KINETIC AND THERMODYNAMIC CONTROL OF ASYMMETRIC INDUCTION BY CHIRAL DIPHOSPHINE IN RING CONTRACTION OF (CHIRAL DIPHOSPHINE)NiCH2CH2CH2COO TO (CHIRAL DIPHOSPHINE) NiCH (CH3)CH2COO

1984 ◽  
Vol 13 (6) ◽  
pp. 941-944 ◽  
Author(s):  
Kenji Sano ◽  
Takakazu Yamamoto ◽  
Akio Yamamoto
Keyword(s):  
Asymmetric Induction ◽  
Thermodynamic Control ◽  
Ring Contraction

Stereodivergent Alkyne Hydrofluorination Using a Simple Practical Reagent

2020 ◽  
Author(s):  
Rui Guo ◽  
Xiaotian Qi ◽  
Hengye Xiang ◽  
Paul Geaneoates ◽  
Ruihan Wang ◽  
...  
Keyword(s):  
Bond Formation ◽  
Biologically Active ◽  
Dft Studies ◽  
Thermodynamic Control ◽  
Important Goal ◽  
Peptide Bonds ◽  
Metal Free ◽  
Vinyl Cation ◽  
E And Z Isomers ◽  
Vinyl Fluorides

Vinyl fluorides play an important role in drug development as they serve as bioisosteres for peptide bonds and are found in a range of biologically active molecules. The discovery of safe, general and practical procedures to prepare vinyl fluorides remains an important goal and challenge for synthetic chemistry. Here we introduce an inexpensive and easily-handled reagent and report simple, scalable, and metal-free protocols for the regioselective and stereodivergent hydrofluorination of alkynes to access both the E and Z isomers of vinyl fluorides. These conditions were suitable for a diverse collection of alkynes, including several highly-functionalized pharmaceutical derivatives. Mechanistic and DFT studies support C–F bond formation through a vinyl cation intermediate, with the (E)- and (Z)-hydrofluorination products forming under kinetic and thermodynamic control, respectively.<br>

P-Chiral 2-{1'-[Butyl(phenyl)phosphanyl]ferrocen-1-yl}-4-isopropyl-4,5-dihydrooxazoles: A Second Chirality Center in Catalytic System

2005 ◽  
Vol 70 (3) ◽  
pp. 361-369 ◽  
Author(s):  
Dušan Drahoňovský ◽  
Petr Štěpnička ◽  
Dalimil Dvořák
Keyword(s):  
Catalytic System ◽  
Asymmetric Induction ◽  
Dimethyl Malonate ◽  
Enantiomerically Pure

P-Chiral (S,RP)-2-{1'-[butyl(phenyl)phosphanyl]ferrocen-1-yl}-4-isopropyl-4,5-dihydrooxazole (6) and (S,SP)-2-{1'-[butyl(phenyl)phosphanyl]ferrocen-1-yl}-4-isopropyl-4,5-dihydrooxazole (7) were prepared by the procedure developed by Jugé, starting from enantiomerically pure (-)- or (+)-ephedrine and dichloro(phenyl)phosphine. Compounds 6 and 7 were examined for asymmetric induction in the Pd-catalyzed reaction of rac-1,3-diphenylallyl acetate with dimethyl malonate. The best results were obtained with 7 (98% ee), while 6 gave 82% ee.

The Influence of Anomeric Configuration and Aglycone Structure on the Outcome of Acid‐Promoted Ring Contraction in 2,3‐Di‐ O ‐Silylated S‐Galactopyranosides

2021 ◽  
Vol 6 (24) ◽  
pp. 6223-6229
Author(s):  
Polina I. Abronina ◽  
Alexander I. Zinin ◽  
Nelly N. Malysheva ◽  
Maxim Y. Karpenko ◽  
Natalya G. Kolotyrkina ◽  
...  
Keyword(s):  
Ring Contraction ◽  
Anomeric Configuration
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