Relationship between the Cyclization and Conformation of Pentapeptide Active Esters Related to Gramicidin S Having No Protecting Group on the Side Chain of the Ornithine Residue

1997 ◽  
Vol 70 (4) ◽  
pp. 899-904 ◽  
Author(s):  
Makoto Tamaki ◽  
Seiji Komiya ◽  
Sadatoshi Akabori ◽  
Ichiro Muramatsu
Keyword(s):  
Side Chain ◽  
Protecting Group ◽  
Active Esters ◽  
Gramicidin S

scholarly journals Practical synthesis of 4-aryl- and 4-heteroarylazetidin-2-ones: applications in the synthesis of the Taxol® side chain

1994 ◽  
Vol 72 (10) ◽  
pp. 2131-2136 ◽  
Author(s):  
Allan W. Rey ◽  
Robert Droghini ◽  
James L. Douglas ◽  
Purushotham Vemishetti ◽  
Susan D. Boettger ◽  
...  
Keyword(s):  
Side Chain ◽  
Staudinger Reaction ◽  
Protecting Group ◽  
Practical Synthesis

A convenient, high-yielding procedure has been developed for the kilogram-scale synthesis of (±)-cis-3-acetoxy-4-phenylazetidin-2-one (3), a β-lactam that has been used in the semi-synthesis of Taxol®. The Staudinger reaction between hydrobenzamide (5) and acetoxyacetyl chloride in the presence of a base provided the α-benzylideneiminotoluene protected β-lactam 8. Without isolation of the intermediate β-lactam, the protecting group was removed under various reductive or hydrolytic conditions. The overall yields were about 80%. The synthesis of other (±)-cis-4-aryl- and 4-heteroarylazetidin-2-ones by this methodology has also been accomplished. These compounds are of value for the synthesis of 3′-Taxol® side-chain analogs and their preparation demonstrates the generality of this approach.

Cyclopropyldimethylcarbinyl: A new acid-labile side-chain protecting group for asparagine and glutamine

Peptides 1994 ◽  
1995 ◽  
pp. 155-156
Author(s):  
L. A. Carpino ◽  
H. N. Shroff ◽  
H.-G. Chao ◽  
E. M. E. Mansour ◽  
F. Albericio
Keyword(s):  
Side Chain ◽  
Protecting Group ◽  
Acid Labile

scholarly journals GlucoSiFA and LactoSiFA: New Types of Carbohydrate-Tagged Silicon-Based Fluoride Acceptors for 18F-Positron Emission Tomography (PET)

Synthesis ◽  
2019 ◽  
Vol 51 (05) ◽  
pp. 1196-1206
Author(s):  
Anja Wiegand ◽  
Vera Wiese ◽  
Britta Glowacki ◽  
Ljuba Iovkova ◽  
Ralf Schirrmacher ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Emission Tomography ◽  
Side Chain ◽  
Protecting Group ◽  
Positron Emission ◽  
Silicon Based

GlucoSiFA derivatives bearing an azide or alkynyl side chain were obtained from peracetyl-d-glucose using as key step a tosylate substitution by a SiFA thiolate obtained from 4-(di-tert-butylfluorsilyl)benzenethiol. In analogy, two-fold SiFA-substituted maltose and lactose derivatives were synthesized via bistosylates. Introduction of an ­acetal-protecting group in β-d-azidolactose allowed the synthesis of a LactoSiFA derivative bearing only one SiFA moiety.

Synthesis of the major encephalitogenic determinant of myelin basic protein and the 13C N.M.R. of some protected intermediates

1977 ◽  
Vol 30 (11) ◽  
pp. 2533 ◽  
Author(s):  
SJ Pasaribu
Keyword(s):  
Myelin Basic Protein ◽  
Catalytic Hydrogenation ◽  
Basic Protein ◽  
Side Chain ◽  
Benzyl Ether ◽  
Protecting Group ◽  
Fragment Condensation

The main encephalitogenic determinant of bovine myelin basic protein (MBP 114-122) has been synthesized through fragment condensation of tetrapeptide, Boc-Phe-Ser-Trp-Gly-OH, and penta-peptide, H-Ala- Glu(OBzl)-Gly-Gln-Lys(Nε-Cbz)-Obzl. It was observed that the benzyl ether protecting group of the serine side chain was not removed during catalytic hydrogenation (Pd/C-H2) of the tetrapeptide, Boc-Phe- Ser(OBzl)-Trp-Gly-OBzl. 13C N.M.R. spectra of some other intermediates are discussed.

Derivatives of 5α-androstan-3α- and 3β-ol with acrylate side chain

1990 ◽  
Vol 55 (5) ◽  
pp. 1243-1256 ◽  
Author(s):  
Vladimír Pouzar ◽  
Hana Chodounská ◽  
Dalibor Sameš ◽  
Pavel Drašar ◽  
Miroslav Havel
Keyword(s):  
Ethyl Esters ◽  
Side Chain ◽  
Protecting Group ◽  
Derivatives Of

Hydroxy derivatives I, II, III, XVII and XX were oxidized to give the respective aldehydes IV, V, VI, XVIII and XXI which were further converted by Wittig-Horner reaction into unsaturated methyl and ethyl esters. Removal of the acetal protecting group in position 3 afforded methylesters X, XXIV and XXXVI and ethyl esters XIV, XXV and XXXVII. Compounds XXIV, XXV, XXXVI and XXXVII were converted into the corresponding hemisuccinates XXVIII, XXIX, XL and XLI and β-D-glucosides XXXII, XXXIII, XLIV and XLV.

scholarly journals Revisiting NO2 as Protecting Group of Arginine in Solid-Phase Peptide Synthesis

2020 ◽  
Vol 21 (12) ◽  
pp. 4464
Author(s):  
Mahama Alhassan ◽  
Ashish Kumar ◽  
John Lopez ◽  
Fernando Albericio ◽  
Beatriz G. de la Torre
Keyword(s):  
Peptide Synthesis ◽  
Solid Phase ◽  
Solid Phase Peptide Synthesis ◽  
Side Reaction ◽  
Reducing Agent ◽  
Protecting Groups ◽  
Side Chain ◽  
Protecting Group ◽  
Mild Acid

The protection of side-chain arginine in solid-phase peptide synthesis requires attention since current protecting groups have several drawbacks. Herein, the NO2 group, which is scarcely used, has been revisited. This work shows that it prevents the formation of δ-lactam, the most severe side-reaction during the incorporation of Arg. Moreover, it is stable in solution for long periods and can be removed in an easy-to-understand manner. Thus, this protecting group can be removed while the protected peptide is still anchored to the resin, with SnCl2 as reducing agent in mild acid conditions using 2-MeTHF as solvent at 55 °C. Furthermore, we demonstrate that sonochemistry can facilitate the removal of NO2 from multiple Arg-containing peptides.

scholarly journals Diastereoselective Pictet–Spengler Reactions of a Tethered 2-Aminoimidazole

2014 ◽  
Vol 67 (2) ◽  
pp. 184 ◽  
Author(s):  
Sudhir R. Shengule ◽  
Peter Karuso
Keyword(s):  
Amino Acid ◽  
Molecular Modelling ◽  
Lewis Acids ◽  
Side Chain ◽  
Amino Acid Side Chain ◽  
Protecting Group ◽  
Nmr Data ◽  
The Absolute ◽  
Absolute Stereochemistry

The diastereoselective Pictet–Spengler reaction of aminopropyl-2-aminoimidazole with enantiopure aldehydes has been investigated. With amino acid-derived aldehydes, anti stereochemistry is favoured, with a diastereoselectivity up to 92 % achievable. The absolute stereochemistry of the products was determined through synthesis of a rigid derivative and from NMR data in combination with molecular modelling. The diastereoselectivity was shown to be dependent on the steric bulk of the amino acid side chain and independent of the nitrogen protecting group. Lewis acids catalysed the reaction but did not affect the diastereoselectivity.

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