Trimethylsilyl trifluoromethanesulfonate (0.170 ml, 0.880 mmol), was added to CH₂Cl₂ (30 ml) under a nitrogen atmosphere at -84 °C (using a liquid N₂/EtOAc bath), and stirred for five mins. Allyloxytrimethylsilane (36.4 ml, 220 mmol) and o-anisaldehyde (12.0 g, 88.0 mmol), dissolved in CH₂Cl₂ (25 ml) were added sequentially and drop wise, whilst maintaining the same temperature. The resulting yellow mixture was stirred at -84 °C for three hours, then allowed to warm to -60 °C (requires a chloroform/dry ice bath) and stirred for a further hour, the solution turning a deep red. The reaction was quenched with pyridine (15 ml) at the same temperature, and then poured into a saturated solution of NaHCO₃ (100 ml). The aqueous layer was extracted with Et₂O (3 x 100 ml); and the combined organic layers dried over anhydrous MgSO₄. Excess solvent was removed under reduced pressure and the resulting oil was purified, when required, by flash column chromatography (EtOAc/petrol 2:98); to yield the acetal (20.2 g, 98%) as a colourless oil.