Crude E and Z alkene scrambling product

(E/Z)-4-(p-tolyl)but-3-en-1-ol (Z/E= 2.7/1) (6.5 mg, 0.04 mmol, 1 equiv) was weighed into an NMR tube. In a separate vial, CSA (4.6 mg, 0.02 mmol, 0.5 equiv) was dissolved in 0.05 mL HFIP and 0.35 mL CDCl3. To this vial, was added salicylaldehyde (4.4 µL, 0.04 mmol, 1.1 equiv). This was then transferred to the NMR tube and subjected to 1H NMR analysis. A separate reaction (0.02 mmol of homoallylic alcohol with 0.02 mmol of CSA) was also conducted in the absence of the salicylaldehyde to observe if double bond isomerisation occurred under reaction conditions. Within 15 mins, inspection of the NMR revealed complete consumption of the alkene in the presence of salicylaldehyde. This reaction was then quenched by addition of the aq. NaHCO3, extracted with DCM and analysed by NMR to show a mixture of 1.4:1 cis-fused-3a,4-trans to cis-fused-3a,4-cis.