## 3 Results and Discussion  
5-Methylcyclohexane-1,3-dione during the five-step synthesis was converted into the known \(\gamma\),\(\delta\)-unsaturated acid [24]. This acid was then converted into chloro- **2**, bromo- **3** and iodolactone **4** according to the procedure described earlier [23]. Two of these compounds, chloro- **2** and bromolactone **3**, were the new ones, only iodolactone **4** was obtained earlier [26] (Scheme 1). **Scheme 1. ** Synthesis of halolactones **2-4**. Our earlier experience [23; 27; 28; 29; 30; 31] indicated that the most common reaction for halolactones during biotransformation was the conversion into hydroxylactones. The mechanism of such reaction was similar to S\({}_{\text{N}}\)2 substitution and OH group was usually introduced in an equatorial position. This kind of transformation most often is catalysed by haloalcare dehalogenases during biotransformation. The research made by [PERSON] et al. [32] conducted on iodolactone **4** proved that this compound was transformed into hydroxylactone. During this biotransformation, only one strain--_Absidia cylindrosopora_--was tested. This strain was able to transform iodolactone into hydroxylactone with high yield but without any enantiomeric excess. Our research assumed a comparison of 22 fungal strains of their ability to biotransformation three halolactones. The iodolactone in these studies was the reference compound. During the experiments, the effect of the type of halogen on the reaction was compared (Scheme 2). The progress of all screening transformations was monitored using standard techniques (TLC and GC). The chosen results of these tests are presented in Table 1. The others strains were not able to convert lactones **2**-**4** into any product. The results of the conducted experiments were very surprising. It turned out that of the 22 tested microorganisms, only some were capable of converting the chosen substrates. The best biocatalyst was _C. japonica_ AM472 strain (entry 8). This strain was able to transform all three halolactones with a high degree of conversion (between 54.8% and 67.5%). Of the strains of genus _Fusarium_, only _F. culmorum_ AM10 (entry 1) converted bromolactone **3** with a satisfying yield (almost 73%). Usually strains of genus _Fusarium_ were very good biocatalysts for halolactones and transform halolactones independently of halogen. Contrary to the results described in our earlier papers [26; 28; 29; 32] from five strains of genus _Fusarium_, only one was able to convert the chosen substrates into product with a good yield. Independent of the structure of the compound, the best substrate for biotransformation was \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Entry**} & \multirow{2}{*}{**Microorganism**} & \multicolumn{6}{c}{**Screening Biotransformation (\%)**} \\ \cline{3-8}  & & **(2)** & **(5)** & **(3)** & **(5)** & **(4)** & **(5)** \\ \hline
1 & _F. culmorum_ AM10 & 67.4 & 42.6 & 21.3 & **72.7** & 56.0 & 44.0 \\
2 & _F. avencecum_ AM11 & 100 & - & 77.7 & 22.3 & 100 & - \\
3 & _F. tricitcutum_ AM16 & 100 & - & 92.4 & 7.6 & 93.7 & 6.3 \\
4 & _F. semitcutum_ AM20 & 100 & - & 87.3 & 12.7 & 95.3 & 4.7 \\
5 & _F. oxysporum_ AM21 & 100 & - & 89.7 & 10.3 & 100 & - \\
6 & _S. rac unconsum_ AM105 & 100 & - & 72.7 & 27.3 & 100 & - \\
7 & _F. solani_ AM203 & 87.7 & 12.3 & 67.1 & 32.9 & 61.7 & 38.3 \\
8 & _C. japonica_ AM472 & 32.5 & **67.5** & 45.2 & 54.8 & 34.0 & **66.0** \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The positive results of screening biotransformation of halolactones **2**, **3** and **4** after 7 days of incubation (in % according to GC). bromolactone **3**, which was converted by eight strains. A slightly worse situation was observed for iodolactone **4**, converted by five strains. The chlorolactone **2** was the least susceptible to biotransformation (three strains only). Only two strains, _C. japonica_ AM472 and _F. culmorum_ AM10, were able to transform all of the compounds in good yield.