7, CO.CHOCH2Ph],
7.01–7.45 [20H, m, PhH]; dC (100 MHz, CDCl3) −5.2 and −4.7
[Si(CH3)2], 18.1 [SiC(CH3)3], 22.0 and 27.8 [C(CH3)2], 25.8
[SiC(CH3)3], 34.8 [CHCH2Ph], 63.4 [CHCH2Ph], 72.2 [CH(OH)],
73.1 and 73.7 [2 × CHOCH2Ph], 74.1 [CH(OTBDMS)], 79.1
[CO.CHOCH2Ph], 81.9 [CH(OCH2Ph).CH(OTBDMS)], 83.3
[C(CH3)2], 126.5, 127.0, 127.1, 127.4 [p-Ph], 127.4, 127.8, 128.1
128.4, 128.5, 128.6, 128.7, 128.9 [m/o-Ph], 137.1, 137.8, 138.5,
141.2 [i-Ph], 152.7 [CO endocyclic], 169.7 [CO exocyclic];
mmax(KBr disc, cm−1) 1768 [CO endocyclic], 1712 [CO exo-
Preparation of (2R,3S,4R,4R,5S)-4-benzyl-3-[2,4-bis-
benzyloxy-5-(tert-butyl-dimethyl-silanyloxy)-5-furan-2-
yl-3-hydroxy-pentanoyl]-5,5-dimethyl–oxazolidin-2-one
(2R,3S,4R,4R,5S)-18. Following representative procedure
1, CF3SO3H (0.24 mL, 2.72 mmol), Et3B (2.72 mL, 2.72 mmol),
(R)-4 (800 mg, 2.27 mmol), i-Pr2NEt (0.55 mL, 3.18 mmol)
and 17 (817 mg, 2.27 mmol) in CH2Cl2 (20 mL) furnished 18
(565 mg, 0.91 mmol, 40%) as a white solid contaminated
with <10% of (R)-4 after column chromatography.
18:Rf 0.1[1:1pentane–Et2O];dH(400 MHz,CDCl3) −0.08 [3H,
s, Si(CH3)A(CH3)B], 0.01 [3H, s, SiC(CH3)A(CH3)B], 0.87
[9H, s, SiC(CH3)3], 1.34 [3H, s, C(CH3)A(CH3)B], 1.35 [3H,
s, C(CH3)A(CH3)B], 2.83–2.94 [2H, m, CHCHAHBPh and
CH(OH)], 3.14 [1H, dd, J 14.4, 3.7, CHCHAHBPh], 3.86 [1H,
dd, J 8.8, 3.3, CHOCH2Ph.CH(OTBDMS)], 4.20 [2H, app. d, J
11.0, CH(OH) and CHOCHAHBPh], 4.39 [2H, s, CHOCH2Ph],
4.45 [1H, d, J 11.0, CHOCHAHBPh], 4.48 [1H, dd, J 11.6, 3.8,
CHCH2Ph], 5.06 [1H, d, J 3.3, CH(OTBDMS)], 5.56 [1H, d, J
2.2, CO.CHOCH2Ph], 6.30–6.34 [2H, m, CH(furan)], 7.20–7.42
[16H, m, ArH]; dC (100 MHz, CDCl3) −5.4, −5.1 [SiC(CH3)2],
18.2 [SiC(CH3)3], 22.1, 28.2 [C(CH3)2], 25.8 [SiC(CH3)3], 35.2
[CHCH2Ph], 64.0 [CHCH2Ph], 69.1 [CH(OTBDMS)], 71.3
[CH(OH)], 72.4, 72.7 [2 × CHOCH2Ph], 77.7 [CO.CHOCH2Ph],
80.1 [CHOCH2Ph.CH(OTBDMS)], 83.7 [C(CH3)2], 107.8,
110.4, 141.3 [CH(furan)], 126.7, 126.9, 127.2 [p-Ph], 127.5,
127.9, 128.0, 128.3, 128.6, 129.1 [m/o-Ph], 137.0, 137.3, 138.7
[i-Ph], 152.5 [i-Ar furan], 154.4 [CO endocyclic], 171.1 [CO
exocyclic]; mmax(KBr disc, cm−1) 3531 [O–H], 1779 [CO endo-
cyclic], 1708 [CO endocyclic]; HRMS C41H55N2O8Si [MNH4+]
requires 731.3728, found 731.3727; m/z LD+ (MALDI) 736,
737, 738, 739 [100%, 60%, 20%, 5%, MNa+], 752, 753, 754, 755
[80%, 30%, 20%, 5%, MK+].
+
cyclic]; HRMS C43H57N2O7Si [MNH4 ] requires 741.3935, found
741.3937; [a]2D5 −12.0 (c = 1, CHCl3); m/z LD+ (MALDI) 746
[100%, MNa+], 762 [50%, MK+].
16: Rf 0.11 [5:1 pentane–Et2O]; mp 116–117 °C [pentane–
Et2O]; dH (400 MHz, CDCl3) −0.21 [3H, s, Si(CH3)A(CH3)B],
0.01 [3H, s, Si(CH3)A(CH3)B], 0.84 [9H, s, SiC(CH3)3], 1.04 [3H,
s, C(CH3)A(CH3)B], 1.23 [3H, s, C(CH3)A(CH3)B], 2.73 [1H, d, J
7.6, CH(OH)], 2.79 [1H, dd, J 14.5, 9.8, CHCHAHBPh], 3.08
[1H, dd, J 14.5, 3.5, CHCHAHBPh], 3.79–3.83 [1H, m, CH(OH)],
3.92 [1H, dd, J 6.9, 1.7, CHOCH2Ph.CH(OTBDMS)], 4.16 [1H,
dd, J 9.8, 3.5, CHCH2Ph], 4.26 [1H, d, J 11.2, CHOCHAHBPh],
4.49 [1H, d, J 11.2, CHOCHAHBPh], 4.63 [1H, d, J 10.8, CHO-
CHCHDPh], 4.91 [1H, d, J 6.9, CH(OTBDMS)], 4.94 [1H, d,
J 10.8, CHOCHCHDPh], 5.25 [1H, d, J 4.0, CO.CHOCH2Ph],
7.18–7.42 [20H, m, PhH]; dC (100 MHz, CDCl3) −4.9, −4.7
[Si(CH3)2], 18.0 [SiC(CH3)3], 22.0, 27.8 [C(CH3)2], 25.8
[SiC(CH3)3], 35.1 [CHCH2Ph], 63.8 [CHCH2Ph], 70.5 [CH(OH)],
72.6, 74.3 [2 × CHOCH2Ph], 76.7 [CH(OTBDMS)], 77.8
[CO.CHOCH2Ph], 82.2 [CHOCH2Ph.CH(OTBDMS)], 83.1
[C(CH3)2], 126.7, 127.3, 127.3, 127.4 [p-Ph], 127.7, 127.8, 128.0,
128.1, 128.3, 128.5, 128.8, 129.1 [m/o-Ph], 137.0, 137.2, 138.7,
141.6 [i-Ph], 152.7 [CO endocyclic], 170.6 [CO exocyclic];
O r g . B i o m o l . C h e m . , 2 0 0 4 , 2 , 3 3 8 5 – 3 4 0 0
3 3 9 3