- Remote Construction of Chiral Vicinal Tertiary and Quaternary Centers by Catalytic Asymmetric 1,6-Conjugate Addition of Prochiral Carbon Nucleophiles to Cyclic Dienones
-
An unprecedented remote construction of chiral vicinal tertiary and quaternary centers by a catalytic asymmetric 1,6-conjugate addition of prochiral carbon nucleophiles to cyclic dienones has been developed. Both 5H-oxazol-4-ones and 2-oxindoles were found to be very efficient carbon nucleophiles in this reaction at a remote position, giving products with excellent enantio- and diastereoselectivities (up to 99 % ee and >19:1 d.r. for 5H-oxazol-4-ones and up to 97 % ee and >19:1 d.r. for 2-oxindoles).
- Wei, Yuan,Liu, Zunwu,Wu, Xinxin,Fei, Jie,Gu, Xiaodong,Yuan, Xiaoqian,Ye, Jinxing
-
-
Read Online
- Synthesis of enantiomerically pure β,β-diphenylalanine (Dip) and fluorenylglycine (Flg)
-
A new strategy for the preparation of both enantiomers of two phenylalanine analogues, β,β-diphenylalanine and fluorenylglycine, has been developed. The combination of a high yielding racemic synthesis and a very efficient resolution procedure has provided significant amounts of each amino acid in enantiomerically pure form and suitably protected for use in peptide synthesis. This methodology can be easily applied to the preparation of larger quantities of enantiopure compounds.
- Royo, Soledad,Jimenez, Ana I.,Cativiela, Carlos
-
p. 2393 - 2400
(2007/10/03)
-
- An efficient synthesis of N-Boc-D-diphenylalanine from a chiral azirdine-2-carboxylate
-
N-Boc-D-diphenylalanine was prepared from a commercially available aziridine-2(S)-carboxylate through alkylation, regiospecific aziridine ring opening, and benzylic deoxygenation followed by oxidation in 57% overall yield.
- Chang, Jae-Won,Ha, Hyun-Joon,Park, Chan Sun,Kim, Min Sung,Lee, Won Koo
-
p. 1143 - 1148
(2007/10/03)
-
- Bisoxazoline and bioxazoline chiral ligands bearing 4-diphenylmethyl shielding substituents. Diels-Alder reaction of cyclopentadiene with 3-acryloyl-2-oxazolidinone catalyzed by the aqua nickel(II) complex
-
Enantiopure 2-amino-3,3-diphenyl-1-propanol was synthesized by the hidantoin route starting from diphenyl-acetaldehyde followed by subsequent functional group transformations and optical resolution by a chiral HPLC. The amino alcohol can be converted into two new chiral ligands: 4,4'-bis(diphenylmethyl)-2,2'-bioxazoline and 2,2'-isopropylidenebis(4-diphenylmethyloxazoline), and further to complexes with copper(II) trifluoromethanesulfonate and nickel(II) perchlorate hexahydrate. The nickel(II) aqua complex obtained from the bisoxazoline effectively catalyzed the Diels-Alder reactions of cyclopentadiene with 3-acryloyl-2-oxazolidinone in high endo-selectivities and moderate enantioselectivities via a square planar transition structure.
- Kanemasa,Adachi,Yamamoto,Wada
-
p. 681 - 687
(2007/10/03)
-
- Stereocontrolled Conversion of L-Serine into a Series of Valuable Unnatural α-Amino Acids
-
Stereocontrolled synthesis of (2R,3S)- and (2R,3R)-phenylserine, (R)-3,3-diphenylserine and (R)-3,3-diphenylalanine are described.
- Koskinen, Ari M. P.,Hassila, Heikki,Myllymaeki, Vesa T.,Rissanen, Karl
-
p. 5619 - 5622
(2007/10/02)
-
- Synthesis of N-BOC-D-Diphenylalanine from L-Serine Methyl Ester Hydrochloride
-
A convenient six step synthesis of N-BOC-D-diphenylalanine from L-serine methyl ester hydrochloride is described.The preparation of a novel chiral auxiliary, an oxazolidinone derived from D-diphenylalaninol, is also described.
- Sibi, Mukund P.,Deshpande, Prasad K.,Loggia, Anthony J. La,Christensen, James W.
-
p. 8961 - 8964
(2007/10/02)
-