Hartwig

K. T. Hartwig, "An Eddy-Current Decay Technique for Low Temperature Resistivity Measurements," in G. Birnbaum and G. Eree, eds.,ASTM STP 722, American Society for Testing and Materials, Philadelphia, Pa., 1981, pp. 157—172. 

Hirst, W. J. S., and J. A. Eyre. 1983. Maplin Sands experiments 1980 Combustion of large LNG and refrigerated liquid propane spills on the sea. Heavy Gas and Risk Assessment II. Ed. by S. Hartwig. pp. 211-224. Boston D. Reidel. 

To understand the unpredictable nature of the Pictet-Gams reaction, Hartwig and Whaley conducted the first mechanistic studies in 1949. Their work focused on substituent effects when directly attached to the ethylamine side chain. They also investigated a variety of dehydration agents in order to identify optimal reaction conditions. It was determined that formation of the isoquinoline structure was virtually impossible when alkyl or phenyl substituents were placed in the 4-position of the ethylamine side chain. 

Hartwig and Whaley suggested that when substituents are placed in the 4-position of the ethylamine side chain, an oxazoline intermediate (7) is formed a side reaction that was first mentioned by Krabbe in 1940. However, Hartwig and Whaley did not isolate the putative intermediate. 

Hartwig and Whaley also demonstrated that increasing the size of the alkyl side chain off the 3-position, resulted in low yields of expected product. In fact, when Ri is larger than a propyl group, the expected products were not isolated (n-butyl gave a 1% of the corresponding isoquinoline ). Furthermore, isoquinolines were formed more... 

Prof. Dr. Hartwig Hocker, Deutsches Wollforschungs-Institut e. V. an der Technischen Hochschule Aachen, Veltmanplatz 8, W 5100 Aachen, FRG Prof. Hans-Henning Kausch, Laboratoire de Polymeres, Ecole Polytechnique Federale de Lausanne, 32, ch. de Bellerive, 1007 Lausanne, Switzerland... 

Nicolaou KC, Hanko R, Hartwig W (eds) (2002) Handbook of combinatorial chemistry, vol 2. Wiley, Weinheim... 

Carbon-carbon bond formation reactions and the CH activation of methane are another example where NHC complexes have been used successfully in catalytic applications. Palladium-catalysed reactions include Heck-type reactions, especially the Mizoroki-Heck reaction itself [171-175], and various cross-coupling reactions [176-182]. They have also been found useful for related reactions like the Sonogashira coupling [183-185] or the Buchwald-Hartwig amination [186-189]. The reactions are similar concerning the first step of the catalytic cycle, the oxidative addition of aryl halides to palladium(O) species. This is facilitated by electron-donating substituents and therefore the development of highly active catalysts has focussed on NHC complexes. 

Palladium-catalyzed aminations of aryl halides is now a well-documented process [86-88], Heo et al. showed that amino-substituted 2-pyridones 54 and 55 can be prepared in a two-step procedure via a microwave-assisted Buchwald-Hartwig amination reaction of 5- or 6-bromo-2-benzyloxypyri-dines 50 and 51 followed by a hydrogenolysis of the benzyl ether 52 and 53, as outlined in Fig. 9 [89]. The actual microwave-assisted Buchwald-Hartwig coupling was not performed directly at the 2-pyridone scaffold, but instead at the intermediate pyridine. Initially, the reaction was performed at 150 °C for 10 min with Pd2(dba)3 as the palladium source, which provided both the desired amino-pyridines (65% yield) as well as the debrominated pyridine. After improving the conditions, the best temperature and time to use proved... 

Fig. 9 Examples of Buchwald-Hartwig amination of bromo-pyridines and subsequent hydrogenolysis leading to amino-substituted 2-pyridones...

Independently, Antane reported that arylisonipecotic acids were obtained from aryl bromides in a two-step process involving microwave-assisted palladium-catalyzed amination with ethyl isonipecotate followed by ester hydrolysis with KOH (Scheme 91) [96]. Interestingly, toluene, which is the standard solvent for Buchwald-Hartwig aminations under conventional heating, was used as the sole reaction medium, although it is a very weak... 

AT-Arylquinolin-2(lff)-ones have been prepared in a four step process from commercially available coumarins, utilizing a Buchwald-Hartwig ami-... 

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