Topics in Current Chemistry (2019) 377:38
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spirocyclopentanes 104 [86], formal ring contraction for the generation of spiropyrazolones 106 [87], the asymmetric synthesis of cyclopentanes with four stereogenic
centers 108 [88], the enantioselective acetyl aza-arene addition to α,β-unsaturated
aldehydes affording chiral 2-acyl pyridines and pyrazines 110 [89], or, very recently
disclosed, the highly enantioselective cascade reaction for the synthesis of dihydroacridines 112 (Scheme 23) [90].
+
90
98
99a R = C 6 H 5 84% yield, 8:1 d.r., >99% ee
99b R = 2-BrC 6 H 4 64% yield, 8:1 d.r., >99% ee
99c R = 3-MeC 6 H 4 87% yield, 8:1 d.r., 99% ee
99d R = 2-furyl 88% yield, 17:1 d.r., 98% ee
99e R = Pr 67% yield, >20:1 d.r., 97% ee
Cat. 7 (20 mol%), PdCl 2 (5 mol%)
PhCO 2 H (20 mol%), MTBE, r.t.
R
H
O
N
H
O
99
N
H
O
R
CHO
+
90
100
102a R = H 86% yield, 77:23 d.r., 99% ee
102b R = 4-MeOC 6 H 4 87% yield, 71:29 d.r., 98% ee
102c R = 4-BrC 6 H 4 84% yield, 72:28 d.r., 97% ee
102d R = Pr 89% yield, 84:16 d.r., 97% ee
102e R = naphthyl 81% yield, 73:27 d.r., 98% ee
101 (10 mol%) Ar = 4-MeOC 6 H 4
Cat. 7 (20 mol%), Pd 2 (dba) 3 CHCl 3 (5 mol%)
CH 3 CN, 40
o
C, 6 h
R
H
O
N
O
102
N
O
R
Bn
OAc
Bn
O
H
P
Ar
Ar
Ar
Scheme 22 Stereoselective preparation of spirocyclic oxindoles through combined palladium and chiral
amine catalysts
90
R
H
O
103
O
O
O
O
CHO
R
104a R = C 6 H 5 87% yield, 7:1 d.r., 99% ee
104b R = 4-BrC 6 H 4 95% yield, 12:1 d.r., 99% ee
104c R = 4-MeC 6 H 4 88% yield, 10:1 d.r., 99% ee
104d R = Me 94% yield, 12:1 d.r., 94% ee
O
N
N
Ph
Pd 2 (dba) 3 (5 mol%)
EtOAc
O
N
N
Ph
CHO
R
106a R = C 6 H 5 79% yield, 7.3:2:1 d.r., >99% ee
106b R = 4-BrC6H4 72% yield, 5:3:1 d.r., 98% ee
106c R = 4-MeC 6 H 4 76% yield, 5:3:1 d.r., 99% ee
106d R = Me 76% yield, 8.2:1.3:1 d.r., 96% ee
CN
MeO 2 C
MeO 2 C
CN
CHO
R
108a R = C 6 H 5 99% yield, 25:3:2:1 d.r., 99% ee
108b R = 3-BrC 6 H 4 70% yield, 17:4:2:1 d.r., 97% ee
108c R = 4-MeC6H4 70% yield, 20:1:1 d.r., 99% ee
108d R = Me 79% yield, 3:3:1 d.r., 89% ee
Cat. 7 (20 mol%)
Pd2(dba)3 (5 mol%)
EtOAc, r.t.
N
CHO
N
CHO
R
Cat. 7 (20 mol%)
Yb(OTf) 3 (20 mol%)
2-NO 2 PhCO 2 H (30 mol%)
1,2-DCE (4-15 days), 50
o
C
112a R = C 6 H 5 74% yield, 92% ee
112b R = 4-BrC 6 H 4 57% yield, 82% ee
112c R = 4-OMeC6H4 59% yield, 87% ee
112d R = Bu 20% yield, 89% ee
105
107
Cat. 7 (20 mol%)
N
O
N
O
R
R
CHO
In(OAc) 3 or
Zn(acac) 2 (10 mol%)
PhCO 2 H (50 mol%)
DCE, r.t.
109
110a R = C 6 H 5 56% yield, 6.5:1 d.r., >99% ee
110b R = 4-MeC 6 H 4 90% yield, 7:1 d.r., >99% ee
110c R = 4-ClC6H4 71% yield, 4:1 d.r., >99% ee
110d R = 4-FC 6 H 4 75% yield, 7:1 d.r., >99% ee
111
Scheme 23 Various chemical strategies for the preparation of various carbocyclic compounds
Reprinted from the journal
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