The yeast mediated reduction of ethyl acetoacetate to ethyl (S)-3-hydroxy butyrate proceeds with good yield and high
enantioselectivity in liquefied petroleum gas (LPG). It was found that slightly more water (2 ml/g yeast) and more yeast (1.6g/mmol substrate) were required to effect complete conversion than was the case with more conventional organic solvents, such as petroleum spirit.