Sulfinamide
Molecules of the form >N–S(=O)–
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In organosulfur chemistry, sulfinamide is a functional group with the structure R−S(O)−NR2 (where R = alkyl or aryl).[1] This functionality is composed of a sulfur-carbon (S−C) single bond, a sulfur-nitrogen (S−N) single bond, and a sulfur-oxygen (S-O) bond (see Sulfoxide for the nature of this bond).[2] As a non-bonding electron pair is present on the sulfur, the sulfur atom is a stable stereogenic centre, and so these compounds are chiral. They are sometimes referred to as S-chiral sulfinamides. Sulfinamides are amides of sulfinic acid (R−S(O)OH).
Structure
Sulfinamides do not undergo inversion. They can therefore be synthesised and/or isolated in enantiopure forms. This has led to their use as chiral ammonia equivalents. Chiral sulfinamides such as tert-butanesulfinamide, p-toluenesulfinamide[4][5] and 2,4,6-trimethylbenzenesulfinamide[6] are all chiral auxiliaries.
Synthesis
Sulfinamides are traditionally produced by the reaction of sulfinyl chlorides with primary or secondary amines.[1] They also arise by the addition of Grignard reagents to sulfinylamines, followed by protonation:
- RMgX + R'N=S=O → RS(O)(NR'MgX)
- RS(O)(NR'MgX) + H2O → RS(O)(NR'H) + "MgX(OH)"
Yet another route entails peracid-oxidation of sulfenylphthalimides, which gives sulfinylphthalimides.