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of the combined organic fractions was almost completely removed under reduced pressure. Without any
further purification 10 ml of distilled H2O and Na2CO3 (82.8 mg, 7.8 mmol) were added to the resulting
mixture, cooled to 0°C and benzylchloroformate (1.1 ml, 7.8 mmol) was added dropwise and stirred for
6 h. Then, the mixture was extracted with CH2Cl2 (3×50 ml) and the combined organic fractions were
dried over Na2SO4, filtered and evaporated under reduced pressure. The residue was purified by flash
chromatography on silica gel with hexane:AcOEt (7:3), to give the piperidin-3-ol (R)-4 as a colourless
oil in 40% yield. [α]25 −11.9 (c=1.0, CHCl3), ee 96%; 1H NMR (CDCl3) δ 1.54 (m, 1H), 1.92 (m, 3H),
D
3.16 (m, 1H), 3.51 (m, 1H), 3.79 (m, 2H), 4.00 (m, 1H), 5.11 (s, 2H), 5.12 (br s, 1H), 7.35, (s, 5H); 13
C
NMR (CDCl3) δ 25.7, 28.3, 44.7, 66.5, 67.9, 77.7, 127.9, 128.3, 136.4, 157.6; MS (EI) m/z 235 (M+,
23), 191, (26), 144 (40), 91 (74), 71 (100); HRMS calcd for C13H17NO3 235.1207, found 235.1208.
3.3. (R)-(−)-Benzyl N-(6-bromo-2-hydroxyhexyl)carbamate (R)-5b
The title compound was prepared as described for (R)-4. White solid; yield 75%; mp 50–52°C; [α]25
D
1
−8.5 (c=1.0, CHCl3), ee 91%; H NMR (CDCl3) δ 1.45 (m, 4H), 1.83 (m, 2H), 2.51 (br s, 1H), 3.07
(m, 1H), 3.34 (m, 1H), 3.42 (t, 2H), 3.73 (s, 1H), 5.09 (s, 2H), 5.34 (br s, 1H), 7.37 (s, 5H); 13C NMR
(CDCl3) δ 24.0, 32.4, 33.4, 33.5, 46.8, 66.8, 70.9, 128.0, 128.1, 128.4, 136.8, 157.1; MS (EI) m/z 331
[M+(81Br)<1], 329 [M+(79Br)<1], 165 (34), 108 (32), 104 (95), 91 (100); HRMS calcd for C14H20BrNO3
329.0625, found 329.0626. Anal. calcd for C14H20BrNO3: C, 50.92; H, 6.10; N, 4.24, found: C, 51.10;
H, 6.17; N, 4.18.
3.4. (R)-(−)-Benzyl N-(7-bromo-2-hydroxyheptyl)carbamate (R)-5c
The title compound was prepared as described for (R)-4. White solid; yield 78%; mp 55–58°C; [α]25
D
1
−4.6 (c=1.0, CHCl3), ee 90%; H NMR (CDCl3) δ 1.43 (m, 6H), 1.82 (m, 2H), 2.64 (br s, 1H), 3.11
(m, 1H), 3.33 (m, 1H), 3.41 (t, 2H), 3.69 (s, 1H), 5.10 (s, 2H), 5.32 (br s, 1H), 7.36 (s, 5H); 13C NMR
(CDCl3) δ 24.52, 27.91, 32.5, 33.7, 34.28, 46.8, 66.8, 70.9, 128.0, 128.4, 136.2, 157.0; FABS m/z 346
[(M+1)+(81Br), 15], 344 [(M+1)+(79Br), 15], 91 (100). Anal. calcd for C15H22BrNO3: C, 52.48; H, 6.17;
N, 4.08; found: C, 52.55; H, 6.48; N, 4.02.
3.5. (R)-(−)-Benzyl N-(8-bromo-2-hydroxyoctyl)carbamate (R)-5d
The title compound was prepared as described for (R)-4. White solid; yield 77%; mp 57–59°C; [α]25
D
1
−8.8 (c=0.9, CHCl3), ee 92%; H NMR (CDCl3) δ 1.43 (m, 8H), 1.86 (m, 2H), 2.49 (br s, 1H), 3.06
(m, 1H), 3.34 (m, 1H), 3.41 (t, 2H), 3.69 (s, 1H), 5.10 (s, 2H), 5.32 (br s, 1H), 7.35 (s, 5H); 13C NMR
(CDCl3) δ 25.1, 27.8, 28.5, 32.5, 33.8, 34.3, 46.8, 66.7, 71.0, 127.9, 127.9, 128.3, 136.1, 156.9; MS (EI)
m/z 359 [M+(81Br)<1], 357 [M+(79Br)<1], 165 (31), 108 (29), 91 (100). Anal. calcd for C15H22BrNO3:
C, 53.79; H, 6.49; N, 3.92; found: C, 53.59; H, 6.88; N, 3.90.
3.6. (R)-(−)-Benzyl N-(9-bromo-2-hydroxynonyl)carbamate (R)-5e
The title compound was prepared as described for (R)-4. White solid; yield 30%; mp 70–72°C; [α]25
D
1
−5.6 (c=1.0, CHCl3), ee 97%; H NMR (CDCl3) δ 1.28–1.59 (m, 10H), 1.90 (m, 2H), 2.29 (br s, 1H),
3.10 (m, 1H), 3.34 (m, 1H), 3.43 (t, 2H), 3.71 (s, 1H), 5.12 (s, 2H), 5.23 (br s, 1H), 7.35 (s, 5H); 13C
NMR (CDCl3) δ 25.3, 28.0, 28.5, 25.3, 32.6, 33.9, 34.6, 46.9, 66.8, 71.2, 128.0, 128.1, 128.5, 136.3,