Yoshinori Nishii and Yoo Tanabe
Novel, sequential and regioselective Friedel–Crafts type
reactions of (E)-3-aryl-2,2-dihalogenocyclopropanecarbonyl
chlorides 1 and 2,2-dichlorocyclopropanecarbonyl chlorides 3 with
benzenes produce various 4-aryl-3-halogeno-1-naphthols 2 and
4-aryl-1-naphthols 4, respectively. One of the benzannulations involves
the intramolecular cyclization of acid chlorides 1, followed by
intermolecular coupling with substituted benzenes to give
4-aryl-3-halogeno-1-naphthols 2. As a demonstration of this annulation,
4-aryl-3-bromo-1-naphthols 2i and 2k are successfully converted into new
analogues of 1-aryl-3-hydroxymethyl-4-methoxy-2-naphthoic acid lactones
13, a class of lignan lactones. The other benzannulation involves three
series of reactions using acid chlorides 3a–c: (1) the
intermolecular Friedel–Crafts acylation of 3 with one benzene
molecule giving the intermediary
2,2-dichlorocyclopropyl(phenyl)methanones 14a–c; (2) the
intermolecular trapping of 14a–c with another benzene molecule
accompanied by regioselective ring opening; and (3) the final
intramolecular cyclization giving 4-phenyl-1-naphthols 4a–c. The
use of p-xylene also gives the corresponding
4-(p-xylyl)-1-naphthol 4d. The reactions of
alternatively prepared ketones 14 with benzenes gives a variety of
‘unsymmetrically’ substituted 4-aryl-1-naphthols
4c,e–k under identical conditions. However, the reaction using
p-methoxyphenyl ketone analogues 14g does not produce
4-aryl-1-naphthols, but gives
5-aryl-2-(
p-methoxyphenyl)-3-methylfurans 16. These
annulations proceed straightforwardly (in a one-pot manner) and this
variation is due to the highly regioselective cyclopropane
ring-openings.