1,2-Aminoalcohols have been demonstrated to be excellent chiral auxiliaries and chiral catalysts , including aldol reaction , addition of organozincs to aldehydes , reduction of ketones to alcohols in asymmetric syntheses.
In this work, a library of neoisopulegol-based octahydrobenzofuran core 1,2-aminoalcohol derivatives was developed and applied as chiral catalysts in the enantioselective addition of diethylzinc to benzaldehyde.
Allylic chlorination of (+)-neoisopulegol, derived from natural (-)-isopulegol , followed by cyclisation was accomplished to provide the key intermediate exo-methylene-substituted perhydrobenzofurane. Stereoselective epoxidation of the double bond followed by aminolysis with primary amines produced 1,2-aminoalcohols. The treatment of aminoalcohols with formaldehyde resulted in the formation of spiro-oxazolidines. The syn -selective dihydroxylation with OsO4/NMO of the key-intermediate produced bicyclic, terpenoid –type diol in highly stereoselective reaction.
The antimicrobial activity of the prepared compounds was evaluated on multiple bacterial and fungal strains.
The stereochemistry of the resulting compounds was determined by 2D-NMR techniques (COSY, NOESY, HSQC and HMBC).
