398
In another report, it was demonstrated that even free thiophenols can be employed
for the direct thioetherification of β-C–H bonds of terminal methyl groups in
8- aminoquinoline-derived carboxamides (Scheme 26) [72].
Not only arylthiolations, 8-amidoquinolines also direct the palladium-catalyzed
arylsulfonylation of C(sp
3
)–H bonds with sodium sulfinates as the S-coupling counterpart to provide an extensive range of aryl alkyl sulfones (Scheme 27) [73]. The
sulfur atom in sodium sulfinate, being soft in nature, prefers to coordinate to the
palladium catalyst over oxygen atoms and thus reductively eliminates arylsulfonylated products. Several complex molecules, including a cholic acid derivative, underwent late-stage sulfonylations under the operative condition.
Direct trifluoromethylthiolation also proceeded swiftly with the electrophilic
SCF 3 agent 95 to afford the β-thiolated carboxamide products (Scheme 28) [74].
The reaction relies on a higher-valent Pd
IV
intermediate formed in situ by oxidizing
the trifluoromethylthiolating agent [75, 76].
Scheme 24 Chiral
auxiliary-directed
C(sp
3 )–O bond formation
Scheme 25 Nickelcatalyzed direct
thioetherification of
carboxamides
A. Gupta et al.
In another report, it was demonstrated that even free thiophenols can be employed
for the direct thioetherification of β-C–H bonds of terminal methyl groups in
8- aminoquinoline-derived carboxamides (Scheme 26) [72].
Not only arylthiolations, 8-amidoquinolines also direct the palladium-catalyzed
arylsulfonylation of C(sp
3
)–H bonds with sodium sulfinates as the S-coupling counterpart to provide an extensive range of aryl alkyl sulfones (Scheme 27) [73]. The
sulfur atom in sodium sulfinate, being soft in nature, prefers to coordinate to the
palladium catalyst over oxygen atoms and thus reductively eliminates arylsulfonylated products. Several complex molecules, including a cholic acid derivative, underwent late-stage sulfonylations under the operative condition.
Direct trifluoromethylthiolation also proceeded swiftly with the electrophilic
SCF 3 agent 95 to afford the β-thiolated carboxamide products (Scheme 28) [74].
The reaction relies on a higher-valent Pd
IV
intermediate formed in situ by oxidizing
the trifluoromethylthiolating agent [75, 76].
Scheme 24 Chiral
auxiliary-directed
C(sp
3 )–O bond formation
Scheme 25 Nickelcatalyzed direct
thioetherification of
carboxamides
A. Gupta et al.