1 3
Topics in Current Chemistry (2019) 377:38
carbocyclic products 97 were afforded with high yields and diastereoselectivity
and excellent enantioselectivity (Scheme 21).
Wang and colleagues disclosed a chemical transformation for the preparation
of spirocyclopentene oxindoles through combined palladium and chiral amine
catalysis by employing alkyne-based substrates 198 [83]. In contrast, Córdova
and colleagues employed allyl acetate-based substrates 100, proceeding through
a DYKAT process that generated polysubstituted spirocyclic oxindoles 102 [84].
Both the protocols presented provided structurally interesting compounds with
high-to-excellent stereoselectivity and efficiency (Scheme 22). Furthermore, the
group of Jørgensen employed a decarboxylative [4 + 2] cycloaddition strategy by
merging palladium and amine catalysts for the preparation of vinyl tetrahydroquinolines [85]. Coupling between vinyl benzoxazinanones and α,β-unsaturated
aldehydes, ensuing through iminium ion and enamine activation by the amine
catalyst and simultaneous palladium-π-allyl complex activation of the vinyl benzoxazinanone, provided vinyl tetrahydroquinolines in good-to-high yields and
with excellent stereoselectivity (up to 92% yield, > 98% ee and > 20:1 d.r.).
Furthermore, the group of Rios also successfully disclosed various strategies
for the preparation of carbocycles type molecules. For instance, through the enantioselective ring expansion of vinyl cyclopropanes, providing highly substituted
90
91
N
Ts
Cat. 7 (20 mol%)
H 2 O (1.0 equiv.)
NaOAc (1.0 equiv.)
92a R = Ph, 52% yield, 99% ee
92b R = 2-ClC 6 H 4 , 80% yield, >99% ee
92c R = 2-MeC 6 H 4 , 68% yield, >99% ee
92d R = Pr, 44% yield, 87% ee
R
H
O
X
R
O
H
Cat. 7 (20 mol%)
[Pd(PPh 3 ) 4 ] (5 mol%)
CH 3 CN, r.t.
R
O
H
CO 2 Me
NC
+
DMAP (10 mol%)
PdCl 2 (5 mol%)
toluene, 0
o
C, 36 h
X = NHTs
93a R = 4-BrC 6 H 4 , 59% yield, 7:1 d.r., 95% ee
93b R = 4-NO 2 C 6 H 4 , 60% yield, 12:1 d.r., 86% ee
93c R = Me, 56% yield, 3:1 d.r., 92% ee
93d R = 4-NO 2 C 6 H 4 , 55% yield, 7:1 d.r.,89% ee
N
H
OTES
Ph
Ph
O
R
O
H
95a R = 4-NO 2 C 6 H 4 , 77% yield, 93% ee
95b R = C 6 H 5 , 57% yield, 99% ee
95c R = 4-MeC 6 H 4 , 51% yield, 99% ee
95d R = Pr, 40% yield, 91% ee
94 (20 mol%)
PdCl 2 (5 mol%)
PhCO 2 H (20 mol%)
CHCl 3 or THF, 4
o
C
X = O
X = CH(CO 2 Me)CN
Scheme 20 Preparation of various multifunctionalized carbocyclopentenes
+
90
16
97a R = C 6 H 5 74% yield, 93:7 d.r., 99% ee
97b R = 4-BrC 6 H 4 82% yield, 93:7 d.r., >99% ee
97c R = 4-MeOC 6 H 4 86% yield, 93:7 d.r., 99% ee
97d R = Pr 70% yield, 80:20 d.r., 99% ee
CN
MeO 2 C
Cat. 7 (20 mol%), [Pd 2 (dba) 3 ] (5 mol%)
dppe (10 mol%), CH 3 CN, 22
o
C
97
R
H
O
NC
CO 2 Me
OAc
O
H
R
Scheme 21 Enantioselective dynamic cascade reaction for the preparation of polysubstituted carbocycles
including quaternary carbon stereocenter
Reprinted from the journal
15
Topics in Current Chemistry (2019) 377:38
carbocyclic products 97 were afforded with high yields and diastereoselectivity
and excellent enantioselectivity (Scheme 21).
Wang and colleagues disclosed a chemical transformation for the preparation
of spirocyclopentene oxindoles through combined palladium and chiral amine
catalysis by employing alkyne-based substrates 198 [83]. In contrast, Córdova
and colleagues employed allyl acetate-based substrates 100, proceeding through
a DYKAT process that generated polysubstituted spirocyclic oxindoles 102 [84].
Both the protocols presented provided structurally interesting compounds with
high-to-excellent stereoselectivity and efficiency (Scheme 22). Furthermore, the
group of Jørgensen employed a decarboxylative [4 + 2] cycloaddition strategy by
merging palladium and amine catalysts for the preparation of vinyl tetrahydroquinolines [85]. Coupling between vinyl benzoxazinanones and α,β-unsaturated
aldehydes, ensuing through iminium ion and enamine activation by the amine
catalyst and simultaneous palladium-π-allyl complex activation of the vinyl benzoxazinanone, provided vinyl tetrahydroquinolines in good-to-high yields and
with excellent stereoselectivity (up to 92% yield, > 98% ee and > 20:1 d.r.).
Furthermore, the group of Rios also successfully disclosed various strategies
for the preparation of carbocycles type molecules. For instance, through the enantioselective ring expansion of vinyl cyclopropanes, providing highly substituted
90
91
N
Ts
Cat. 7 (20 mol%)
H 2 O (1.0 equiv.)
NaOAc (1.0 equiv.)
92a R = Ph, 52% yield, 99% ee
92b R = 2-ClC 6 H 4 , 80% yield, >99% ee
92c R = 2-MeC 6 H 4 , 68% yield, >99% ee
92d R = Pr, 44% yield, 87% ee
R
H
O
X
R
O
H
Cat. 7 (20 mol%)
[Pd(PPh 3 ) 4 ] (5 mol%)
CH 3 CN, r.t.
R
O
H
CO 2 Me
NC
+
DMAP (10 mol%)
PdCl 2 (5 mol%)
toluene, 0
o
C, 36 h
X = NHTs
93a R = 4-BrC 6 H 4 , 59% yield, 7:1 d.r., 95% ee
93b R = 4-NO 2 C 6 H 4 , 60% yield, 12:1 d.r., 86% ee
93c R = Me, 56% yield, 3:1 d.r., 92% ee
93d R = 4-NO 2 C 6 H 4 , 55% yield, 7:1 d.r.,89% ee
N
H
OTES
Ph
Ph
O
R
O
H
95a R = 4-NO 2 C 6 H 4 , 77% yield, 93% ee
95b R = C 6 H 5 , 57% yield, 99% ee
95c R = 4-MeC 6 H 4 , 51% yield, 99% ee
95d R = Pr, 40% yield, 91% ee
94 (20 mol%)
PdCl 2 (5 mol%)
PhCO 2 H (20 mol%)
CHCl 3 or THF, 4
o
C
X = O
X = CH(CO 2 Me)CN
Scheme 20 Preparation of various multifunctionalized carbocyclopentenes
+
90
16
97a R = C 6 H 5 74% yield, 93:7 d.r., 99% ee
97b R = 4-BrC 6 H 4 82% yield, 93:7 d.r., >99% ee
97c R = 4-MeOC 6 H 4 86% yield, 93:7 d.r., 99% ee
97d R = Pr 70% yield, 80:20 d.r., 99% ee
CN
MeO 2 C
Cat. 7 (20 mol%), [Pd 2 (dba) 3 ] (5 mol%)
dppe (10 mol%), CH 3 CN, 22
o
C
97
R
H
O
NC
CO 2 Me
OAc
O
H
R
Scheme 21 Enantioselective dynamic cascade reaction for the preparation of polysubstituted carbocycles
including quaternary carbon stereocenter
Reprinted from the journal
15