M.Isobe et al.
FULL PAPER
1= , s; Ac), 2.05 (3Hî1= , s; Ac), 2.06 (3Hî1= , s; Ac), 2.30 (1Hî1= , dd,
5.07 ppm (1H, s; CHꢀOMe); 13C NMR (CD3OD, 150 MHz): d=24.8,
28.2, 46.9, 55.7, 60.1, 65.2, 77.7, 77.9, 82.0, 94.1, 108.4, 109.7, 162.3 ppm;
HRMS (FAB): m/z calcd for C13H17Cl3NO7 [M+H]+ : 404.0071; found:
404.0071.
2
2
2
2
J=16, 5.5 Hz; CHAHB), 2.45 (1Hî1= , t, J=1.5 Hz; ꢀCHꢀ), 2.70 (1Hî
2
1= , dd, J=16, 5.5 Hz; CHAHB), 2.90 (1Hî1= , t, J=1.5 Hz; ꢀCHꢀ), 2.91
2
2
(1Hî1= , dd, J=16, 3 Hz; CHAHB), 3.00 (1Hî1= , dd, J=16, 3 Hz;
2
2
CHAHB), 3.38 (3Hî1= , s; OMe), 3.41 (3Hî1= , s; OMe), 3.74 (1Hî1= ,
2
2
2
Ortho ether 35b: Ortho ester 35a (23 mg, 0.057 mmol) and pyridine
(30 mL, 0.30 mmol) were dissolved in CH3CN (1 mL), and the solution
was cooled to ꢀ408C.TBSOTf (40 mL, 0.17 mmol) was added to the solu-
tion, and then the cooling bath was removed.After stirring for 1 h, the
reaction mixture was poured into ice-cold H2O (5 mL), and the resulting
solution was extracted with AcOEt (7 mLî3).The combined organic
layer was washed with saturated aqueous NH4Cl (20 mL) and brine
(20 mL), dried over anhydrous Na2SO4, and concentrated under reduced
pressure.The residue was purified by column chromatography (silica gel
2 g; AcOEt/hexane, 1:1) to afford ortho ether 35b (27 mg, 93%).Mp..
182 183.58C (as tiny needles from diethyl ether/hexane); [a]2D3 =ꢀ3.0
d, J=15.5 Hz; CHAHBꢀPh), 4.01 (1H, d, J=15.5 Hz; CHAHBꢀPh), 4.09
(1H, d, J=15 Hz; CHAHBꢀPh), 4.21 (1Hî1= , d, J=15 Hz; CHAHBꢀPh),
2
4.33 (1Hî1= , d, J=14 Hz; CHAHBꢀPh), 4.34 (1Hî1= , d, J=14 Hz;
2
2
CHAHBꢀPh), 4.83 (1Hî1= , brs; NH), 4.92 (1Hî1= , d, J=1.5 Hz; CHꢀ
2
2
OCO), 4.94 (1Hî1= , d, J=14 Hz; CHAHBꢀPh), 4.98 (1Hî1= , d, J=
2
2
14 Hz; CHAHBꢀPh), 5.06 (1Hî1= , brs; NH), 5.08 (1Hî1= , s; CHꢀ
2
2
OMe), 5.10 (1Hî1= , m; CHꢀCOO), 5.13 (1Hî1= , d, J=1.5 Hz; CHꢀ
2
2
COO), 5.15 (1Hî1= , s; CHꢀOMe), 5.09 5.21 (3Hî1= , m; CHꢀOAc î 2,
2
2
CHꢀOCO), 6.94 7.38 ppm (m; 10H, aromatic); 13C NMR (CDCl3,
100 MHz): d=17.8, 20.8, 21.1, 21.2, 21.8, 22.0, 29.3, 29.6, 44.7, 44.8, 44.9,
48.6, 48.8, 52.2, 52.3, 56.5, 56.7, 57.2, 57.7, 69.2, 69.5, 77.7, 79.8, 80.0, 80.2,
106.4, 106.7, 106.8, 126.5, 126.8, 126.6, 126.9, 127.4, 127.8, 128.1 128.2,
128.3, 128.6, 128.7, 128.8, 129.2, 129.2, 136.3, 136.8, 140.0, 140.2, 144.4,
166.3, 168.8, 169.0, 169.3, 169.4, 169.6 ppm; HRMS (FAB): m/z calcd for
C32H37N3O9 [M+H]+ : 608.2608; found: 608.2582.
1
(c=0.31 in CHCl3); IR (KBr): n˜max =3480, 1719, 1250, 842 cmꢀ1; H NMR
(400 MHz, CDCl3): d=0.18 (6H, s; Si(CH3)2), 0.91 (9H, s; SiꢀtBu), 1.62
(3H, s; CH3), 2.63 (1H, dd, J=13.5, 2 Hz; CHAHB), 2.80 (1H, dd, J=3.5,
1.5 Hz; ꢀCHꢀ), 3.06 (1H, dd, J=13.5, 4 Hz; CHAHB), 3.43 (3H, s;
OMe), 3.83 (1H, dd, J=3.5, 2 Hz; ꢀCHꢀCHꢀOꢀCꢀOSi), 3.88 (1H, dt,
J=4, 2 Hz; ꢀCH2ꢀCHꢀOꢀCꢀOSi), 4.33 (1H, d, J=1.5H, CHꢀCꢀOSi),
5.09 (1H, s; CHꢀOMe), 7.81 ppm (1H, brs; NH); 13C NMR (CDCl3,
100 MHz): d=ꢀ3.2, ꢀ3.1, 17.8, 25.4, 25.7, 26.6, 46.1, 55.4, 58.9, 65.2, 76.0,
76.2, 82.3, 93.0, 106.5, 109.0, 160.9 ppm; HRMS (FAB): m/z calcd for
C19H31Cl3NO7Si [M++H]: 518.0935; found: 518.0911.
Diacetylguanidine 32a: 20% Pd(OH)2 on carbon (Pearlman×s catalyst,
35 mg) was added to a solution of dibenzylacetylguanidine 31a (35 mg,
0.075 mmol) in acetic anhydride (3 mL), and the reaction flask was filled
with hydrogen.After stirring under atmospheric pressure of hydrogen for
24 h at room temperature, the reaction mixture was filtered through a
pad of Super-Cel and washed with AcOEt.The filtrate was concentrated
in vacuo.The residue was purified by column chromatography (silica gel
3 g; AcOEt/hexane, 2:1) to afford diacetylguanidine 32a (23 mg, 85%) as
N,N’-Bis(tert-butoxycarbonyl)guanidine 36b: Ortho ether 35b (13 mg,
0.026 mmol) was dissolved in CH2Cl2 (1 mL) and the solution was cooled
to ꢀ788C.DIBAL-H (09.3 m in hexane, 0.14 mL, 0.13 mmol) was then
added to this solution.After stirring at ꢀ788C for 1 h, the mixture was
quenched with AcOEt (0.5 mL), and then allowed to warm to room tem-
perature.Saturated aqueous NH 4Cl (5 drops) and Et2O (10 mL) were
an amorphous solid.[ a]D25 =+68 (c=0.81 in CHCl3); IR (KBr): n˜max
3233, 2935, 1773, 1746, 1617, 1210 cmꢀ1 1H NMR (400 MHz, CDCl3) d=
=
;
1.64 (3H, s; Me), 2.07 (3H, s; Ac), 2.09 (3H, s; Ac), 2.10 (3H, s; Ac),
2.18 (3H, s; Ac), 2.54 (1H, dd, J=16, 5 Hz; CHAHB), 2.89 (1H, dd, J=
2.5, 1.5 Hz; ꢀCHꢀ), 3.17 (1H, dd, J=16, 4.5 Hz; CHAHB), 3.42 (3H, s;
OMe), 5.15 (1H, d, J=1.5 Hz; CHꢀCOO), 5.18 (1H, s; CHꢀOMe), 5.18
(1H, m; CHꢀOCO), 5.28 (1H, m; CHꢀOAc), 9.68 (1H, brs; NH),
13.60 ppm (1H, brs; NH); 13C NMR (CDCl3, 150 MHz): d=17.7, 20.8,
22.1, 24.9, 28.8, 30.1, 45.1, 55.7, 58.1, 69.5, 77.6, 80.0, 80.8, 105.7, 153.7,
166.1, 169.3, 169.4, 172.0, 185.5 ppm; HRMS (FAB): m/z calcd for
C20H27N3O10 [M+H]+ : 470.1775; found: 470,1801.
added, and the mixture was vigorously stirred for 3 h.Anhydrous Na SO4
2
was added, and the mixture was further stirred for 1 h.The resulting mix-
ture was filtered through a pad of Super-Cel, and the precipitate was
washed with Et2O.The combined filtrate was concentrated.The residue
was dissolved in DMF (1 mL), and Et3N (11 mL, 0.077 mmol) and N,N’-
bis(tert-butoxycarbonyl)-S-methylisothiourea (13 mg, 0.045 mmol) were
added.The solution cooled to 0 8C and HgCl2 (13 mg, 0.048 mmol) was
added.After stirring at room temperature for 90 min, AcOEt (5 mL) was
added.After stirring for 1 h, the resulting mixture was filtered through a
pad of Super-Cel with AcOEt, and the combined filtrate was washed
with H2O (20 mL) and brine (20 mL), dried over anhydrous Na2SO4, and
concentrated under reduced pressure.The residue was purified by prepa-
rative TLC (diethyl ether/hexane, 1:1) to afford N,N’-bis(tert-butoxycar-
bonyl)guanidine 36b (14 mg, 85% in 2 steps from 35b) as a white amor-
phous solid.[ a]2D3 =+31 (c=0.22 in CHCl3); IR (KBr): n˜max =3269, 1729,
Dihydropyrimidine 33: Aqueous NH3 (20%, 0.3 mL) was added to a sol-
ution of diacetylguanidine 32a (5 mg) in MeOH (0.3 mL) and H2O
(0.6 mL). After stirring for 24 h at room temperature, the reaction mix-
ture was concentrated in vacuo to give crude dihydropyrimidine 33
(6 mg). lHma2Ox =237, 210 nm (e=7.28î103, 1.06î104); 1H NMR (300 MHz,
D2O): d=1.21 (3H, s; Me), 1.62 1.79 (2H, m; CH2), 2.69 (1H, dd, J=
7.5, 4.5 Hz; ꢀCHꢀ), 3.50 (3H, s; OMe), 3.68 (1H, brd, J=12 Hz; CHꢀ
CH2), 4.05 (1H, d, J=7.5 Hz; CHꢀCHꢀCMe), 4.60 (1H, brs; CHꢀCOꢀ
N), 5.38 ppm (1H, d, J=4.5 Hz; CHꢀOMe); HRMS (FAB): m/z calcd
for C12H19N3O6 [M+H]+ : 302.1352, found: 302.1327.
1
1644, 1617, 1351, 1132 cmꢀ1; H NMR (400 MHz, CDCl3): d=0.19 (6H, s;
Si(CH3)2), 0.91 (9H, s; SiꢀtBu), 1.44 (9H, s; Boc), 1.48 (9H, s; Boc), 1.55
(3H, s; CH3), 2.30 (1H, dd, J=14, 3.5 Hz; CHAHB), 3.34 (3H, s; OMe),
3.37 (1H, dd, J=14, 2 Hz; CHAHB), 3.41 (1H, dd, J=3.5, 1.5 Hz; ꢀCHꢀ
), 3.83 (1H, dd, J=3.5, 2 Hz; CHꢀCHꢀOꢀCꢀOSi), 3.86 (1H, m; CH2ꢀ
CHꢀOꢀCꢀOSi), 4.11 (1H, d, J=1.5 Hz; CHꢀCꢀOSi), 5.05 (1H, s; CHꢀ
OMe), 8.67 (1H, brs; NH), 11.26 ppm (1H, brs; NH); 13C NMR (CDCl3,
100 MHz): d=ꢀ3.3, ꢀ3.1, 17.9, 23.6, 25.8, 28.0, 28.2, 29.1, 44.3, 55.2, 56.8,
65.5, 76.3, 76.5, 78.8, 83.0, 83.6, 107.0, 109.1, 152.7, 155.0, 162.5 ppm;
HRMS (FAB): m/z calcd for C28H50N3O10Si [M++H]: 616.3265; found:
616.3237.
Compound 34: TFA (0.3 mL) was added to a solution of the crude dihy-
dropyrimidine 33 (6 mg) in H2O (0.6 mL). After stirring for 15 h at room
temperature, the reaction mixture was concentrated in vacuo to give
crude 34 (10 mg). 1H NMR (300 MHz, D2O): d=1.33 (3H, s; Me), 2.18
(1H, dd, J=15, 4 Hz; CHAHB), 2.44 (1H, d, J=15 Hz; CHAHB) 2.91
(1H, t, J=3.5 Hz; CHꢀCHꢀOH), 3.80 (1H, brd, J=4 Hz; CH2ꢀCHꢀO),
4.20 (1H, d, J=3 Hz; CHꢀOH), 4.71 (1H, s; CHꢀCOꢀN), 5.66 ppm
(1H, d, J=4 Hz; OꢀCHꢀO); HRMS (FAB): m/z calcd for C11H16N3O5
[M++H]: 270.1090; found: 270.1104.
8,11-Dideoxytetrodotoxin (3) and 4,9-anhydro-8,11-dideoxytetrodotoxin
(5): N,N’-Bis(tert-butoxycarbonyl)guanidine 36b (13 mg, 0.021 mmol) was
dissolved in MeOH (0.5 mL), H2O (0.5 mL), and TFA (0.5 mL). The sol-
ution was stirred at room temperature for 15 h, and then concentrated
under reduced pressure.The residue was purified by HPLC on a Hitachi-
gel 3013-c column (H+ form, 0.4î15 cm, 0.025m AcOH) to afford 8,11-
dideoxytetrodotoxin (3) (2.6 mg, 43%) and 4,9-anhydro-8,11-dideoxyte-
trodotoxin (5) (1.8 mg, 32%) as a white solid.
8,11-Dideoxytetrodotoxin (3): [a]2D6 =+1.5 (c=0.065 in 0.05m AcOH);
1H NMR (600 MHz, 4% CD3COOD/D2O) (hemilactal form): d=1.62
(3H, s; Me-11), 2.17 (1H, dd, J=13, 4 Hz; H-8a), 2.34 (1H, d, J=13 Hz;
H-8b), 2.45 (1H, d, J=9.5 Hz; H-4a), 3.61 (1H, s; H-9), 4.03 (1H, brs;
H-7), 4.10 (1H, brs; H-5), 5.46 (1H, d, J=9.5 Hz; H-4); (lactone form):
d=1.48 (3H, s; Me-11), 2.37 (1H, dd, J=14, 4 Hz; H-8a), 2.42 (1H, dd,
Ortho ester 35a: K2CO3 (15 mg, 0.11 mmol) was added to a solution of
acetal 28a (33 mg, 0.074 mmol) in MeOH (2 mL). After stirring at room
temperature for 1 h, the reaction was quenched with saturated aqueous
NH4Cl (2 mL), and the resulting mixture was extracted with CHCl3
(5 mLî3).The combined organic layer was dried over anhydrous
Na2SO4 and concentrated under reduced pressure.The residue was puri-
fied by column chromatography (silica gel 2 g; AcOEt/hexane, 4:1) to
afford ortho ester 35a (23 mg, 75%) as an amorphous solid.[ a]2D7 =+13.8
(c=0.29 in MeOH); IR (KBr): n˜max =3367, 2925, 1713, 1525, 822 cmꢀ1
;
1H NMR (600 MHz, CD3OD): d=1.48 (3H, s; Me), 2.64 (1H, d, J=
12 Hz; CHAHB), 2.66 (1H, d, J=12 Hz; CHAHB), 2.96 (1H, dd, J=3.5,
1 Hz; ꢀCHꢀ), 3.34 (3H, s; OMe), 3.76 (1H, m; CH2ꢀCHꢀO), 3.78 (1H,
dd, J=3.5, 1.5 Hz; CHꢀCHꢀCꢀMe), 4.33 (1H, d, J=1 Hz; CHꢀCꢀNH),
460
¹ 2004 Wiley-VCH Verlag GmbH & Co.KGaA, Weinheim
Chem. Eur. J. 2004, 10, 452 462