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2848
Highly Enantioselective Catalytic Asymmetric [2+2]
Cycloadditions of Cyclic α-Alkylidene β-Oxo Imides with Ynamides
Chem. Eur. J. 2015, 21, 2798–2802
Kondo
Waseda University
Kazuaki Enomoto, Harufumi Oyama, and Masahisa Nakada*
Ts
CO 2Me
O HN
O
N
Bn
ligand-Cu(OTf) 2 (20 mol%)
+
O
MS 4Å, CH 2Cl 2, 0 ºC
CO 2Me
HN
O
O
O
NBnTs O
O
H H
91%, 89% ee
O
HN
O
CO 2Me
O
NBnTs O
H Me
80%, 86% ee
HN
O
H Cy
74%, 10% ee
O
O
R
R2
R
N 3
·
R
O
R1
N
R3
O
O
HN
O
CO 2Me
O
O
HN
H H
73%, 96% ee
O
H Me
93%, 88% ee
N
Cu 2+
O
R2
O
NBnTs
O
N
R
CO 2Me
O
NBnTs
R2
ON
R3
O
NHMs
ligand
NBnTs
R
N
MsHN
O
H Ph
15%, 35% ee
O
N
R
CO 2Me
NBnTs O
O
NBnTs
H
CO 2Me
O
O
O
R
HN
O
CO 2Me
HN
O
O
R
O
N
H
OR
hydrogen bond
Enantioselective Synthesis of α-Quaternary Mannich Adducts by
Palladium-Catalyzed Allylic Alkylation: Total Synthesis of (+)-Sibirinine
2849
Kotomori
J. Am. Chem. Soc. 2015, 137, 1040-1043 California Institute of Technology
Yoshitaka Numajiri, Beau P. Pritchett, Koji Chiyoda, and Brian M. Stoltz*
NHBoc
BocHN
SO2Ph
O
O
CsCO3
X
OR
CH 2Cl 2
X
OR
Y
23
°C
YA
( )n
( )n
CF3
NHBoc
Pd 2(dba) 3
O
(5 mol%)
L1
O
L1 (12.5 mol%) X
P
N
toluene
Y
X
( )n B
F 3C
23 °C, 12-48 h
2
O
O
O
NHBoc
O
NHBoc
O
NHBoc
Ph
A1 79%
A2 72%
B1 91%, 90% ee B2 93%, 87% ee
O
NHBoc
A4 99%
B4 74%, 93% ee
O
A3 86%
B3 98%, 82% ee
NHBoc
N
Bn
A1 80%
B1 78%, 90% ee
Natural Product Synthesis
O
NHCbz
O
Pd 2(dba) 3 (2.5 mol%)
L1 (6.25 mol%)
toluene, 23 °C, 24 h
94%
O
A
1. DIBAL
−78 °C
2. Ac2O
pyridine
60 °C
OAc NHCbz Cy BH, THF
2
0 °C;
NaHBO 3• 4H 2O
H 2O, 23 °C
86%, 3 steps
1. MsCl, Et 3N
CH 2Cl 2, 0 °C
2. NaH, THF
reflux
89%, 2 steps
Cbz
OAc N
1. CH3CHO, 3 Å s.m.
CH 2Cl 2, 23 °C
2. m-CPBA, CH 2Cl 2
0 °C
92%, 2 steps
O
NHCbz
86% ee
OAc NHCbz
OH
H
KOH
OH N
NH 2NH 2•H 2O
ethylene glycol
120 °C
77%
(−)-isonitramine
O OMe
N
(+)-sibirinine
2846
Enantioselective Rhodium-Catalyzed Isomerization of
4-minocrotonates: Asymmetric Synthesis of a Unique Chiral Synthon
†Colorado
J. Am. Chem. Soc. 2015, 137, 553-555
Kotomori
State University, ‡Dalian University
Wen-Zhen Zhang,†,‡ John C. K. Chu,† Kevin M. Oberg,† and Tomislav Rovis*,†
O
R
N
O
[Rh(C 2H 4) 2Cl] 2 (10 mol%)
TIPS-Guiphos (20 mol%)
toluene, 110 °C, 24 h
i
O Pr
N R
N PMB
O iPr
X=
X=
X=
X=
X=
N
O iPr
2-Me, 62%, 94% ee X =
4-tBu, 68%, 95% ee X =
4-OMe, 59%, 95% ee X =
2-OMe, 73%, 95% ee X =
2-OiPr, 60%, 94% ee
a, b
4-COOMe, 50%, 96% ee
4-F, 65%, 95% ee
4-Cl, 63%, 95% ee
Me
4-Br, 52%, 95% ee
N
COOR'
N
c
N R
OR'
Rh(I)L*
Rh(I)L*
trans to cis
R
O
60%
95% ee, >99:1 dr
e
TMS
O
d
N R
O
N H
O
Me
O iPr indole
84%
95% ee, >99:1 dr
Me
O
O
Me
N H
N H
O
Me
O iPr
O
Me
O
N
84% H
95% ee, >99:1 dr
(a) cat. OsO4, NMO, acetone/H2O, rt, 18 h.
(b) 2,2-Dimethoxypropane, cat. TsOH, acetone, rt, 18 h. (c) CAN,
CH 3CN/H2O, 0 °C to rt, 1 h. (d) Cat. AuCl/AgOTf, indole, DCM,
40 °C, 24 h. (e) BF 3·OEt 2/TMSOTf, allyltrimethylsilane, DCM, 40
°C, 18 h. (f) Ac2O, pyridine, cat. DMAP, rt, 2 h.
Rh(I)L*
Rh(I)L*
O
O
O
Me
N PMB
63%
95% ee, >99:1 dr
O
R
O iPr
61%, 94% ee
O
O
Me
Rh(I)L*
N Ac
c, f
O iPr
95% ee
X X = 4-Me, 77%, 95% ee X = 2-CF3, 65%, 95% ee
O
O
O
OR'
2847
Highly Enantioselective Intermolecular Cross Rauhut–Currier
Reaction Catalyzed by a Multifunctional Lewis Base Catalyst
Ando
Nankai University
Angew. Chem. Int. Ed. 2015, 54, 1621–1624.
Xuelin Dong, Ling Liang, Erqing Li, and You Huang*
O
CO 2Et
Cl
1a
2
PPh 2
O
cat. 4a: R = H,
2 h, 87%, 89% ee
OR cat. 4b: R = Me,
1.5 h, 83%, 40% ee
HN
cat. 4
O
CHCl3
16 °C
CO 2Et
HN
O
PPh 2
O
OH
CO 2R1
Ar
1
2
4c
(10 mol%)
CHCl3
16 °C
O
cat. 4c
(20 mol%)
3 h, 84%, 90% ee
(10 mol%)
4 h, 89%, 90% ee
CO 2R1
3a
15
examples
Ar = 4-ClC6H 4, 4-FC6H 4, 4-BrC6H 4, C6H 5
4-MeC6H 4, 4-MeOC6H 4, 3-BrC6H 4 et al. up to 98% yield
up to 91% ee
1
R = Et, Me, iPr, Bn
O
H
Ph 2 N
P
O
O
Ar
CO 2Et
O
O
Ar1
O
Ar
H
3a
Cl
O
O
Proposed transition state model
O
O
Ar2
CO 2Et
1
2
4c
(10 mol%)
CHCl3
16 °C
Ar1 = 4-BrC6H 4
Ar2 = 4-MeC6H 4,
4-MeOC6H 4
4-FC6H 4 et al.
O
Ar2
O
Ar1
CO 2Et
3a
10 examples
up to 98% yield
up to 96% ee

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