The title compounds were synthesized from (−)-(S)- or (+)-(R)-2,3-dihydrobenzofuran-2-carboxylic acid. And their absolute configurations were determined.

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2-Isopropenyl-2,3-dihydrobenzofuran was effectively prepared by two new methods. Fomannoxin and 5-acetyl-2-[1-(hydroxymethyl)vinyl]-2,3-dihydrobenzofuran were synthesized from 2-isopropenyl-2,3-dihydrobenzofuran, while anodendroic acid was synthesized from 2-(1-hydroxy-1-methylethyl)-2,3-dihydrobenzofuran.

Two benzofuroquinolinones, 6,11-dihydrobenzofuro[2,3-b]quinolin-11-one and 5,6-dihydrobenzofuro[3,2-c]quinolin-6-one, were obtained by the demethyl-cyclization of 4-hydroxy-3-(o-methoxyphenyl)-1,2-dihydroquinolin-2-one. The chlorination of these benzofuroquinolinones afforded the corresponding chlorobenzofuroquinolines which were then converted to the cyanobenzofuroquinolines. The linear chlorobenzofuroquinoline was converted to 11-methoxy- and 11-ethoxybenzofuro[2,3-c]quinolines, and the linear cyanobenzofuroquinoline to benzofuro[2,3-b]quinoline-11-carboxylic acid and -11-carboxamide. The linear benzofuroquinolines thus obtained were oxidized to the corresponding N-oxides.

Methoxy-substituted 2-isopropenyl-2,3-dihydrobenzofurans were prepared from methoxy-substituted phenols and 1,4-dibromo-2-methyl-2-butene in one-step reactions. Their acylations with acetic acid–trifluoroacetic anhydride or N-methylformanilide–phosphoryl chloride were studied.