Solid form of (−)-Ambrox formed by a bioconversion of homofarnesol in the presence of a biocatalyst

A method of preparing a solid form of (−)-Ambrox of formula (I)

• wherein the solid form of (−)-Ambrox is formed by a bioconversion process;
• said method comprising the steps of:
• I) forming crystalline (−)-Ambrox in a bioconversion medium by means of a biocatalytic process;
• II) separating the crystalline (−)-Ambrox from the bioconversion medium;
• wherein the bioconversion medium obtained from the bioconversion process comprises a solid phase containing crude (−)-Ambrox, a liquid phase or phases consisting of water and an oily phase containing residual homofarnesol and other oily or oil-soluble impurities or by-products (II), (III) and (IV) present in the oily phase;
• wherein the bioconversion process is an enzyme-catalyzed cyclization of homofarnesol comprising a mixture of 7E,3E and 7E,3Z isomers of homofarnesol wherein the cyclization reaction is carried out in the presence of an SHC biocatalyst capable of bioconverting a homofarnesol mixture enriched in the 7E,3E isomer to (−)-Ambrox, wherein in the presence of appreciable amounts of homofarnesol, (−)-Ambrox and the by-products remain dissolved together;
• and wherein a reduction in the level of unreacted homofarnesol in admixture with (−)-Ambrox and the compounds (II), (III) and (IV) results in crystallization of (−)-Ambrox and facilitates downstream processing and isolation and/or purification of (−)-Ambrox in a solid form from the bioconversion medium.