Topics in Current Chemistry (2020) 378:16
1 3
and to address limitations in stereochemical control have led to the combination of
these two reaction modes [for relevant reviews, see 5–7]. Accordingly, cooperation
between transition metal complexes and organocatalysts during bond formation
offers reactivity and stereocontrol that is beyond each catalyst in isolation. Specifically, interest in the potential of combining transition metal catalysts with tertiary
amine Lewis base catalyst systems has increased dramatically and, in this chapter,
we summarize the recent developments in this field.
The first section of this chapter describes tertiary amine Lewis base catalysts in
combination with d-block Lewis acids and is subdivided into two sections: (1) chiral
tertiary amine Lewis base catalysts in combination with Lewis acids, and (2) achiral tertiary amine Lewis base catalysts in combination with Lewis acids. The vast
majority of research in this area concerns the modulation and control of Lewis basederived C1-ammonium enolates (and related) by a second Lewis acid catalyst and is
presented largely in chronological order.
The second section of this chapter describes tertiary amine Lewis base catalysts
in combination with transition metal catalysis and is subdivided into three sections:
tertiary amine Lewis base catalysis in cooperation with (1) palladium catalysis, (2)
iridium catalysis, and (3) copper catalysis. Research in this section concerns allylic
alkylation, conjugate addition reactions, and amination reactions, and again is presented largely chronologically.
Overall, a significant proportion of research described in this chapter concerns
the chemistry and synthetic utility of C1-ammonium enolates. By interfacing these
(and related) species with a second transition metal catalyst, their reactivity and
hence utility can be greatly expanded and developed.
2 Tertiary Amine Lewis Base Catalysis in Combination with d‑Block
and Transition Metal Lewis Acids
2.1 Chiral Tertiary Amine Lewis Base Catalysts in Combination with Lewis Acids
The vast majority of research in this area has centered on the chemistry of C1-ammonium enolate nucleophiles. The reactivity of both these catalytically accessible ester
enolate equivalents and their electrophile partners can be tuned in combination with
various Lewis acids. While the greatest success has been realized using non-transition metal Lewis acid co-catalysts, transition metal and other d-block Lewis acids
demonstrate various levels of efficacy and it is pertinent to describe the development
of both here.
The recognition that C1-ammonium enolate reactivity could be augmented and
regulated by the actions of a Lewis acid co-catalyst was recognized in 2002 by
Leckta et al. They investigated the synthesis of β-lactams via the direct enantioselective reaction of acyl chlorides using C1-ammonium enolates with electron-deficient imines [8]. This procedure sought to combine a cinchona alkaloidderived Lewis base catalyst (BzQ) with various metal Lewis acids, the latter
Reprinted from the journal
100
1 3
and to address limitations in stereochemical control have led to the combination of
these two reaction modes [for relevant reviews, see 5–7]. Accordingly, cooperation
between transition metal complexes and organocatalysts during bond formation
offers reactivity and stereocontrol that is beyond each catalyst in isolation. Specifically, interest in the potential of combining transition metal catalysts with tertiary
amine Lewis base catalyst systems has increased dramatically and, in this chapter,
we summarize the recent developments in this field.
The first section of this chapter describes tertiary amine Lewis base catalysts in
combination with d-block Lewis acids and is subdivided into two sections: (1) chiral
tertiary amine Lewis base catalysts in combination with Lewis acids, and (2) achiral tertiary amine Lewis base catalysts in combination with Lewis acids. The vast
majority of research in this area concerns the modulation and control of Lewis basederived C1-ammonium enolates (and related) by a second Lewis acid catalyst and is
presented largely in chronological order.
The second section of this chapter describes tertiary amine Lewis base catalysts
in combination with transition metal catalysis and is subdivided into three sections:
tertiary amine Lewis base catalysis in cooperation with (1) palladium catalysis, (2)
iridium catalysis, and (3) copper catalysis. Research in this section concerns allylic
alkylation, conjugate addition reactions, and amination reactions, and again is presented largely chronologically.
Overall, a significant proportion of research described in this chapter concerns
the chemistry and synthetic utility of C1-ammonium enolates. By interfacing these
(and related) species with a second transition metal catalyst, their reactivity and
hence utility can be greatly expanded and developed.
2 Tertiary Amine Lewis Base Catalysis in Combination with d‑Block
and Transition Metal Lewis Acids
2.1 Chiral Tertiary Amine Lewis Base Catalysts in Combination with Lewis Acids
The vast majority of research in this area has centered on the chemistry of C1-ammonium enolate nucleophiles. The reactivity of both these catalytically accessible ester
enolate equivalents and their electrophile partners can be tuned in combination with
various Lewis acids. While the greatest success has been realized using non-transition metal Lewis acid co-catalysts, transition metal and other d-block Lewis acids
demonstrate various levels of efficacy and it is pertinent to describe the development
of both here.
The recognition that C1-ammonium enolate reactivity could be augmented and
regulated by the actions of a Lewis acid co-catalyst was recognized in 2002 by
Leckta et al. They investigated the synthesis of β-lactams via the direct enantioselective reaction of acyl chlorides using C1-ammonium enolates with electron-deficient imines [8]. This procedure sought to combine a cinchona alkaloidderived Lewis base catalyst (BzQ) with various metal Lewis acids, the latter
Reprinted from the journal
100