Tertbutylthio

The tert-butylthio group, usually written as S-tert-butyl (StBu), is the thioether substituent -S-C(CH3)3. It denotes a sulfur atom bonded to a tert-butyl group and is encountered as part of a larger molecule or as a protective group for thiols in organic synthesis.

Preparation of a tert-butylthio-containing compound typically involves alkylation of a thiolate (RS−) with a tert-butyl halide (t-BuX). Thiols are deprotonated with base to form RS−, which then reacts with tert-butyl halide to yield RS-tBu. Alternative routes use tert-butyl sulfenylating reagents to install the tert-butylthio moiety.

Properties and reactivity: Tert-butylthio groups are relatively resistant to many reagents, reflecting the stability of thioethers. They are sterically bulky, providing significant shielding around the sulfur center. Oxidation of the thioether can give sulfoxide or sulfone derivatives (R-S(O)n-tBu). Under certain conditions the S-tBu group can be removed to release the free thiol, enabling deprotection strategies in synthesis.

Applications: In peptide and small-molecule synthesis, S-tert-butyl protection of thiols (StBu) is used to temporarily mask sulfhydryl functionality, allowing selective manipulation of other parts of a molecule. The bulky group also influences lipophilicity and conformational properties, which can be advantageous in medicinal chemistry and materials science.

Safety: Reagents used to install or remove S-tBu groups (thiols, halides, bases) can be irritants or hazardous. Standard chemical hygiene practices, including appropriate ventilation and personal protective equipment, should be followed.