1,4-Bis(2-chloroethoxy)benzene (9).19 Pyridine (29.4 mL,
364 mmol) was added to a mechanically stirred solution of 1,4-
bis(hydroxyethoxy)benzene ( (Aldrich; 30.0 g, 152 mmol) in
CH2Cl2 (300 mL) at 0 °C. Next, thionyl chloride (25.4 mL, 348
mmol) was added dropwise such that the internal temperature
did not exceed 5 °C.20 This mixture was allowed to warm
gradually to room temperature and was stirred overnight.
Aqueous 2 N HCl (500 mL) was added slowly and the layers
were separated. The aqueous layer was extracted with CH2-
Cl2 (3  75 mL) and the organic extracts were combined. The
pooled organic extracts were then washed with aqueous 2 N
HCl (2  200 mL), water (200 mL), 1 N NaOH (100 mL), and
brine (100 mL). The organic extracts were then dried (MgSO4),
filtered, and evaporated to leave a tan solid that was recrystallized
from ethanol to afford white crystals: 31.4 g, 88%; mp
90-91 °C;

1,4-Bis(2-chloroethoxy)-2,5-dibromobenzene (10).11 Zinc
chloride (38.2 g, 280 mmol) was added to a solution of 9 (27.5
g, 117 mmol) in acetic acid (280 mL). After enclosing the
apparatus in aluminum foil to exclude light, bromine (39.3 g,
246 mmol) dissolved in acetic acid (55 mL) was added dropwise
to the suspension over 1.5 h. The reaction was allowed to stir
overnight, during which time a precipitate had formed. The
reaction was diluted with aqueous saturated sodium thiosulfate
(500 mL) and extracted with CH2Cl2 (5  200 mL). The
organic layers were combined and washed with aqueous 1 N
NaOH (1  200 mL), brine (100 mL), dried (MgSO4), filtered,
and evaporated to leave an off-white solid. Recrystallization
from ethanol afforded a crystalline white product: 50.0 g, 91%;
mp 120 °C

2,3,6,7-Tetrahydrobenzo[1,2-b;4,5-b¢]difuran (7).10 To a
suspension of magnesium powder (Aldrich, -50 mesh, 99+%;
3.7 g, 152 mmol) in anhydrous THF (50 mL) was slowly added
EtMgBr (3.4 mL, 10 mmol, 3 M solution in Et2O).21 An
anhydrous THF solution (125 mL) of the dibrominated compound
10 (20.0 g, 51.0 mmol) was then added dropwise such
that the internal reaction temperature did not exceed 35 °C.
Upon completion of the addition, the reaction was heated at
reflux for 3 h. The reaction was then cooled to room temperature
and carefully poured into cold 1 N HCl (200 mL). Upon
cessation of gas evolution, the mixture was extracted with Et2O
(3  300 mL). The organic layers were combined and washed
with aqueous 1 N NaOH (4  75 mL), brine (50 mL), dried
(MgSO4), filtered, and concentrated by rotary evaporation to
afford a tan solid. This was recrystallized from ethanol to
afford off-white, platelike crystals: 6.5 g, 79%; mp 155 °C