Benzoyl group regioselective benzylation

The methyl group at position 6 is more reactive for radical bromination than the 2-methyl group of 2,6-dimethylquinazolin-4 3//)-one ° or 2,6-dimethyl-4-methylsulfanylquinazo-line. Regioselective bromination with N-bromosuccininiide (NBS) or 1,3-dibromo-5,5-dimethylhydantoin (DDH) using benzoyl peroxide as a catalyst gives the respective benzyl bromides in good yields. 

In the majority of cases, hydroxylation by Beauveria bassiana occurs in a regioselective manner, but high enantioselectivity is not always observed. As shown in Scheme 2.152, both enantiomers of the A -benzyl-protected bicyclic lactam are hydroxylated with high regioselectivity in position 11, but the reaction showed very low enantioselectivity. On the other hand, when the lactam moiety was replaced by a more polar benzoyl-amide, which functions as polar anchor group, high enantiodifferentiation occurred. The (l/ )-enantiomer was hydroxylated at carbon 12 and the (IS)-counterpart gave the 11-hydroxylated product [1116]. A minor amount of 6-exo-alcohol was formed with low enantiomeric excess. 

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