A simple approach to several derivatives of pipecolic acid is via a multicomponent reaction starting from cyclic imines 2, which are synthesized on a large scale and with different substitution patterns. The protected amino acids 3 are formed in high yields. In cases where chiral imines are used the target compounds are obtained with remarkable diastereoselectivity. Bisamides 3 serve as versatile precursors for the preparation of a wide range of amino acid derivatives. Different methods of hydrolysis of 3 lead to the free pipecolic acids or its derivatives. Employment of methanol or ethanethiol as a nucleophile in the acid-mediated conversion of enamides 3 results in N-acylated amino acid esters 5. Furthermore a method for the resolution of the obtained racemic α-amino acids via diastereomeric salt formation is described.
Two-step syntheses of fused quinoxaline-benzodiazepines and bis-benzodiazepines
作者:Zhigang Xu、Justin Dietrich、Arthur Y. Shaw、Christopher Hulme
DOI:10.1016/j.tetlet.2010.06.116
日期:2010.8
A two-step solution phase synthesis employing a double UDC (Ugi/Deprotect/Cyclize) strategy has been utilized to obtain fused 6,7,6,6-quinoxalinone-benzodiazepines and 6,7,7,6-bis-benzodiazepines. Optimization of the methodology to produce these tetracyclic scaffolds was enabled by microwave irradiation, incorporation of trifluoroethanol as solvent, and the use of the convertible isocyanide, 4-tert-butyl
The synthesis of PNA-monomers with variations in the substitution pattern using the Ugi-Reaction is described. The one-pot procedure leads to new totally protected PNA-monomers which can be selectively cleaved to N-protected monomeric building blocks for PNA synthesis.
Hydrazine-mediated cyclization of Ugi products to synthesize novel 3-hydroxypyrazoles
作者:Arthur Y. Shaw、Jonathan A. McLaren、Gary S. Nichol、Christopher Hulme
DOI:10.1016/j.tetlet.2012.03.033
日期:2012.5
This report discloses a novel concise synthesis of a series of 3-hydroxypyrazoles 5 via a tandem Ugi/debenzylation /hydrazine-mediated cyclization sequence. Herein, n-butyl isocyanide 4b was utilized as an alternative to classical convertible isocyanides enabling high yielding hydrazine-mediated cyclization. Taken together, a novel class of 3-hydroxypyrazoles 5a-5i was synthesized with a potential to be of interest in future library enrichment strategies. (C) 2012 Elsevier Ltd. All rights reserved.
[EN] PRECUSORS FOR PNA-MONOMERS<br/>[FR] PRECURSEUR POUR MONOMERES DE PNA
申请人:MARTENS JUERGEN
公开号:WO2000002864A1
公开(公告)日:2000-01-20
The invention is directed to compounds of formula (I) wherein A, B, D, E, X and Y are defined in the description. These compounds are useful precursors for the synthesis of monomers for Peptide Nucleic Acids (PNA).