Reaction #5924

Reaction equation

methyl α-bromo-4-chlorophenylacetate

1-amino-2-naphthalenethiol

sodium borohydride

sodium acetate

→

3-(4-chlorophenyl)-1H-naphtho-[2,1-b][1,4]thiazin-2(3H)-one

Yield 86.0%

Solvents

ethanol

acetic acid

Conditions

Workup

1. 1
   workup.WAITthe mixture is sitrred at room temperature under argon overnight
2. 2
   Otherthe resulting precipitate is separated by filtration
3. 3
   Washwashed
4. 4
   Otherdried
5. 5
   Otherrecrystallized from tetrahydrofuran-n-hexane

Procedure

To a solution of 1-amino-2-naphthalenethiol (27.81 g) in ethanol (500 ml) is added sodium borohydride (11.35 g) at room temperature. The mixture is stirred for 20 minutes, and thereto is added dropwise acetic acid (200 ml) and is further added sodium acetate (24.6 g). To the mixture is further added dropwise methyl α-bromo-4-chlorophenylacetate (46.8 g), and the mixture is sitrred at room temperature under argon overnight. The reaction mixture is poured into ice water and the resulting precipitate is separated by filtration, washed, dried and recrystallized from tetrahydrofuran-n-hexane to give 3-(4-chlorophenyl)-1H-naphtho-[2,1-b][1,4]thiazin-2(3H)-one (44.45 g, yield 82.6%) as crystals.

Source