Terpenoid chemistry. XIII. Derivatives of optically pure (+)-citronellal

1966 ◽  
Vol 19 (3) ◽  
pp. 525 ◽  
Author(s):  
GW O'Donnell ◽  
MD Sutherland
Keyword(s):  
Optically Pure ◽  
Derivatives Of

Esters of arylpropionic acids with 1,2:5,6-di-O-isopropylidene- and 1,2-O-isopropylidene-α-D-glucofuranose

1987 ◽  
Vol 52 (3) ◽  
pp. 766-774 ◽  
Author(s):  
Jiří Svoboda ◽  
Karel Čapek ◽  
Jaroslav Paleček
Keyword(s):  
Fractional Crystallization ◽  
Kinetic Resolution ◽  
Methyl Esters ◽  
Optically Pure ◽  
Derivatives Of

On fractional crystallization of 3-O-(2-(2-fluoro-4-biphenylyl)propionyl)-, 3-O-(2-(4-isobutylphenyl)propionyl)- and 3-O-(2-(6-methoxy-2-naphthyl)propionyl)-1,2 :5,6-di-O-isopropylidene-α-D-glucofuranoses V-VII optically pure R-diastereoisomers were isolated. The derivatives of 1,2-O-isopropylidene-α-D-glucofuranose obtained on partial deacetylation of esters V-VII were separated chromatographically to R and S-diastereoisomers. Their hydrolysis or transesterification afforded optically pure arylpropionic acids or their methyl esters, respectively. Kinetic resolution of the acids gives rise to esters V-VII enriched in R-diastereoisomer.

Synthesis of Optically Active N6-Alkyl Derivatives of (R)-3-(Adenin-9-yl)-2-hydroxypropanoic Acid and Related Compounds

2003 ◽  
Vol 68 (5) ◽  
pp. 931-950 ◽  
Author(s):  
Marcela Krečmerová ◽  
Miloš Buděšínský ◽  
Milena Masojídková ◽  
Antonín Holý
Keyword(s):  
Nmr Spectra ◽  
Enantiomeric Purity ◽  
Optically Active ◽  
Secondary Amines ◽  
H Nmr ◽  
Alkyl Derivatives ◽  
Optically Pure ◽  
Derivatives Of ◽  
Related Compounds

Reaction of ethyl (R)-oxiranecarboxylate (2a) with various nucleobases (adenine, 6-chloropurine, thymine, cytosine, N6-benzoyladenine, 4-methoxy-5-methylpyrimidin-2(1H)-one and 4-methoxypyrimidin-2(1H)-one) afforded ethyl 3-substituted-2-hydroxypropanoates 4-10. Enantioselectivity of this reaction is dependent on the type of the base: 6-chloropurine, N6-benzoyladenine, 4-methoxy-5-methylpyrimidin-2(1H)-one, thymine and cytosine gave optically pure R enantiomers. In other cases, partial or complete racemization occurred. Optically pure ethyl (R)-3-(6-chloropurin-9-yl)-2-hydroxypropanoate (5a) was hydrolyzed to give (R)-3-(6-chloropurin-9-yl)-2-hydroxypropanoic acid (11). Reactions of 11 with various primary or secondary amines led to N6-substituted (R)-3-(adenin-9-yl)-2-hydroxypropanoic acids 14-19. Enantiomeric purity was determined from 1H NMR spectra measured in the presence of (-)-(R)-1-(9-anthryl)-2,2,2-trifluoroethan-1-ol.

scholarly journals Preparation of Sterically Demanding 2,2-Disubstituted-2-Hydroxy Acids by Enzymatic Hydrolysis

Catalysts ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 113 ◽  
Author(s):  
Andrea Pinto ◽  
Immacolata Serra ◽  
Diego Romano ◽  
Martina Contente ◽  
Francesco Molinari ◽  
...  
Keyword(s):  
Enzymatic Hydrolysis ◽  
Phenylacetic Acid ◽  
General Structure ◽  
Hydroxy Acids ◽  
Pig Liver Esterase ◽  
Liver Esterase ◽  
Sterically Demanding ◽  
Optically Pure ◽  
Hydrolysis Of ◽  
Derivatives Of

Preparation of optically-pure derivatives of 2-hydroxy-2-(3-hydroxyphenyl)-2-phenylacetic acid of general structure 2 was accomplished by enzymatic hydrolysis of the correspondent esters. A screening with commercial hydrolases using the methyl ester of 2-hydroxy-2-(3-hydroxyphenyl)-2-phenylacetic acid (1a) showed that crude pig liver esterase (PLE) was the only preparation with catalytic activity. Low enantioselectivity was observed with substrates 1a–d, whereas PLE-catalysed hydrolysis of 1e proceeded with good enantioselectivity (E = 28), after optimization. Enhancement of the enantioselectivity was obtained by chemical re-esterification of enantiomerically enriched 2e, followed by sequential enzymatic hydrolysis with PLE. The preparation of optically-pure (S)-2e was validated on multi-milligram scale.

Dimedone (5,5-Dimethylcyclohexane-1,3-dione) as a protecting agent for amino groups in peptide synthesis

1964 ◽  
Vol 17 (11) ◽  
pp. 1282 ◽  
Author(s):  
B Halpern ◽  
LB James
Keyword(s):  
Amino Acid ◽  
Peptide Synthesis ◽  
Amino Acid Esters ◽  
Protecting Group ◽  
Amino Groups ◽  
Active Esters ◽  
Optically Pure ◽  
Derivatives Of ◽  
Protected Peptides ◽  
Acid Esters

The reaction of dimedone (5,5-dimethylcyclohexane-1,3-dione) with amino-acid "active" esters leads to optically pure enamine derivatives. The dimedone derivatives of amino acid esters could also be converted by way of their hydrazides to the corresponding azides. The thiophenyl ester and azide derivatives have been used directly for peptide synthesis. The protecting group can easily be removed from the N-protected peptides by means of aqueous bromine, with the formation of 2,2-dibromodimedone and the hydrobromide of the corresponding peptide ester.

An improved method for the synthesis of optically pure epoxide and alcohol derivatives of chiral bromohydrins

1981 ◽  
Vol 22 (34) ◽  
pp. 3277-3280 ◽  
Author(s):  
Suresh K. Balani ◽  
Derek R. Boyd ◽  
E.Sally Cassidy ◽  
Ruth M.E. Greene ◽  
Kenneth M. McCombe ◽  
...  
Keyword(s):  
Improved Method ◽  
Optically Pure ◽  
Derivatives Of
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