Total synthesis of (+)-erogorgiaene using lithiation-borylation methodology, and stereoselective synthesis of each of its diastereoisomers.

A short (8 steps) synthesis of (+)-erogorgiaene in 44% overall yield from p-methylacetophenone is described. Key steps include lithiation/borylation-protodeboronation to build up the molecule and control the stereochemistry at C1 and C4. The C11 stereochemistry was similarly set up by using lithiation/borylation methodology.

Protodeboronation of tertiary boronic esters: asymmetric synthesis of tertiary alkyl stereogenic centers.

While tertiary boranes undergo efficient protodeboronation with carboxylic acids, tertiary boronic esters do not. Instead, we have discovered that CsF with 1.1 equiv of H2O (on tertiary diarylalkyl boronic esters) or TBAF·3H2O (on tertiary aryldialkyl boronic esters) effect highly efficient protodeboronation of tertiary boronic esters with essentially complete retention of configuration.

Stereoselective syntheses of enantiomerically pure 2,5-disubstituted dihydropyrans based on olefin metathesis.

A short synthesis of 2,5-disubstituted dihydropyrans starting from d-mannitol as a chiral building block is described. Our synthetic approach combines ruthenium-catalyzed ring closing olefin metathesis and palladium-catalyzed nucleophilic substitution.

Control of ring size selectivity by substrate directable RCM.

Hydroxy groups may exert strong catalyst-directing effects in olefin metathesis reactions, which are exploited for a ring size-selective RCM reaction.