4-Toluenesulfonyl chloride → 2-Chloro-5-tosyl-5,6,6a,7,9,10-hexahydro-[1,4]oxazino[3,4-h]pteridine

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Reaction Conditions

Reaction Steps

2-Chloro-5,6,6a,7,9,10-hexahydro-[1,4]oxazino[3,4-h]pteridine (PREPARATION x2, 300 mg, 1.324 mmol) was dissolved in DMSO (20 mL). Sodium tert-butoxide (153 mg, 1.588 mmol) was added followed by 4-methylbenzene-1-sulfonyl chloride (278 mg, 1.456 mmol). The reaction mixture was heated to 50° C. and stirred for 18 hours. Additional 4-methylbenzene-1-sulfonyl chloride (0.5 eq) was added and the reaction mixture was stirred for 18 hours at 50° C. The reaction mixture was subsequently quenched with aqueous saturated NH4Cl, diluted with ethyl acetate, and washed with aqueous saturated NH4Cl (3×20 mL). The combined organic layers were dried over MgSO4, filtered, and concentrated. The crude product was loaded onto an ISCO® silica gel cartridge (12 g) and eluted using an ethyl acetate/hexane gradient. The product was collected and concentrated in vacuo to afford the title compound as a yellow solid (68 mg, 14%). ESI-MS m/z [M+H]+ calc'd for C16H17ClN4O3S, 381.07. found 381.3.

Provenance & Evidence