1,3-dithiane

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: An ice-cold solution of 1,3-dithiane (2.0 mL, 19.9 mmol) in THF (40 mL) was treated with NaH (819 mg, 20.5 mmol). After 30 min., methyl bromoacetate (1.9 mL, 20.0 mmol) was added and the mixture stirred for 3.5 h at room temperature. The reaction was quenched by addition of MeOH and then 50 mL 1 M HCl. The mixture was extracted with ether (2×50 mL) and the combined ether solution washed with saturated sodium bicarbonate solution (50 mL) and brine (50 mL) and then was dried (MgSO4), filtered and evaporated. Purification by flash chromatography on silica gel (10-15% ethyl acetate/hexanes) gave 971 mg (5.38 mmol, 27%) of the thiol. The reaction was quenched by addition of MeOH The mixture was extracted with ether (2×50 mL) the combined ether solution washed with saturated sodium bicarbonate solution (50 mL) and brine (50 mL) was dried (MgSO4) filtered evaporated Purification by flash chromatography on silica gel (10-15% ethyl acetate/hexanes)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution (13.8 ml) of 1.6M n-butyllithium in hexane was added dropwise to a solution of 1,3-dithian (1.5 g) in anhydrous tetrahydrofuran (35 ml) at -78° C. under an argon atmosphere over 10 minutes. After stirring for 30 minutes, a solution of 5-bromo-2-(2-methoxy-2-methylethoxy)benzonitrile, which was prepared from 4-bromo-2-cyanophenol (m.p. 148°-150° C., 2.48 g) and 2-methoxypropene (1.1 g) according to the same manner as described in Example 29, in anhydrous tetrahydrofuran (5 ml) was added to the mixture. The mixture was treated in the same manner as that in Example 29 to obtain 6-bromo-2,2-dimethyl-4-(1,3-dithian-2-yl)-2H-1,3-benzoxazine (0.90 g) (Compound 105). was added to the mixture The mixture was treated in the same manner as that in Example 29

Conditions: temp:-78.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of 26.7 g of 1,3-dithiane in 222 ml of tetrahydrofuran which has been cooled to -78° C. was added over a period of 15 minutes, 137 ml of 1.7M solution of tetra-butyl lithium in pentane. The resultant mixture was then stirred for 45 minutes, while maintaining the temperature at -78° C., after which time it was warmed to 0° C. The mixture was then added to an ice-cold solution of 48.0 g of 3,4,5-trimethoxybenzyl chloride in 222 ml of tetrahydrofuran over a period of 20 minutes, after which time it was stirred for an additional 90 minutes at 0° C. 50 ml of water was then carefully added and the tetrahydrofuran was removed by evaporation at a temperature below 40° C. The resultant white slurry was then extracted with a mixture of methylene chloride and water. The organic layer was then evaporated and the crude product was washed with petroleum ether to yield a white solid. was added over a period of 15 minutes after which time it was warmed to 0° C the tetrahydrofuran was removed by evaporation at a temperature below 40° C The resultant white slurry was then extracted with a mixture of methylene chloride and water The organic layer was then evaporated the crude product was washed with petroleum ether to yield a white solid

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of 1,3-dithiane (11.1 g, 91.9 mmol) in THF (150 mL) at −78° C. was added dropwise over 10 min n-butyllithium (1.6 M in hexane, 76.6 mmol), and the solution was stirred for 2 h under argon. A solution of 42 (11.9 g, 61.3 mmol) in THF (120 mL) was added dropwise over 30 min, and the mixture was stirred for 3 h at −78° C. and overnight at rt. The reaction mixture was quenched with water (100 mL) and extracted thrice with 100-mL portions of EtOAc. The combined organic extracts were washed with saturated aqueous NaCl, dried over Na2SO4, and concentrated. Flash chromatography over silica gel (1/9 EtOAc:hexane) gave 43 contaminated with 1,3-dithiane. The latter was removed by sublimation (54° C., 8.0 mm Hg) to provide pure 43 as a yellow oil (9.0 g, 50% for three steps from dichlorosilane):Rf=0.55 (1/9 EtOAc:hexane), 1H NMR (300 MHz, CDCl3) δ 7.63-7.61 (m, 2H), 7.42-7.38 (m, 3H), 5.97-5.84 (m, 1H), 5.06-4.90 (m,2H), 3.95 (s, 1H) 2. 93-2.83 (m, 2H), 2.72-2.67 (m, 2H), 2.21-1.97 (m, 4H), 1.18-1.09 (m, 2H), 0.49 (s, 3H); 13C NMR (75 MHz, CDCl3) δ 141.0, 134.5, 134.1, 129.9, 127.9, 113.2, 32.9, 31.1, 31.0, 27.2, 25.8, 10.8, −7.0; MS (FAB) m/e (rel. intentsity) 293 (MH+, 23), 239 (21), 175 (20), 159 (9), 149 (58), 121 (100), 119 (37), 115 (23), 105 (34), 97 (28), 92 (22); HRMS (FAB) calcd for C15H23S2Si: 293.0854. found: 293.0861. Anal. Calcd for C15H22S2Si: C, 61.16; H, 7.53. Found C, 61.31; H, 7.74. the mixture was stirred for 3 h at −78° C. and overnight at rt The reaction mixture was quenched with water (100 mL) extracted thrice with 100-mL portions of EtOAc The combined organic extracts were washed with saturated aqueous NaCl dried over Na2SO4 concentrated

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of 1,3-dithiane (6.77 g, 56.3 mmol) in THF (120 mL) at −78° C. was added dropwise over 10 min n-butyllithium (1.6 M in hexane, 50 mmol), and the solution was stirred for 2 h under argon. A solution of 31 (11.1 g, 43.3 mmol) in THF (100 mL) was added, the mixture was stirred for 3 h at −78° C., and overnight at rt. The reaction mixture was quenched with water (100 mL) and the organic layer isolated. The aqueous layer was extracted with two 100-mL portions of ethyl ether. The combined organic extracts were washed with saturated aqueous NaCl, dried over Na2SO4, and concentrated. Flash chromatography over silica gel (1/9EtOAc:hexane) gave 32 contaminated with 1,3-dithiane. The latter was removed by sublimation (54° C., 8.0 mm Hg). Recrystallization from Et2O provided pure 32 as a colorless solid (14.8 g, 96%): Rf=0.40 (1/49 EtOAc:hexane); mp 47-49° C.; 1H NMR (300 MHz, CDCl3) δ 7.66 (d, J=7.8 Hz, 4H), 7.43 (m, 6H), 5.90 (m, 1H), 5.02 (dd, J=17.1, 1.7 Hz 1H), 4.91 (dd, J=10.2, 1.7 Hz, 1H), 4.26 (s, 1H), 2.92 (t, J=11.8 Hz, 2H), 2.71 (m, 2H), 2.19 (m, 2H), 2.07 (m, 2H), 1.37 (m, 2H); 13C NMR (75 MHz, CDCl3)δ 141.1, 135.9, 132.4, 130.2, 128.0, 113.2, 32.3, 31.5, 27.5, 25.8, 10.5; IR (film) 3068 (m), 3047 (m), 2897 (s), 2840 (m), 1961 (w), 1890 (w), 1826 (w), 1639 (m), 1490 (w), 1429 (s), 1275 (m), 1112 (s), 1003 (m), 911 (s), 785 (m), 744(s), 703 (s) cm−1; MS (FAB) m/e (rel. intensity) 357 (MH+, 11), 356 (11), 355 (25), 301 (18), 279 (13), 237 (36), 227 (11), 225 (18), 221 (14), 215 (14), 213 (18), 212 (12), 211 (100), 209 (9), 207 (15); HRMS (FAB) calcd for C20H23S2Si: 355.1010 (MH+−2). found: 355. 1020. Anal. Calcd for C20H24S2Si: C, 67.36; H, 6.78. Found: C, 67.08; H, 6.78. the mixture was stirred for 3 h at −78° C. overnight at rt The reaction mixture was quenched with water (100 mL) the organic layer isolated The aqueous layer was extracted with two 100-mL portions of ethyl ether The combined organic extracts were washed with saturated aqueous NaCl dried over Na2SO4 concentrated

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of 1,3-dithiane (6.77 g, 56.3 mmol) in THF (120 mL) at −78° C. was added dropwise over 10 min n-butyllithium (1.6 M in hexane, 50 mmol), and the solution was stirred for 2 h under argon. A solution of 31 (11.1 g, 43.3 mmol) in THF (100 mL) was added, the mixture was stirred for 3 h at −78° C., and overnight at rt. The reaction mixture was quenched with water (100 mL) and the organic layer isolated. The aqueous layer was extracted with two 100-mL portions of ethyl ether. The combined organic extracts were washed with saturated aqueous NaCl, dried over Na2SO4, and concentrated. Flash chromatography over silica gel (1/9EtOAc:hexane) gave 32 contaminated with 1,3-dithiane. The latter was removed by sublimation (54° C., 8.0 mm Hg). Recrystallization from Et2O provided pure 32 as a colorless solid (14.8 g, 96%): Rf=0.40 (1/49 EtOAc:hexane); mp 47-49° C.; 1H NMR (300 MHz, CDCl3) δ 7.66 (d, J=7.8 Hz, 4H), 7.43 (m, 6H), 5.90 (m, 1H), 5.02 (dd, J=17.1, 1.7 Hz 1H), 4.91 (dd, J=10.2, 1.7 Hz, 1H), 4.26 (s, 1H), 2.92 (t, J=11.8 Hz, 2H), 2.71 (m, 2H), 2.19 (m, 2H), 2.07 (m, 2H), 1.37 (m, 2H); 13C NMR (75 MHz, CDCl3)δ 141.1, 135.9, 132.4, 130.2, 128.0, 113.2, 32.3, 31.5, 27.5, 25.8, 10.5; IR (film) 3068 (m), 3047 (m), 2897 (s), 2840 (m), 1961 (w), 1890 (w), 1826 (w), 1639 (m), 1490 (w), 1429 (s), 1275 (m), 1112 (s), 1003 (m), 911 (s), 785 (m), 744(s), 703 (s) cm−1; MS (FAB) m/e (rel. intensity) 357 (MH+, 11), 356 (11), 355 (25), 301 (18), 279 (13), 237 (36), 227 (11), 225 (18), 221 (14), 215 (14), 213 (18), 212 (12), 211 (100), 209 (9), 207 (15); HRMS (FAB) calcd for C20H23S2Si: 355.1010 (MH+−2). found: 355. 1020. Anal. Calcd for C20H24S2Si: C, 67.36; H, 6.78. Found: C, 67.08; H, 6.78. the mixture was stirred for 3 h at −78° C. overnight at rt The reaction mixture was quenched with water (100 mL) the organic layer isolated The aqueous layer was extracted with two 100-mL portions of ethyl ether The combined organic extracts were washed with saturated aqueous NaCl dried over Na2SO4 concentrated