A benzyl protecting group is often used to protect alcohols in synthetic reactions. Benzyl groups are usually introduced via the Williamson S_N2 reaction, requiring a benzyl halide, a base and a solvent such as DMF.

 Lab Tips:

• Benzyl protection can also be achieved under non basic conditions (via the fluoboric acid catalyzed reaction of phenyldiazomethane) if necessary. ^[1]

_{1. Wuts, P. G. M. (2014). Greene’s Protective Groups in Organic Synthesis (Fifth Ed.) Hoboken, New Jersey: John Wiley & Sons.}

 

Reagents: Benzyl Bromide or Benzyl Chloride, Base (NaOH, KOH, K2CO3, etc.), Solvent (DMSO, DMF, etc.)

Reactant: Alcohol

Product: Benzyl Protected Alcohol

Type of Reaction: S_N2

 

Mechanism

Top Citations

• Benzyl Protection of Phenols under Neutral Conditions: Palladium-Catalyzed Benzylations of Phenols. Org. Lett. 2008, 10 (10), 1979-1982.

• Installation of the Phosphonate and (α,α-Difluoromethyl)Phosphonate Functionalities Equipped with Benzyl Protection. Tetrahedron Letters 1999, 40 (10), 1869–1872.
• Superarming the S-Benzoxazolyl Glycosyl Donors by Simple 2-O-Benzoyl-3,4,6-Tri-O-Benzyl Protection. Org. Lett. 2008, 10 (10), 2103–2106.

Related Reactions

• N-Boc Protection and Deprotection

• Benzyl Deprotection of Alcohols

• Methyl-Ester Protection and Deprotection

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