Protective-Groups
Acetals as Carbonyl Protecting Groups
Acetals and ketals protect aldehydes and ketones from nucleophilic attack. They are stable to base and nucleophiles but removed by aqueous acid.
Carbamate Protecting Groups for Amines
Carbamate protecting groups (Boc, Cbz, Fmoc) are the most important amine protecting groups. Each has different installation and removal conditions.
Ester Protecting Groups for Carboxylic Acids
Esters protect carboxylic acids from nucleophilic attack. Common ester types include methyl, benzyl, allyl, and tert-butyl esters.
Ether Protecting Groups
Ether protecting groups include benzyl, methoxymethyl (MOM), and p-methoxybenzyl (PMB) groups. They are stable to a wide range of conditions.
Olefin Protecting Groups
Olefins can be protected by conversion to dibromides or by complexation with metals. This prevents unwanted reactions at the double bond.
Phosphate Protecting Groups
Phosphate protecting groups are essential for oligonucleotide synthesis. Common groups include cyanoethyl, methyl, and benzyl phosphates.
Silyl Protecting Groups
Silyl protecting groups mask alcohols and phenols as silyl ethers. Common silyl groups include TMS, TES, TBS, TIPS, and TBDPS, with increasing stability.
Thioacetal Protecting Groups
Thioacetals protect carbonyls and can be reductively desulfurized to give methylene groups (Mozingo reduction). They are stable to both acid and base.