Some applications of the curtius rearrangement?

Pairs of optically pure enantiomers of substituted 1,1-diamines have been prepared from the azides of L-amino-acids via the Curtius rearrangement. This synthesis is based on the interchange of two groups attached to the asymmetrically substituted tetrahedral α-carbon atom of the parent amino acid. Such an interchange occurs without the intermediate formation of a racemate. In addition, some side reactions of isocyanates of N-benzyloxycarbonyl-L-amino acids in aqueous acidic solution have been elucidated

The use of diacetoxyphenyliodine for the direct oxidative conversion of S-protected L-cysteine compounds to L-cystine derivatives

Diacetoxyphenyliodine was used for the direct oxidative conversion of S-Trt, S-Dpm and S-Acm-L-cysteine derivatives to optically pure =L-cystine compounds. © 1984

The role of 2-hydroxypropanal in the biosynthesis of 2,5-dimethyl-4-hydroxy-2H-furan-3-one in strawberry (Fragaria x ananassa, cv. Elsanta) callus cultures

2-Hydroxypropanal was synthesized utilising a new approach via the Curtius rearrangement, which has the great advantage that the only co-product is ammonium chloride. 2-Hydroxypropanal was, without isolation, fed in situ to strawberry callus cultures in order to study the biosynthesis of 2,5-dimethyl-4-hydroxy-2H-furan-3-one. The high levels of the furanone obtained suggest that 2-hydroxy-propanal is a key precursor of 2,5-dimethyl-4-hydroxy-2H-furan-3-one in strawberry. Copyright (C) 1998 Elsevier Science Ltd

Selective deprotection of N-Boc-imidazoles and pyrazoles by NaBH4 in EtOH

Herein, a novel method for the selective N-Boc deprotection of imidazoles, benzimidazoles and pyrazoles in good to excellent yield (75-98%), using NaBH4 in EtOH at room temperature is reported. Under these conditions, the primary Boc-protected amines and a number of N-Boc-protected aromatic heterocycles such as pyrrole and indole remain completely intact. © AUTHOR (S)

Reduction of pentafluorophenyl esters to the corresponding primary alcohols using sodium borohydride

Primary alcohols and chiral N-protected 2-amino alcohols can be obtained in high yields from the reaction of pentafluorophenyl esters of the corresponding carboxylic acids with sodium borohydride in THF under mild conditions. This reductive method is rapid and compatible with various functional groups as well as with the most common N-protective groups Z, Boc and Fmoc. © 2007 Elsevier Ltd. All rights reserved

Synthesis of non-natural amino acids based on the ruthenium-catalysed oxidation of a phenyl group to carboxylic acid

An efficient method for the synthesis of enantiopure β-, β-, and δ-amino acids with proteinogenic side chains, starting from natural α-amino acids, was developed. The method is based on the ruthenium-catalyzed oxidation of a phenyl group to a carboxylic acid. β-Amino acids may be prepared starting from Boc-phenylalaninol. The route described for the synthesis of γ- and δ-amino acids permits the insertion of any chain length between the amino and carboxy functionalities as a result of the original choice of the starting ylide chain length. © Georg Thieme Verlag Stuttgart

Synthesis of tetrazole analogs of γ- and δ-amino acids

N-benzyloxycarbonyl-protected α- or β-amino alcohols, easily prepared from α- and β-amino acids, were converted into aldehydes and directly reacted with (triphenyl phosphoranylidene) acetonitrile, leading to unsaturated nitriles. Treatment of nitriles with NaN3 and ZnBr2 produced unsaturated γ- and δ-amino tetrazoles, which were deprotected and converted to the corresponding saturated compounds by catalytic hydrogenation. For the case of δ-amino tetrazole, the methylation of the acidic moiety occurred after treatment with CH2N2, leading to the N1- and N2-methylated constitutional isomers, which were separated by column chromatography and hydrogenated. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd

Autotaxin inhibitors: A patent review

Introduction: Autotaxin (ATX) is a lysophospholipase D enzyme that hydrolyzes lysophosphatidylcholine to lysophosphatidic acid (LPA) and choline. LPA is a bioactive lipid mediator that activates several transduction pathways, and is involved in migration, proliferation and survival of various cells. Thus, ATX is an attractive medicinal target. Areas covered: The aim of this review is to summarize ATX inhibitors, reported in patents from 2006 up to now, describing their discovery and biological evaluation. Expert opinion: ATX has been implicated in various pathological conditions, such as cancer, chronic inflammation, neuropathic pain, fibrotic diseases, etc. Although there is an intensive effort on the discovery of potent and selective ATX inhibitors in order to identify novel medicinal agents, up to now, no ATX inhibitor has reached clinical trials. However, the use of ATX inhibitors seems an attractive strategy for the development of novel medicinal agents, for example anticancer therapeutics. © 2013 Informa UK, Ltd