References
1a
Surnam MD.
Miller MJ.
J. Org. Chem.
2001,
66:
2466 ; and numerous references there cited
1b
Miller MJ.
Chem. Rev.
1989,
89:
1563
1c
Michaelides MR.
Curtin ML.
Curr. Pharm. Des.
1999,
5:
787
1d
Nikam SS.
Kornberg BE.
Johnson DR.
Doherty AM.
Tetrahedron Lett.
1995,
36:
197
1e
Karunartne V.
Hoveyda HR.
Orvig C.
Tetrahedron Lett.
1992,
33:
1827
1f
Schwartz BD.
De Voss JJ.
Tetrahedron Lett.
2001,
42:
3653
1g
Sato T.
Takebayashi Y.
Tokunaga T.
Ozasa T.
J. Antibiot.
1996,
49:
811
2a
Wroblonsky H.-J.
Andree R.
Kluth JF. In Methoden der Organischen Chemie (Houben-Weyl)
Vol. E16a:
Klamann D.
Georg Thieme Verlag;
Stuttgart:
1990.
p.1
2b
Jensen-Korte U.
Müller N. In Methoden der Organischen Chemie (Houben-Weyl)
Vol. E16a:
Klamann D.
Georg Thieme Verlag;
Stuttgart:
1990.
p.421
2c
Chang Z.-Y.
Coates RM.
J. Org. Chem.
1990,
55:
3464
2d
Merino P.
Lanaspa A.
Merchan FL.
Tejero T.
J. Org. Chem.
1996,
61:
9028 ; and references there cited
3a
Zard SZ.
Angew.Chem., Int. Ed. Engl.
1997,
36:
672
3b
Quiclet-Sire B.
Zard SZ.
Phosphorus, Sulfur, Silicon
1999,
153
3c
Zard SZ.
Angew.Chem., Int. Ed. Engl.
1997,
36:
137
3d
Zard SZ.
J. Chin. Chem. Soc.
1999,
46:
139
3e For addition of xanthates to allyl amines, see: Boivin J.
Pothier J.
Zard SZ.
Tetrahedron Lett.
1999,
40:
3701
4a
Staszak MA.
Doecke CW.
Tetrahedron Lett.
1993,
34:
7043
4b
Mellor SL.
Chan WC.
Chem. Commun.
1997,
2005
4c
Genet JP.
Thorimbert S.
Touzin AM.
Tetrahedron Lett.
1993,
34:
1159
4d
Maëorg U.
Ragnarsson U.
Tetrahedron Lett.
1998,
39:
681
5a
Ramon F.
Degueil-Castaing M.
Maillard B.
J. Org. Chem.
1996,
61:
2071
5b
Ramon F.
Degueil-Castaing M.
Maillard B.
Tetrahedron
1998,
54:
11489 ; and references there cited
6
Liard A.
Quiclet-Sire B.
Saicic RN.
Zard SZ.
Tetrahedron Lett.
1997,
38:
1759
7
Smith PAS.
Pars HG.
J. Org. Chem.
1959,
24:
1325
For some examples see:
8a
Kane JM.
Stewart KT.
J. Heterocycl. Chem.
1988,
25:
1471
8b
Kalyanam KG.
Likhate MA.
Synth. Commun.
1988,
18:
2183
8c
Zimmerman HE.
Eberbach W.
J. Am. Chem. Soc.
1973,
95:
3970
9a
Huckin SN.
Weiler L.
J. Am. Chem Soc.
1974,
96:
1082
9b
Chan T.-H.
Brownbridge P.
J. Chem. Soc., Chem. Commun.
1979,
578
9c
Hagiwara H.
Kimura K.
Uda H.
J. Chem. Soc., Perkin Trans. 1
1992,
693
10
Typical Procedure for 19: Lauroyl peroxide (10-15 mol%) was added portion-wise (in 3-4 portions over several hours) to a degassed, refluxing solution of 800 mg (2 mmol) of xanthate 16 and 1.1 g (4.0 mmol) of olefin 2b in 2 mL of
1,2-dichloroethane under argon. The reaction was regularly monitored for the disappearance of the starting material by thin layer chromatography. Upon completion, the solvent was removed under reduced pressure and the residue purified by chromatography on silica gel (heptane/EtOAc 98/2-95/5) to give compound 17 (1.58 g, 98%) as a colourless oil; it consisted of a 3:2 mixture of diastereo-isomers, which were used without further purification in the next step. 1H NMR (CDCl3, 250 MHz, ppm): δ = 6.72 (bs, 1 H, NH), 4.62 (q, 2 H, OCH2, J = 6.5 Hz), 4.52 (d, 1 H, CH, J = 7.2 Hz), 4.01-3.79 (m, 3 H, CH2N, CHS), 3.71 (s, 3 H, COOCH3), 3.35 (s, 3 H, OCH3), 3.31 (s, 3 H, OCH3), 3.08-3.02 (m, 0.6 H, CHCOO), 2.99-2.91 (m, 0.4 H, CHCOO), 2.14-1.79 (m, 2 H, CH2), 1.60 (s, 18 H, 6CH3), 1.59 (t, 3 H, CH3, J = 6.5 Hz); 13C NMR (CDCl3, 62.5 MHz, ppm): δ = 211.6 (CS), 172.4 (COO), 154.5-154.4 (2 COO), 104.1/104.0 (CH), 81.2-80.9 (2 Cq, Boc), 69.9 (OCH2), 54.4-54.2 (2 CH3), 53.0/52.9 (NCH2), 51.8 (CH3), 47.7/46.7 (CHS), 45.2 (CHCOO), 46.1 (CH2), 27.9 (CH3), 13.5 (CH3); IR (CCl4): 3326 (m), 1736(vs), 1479 (m), 1443 (m), 1394 (m), 1368 (m), 1220 (s), 1155 (s), 1051 (s)cm-1.
A solution of xanthate 17 (800 mg, 1.5 mmol), Bu3SnH (0.75 mL), and AIBN (22 mg) in benzene (15 mL) was heated to reflux for 2 h under an inert atmosphere. The solvent was then removed under reduced pressure and the residue was purified by chromatography on silica gel (pentaneÆheptane-EtOAc, 7:3) to give 18 (602 mg, 97%) as a colourless oil. This material was used in the next step without further purification. 1H NMR (CDCl3, 300 MHz, ppm): δ = 6.58 (s, 1 H, NH), 4.50 (d, 1 H, CH), 3.69 (s, 3 H, COOCH3), 3.53-3.34 (m, 2 H, CH2N), 3.35 (s, 3 H, OCH3), 3.34 (s, 3 H, OCH3), 2.76-2.72 (m, 1 H, CH), 1.68-1.37 (22 H, 2 CH2 and 6 CH3); 13C NMR (CDCl3, 75 MHz, ppm): δ = 173.3 (COO), 155.3-155.2 (2 COO), 104.6 (CHO) 80.8-80.7 (2 Cq), 54.5-54.4 (2 CH3), 52.6 (CH), 51.5 (NCH2), 48.7 (OCH3), 28.1 (CH3), 25.2-25.0 (2 CH2); IR (CCl4): 3329 (broad), 1735(vs), 1454 (m), 1398 (m), 1369 (m), 1253 (m), 1161 (s), 1067 (m)cm-1.
A solution of 18 (280 mg, 0.7 mmol) in 1,2-dichloroethane (2 mL) and trifluoroactic acid (2 mL) was stirred for 1 h at r.t. under argon. The mixture was then evaporated under reduced pressure and the residue dissolved in a mixture of 1,2-dichloroethane (2 mL) and triethylamine (2 mL) and kept at r.t. for 48 h. The solvent was removed and the crude residue was extracted with dichoromethane and distilled water. The organic layer was dried over sodium sulfate. Evaporation under reduced pressure and purification by chromatography on silica gel (heptane-EtOAc, 1:1) afforded 19 as a colourless oil (50 mg, 48%). 1H NMR (CDCl3, 250 MHz, ppm): δ = 6.25 (d, 1 H, CH=, J = 7.3 Hz), 3.68 (s, 3 H, OOCH3), 3.04 (m, 1 H, CH), 2.52-2.34 (m, 1 H, NH), 2.34-2.25 (m, 2 H, CH2N), 2.24-2.12 (m, 2 H, CH2), 1.94-1.89 (m, 2 H, CH2); 13C NMR (CDCl3, 62.5 MHz, ppm): δ = 173.1 (COO), 153.1 (CH=), 53.9 (CH2N), 51.8 (OOCH3), 46.8 (CH), 27.6 (CH2), 23.8 (CH2); IR (CCl4): 3432, 2947, 1735, 1670, 1322, 1266, 735 cm-1. Calcd for C7H12N2O2: C, 53.83; H, 7.74%. Found: C, 53.69; H, 7.51%.