Regioselective Synthesis of 4-(Aryloxymethyl)Thiopyrano [2,3-B][1]Benzothiopyran-5(2H)-Ones

Regioselective Synthesis of 3‐(Aryloxyacetyl)‐2,3‐dihydrothieno[2,3‐b][1]benzothiopyran‐4‐ones via Tandem Cyclization

“…1) were prepared in 80-85% yield according to published procedure. [18] Scheme 1. Reagents and conditions: (i) NaOH, CHCl 3 , benzyl triethyl ammonium chloride (BTEAC), r.t, 4 hr.…”

“…The sulphides 3a, [20] 3e, [20] and 3f [18] were reported previously. General Procedure for the Preparation of Compounds 5a-f m-Chloroperoxybenzoic acid (50%, 142 mg, 0.41 mmol) in chloroform (20 mL) was slowly added to a well-stirred solution of the sulphide 3a (150 mg, 0.4 mmol) in chloroform (20 mL) at 0-58C over a period of 30 min.…”

Phase-Transfer Catalysis Reaction with Strong Bases

“…A number of water-soluble quaternary ammonium catalysts allowed for recycle of the aqueous layer containing the catalyst and excess reactants (thiolate and base) leading to waste minimization. An interesting case of regioselective S-alkylation was reported in which there was the potential for competition between S-and O-alkylation (see Figure 8-30) [190]. These compounds are useful in the isolation of sulfide-containing minerals from ores.…”