Racemate of (3aS,4S,9bR)-4-(p-tolyl)-2,3,3a,9b-tetrahydro-4H-furo[3,2-c]chromene

In a vial, a stock solution of CSA (13.8 mg, 0.06 mmol) was made in chloroform-d (1.05 mL) and HFIP (0.15 mL). To this was added salicylaldehyde (13.3 µL, 0.13 mmol). From this stock solution 0.6 mL was taken out and transferred into and NMR tube containing the -pMe homoallylic alcohol (0.06 mmol). This was then immediately transferred into an NMR spectrometer. The first spectrum was recorded after 3.5 mins from addition of starting materials into NMR tube (time required to load sample, lock, shim etc). The reaction was monitored by NMR and quenched by addition of NaHCO3 after the stated time. The organic layer was extracted with DCM, dried over anhydrous Na2SO4 and concentrated under a stream of N2. The product was isolated by flash column chromatography 25% diethyl ether/petroleum ether.