The condensation of thiophenol (II) with 3-methyl-2-butenyl bromide (I) by means of NaOH in refluxing acetone gives 3-methyl-2-butenyl(phenyl)sulfide (III), which is cyclized by means of P2O5 and H3PO4 in refluxing benzene to yield 4,4-dimethyl-3,4-dihydro-1H-1-benzothiopyran (IV). The acylation of (IV) with acetyl chloride catalyzed by SnCl4 in benzene affords the corresponding 6-acetyl derivative (V), which by dehydration with lithium diisopropylamide and diethyl chlorophosphate in THF is converted into 6-ethynyl-4,4-dimethyl-3,4-dihydro-2H-1-benzothiopyran (VI). Finally, this compound is condensed with ethyl 6-chloropyridine-3-carboxylate (VII) by means of butyllithium in THF. The ester (VII) is obtained by esterification of the corresponding acid (VIII) with ethanol by means of dicyclohexylcarbodiimide (DCC) and dimethylaminopyridine (DMAP).

The condensation of thiophenol (II) with 3-methyl-2-butenyl bromide (I) by means of NaOH in refluxing acetone gives 3-methyl-2-butenyl(phenyl)sulfide (III), which is cyclized by means of P2O5 and H3PO4 in refluxing benzene to yield 4,4-dimethyl-3,4-dihydro-1H-1-benzothiopyran (IV). The acylation of (IV) with acetyl chloride catalyzed by SnCl4 in benzene affords the corresponding 6-acetyl derivative (V), which by dehydration with lithium diisopropylamide and diethyl chlorophosphate in THF is converted into 6-ethynyl-4,4-dimethyl-3,4-dihydro-2H-1-benzothiopyran (VI). Finally, this compound is condensed with ethyl 6-chloropyridine-3-carboxylate (VII) by means of butyllithium in THF. The ester (VII) is obtained by esterification of the corresponding acid (VIII) with ethanol by means of dicyclohexylcarbodiimide (DCC) and dimethylaminopyridine (DMAP).

The condensation of thiophenol (II) with 3-methyl-2-butenyl bromide (I) by means of NaOH in refluxing acetone gives 3-methyl-2-butenyl(phenyl)sulfide (III), which is cyclized by means of P2O5 and H3PO4 in refluxing benzene to yield 4,4-dimethyl-3,4-dihydro-1H-1-benzothiopyran (IV). The acylation of (IV) with acetyl chloride catalyzed by SnCl4 in benzene affords the corresponding 6-acetyl derivative (V), which by dehydration with lithium diisopropylamide and diethyl chlorophosphate in THF is converted into 6-ethynyl-4,4-dimethyl-3,4-dihydro-2H-1-benzothiopyran (VI). Finally, this compound is condensed with ethyl 6-chloropyridine-3-carboxylate (VII) by means of butyllithium in THF. The ester (VII) is obtained by esterification of the corresponding acid (VIII) with ethanol by means of dicyclohexylcarbodiimide (DCC) and dimethylaminopyridine (DMAP).

The condensation of thiophenol (II) with 3-methyl-2-butenyl bromide (I) by means of NaOH in refluxing acetone gives 3-methyl-2-butenyl(phenyl)sulfide (III), which is cyclized by means of P2O5 and H3PO4 in refluxing benzene to yield 4,4-dimethyl-3,4-dihydro-1H-1-benzothiopyran (IV). The acylation of (IV) with acetyl chloride catalyzed by SnCl4 in benzene affords the corresponding 6-acetyl derivative (V), which by dehydration with lithium diisopropylamide and diethyl chlorophosphate in THF is converted into 6-ethynyl-4,4-dimethyl-3,4-dihydro-2H-1-benzothiopyran (VI). Finally, this compound is condensed with ethyl 6-chloropyridine-3-carboxylate (VII) by means of butyllithium in THF. The ester (VII) is obtained by esterification of the corresponding acid (VIII) with ethanol by means of dicyclohexylcarbodiimide (DCC) and dimethylaminopyridine (DMAP).