Structures and Syntheses of Sterically Hindered Thiols

The structures and abbreviations for the most commonly used bulky 2,6- and 2,4,6-substituted aromatic thiols are shown in Fig. 1. These aromatic thiols have the advantage over those with aliphatic groups that the tendency for C—S bond cleavage is virtually eliminated, which in turn lessens the probability of generating unreactive sulfide-bridged polymers. 

The synthesis of these thiols is relatively straightforward from commercially available phenols via the Newman-Karnes rearrangement (6) (Eq. (1)) or from sulfonyl chlorides (also obtainable commercially) by Li[AlH4] reduction (7) (Eq. (2)). 

Recently the range of sterically demanding aromatic thiols has been expanded by the introduction of a comparatively simple high-yield synthetic route to 2,6-diorganosilylthiophenols via the lithiation of thiophenol (8, 9) (Eq.(3)). An attractive feature of this class of ligand 

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