3-Phenyl-3,4-dihydroisocoumarins

In a similar way bromination of powdered (E)-o-stilbene carboxylic acid with bromine vapour or with powdered pyridine. HBr.Brj complex in solid state at room temperature gave selectively erythro-1,2-dibromo-l, 2-dihydro-o-stilbene carboxylic acid. However, bromination with bromine in solution gives 4-bromo-3-phenyl-3,4-dihydroisocoumarin as the major product (Scheme 3). 

The locked substrate may bind to the enzyme in a different way from an unrestricted substrate. If the phenyl portion of D-24 binds in the aromatic subsite, then its acylamido group cannot bind at the usual acylamido subsite (82). Cohen justifies this proposal from the fact that some cyclized compounds lacking the acylamido group, e.g., Dmethyl-3,4-dihydroisocoumarin-3-carboxy-late, 39, are good substrates for the enzyme. 

R)-l-[4-Methoxy-3-[(triisopropylsilyl)oxyphenyl)-2-[3-(methoxymethoxy)phenyl]ethanol 1123 undergoes selective hydrogen metal exchange followed by carbonylation to form the lithiated intermediate 1124, which undergoes cyclization in acid conditions to provide the dihydroisocoumarin 1125, a key intermediate during an enantioselective synthesis of phyllodulcin (Scheme 279) <1996JOC5371>. 

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