Synthesis of functionalized imidazolidine-2-thiones via NHC/base-promoted aza-benzoin/aza-acetalization domino reactions
作者:Graziano Di Carmine、Daniele Ragno、Carmela De Risi、Olga Bortolini、Pier Paolo Giovannini、Giancarlo Fantin、Alessandro Massi
DOI:10.1039/c7ob02259j
日期:——
A strategy for the synthesis of biologically relevant 5-hydroxy-imidazolidine-2-thione derivatives is presented. A novel class of α-sulfonylamines have been suitably prepared (46–81% yield) as precursors of formal benzylidenethiourea acceptors; these are generated in situ and intercepted by N-heterocyclic carbene (NHC)-activated aldehydes affording open-chain aza-benzoin-type adducts, which in turn
Concise Synthesis of 1<i>H</i>-Pyrazin-2-ones and 2-Aminopyrazines
作者:Peter Meier、Isabelle Adam、David Orain
DOI:10.1055/s-2004-830866
日期:——
Convenient syntheses of 1H-pyrazin-2-ones and 2-aminopyrazines are described. By coupling Boc-protected amino acids with α-amino ketones or with amino alcohols and subsequent oxidation, 1H-pyrazin-2-ones were obtained. Transformation into the corresponding pyrazine triflates and substitution with primary or secondary amines led to 2-aminopyrazines. Since these syntheses take advantage of the use of readily available starting materials (e.g., amino acids, aminoalcohols and amines) a variety of the entitled structures can be obtained in few, high yielding steps.
Antimitotic agents. Alterations at the 2,3-positions of ethyl (5-amino-1,2-dihydropyrido[3,4-b]pyrazin-7-yl)carbamates
作者:Carroll Temple、Gregory A. Rener、Robert N. Comber、William R. Waud
DOI:10.1021/jm00115a005
日期:1991.11
with alpha-amino ketone oximes gave 4-[(2-oxoethyl)amino]pyridine oximes 3, which were reductively cyclized to give a series of ethyl (1,2-dihydro-pyrido[3,4-b]pyrazin-7-yl)carbamates (6). In another approach, alpha-nitro ketones, alpha-oximino ketones, and alpha-nitro alcohols were reduced to give alpha-amino alcohols, which were reacted with 2 to give 4-[(2-hydroxyethyl)amino]pyridines (5). Oxidation