12-Hydroxy-ll-methoxy-diaboline: A New Alkaloid from Strychnos spinosa

Carboxylic acids react with diazomethane in an ether solvent via alkylation at the carboxylate oxygen atom to give methyl esters of the corresponding acid with excellent yields.

Compounds bearing two hydroxyl groups are known as diols. When the hydroxyl groups are located on adjacent carbon atoms, the diols are called vicinal diols or glycols. Under acidic conditions, vicinal diols undergo a specific reaction called pinacol rearrangement.
The reaction begins with transferring a proton from the acid catalyst to one of the hydroxyl groups, producing an oxonium ion.

Alkenes are converted to 1,2-diols or glycols through a process called dihydroxylation. It involves the addition of two hydroxyl groups across the double bond with two different stereochemical approaches, namely anti and syn. Dihydroxylation using osmium tetroxide progresses with syn stereochemistry.