Synthesis and Selected Transformation of Optically Active Cyclopentenyl Sulfoxides: New Approach to Optically Active Cyclopentenones.

ChemInform ◽  
2007 ◽  
Vol 38 (27) ◽  
Author(s):  
W. H. Midura ◽  
J. Krysiak ◽  
M. W. Wieczorek ◽  
A. Filipczak
Keyword(s):  
Optically Active ◽  
New Approach

New Approach to the Theory of Circular Dichroism

1998 ◽  
Vol 63 (8) ◽  
pp. 1187-1201 ◽  
Author(s):  
Jaroslav Zamastil ◽  
Lubomír Skála ◽  
Petr Pančoška ◽  
Oldřich Bílek
Keyword(s):  
Electromagnetic Wave ◽  
Circular Dichroism ◽  
Electromagnetic Waves ◽  
Maxwell Equations ◽  
Optically Active ◽  
Semiclassical Approach ◽  
New Approach ◽  
Isotropic Media ◽  
New Formula ◽  
Circular Dichroïsm

Using the semiclassical approach for the description of the propagation of the electromagnetic waves in optically active isotropic media we derive a new formula for the circular dichroism parameter. The theory is based on the idea of the time damped electromagnetic wave interacting with the molecules of the sample. In this theory, the Lambert-Beer law need not be taken as an empirical law, however, it follows naturally from the requirement that the electromagnetic wave obeys the Maxwell equations.

A new approach to the stereoselective synthesis of trans-3-carbamoyl-β-lactam moieties

2017 ◽  
Vol 41 (6) ◽  
pp. 2479-2489 ◽  
Author(s):  
Anna Zakaszewska ◽  
Ewelina Najda-Mocarska ◽  
Sławomir Makowiec
Keyword(s):  
Stereoselective Synthesis ◽  
Optically Active ◽  
Thermal Generation ◽  
New Approach

Optically active 1,4-disubstituted-3-carbamoyl-azetidinones are synthesized from 5-[(N-arylamino)(hydroxyl)methylene]-2,2-dimethyl-1,3-dioxa-4,6-diones and chiral aldimines via thermal generation of carbamoyl ketenes and subsequent [2+2] cycloaddition.

Alkylation of Phosphinite/Phosphonite-Boranes via Temporary Protection of the P–H Bond

Synthesis ◽  
2020 ◽  
Vol 52 (16) ◽  
pp. 2410-2426
Author(s):  
Sylwia Sowa ◽  
Kamil Modzelewski
Keyword(s):  
Optically Active ◽  
New Approach ◽  
Mild Conditions ◽  
Temporary Protection ◽  
Step Procedure ◽  
Oxidative Removal ◽  
One Step ◽  
Synthetic Routes ◽  
Organophosphorus Chemistry

A new alkylation protocol for the synthesis of tertiary phosphonite­/phosphinite-boranes is developed. P-Alkylation products are obtained exclusively in moderate to very good yields from easily accessible (1-hydroxy-1-methylethyl)/(1-hydroxy-1-cyclohexyl) phosphonite/phosphinite-boranes upon reaction with a variety of electrophiles under mild conditions. The methodology opens up new synthetic routes for organophosphorus chemistry and offers access to valuable alkyl phosphonite/phosphinite-boranes. In contrast to previously reported oxidative removal–substitution sequences for the preparation of optically active phosphinite-boranes, our protocol provides a one-step procedure that occurs without loss of stereochemical information at phosphorus. This new approach provides a rather advantageous protocol when compared to direct alkylation methods (which may undergo P-epimerization) and occurs in a stereoselective manner even at 0 °C.

Isoxazolinium Salts in Asymmetric Synthesis. 1. Stereoselective Reduction Induced by a 3’-Alkoxy Stereocentre. A New Approach to Polyfunctionalized β-Amino Acids* [1, 2]

2004 ◽  
Vol 59 (4) ◽  
pp. 451-467 ◽  
Author(s):  
Marco Henneböhle ◽  
Pierre-Yves Le Roy ◽  
Matthias Hein ◽  
Rudolf Ehrler ◽  
Volker Jäger
Keyword(s):  
Amino Acids ◽  
Asymmetric Synthesis ◽  
Catalytic Hydrogenation ◽  
Optically Active ◽  
Side Chain ◽  
Reduction Step ◽  
One Pot ◽  
New Approach ◽  
Stereoselective Reduction

AbstractA new approach to optically active N-methylamino acids is presented, relying on stereoselective reduction of N-methylisoxazolinium salts with a dioxyethyl side-chain. The diastereoselectivity of the reduction step is studied systematically, in comparison with that of respective isoxazolines. A two-step transformation of isoxazolinium salts - with NaBH3(OAc) and subsequent catalytic hydrogenation as well as a one-pot reduction by catalytic hydrogenation led to high (95:5 and 87:13) diastereomeric ratios of protected erythro-N-methylaminopentanetriols. The hydroxyethyl side-chain is elaborated by oxidation to afford the β -N-methylamino acid 37, exemplifying the potential of this strategy.

New approach to the synthesis of optically active trityl systems

1969 ◽  
Vol 47 (21) ◽  
pp. 4073-4076 ◽  
Author(s):  
K. G. Rutherford ◽  
J. L. H. Batiste ◽  
J. M. Prokipcak
Keyword(s):  
Michael Reaction ◽  
Sodium Hydride ◽  
Optically Active ◽  
New Method ◽  
New Approach

A new method for the resolution of potentially optically active trityl alcohols is reported. Three trityl alcohols as pilot compounds were converted to hydracrylic acid derivatives. Esterification with diazo-methane was followed by degradation (reverse Michael reaction) to the original alcohols with sodium hydride. The resolution of phenyl-α-naphthyl-p-tolylcarbinol was effected conveniently by this route.

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