Tetrahydrofuran → Naphthalene

Participants

Reaction Steps

Procedure 2 is illustrated with the conversion of diol (S)-28 to diester (S)-29. To a solution of optically pure (S)-28 (5.8 g., 10.5 mmol) in 250 ml. of tetrahydrofuran was added sodium hydride as a 50% suspension in oil (2.4 g., 50 mmol), and the mixture was stirred at 25° for 2 hr. Methyl bromoacetate (7.6 g., 50 mmol) was added to the above suspension, and the mixture was heated to reflux for 6.5 hours. The reaction mixture was cooled, filtered, and the filter cake was washed with tetrahydrofuran. The combined filtrate was evaporated to an oil that was chromatographed on 150 g. of silica gel. Elution of the column with 1.4 l. of dichloromethane gave non-naphthalene containing products (pmr). Elution with 3.5 l. of 2% methanol-ether gave (S)-29. The eluate was evaporated to give 3.2 g. (44%) of a glass, which was dried at 165° under 0.07 mm for 1 hour, [α]54625 -25.7° (C 1.0, (CH2)4O). The 70 ev mass spectrum of the material gave a parent ion at m/e 692. A 100 MHz pmr spectrum in CDCl3 gave the following signals: δ 7.7-8.05 (m, ArH, 4H), 7.0-7.5 (m, ArH, 6H), 5.0 (s, ArCH2O, 4H), 4.35 (s, OCH2CO2, 4H), 3.80 (s, OCH3, 6H), 2.8-3.8 (m, OCH2CH2O, 2OH). Table I records the analysis. ##STR93##

Provenance & Evidence