Heterocycles potassium tert-butoxide

In 2002, Leadbeater and Torenius reported the base-catalyzed Michael addition of methyl acrylate to imidazole using ionic liquid-doped toluene as a reaction medium (Scheme 6.133 a) [190], A 75% product yield was obtained after 5 min of microwave irradiation at 200 °C employing equimolar amounts of Michael acceptor/donor and triethylamine base. As for the Diels-Alder reaction studied by the same group (see Scheme 6.91), l-(2-propyl)-3-methylimidazolium hexafluorophosphate (pmimPF6) was the ionic liquid utilized (see Table 4.3). Related microwave-promoted Michael additions studied by Jennings and coworkers involving indoles as heterocyclic amines are shown in Schemes 6.133 b [230] and 6.133 c [268], Here, either lithium bis(trimethylsilyl)amide (LiHMDS) or potassium tert-butoxide (KOtBu) was em-... 

Guida WC, Mathre D1 (1980) Phase-transfer alkylaHon of heterocycles in the presence of 18-crown-6 and potassium tert-butoxide. 1 Org Chem 45 3172-3176... 

Guido, W, and Mathre, D. J., Phase-transfer alkylation of heterocycles in the presence of 18-crown-6 and potassium tert-butoxide, J. Org. Chem., 45, 3172, 1980. Mariani, G., Modena, G., Pizzo, G. E, and Scorrano, G., The effect of crown-ethers on the reactivity of alkoxides. Part 2. The reaction of potassium isopropoxide and 2,4-dinitrohalogenobutanes in propan-2-ol-benzene, J. Chem. Soc., Perkin Trans. 2, 1187, 1979. 

A -Arylation. Tii-tert-butylphosphonium tetrafluoroborate is frequently used as a ligand in the iV-arylation reaction of heterocycles containing N-H bonds. The transformation is usually catalyzed by palladium conqilexes and performed in the presence of an organic base such as sodium or potassium tert-butoxide. High temperatures and long reaction times are often required to reach good conversions. Aryl halides are the most frequent electrophiles for this type of arylation. 

Treatment of 7-chloroamine 363 with potassium /i t/-butoxide in refluxing THE gave rise to a mixture of (Z-tert-butyl)-5,5-dimethyl-5,6-dihydro-4f/-l,3-oxazine 366 and 1-pivaloylazetidine 367 (Scheme 67). The heterocycles 366 and 367 were formed through generation of the Favorskii intermediate 364 by dehydrocyanation, which was followed by opening of the cyclopropylideneamine by /r-rt-butoxide with the subsequent loss of isobutene and a subsequent intramolecular N-alkylation or O-alkylation of the amide anion 365 <1999EJ0239>. 

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