Diastereoselective Reduction of Chiral N-Tosyl-2-benzoyl-1,3-oxazine Derived from (1R)-(+)-Camphor

Heterocycles ◽  
2010 ◽  
Vol 81 (10) ◽  
pp. 2351 ◽  
Author(s):  
Kwang-Youn Ko ◽  
Hoseop Yun
Keyword(s):  
Diastereoselective Reduction

Diastereoselective Reduction of Selected α-substituted β-keto Esters and the Assignment of the Relative Configuration by 1H-NMR Spectroscopy

2020 ◽  
Vol 07 ◽  
Author(s):  
Christian Trapp ◽  
Corinna Schuster ◽  
Chris Drewniok ◽  
Dieter Greif ◽  
Martin Hofrichter
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Selective Reduction ◽  
Reducing Agents ◽  
Relative Configuration ◽  
Curtius Rearrangement ◽  
Keto Esters ◽  
Hydroxy Esters ◽  
Diastereoselective Reduction

Background:: Chiral β-hydroxy esters and α-substituted β-hydroxy esters represent versatile building blocks for pheromones, β-lactam antibiotics and 1,2- or 1,3-aminoalcohols. Objective:: Synthesis of versatile α-substituted β-keto esters and their diastereoselective reduction to the corresponding syn- or anti-α-substituted β-hydroxy esters. Assignment of the relative configuration by NMR-spectroscopy after a CURTIUS rearrangement of α-substituted β-keto esters to 4-substituted 5-methyloxazolidin-2-ones. Method:: Diastereoselective reduction was achieved by using different LEWIS acids (zinc, titanium and cerium) in combination with complex borohydrides as reducing agents. Assignment of the relative configuration was verified by 1H-NMR spectroscopy after CURTIUS-rearrangement of α-substituted β-hydroxy esters to 4-substituted 5-methyloxazolidin-2-ones. Results:: For the syn-selective reduction, titanium tetrachloride (TiCl4) in combination with a pyridine-borane complex (py BH3) led to diastereoselectivities up to 99% dr. High anti-selective reduction was achieved by using cerium trichloride (CeCl3) and steric hindered reducing agents such as lithium triethylborohydride (LiEt3BH). After CURTIUS-rearrangement of each α-substituted β-hydroxy ester to the corresponding 4-substituted 5-methyloxazolidin-2-one, the relative configuration was confirmed by 1H NMR-spectroscopy. Conclusion:: We have expanded the procedure of LEWIS acid-mediated diastereoselective reduction to bulky α-substituents such as the isopropyl group and the electron withdrawing phenyl ring.

ChemInform Abstract: Chiral Cyclic β-Amino Esters. Part 2. Synthesis by Diastereoselective Reduction of Enamino Esters.

ChemInform ◽  
2010 ◽  
Vol 29 (9) ◽  
pp. no-no
Author(s):  
J. BLOT ◽  
A. BARDOU ◽  
C. BELLEC ◽  
M.-C. FARGEAU-BELLASOUED ◽  
J. P. CELERIER ◽  
...  
Keyword(s):  
Amino Esters ◽  
Diastereoselective Reduction

Highly enantio- and diastereoselective reduction of sulfur-functionalized cyclic ketones with baker's yeast

1991 ◽  
Vol 32 (3) ◽  
pp. 399-400 ◽  
Author(s):  
Tamotsu Fujisawa ◽  
Kengo Yamanaka ◽  
Bingidimi I. Mobele ◽  
Makoto Shimizu
Keyword(s):  
Baker’S Yeast ◽  
Baker's Yeast ◽  
Cyclic Ketones ◽  
Diastereoselective Reduction

ChemInform Abstract: First TiCl4-Mediated Diastereoselective Reduction of α-Nitro Ketones to anti-β-Nitro Alcohols by BH3×SMe2.

ChemInform ◽  
2000 ◽  
Vol 31 (51) ◽  
pp. no-no
Author(s):  
Roberto Ballini ◽  
Giovanna Bosica ◽  
Enrico Marcantoni ◽  
Patrizia Vita ◽  
Giuseppe Bartoli
Keyword(s):  
Diastereoselective Reduction

ChemInform Abstract: Highly Efficient Diastereoselective Reduction of α-Fluoroimines.

ChemInform ◽  
2010 ◽  
Vol 41 (40) ◽  
pp. no-no
Author(s):  
Roy M. Malamakal ◽  
Whitney R. Hess ◽  
Todd A. Davis
Keyword(s):  
Highly Efficient ◽  
Diastereoselective Reduction

ChemInform Abstract: 1,3-Syn Diastereoselective Reduction of β-Hydroxyketones Utilizing Alkoxydialkylboranes.

ChemInform ◽  
1987 ◽  
Vol 18 (28) ◽  
Author(s):  
K.-M. CHEN ◽  
G. E. HARDTMANN ◽  
K. PRASAD ◽  
O. REPIC ◽  
M. J. SHAPIRO
Keyword(s):  
Diastereoselective Reduction
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