Rh-catalyzed asymmetric hydrogenation of γ-phthalimido-substituted α,β-unsaturated carboxylic acid esters: An efficient enantioselective synthesis of β-aryl-γ-amino acids (Organic Letters (2007) 9)

Full text of DOI:10.1021/ol801179x

ORGANIC
LETTERS
2008
Vol. 10, No. 15
3379
Additions and Corrections
Volume 9, 2007
Page 4828. The corresponding corrections have been made
in the Supporting Information, which is now available.
Jun Deng, Zheng-Chao Duan, Jia-Di Huang, Xiang-Ping
Hu,* Dao-Yong Wang, Sai-Bo Yu, Xue-Feng Xu, and
Zhuo Zheng*
OL801179X
Rh-Catalyzed Asymmetric Hydrogenation of γ-Phthalimido-
Substituted R,ꢀ-Unsaturated Carboxylic Acid Esters: An Ef-
ficient Enantioselective Synthesis of ꢀ-Aryl-γ-amino Acids.
10.1021/ol801179x
Published on Web 06/25/2008
Page 4827. In Table 2, the assignment of the absolute
configuration in entries 1, 6, and 9 was incorrect; the
compounds with (-) optical rotation should have (S), not
(R), configuration. The corrected table is shown here.
Scheme 2. Synthesis of (R)-Baclofen
Pages 4827 and 4828. In Schemes 2 and 3, the ligand should
be (Rc,SFc,SP)-3, not (Sc,RFc,RP)-3. The corrected schemes are
shown here.
Table 2. Asymmetric Hydrogenation of Ethyl (Z)-4-Phthalimido-
3-arylbut-2-enoate 1a
entry
substrate (Ar)
1a: Ar ) Ph
1b: Ar ) 2-MeOC6H4
1c: Ar ) 3-MeOC6H4
1d: Ar ) 4-MeOC6H4
1e: Ar ) 4-FC6H4
1f: Ar ) 4-ClC6H4
1g: Ar ) 4-BrC6H4
1h: Ar ) 4-CF3C6H4
1i: Ar ) 3-cyclopentoxy-4-MeOC6H3
1j: Ar ) 2-naphthyl
ee (%)
Scheme 3. Synthesis of (R)-Rolipram
1
2
3
4
5
6
7
8
95 (S)
96 (-)
94 (-)
94 (-)
96 (-)
95 (S)
94 (-)b
93 (-)
97 (S)
94 (-)
94 (-)
97 (-)b
9
10
11
12
1k: Ar ) 2-(6-methoxynaphthyl)
1 L: Ar ) 2-thiophenyl
aAll reactions were carried out with 0.25 mmol of substrate at room
temperature under a H2 pressure of 60 atm in 2 mL of CH2Cl2 for 24 h, with a
substrate/[Rh(COD)2]BF4/(SC,RFc,RP)-3 ratio of 1/0.01/0.011. Full conversions
were obtained in all reactions. The ee values were determined by HPLC on a
chiral column (Chiralpak AD or Chiralcel OD-H). bThe result was obtained with
ligand 2b.