Hunig’s base

Meth-Cohn has developed an efficient one-pot synthesis of isatins 108 by the sequential treatment of iV-substituted formanilides 107 with oxalyl chloride, Hunig s base, and bromine... 

The reaction of 73 with 2-aminotetrazole hydrate gave different products depending on the reaction conditions. Under the conditions applied for the preparation of 74 4-oxo-3-phenylpyrido[2,1 -/] [ 1,2,4]triazinium-2-olate 75 was obtained, whereas the amino derivative 76 was obtained by using diisopropylethylamine (Hunig s base) as the base (Scheme 1) <1996T11349>. 

BOC- o/woPhe, CH2-(4-Pr C6H4), CH2-(4-ClC6H4), Hunig s base 1999BML2359... 

As a result, diastereo- and enantiomerically pure functionalized nitro derivative (205) was synthesized in satisfactory yield. This compound was used in the ISOC procedure, which gave diastereo- and enantiomerically pure isoxazolidine (206) in good yield. The latter compound can be considered as a possible reagent for asymmetric synthesis. It should be noted that silylation in this procedure, like that described above (Scheme 3.145), was performed with the use of BSA as the silylating agent in the presence of a small amount of Hunig s base, the latter being evidently added for acceleration of silylation and stabilization of intermediate silyl nitronate. 

Hunig s Base, 2 549t Hunter Color Spaces, 7 321 Hunter-Nash procedure, 10 757 Huntsman fixed-bed maleic anhydride process, 15 501... 

During an investigation of the synthesis of oxazole-4-carboxylates, Shapiro reported that chlorination of amino[(phenylthio)methyl]malonate derivatives 91 with A -chlorosuccinimide (NCS), followed by treatment with Hunig s base, afforded the oxazolines 93. The oxazolines 93 were then converted to the respective oxazole-4-carboxylates 94-97 through decarbomethoxylation and elimination of thiophenoxide in the presence of methyl iodide. Methyl iodide traps the ejected thiophenoxide that would otherwise demethylate the oxazole-4-carboxylate (Scheme 8.31). " ... 

Proof of concept for this route was established by activating acid 9 with N,N -carbonyldi-imidazole (CDl) and treating it with Meldrum s acid to afford adduct 24 (Scheme 5.14). Despite its relatively high instability, adduct 24 was isolated by crystallization after aqueous work-up. Isolated 24 was easily converted to 25 in moderate yield by treatment with triazole salt 3 and Hunig s base. Because of the limited stability of intermediate 24 and in order to maximize the efficiency of the... 

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